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-rw-r--r--arch/arm64/net/Makefile1
-rw-r--r--arch/arm64/net/bpf_jit.h116
-rw-r--r--arch/arm64/net/bpf_jit_comp.c1759
3 files changed, 1625 insertions, 251 deletions
diff --git a/arch/arm64/net/Makefile b/arch/arm64/net/Makefile
index da9763378284..5c540efb7d9b 100644
--- a/arch/arm64/net/Makefile
+++ b/arch/arm64/net/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
#
# ARM64 networking code
#
diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h
index 783de51a6c4e..a6acb94ea3d6 100644
--- a/arch/arm64/net/bpf_jit.h
+++ b/arch/arm64/net/bpf_jit.h
@@ -1,19 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
/*
* BPF JIT compiler for ARM64
*
* Copyright (C) 2014-2016 Zi Shen Lim <zlim.lnx@gmail.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _BPF_JIT_H
#define _BPF_JIT_H
@@ -77,6 +66,26 @@
#define A64_STR64(Xt, Xn, Xm) A64_LS_REG(Xt, Xn, Xm, 64, STORE)
#define A64_LDR64(Xt, Xn, Xm) A64_LS_REG(Xt, Xn, Xm, 64, LOAD)
+/* Load/store register (immediate offset) */
+#define A64_LS_IMM(Rt, Rn, imm, size, type) \
+ aarch64_insn_gen_load_store_imm(Rt, Rn, imm, \
+ AARCH64_INSN_SIZE_##size, \
+ AARCH64_INSN_LDST_##type##_IMM_OFFSET)
+#define A64_STRBI(Wt, Xn, imm) A64_LS_IMM(Wt, Xn, imm, 8, STORE)
+#define A64_LDRBI(Wt, Xn, imm) A64_LS_IMM(Wt, Xn, imm, 8, LOAD)
+#define A64_STRHI(Wt, Xn, imm) A64_LS_IMM(Wt, Xn, imm, 16, STORE)
+#define A64_LDRHI(Wt, Xn, imm) A64_LS_IMM(Wt, Xn, imm, 16, LOAD)
+#define A64_STR32I(Wt, Xn, imm) A64_LS_IMM(Wt, Xn, imm, 32, STORE)
+#define A64_LDR32I(Wt, Xn, imm) A64_LS_IMM(Wt, Xn, imm, 32, LOAD)
+#define A64_STR64I(Xt, Xn, imm) A64_LS_IMM(Xt, Xn, imm, 64, STORE)
+#define A64_LDR64I(Xt, Xn, imm) A64_LS_IMM(Xt, Xn, imm, 64, LOAD)
+
+/* LDR (literal) */
+#define A64_LDR32LIT(Wt, offset) \
+ aarch64_insn_gen_load_literal(0, offset, Wt, false)
+#define A64_LDR64LIT(Xt, offset) \
+ aarch64_insn_gen_load_literal(0, offset, Xt, true)
+
/* Load/store register pair */
#define A64_LS_PAIR(Rt, Rt2, Rn, offset, ls, type) \
aarch64_insn_gen_load_store_pair(Rt, Rt2, Rn, offset, \
@@ -99,12 +108,42 @@
/* [Rn] = Rt; (atomic) Rs = [state] */
#define A64_STXR(sf, Rt, Rn, Rs) \
A64_LSX(sf, Rt, Rn, Rs, STORE_EX)
+/* [Rn] = Rt (store release); (atomic) Rs = [state] */
+#define A64_STLXR(sf, Rt, Rn, Rs) \
+ aarch64_insn_gen_load_store_ex(Rt, Rn, Rs, A64_SIZE(sf), \
+ AARCH64_INSN_LDST_STORE_REL_EX)
-/* Prefetch */
-#define A64_PRFM(Rn, type, target, policy) \
- aarch64_insn_gen_prefetch(Rn, AARCH64_INSN_PRFM_TYPE_##type, \
- AARCH64_INSN_PRFM_TARGET_##target, \
- AARCH64_INSN_PRFM_POLICY_##policy)
+/*
+ * LSE atomics
+ *
+ * ST{ADD,CLR,SET,EOR} is simply encoded as an alias for
+ * LDD{ADD,CLR,SET,EOR} with XZR as the destination register.
+ */
+#define A64_ST_OP(sf, Rn, Rs, op) \
+ aarch64_insn_gen_atomic_ld_op(A64_ZR, Rn, Rs, \
+ A64_SIZE(sf), AARCH64_INSN_MEM_ATOMIC_##op, \
+ AARCH64_INSN_MEM_ORDER_NONE)
+/* [Rn] <op>= Rs */
+#define A64_STADD(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, ADD)
+#define A64_STCLR(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, CLR)
+#define A64_STEOR(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, EOR)
+#define A64_STSET(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, SET)
+
+#define A64_LD_OP_AL(sf, Rt, Rn, Rs, op) \
+ aarch64_insn_gen_atomic_ld_op(Rt, Rn, Rs, \
+ A64_SIZE(sf), AARCH64_INSN_MEM_ATOMIC_##op, \
+ AARCH64_INSN_MEM_ORDER_ACQREL)
+/* Rt = [Rn] (load acquire); [Rn] <op>= Rs (store release) */
+#define A64_LDADDAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, ADD)
+#define A64_LDCLRAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, CLR)
+#define A64_LDEORAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, EOR)
+#define A64_LDSETAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, SET)
+/* Rt = [Rn] (load acquire); [Rn] = Rs (store release) */
+#define A64_SWPAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, SWP)
+/* Rs = CAS(Rn, Rs, Rt) (load acquire & store release) */
+#define A64_CASAL(sf, Rt, Rn, Rs) \
+ aarch64_insn_gen_cas(Rt, Rn, Rs, A64_SIZE(sf), \
+ AARCH64_INSN_MEM_ORDER_ACQREL)
/* Add/subtract (immediate) */
#define A64_ADDSUB_IMM(sf, Rd, Rn, imm12, type) \
@@ -113,6 +152,14 @@
/* Rd = Rn OP imm12 */
#define A64_ADD_I(sf, Rd, Rn, imm12) A64_ADDSUB_IMM(sf, Rd, Rn, imm12, ADD)
#define A64_SUB_I(sf, Rd, Rn, imm12) A64_ADDSUB_IMM(sf, Rd, Rn, imm12, SUB)
+#define A64_ADDS_I(sf, Rd, Rn, imm12) \
+ A64_ADDSUB_IMM(sf, Rd, Rn, imm12, ADD_SETFLAGS)
+#define A64_SUBS_I(sf, Rd, Rn, imm12) \
+ A64_ADDSUB_IMM(sf, Rd, Rn, imm12, SUB_SETFLAGS)
+/* Rn + imm12; set condition flags */
+#define A64_CMN_I(sf, Rn, imm12) A64_ADDS_I(sf, A64_ZR, Rn, imm12)
+/* Rn - imm12; set condition flags */
+#define A64_CMP_I(sf, Rn, imm12) A64_SUBS_I(sf, A64_ZR, Rn, imm12)
/* Rd = Rn */
#define A64_MOV(sf, Rd, Rn) A64_ADD_I(sf, Rd, Rn, 0)
@@ -184,6 +231,9 @@
/* Rd = Ra + Rn * Rm */
#define A64_MADD(sf, Rd, Ra, Rn, Rm) aarch64_insn_gen_data3(Rd, Ra, Rn, Rm, \
A64_VARIANT(sf), AARCH64_INSN_DATA3_MADD)
+/* Rd = Ra - Rn * Rm */
+#define A64_MSUB(sf, Rd, Ra, Rn, Rm) aarch64_insn_gen_data3(Rd, Ra, Rn, Rm, \
+ A64_VARIANT(sf), AARCH64_INSN_DATA3_MSUB)
/* Rd = Rn * Rm */
#define A64_MUL(sf, Rd, Rn, Rm) A64_MADD(sf, Rd, A64_ZR, Rn, Rm)
@@ -198,5 +248,37 @@
#define A64_ANDS(sf, Rd, Rn, Rm) A64_LOGIC_SREG(sf, Rd, Rn, Rm, AND_SETFLAGS)
/* Rn & Rm; set condition flags */
#define A64_TST(sf, Rn, Rm) A64_ANDS(sf, A64_ZR, Rn, Rm)
+/* Rd = ~Rm (alias of ORN with A64_ZR as Rn) */
+#define A64_MVN(sf, Rd, Rm) \
+ A64_LOGIC_SREG(sf, Rd, A64_ZR, Rm, ORN)
+
+/* Logical (immediate) */
+#define A64_LOGIC_IMM(sf, Rd, Rn, imm, type) ({ \
+ u64 imm64 = (sf) ? (u64)imm : (u64)(u32)imm; \
+ aarch64_insn_gen_logical_immediate(AARCH64_INSN_LOGIC_##type, \
+ A64_VARIANT(sf), Rn, Rd, imm64); \
+})
+/* Rd = Rn OP imm */
+#define A64_AND_I(sf, Rd, Rn, imm) A64_LOGIC_IMM(sf, Rd, Rn, imm, AND)
+#define A64_ORR_I(sf, Rd, Rn, imm) A64_LOGIC_IMM(sf, Rd, Rn, imm, ORR)
+#define A64_EOR_I(sf, Rd, Rn, imm) A64_LOGIC_IMM(sf, Rd, Rn, imm, EOR)
+#define A64_ANDS_I(sf, Rd, Rn, imm) A64_LOGIC_IMM(sf, Rd, Rn, imm, AND_SETFLAGS)
+/* Rn & imm; set condition flags */
+#define A64_TST_I(sf, Rn, imm) A64_ANDS_I(sf, A64_ZR, Rn, imm)
+
+/* HINTs */
+#define A64_HINT(x) aarch64_insn_gen_hint(x)
+
+#define A64_PACIASP A64_HINT(AARCH64_INSN_HINT_PACIASP)
+#define A64_AUTIASP A64_HINT(AARCH64_INSN_HINT_AUTIASP)
+
+/* BTI */
+#define A64_BTI_C A64_HINT(AARCH64_INSN_HINT_BTIC)
+#define A64_BTI_J A64_HINT(AARCH64_INSN_HINT_BTIJ)
+#define A64_BTI_JC A64_HINT(AARCH64_INSN_HINT_BTIJC)
+#define A64_NOP A64_HINT(AARCH64_INSN_HINT_NOP)
+
+/* DMB */
+#define A64_DMB_ISH aarch64_insn_gen_dmb(AARCH64_INSN_MB_ISH)
#endif /* _BPF_JIT_H */
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index ba38d403abb2..30f76178608b 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -1,42 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* BPF JIT compiler for ARM64
*
* Copyright (C) 2014-2016 Zi Shen Lim <zlim.lnx@gmail.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#define pr_fmt(fmt) "bpf_jit: " fmt
+#include <linux/bitfield.h>
#include <linux/bpf.h>
#include <linux/filter.h>
+#include <linux/memory.h>
#include <linux/printk.h>
-#include <linux/skbuff.h>
#include <linux/slab.h>
+#include <asm/asm-extable.h>
#include <asm/byteorder.h>
#include <asm/cacheflush.h>
#include <asm/debug-monitors.h>
+#include <asm/insn.h>
+#include <asm/patching.h>
#include <asm/set_memory.h>
#include "bpf_jit.h"
-int bpf_jit_enable __read_mostly;
-
#define TMP_REG_1 (MAX_BPF_JIT_REG + 0)
#define TMP_REG_2 (MAX_BPF_JIT_REG + 1)
#define TCALL_CNT (MAX_BPF_JIT_REG + 2)
#define TMP_REG_3 (MAX_BPF_JIT_REG + 3)
+#define FP_BOTTOM (MAX_BPF_JIT_REG + 4)
+
+#define check_imm(bits, imm) do { \
+ if ((((imm) > 0) && ((imm) >> (bits))) || \
+ (((imm) < 0) && (~(imm) >> (bits)))) { \
+ pr_info("[%2d] imm=%d(0x%x) out of range\n", \
+ i, imm, imm); \
+ return -EINVAL; \
+ } \
+} while (0)
+#define check_imm19(imm) check_imm(19, imm)
+#define check_imm26(imm) check_imm(26, imm)
/* Map BPF registers to A64 registers */
static const int bpf2a64[] = {
@@ -55,7 +58,7 @@ static const int bpf2a64[] = {
[BPF_REG_9] = A64_R(22),
/* read-only frame pointer to access stack */
[BPF_REG_FP] = A64_R(25),
- /* temporary registers for internal BPF JIT */
+ /* temporary registers for BPF JIT */
[TMP_REG_1] = A64_R(10),
[TMP_REG_2] = A64_R(11),
[TMP_REG_3] = A64_R(12),
@@ -63,6 +66,7 @@ static const int bpf2a64[] = {
[TCALL_CNT] = A64_R(26),
/* temporary register for blinding constants */
[BPF_REG_AX] = A64_R(9),
+ [FP_BOTTOM] = A64_R(27),
};
struct jit_ctx {
@@ -70,10 +74,21 @@ struct jit_ctx {
int idx;
int epilogue_offset;
int *offset;
+ int exentry_idx;
__le32 *image;
u32 stack_size;
+ int fpb_offset;
+};
+
+struct bpf_plt {
+ u32 insn_ldr; /* load target */
+ u32 insn_br; /* branch to target */
+ u64 target; /* target value */
};
+#define PLT_TARGET_SIZE sizeof_field(struct bpf_plt, target)
+#define PLT_TARGET_OFFSET offsetof(struct bpf_plt, target)
+
static inline void emit(const u32 insn, struct jit_ctx *ctx)
{
if (ctx->image != NULL)
@@ -82,23 +97,6 @@ static inline void emit(const u32 insn, struct jit_ctx *ctx)
ctx->idx++;
}
-static inline void emit_a64_mov_i64(const int reg, const u64 val,
- struct jit_ctx *ctx)
-{
- u64 tmp = val;
- int shift = 0;
-
- emit(A64_MOVZ(1, reg, tmp & 0xffff, shift), ctx);
- tmp >>= 16;
- shift += 16;
- while (tmp) {
- if (tmp & 0xffff)
- emit(A64_MOVK(1, reg, tmp & 0xffff, shift), ctx);
- tmp >>= 16;
- shift += 16;
- }
-}
-
static inline void emit_a64_mov_i(const int is64, const int reg,
const s32 val, struct jit_ctx *ctx)
{
@@ -110,7 +108,8 @@ static inline void emit_a64_mov_i(const int is64, const int reg,
emit(A64_MOVN(is64, reg, (u16)~lo, 0), ctx);
} else {
emit(A64_MOVN(is64, reg, (u16)~hi, 16), ctx);
- emit(A64_MOVK(is64, reg, lo, 0), ctx);
+ if (lo != 0xffff)
+ emit(A64_MOVK(is64, reg, lo, 0), ctx);
}
} else {
emit(A64_MOVZ(is64, reg, lo, 0), ctx);
@@ -119,14 +118,83 @@ static inline void emit_a64_mov_i(const int is64, const int reg,
}
}
-static inline int bpf2a64_offset(int bpf_to, int bpf_from,
- const struct jit_ctx *ctx)
+static int i64_i16_blocks(const u64 val, bool inverse)
{
- int to = ctx->offset[bpf_to];
- /* -1 to account for the Branch instruction */
- int from = ctx->offset[bpf_from] - 1;
+ return (((val >> 0) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
+ (((val >> 16) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
+ (((val >> 32) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
+ (((val >> 48) & 0xffff) != (inverse ? 0xffff : 0x0000));
+}
- return to - from;
+static inline void emit_a64_mov_i64(const int reg, const u64 val,
+ struct jit_ctx *ctx)
+{
+ u64 nrm_tmp = val, rev_tmp = ~val;
+ bool inverse;
+ int shift;
+
+ if (!(nrm_tmp >> 32))
+ return emit_a64_mov_i(0, reg, (u32)val, ctx);
+
+ inverse = i64_i16_blocks(nrm_tmp, true) < i64_i16_blocks(nrm_tmp, false);
+ shift = max(round_down((inverse ? (fls64(rev_tmp) - 1) :
+ (fls64(nrm_tmp) - 1)), 16), 0);
+ if (inverse)
+ emit(A64_MOVN(1, reg, (rev_tmp >> shift) & 0xffff, shift), ctx);
+ else
+ emit(A64_MOVZ(1, reg, (nrm_tmp >> shift) & 0xffff, shift), ctx);
+ shift -= 16;
+ while (shift >= 0) {
+ if (((nrm_tmp >> shift) & 0xffff) != (inverse ? 0xffff : 0x0000))
+ emit(A64_MOVK(1, reg, (nrm_tmp >> shift) & 0xffff, shift), ctx);
+ shift -= 16;
+ }
+}
+
+static inline void emit_bti(u32 insn, struct jit_ctx *ctx)
+{
+ if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL))
+ emit(insn, ctx);
+}
+
+/*
+ * Kernel addresses in the vmalloc space use at most 48 bits, and the
+ * remaining bits are guaranteed to be 0x1. So we can compose the address
+ * with a fixed length movn/movk/movk sequence.
+ */
+static inline void emit_addr_mov_i64(const int reg, const u64 val,
+ struct jit_ctx *ctx)
+{
+ u64 tmp = val;
+ int shift = 0;
+
+ emit(A64_MOVN(1, reg, ~tmp & 0xffff, shift), ctx);
+ while (shift < 32) {
+ tmp >>= 16;
+ shift += 16;
+ emit(A64_MOVK(1, reg, tmp & 0xffff, shift), ctx);
+ }
+}
+
+static inline void emit_call(u64 target, struct jit_ctx *ctx)
+{
+ u8 tmp = bpf2a64[TMP_REG_1];
+
+ emit_addr_mov_i64(tmp, target, ctx);
+ emit(A64_BLR(tmp), ctx);
+}
+
+static inline int bpf2a64_offset(int bpf_insn, int off,
+ const struct jit_ctx *ctx)
+{
+ /* BPF JMP offset is relative to the next instruction */
+ bpf_insn++;
+ /*
+ * Whereas arm64 branch instructions encode the offset
+ * from the branch itself, so we must subtract 1 from the
+ * instruction offset.
+ */
+ return ctx->offset[bpf_insn + off] - (ctx->offset[bpf_insn] - 1);
}
static void jit_fill_hole(void *area, unsigned int size)
@@ -145,20 +213,89 @@ static inline int epilogue_offset(const struct jit_ctx *ctx)
return to - from;
}
-/* Stack must be multiples of 16B */
-#define STACK_ALIGN(sz) (((sz) + 15) & ~15)
+static bool is_addsub_imm(u32 imm)
+{
+ /* Either imm12 or shifted imm12. */
+ return !(imm & ~0xfff) || !(imm & ~0xfff000);
+}
-#define PROLOGUE_OFFSET 8
+/*
+ * There are 3 types of AArch64 LDR/STR (immediate) instruction:
+ * Post-index, Pre-index, Unsigned offset.
+ *
+ * For BPF ldr/str, the "unsigned offset" type is sufficient.
+ *
+ * "Unsigned offset" type LDR(immediate) format:
+ *
+ * 3 2 1 0
+ * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |x x|1 1 1 0 0 1 0 1| imm12 | Rn | Rt |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * scale
+ *
+ * "Unsigned offset" type STR(immediate) format:
+ * 3 2 1 0
+ * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |x x|1 1 1 0 0 1 0 0| imm12 | Rn | Rt |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * scale
+ *
+ * The offset is calculated from imm12 and scale in the following way:
+ *
+ * offset = (u64)imm12 << scale
+ */
+static bool is_lsi_offset(int offset, int scale)
+{
+ if (offset < 0)
+ return false;
+
+ if (offset > (0xFFF << scale))
+ return false;
+
+ if (offset & ((1 << scale) - 1))
+ return false;
+
+ return true;
+}
-static int build_prologue(struct jit_ctx *ctx)
+/* generated prologue:
+ * bti c // if CONFIG_ARM64_BTI_KERNEL
+ * mov x9, lr
+ * nop // POKE_OFFSET
+ * paciasp // if CONFIG_ARM64_PTR_AUTH_KERNEL
+ * stp x29, lr, [sp, #-16]!
+ * mov x29, sp
+ * stp x19, x20, [sp, #-16]!
+ * stp x21, x22, [sp, #-16]!
+ * stp x25, x26, [sp, #-16]!
+ * stp x27, x28, [sp, #-16]!
+ * mov x25, sp
+ * mov tcc, #0
+ * // PROLOGUE_OFFSET
+ */
+
+#define BTI_INSNS (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) ? 1 : 0)
+#define PAC_INSNS (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL) ? 1 : 0)
+
+/* Offset of nop instruction in bpf prog entry to be poked */
+#define POKE_OFFSET (BTI_INSNS + 1)
+
+/* Tail call offset to jump into */
+#define PROLOGUE_OFFSET (BTI_INSNS + 2 + PAC_INSNS + 8)
+
+static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf)
{
const struct bpf_prog *prog = ctx->prog;
+ const bool is_main_prog = prog->aux->func_idx == 0;
const u8 r6 = bpf2a64[BPF_REG_6];
const u8 r7 = bpf2a64[BPF_REG_7];
const u8 r8 = bpf2a64[BPF_REG_8];
const u8 r9 = bpf2a64[BPF_REG_9];
const u8 fp = bpf2a64[BPF_REG_FP];
const u8 tcc = bpf2a64[TCALL_CNT];
+ const u8 fpb = bpf2a64[FP_BOTTOM];
const int idx0 = ctx->idx;
int cur_offset;
@@ -175,7 +312,7 @@ static int build_prologue(struct jit_ctx *ctx)
* | ... | BPF prog stack
* | |
* +-----+ <= (BPF_FP - prog->aux->stack_depth)
- * |RSVD | JIT scratchpad
+ * |RSVD | padding
* current A64_SP => +-----+ <= (BPF_FP - ctx->stack_size)
* | |
* | ... | Function call stack
@@ -185,6 +322,15 @@ static int build_prologue(struct jit_ctx *ctx)
*
*/
+ emit_bti(A64_BTI_C, ctx);
+
+ emit(A64_MOV(1, A64_R(9), A64_LR), ctx);
+ emit(A64_NOP, ctx);
+
+ /* Sign lr */
+ if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL))
+ emit(A64_PACIASP, ctx);
+
/* Save FP and LR registers to stay align with ARM64 AAPCS */
emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
emit(A64_MOV(1, A64_FP, A64_SP), ctx);
@@ -193,26 +339,33 @@ static int build_prologue(struct jit_ctx *ctx)
emit(A64_PUSH(r6, r7, A64_SP), ctx);
emit(A64_PUSH(r8, r9, A64_SP), ctx);
emit(A64_PUSH(fp, tcc, A64_SP), ctx);
+ emit(A64_PUSH(fpb, A64_R(28), A64_SP), ctx);
/* Set up BPF prog stack base register */
emit(A64_MOV(1, fp, A64_SP), ctx);
- /* Initialize tail_call_cnt */
- emit(A64_MOVZ(1, tcc, 0, 0), ctx);
+ if (!ebpf_from_cbpf && is_main_prog) {
+ /* Initialize tail_call_cnt */
+ emit(A64_MOVZ(1, tcc, 0, 0), ctx);
- /* 4 byte extra for skb_copy_bits buffer */
- ctx->stack_size = prog->aux->stack_depth + 4;
- ctx->stack_size = STACK_ALIGN(ctx->stack_size);
+ cur_offset = ctx->idx - idx0;
+ if (cur_offset != PROLOGUE_OFFSET) {
+ pr_err_once("PROLOGUE_OFFSET = %d, expected %d!\n",
+ cur_offset, PROLOGUE_OFFSET);
+ return -1;
+ }
+
+ /* BTI landing pad for the tail call, done with a BR */
+ emit_bti(A64_BTI_J, ctx);
+ }
+
+ emit(A64_SUB_I(1, fpb, fp, ctx->fpb_offset), ctx);
+
+ /* Stack must be multiples of 16B */
+ ctx->stack_size = round_up(prog->aux->stack_depth, 16);
/* Set up function call stack */
emit(A64_SUB_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);
-
- cur_offset = ctx->idx - idx0;
- if (cur_offset != PROLOGUE_OFFSET) {
- pr_err_once("PROLOGUE_OFFSET = %d, expected %d!\n",
- cur_offset, PROLOGUE_OFFSET);
- return -1;
- }
return 0;
}
@@ -237,16 +390,18 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
off = offsetof(struct bpf_array, map.max_entries);
emit_a64_mov_i64(tmp, off, ctx);
emit(A64_LDR32(tmp, r2, tmp), ctx);
+ emit(A64_MOV(0, r3, r3), ctx);
emit(A64_CMP(0, r3, tmp), ctx);
- emit(A64_B_(A64_COND_GE, jmp_offset), ctx);
+ emit(A64_B_(A64_COND_CS, jmp_offset), ctx);
- /* if (tail_call_cnt > MAX_TAIL_CALL_CNT)
+ /*
+ * if (tail_call_cnt >= MAX_TAIL_CALL_CNT)
* goto out;
* tail_call_cnt++;
*/
emit_a64_mov_i64(tmp, MAX_TAIL_CALL_CNT, ctx);
emit(A64_CMP(1, tcc, tmp), ctx);
- emit(A64_B_(A64_COND_GT, jmp_offset), ctx);
+ emit(A64_B_(A64_COND_CS, jmp_offset), ctx);
emit(A64_ADD_I(1, tcc, tcc, 1), ctx);
/* prog = array->ptrs[index];
@@ -260,11 +415,12 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
emit(A64_LDR64(prg, tmp, prg), ctx);
emit(A64_CBZ(1, prg, jmp_offset), ctx);
- /* goto *(prog->bpf_func + prologue_size); */
+ /* goto *(prog->bpf_func + prologue_offset); */
off = offsetof(struct bpf_prog, bpf_func);
emit_a64_mov_i64(tmp, off, ctx);
emit(A64_LDR64(tmp, prg, tmp), ctx);
emit(A64_ADD_I(1, tmp, tmp, sizeof(u32) * PROLOGUE_OFFSET), ctx);
+ emit(A64_ADD_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);
emit(A64_BR(tmp), ctx);
/* out: */
@@ -280,6 +436,217 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
#undef jmp_offset
}
+#ifdef CONFIG_ARM64_LSE_ATOMICS
+static int emit_lse_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
+{
+ const u8 code = insn->code;
+ const u8 dst = bpf2a64[insn->dst_reg];
+ const u8 src = bpf2a64[insn->src_reg];
+ const u8 tmp = bpf2a64[TMP_REG_1];
+ const u8 tmp2 = bpf2a64[TMP_REG_2];
+ const bool isdw = BPF_SIZE(code) == BPF_DW;
+ const s16 off = insn->off;
+ u8 reg;
+
+ if (!off) {
+ reg = dst;
+ } else {
+ emit_a64_mov_i(1, tmp, off, ctx);
+ emit(A64_ADD(1, tmp, tmp, dst), ctx);
+ reg = tmp;
+ }
+
+ switch (insn->imm) {
+ /* lock *(u32/u64 *)(dst_reg + off) <op>= src_reg */
+ case BPF_ADD:
+ emit(A64_STADD(isdw, reg, src), ctx);
+ break;
+ case BPF_AND:
+ emit(A64_MVN(isdw, tmp2, src), ctx);
+ emit(A64_STCLR(isdw, reg, tmp2), ctx);
+ break;
+ case BPF_OR:
+ emit(A64_STSET(isdw, reg, src), ctx);
+ break;
+ case BPF_XOR:
+ emit(A64_STEOR(isdw, reg, src), ctx);
+ break;
+ /* src_reg = atomic_fetch_<op>(dst_reg + off, src_reg) */
+ case BPF_ADD | BPF_FETCH:
+ emit(A64_LDADDAL(isdw, src, reg, src), ctx);
+ break;
+ case BPF_AND | BPF_FETCH:
+ emit(A64_MVN(isdw, tmp2, src), ctx);
+ emit(A64_LDCLRAL(isdw, src, reg, tmp2), ctx);
+ break;
+ case BPF_OR | BPF_FETCH:
+ emit(A64_LDSETAL(isdw, src, reg, src), ctx);
+ break;
+ case BPF_XOR | BPF_FETCH:
+ emit(A64_LDEORAL(isdw, src, reg, src), ctx);
+ break;
+ /* src_reg = atomic_xchg(dst_reg + off, src_reg); */
+ case BPF_XCHG:
+ emit(A64_SWPAL(isdw, src, reg, src), ctx);
+ break;
+ /* r0 = atomic_cmpxchg(dst_reg + off, r0, src_reg); */
+ case BPF_CMPXCHG:
+ emit(A64_CASAL(isdw, src, reg, bpf2a64[BPF_REG_0]), ctx);
+ break;
+ default:
+ pr_err_once("unknown atomic op code %02x\n", insn->imm);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+#else
+static inline int emit_lse_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
+{
+ return -EINVAL;
+}
+#endif
+
+static int emit_ll_sc_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
+{
+ const u8 code = insn->code;
+ const u8 dst = bpf2a64[insn->dst_reg];
+ const u8 src = bpf2a64[insn->src_reg];
+ const u8 tmp = bpf2a64[TMP_REG_1];
+ const u8 tmp2 = bpf2a64[TMP_REG_2];
+ const u8 tmp3 = bpf2a64[TMP_REG_3];
+ const int i = insn - ctx->prog->insnsi;
+ const s32 imm = insn->imm;
+ const s16 off = insn->off;
+ const bool isdw = BPF_SIZE(code) == BPF_DW;
+ u8 reg;
+ s32 jmp_offset;
+
+ if (!off) {
+ reg = dst;
+ } else {
+ emit_a64_mov_i(1, tmp, off, ctx);
+ emit(A64_ADD(1, tmp, tmp, dst), ctx);
+ reg = tmp;
+ }
+
+ if (imm == BPF_ADD || imm == BPF_AND ||
+ imm == BPF_OR || imm == BPF_XOR) {
+ /* lock *(u32/u64 *)(dst_reg + off) <op>= src_reg */
+ emit(A64_LDXR(isdw, tmp2, reg), ctx);
+ if (imm == BPF_ADD)
+ emit(A64_ADD(isdw, tmp2, tmp2, src), ctx);
+ else if (imm == BPF_AND)
+ emit(A64_AND(isdw, tmp2, tmp2, src), ctx);
+ else if (imm == BPF_OR)
+ emit(A64_ORR(isdw, tmp2, tmp2, src), ctx);
+ else
+ emit(A64_EOR(isdw, tmp2, tmp2, src), ctx);
+ emit(A64_STXR(isdw, tmp2, reg, tmp3), ctx);
+ jmp_offset = -3;
+ check_imm19(jmp_offset);
+ emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
+ } else if (imm == (BPF_ADD | BPF_FETCH) ||
+ imm == (BPF_AND | BPF_FETCH) ||
+ imm == (BPF_OR | BPF_FETCH) ||
+ imm == (BPF_XOR | BPF_FETCH)) {
+ /* src_reg = atomic_fetch_<op>(dst_reg + off, src_reg) */
+ const u8 ax = bpf2a64[BPF_REG_AX];
+
+ emit(A64_MOV(isdw, ax, src), ctx);
+ emit(A64_LDXR(isdw, src, reg), ctx);
+ if (imm == (BPF_ADD | BPF_FETCH))
+ emit(A64_ADD(isdw, tmp2, src, ax), ctx);
+ else if (imm == (BPF_AND | BPF_FETCH))
+ emit(A64_AND(isdw, tmp2, src, ax), ctx);
+ else if (imm == (BPF_OR | BPF_FETCH))
+ emit(A64_ORR(isdw, tmp2, src, ax), ctx);
+ else
+ emit(A64_EOR(isdw, tmp2, src, ax), ctx);
+ emit(A64_STLXR(isdw, tmp2, reg, tmp3), ctx);
+ jmp_offset = -3;
+ check_imm19(jmp_offset);
+ emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
+ emit(A64_DMB_ISH, ctx);
+ } else if (imm == BPF_XCHG) {
+ /* src_reg = atomic_xchg(dst_reg + off, src_reg); */
+ emit(A64_MOV(isdw, tmp2, src), ctx);
+ emit(A64_LDXR(isdw, src, reg), ctx);
+ emit(A64_STLXR(isdw, tmp2, reg, tmp3), ctx);
+ jmp_offset = -2;
+ check_imm19(jmp_offset);
+ emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
+ emit(A64_DMB_ISH, ctx);
+ } else if (imm == BPF_CMPXCHG) {
+ /* r0 = atomic_cmpxchg(dst_reg + off, r0, src_reg); */
+ const u8 r0 = bpf2a64[BPF_REG_0];
+
+ emit(A64_MOV(isdw, tmp2, r0), ctx);
+ emit(A64_LDXR(isdw, r0, reg), ctx);
+ emit(A64_EOR(isdw, tmp3, r0, tmp2), ctx);
+ jmp_offset = 4;
+ check_imm19(jmp_offset);
+ emit(A64_CBNZ(isdw, tmp3, jmp_offset), ctx);
+ emit(A64_STLXR(isdw, src, reg, tmp3), ctx);
+ jmp_offset = -4;
+ check_imm19(jmp_offset);
+ emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
+ emit(A64_DMB_ISH, ctx);
+ } else {
+ pr_err_once("unknown atomic op code %02x\n", imm);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+void dummy_tramp(void);
+
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .global dummy_tramp\n"
+" .type dummy_tramp, %function\n"
+"dummy_tramp:"
+#if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)
+" bti j\n" /* dummy_tramp is called via "br x10" */
+#endif
+" mov x10, x30\n"
+" mov x30, x9\n"
+" ret x10\n"
+" .size dummy_tramp, .-dummy_tramp\n"
+" .popsection\n"
+);
+
+/* build a plt initialized like this:
+ *
+ * plt:
+ * ldr tmp, target
+ * br tmp
+ * target:
+ * .quad dummy_tramp
+ *
+ * when a long jump trampoline is attached, target is filled with the
+ * trampoline address, and when the trampoline is removed, target is
+ * restored to dummy_tramp address.
+ */
+static void build_plt(struct jit_ctx *ctx)
+{
+ const u8 tmp = bpf2a64[TMP_REG_1];
+ struct bpf_plt *plt = NULL;
+
+ /* make sure target is 64-bit aligned */
+ if ((ctx->idx + PLT_TARGET_OFFSET / AARCH64_INSN_SIZE) % 2)
+ emit(A64_NOP, ctx);
+
+ plt = (struct bpf_plt *)(ctx->image + ctx->idx);
+ /* plt is called via bl, no BTI needed here */
+ emit(A64_LDR64LIT(tmp, 2 * AARCH64_INSN_SIZE), ctx);
+ emit(A64_BR(tmp), ctx);
+
+ if (ctx->image)
+ plt->target = (u64)&dummy_tramp;
+}
+
static void build_epilogue(struct jit_ctx *ctx)
{
const u8 r0 = bpf2a64[BPF_REG_0];
@@ -288,10 +655,13 @@ static void build_epilogue(struct jit_ctx *ctx)
const u8 r8 = bpf2a64[BPF_REG_8];
const u8 r9 = bpf2a64[BPF_REG_9];
const u8 fp = bpf2a64[BPF_REG_FP];
+ const u8 fpb = bpf2a64[FP_BOTTOM];
/* We're done with BPF stack */
emit(A64_ADD_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);
+ /* Restore x27 and x28 */
+ emit(A64_POP(fpb, A64_R(28), A64_SP), ctx);
/* Restore fs (x25) and x26 */
emit(A64_POP(fp, A64_R(26), A64_SP), ctx);
@@ -305,41 +675,104 @@ static void build_epilogue(struct jit_ctx *ctx)
/* Set return value */
emit(A64_MOV(1, A64_R(0), r0), ctx);
+ /* Authenticate lr */
+ if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL))
+ emit(A64_AUTIASP, ctx);
+
emit(A64_RET(A64_LR), ctx);
}
+#define BPF_FIXUP_OFFSET_MASK GENMASK(26, 0)
+#define BPF_FIXUP_REG_MASK GENMASK(31, 27)
+
+bool ex_handler_bpf(const struct exception_table_entry *ex,
+ struct pt_regs *regs)
+{
+ off_t offset = FIELD_GET(BPF_FIXUP_OFFSET_MASK, ex->fixup);
+ int dst_reg = FIELD_GET(BPF_FIXUP_REG_MASK, ex->fixup);
+
+ regs->regs[dst_reg] = 0;
+ regs->pc = (unsigned long)&ex->fixup - offset;
+ return true;
+}
+
+/* For accesses to BTF pointers, add an entry to the exception table */
+static int add_exception_handler(const struct bpf_insn *insn,
+ struct jit_ctx *ctx,
+ int dst_reg)
+{
+ off_t offset;
+ unsigned long pc;
+ struct exception_table_entry *ex;
+
+ if (!ctx->image)
+ /* First pass */
+ return 0;
+
+ if (BPF_MODE(insn->code) != BPF_PROBE_MEM)
+ return 0;
+
+ if (!ctx->prog->aux->extable ||
+ WARN_ON_ONCE(ctx->exentry_idx >= ctx->prog->aux->num_exentries))
+ return -EINVAL;
+
+ ex = &ctx->prog->aux->extable[ctx->exentry_idx];
+ pc = (unsigned long)&ctx->image[ctx->idx - 1];
+
+ offset = pc - (long)&ex->insn;
+ if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN))
+ return -ERANGE;
+ ex->insn = offset;
+
+ /*
+ * Since the extable follows the program, the fixup offset is always
+ * negative and limited to BPF_JIT_REGION_SIZE. Store a positive value
+ * to keep things simple, and put the destination register in the upper
+ * bits. We don't need to worry about buildtime or runtime sort
+ * modifying the upper bits because the table is already sorted, and
+ * isn't part of the main exception table.
+ */
+ offset = (long)&ex->fixup - (pc + AARCH64_INSN_SIZE);
+ if (!FIELD_FIT(BPF_FIXUP_OFFSET_MASK, offset))
+ return -ERANGE;
+
+ ex->fixup = FIELD_PREP(BPF_FIXUP_OFFSET_MASK, offset) |
+ FIELD_PREP(BPF_FIXUP_REG_MASK, dst_reg);
+
+ ex->type = EX_TYPE_BPF;
+
+ ctx->exentry_idx++;
+ return 0;
+}
+
/* JITs an eBPF instruction.
* Returns:
* 0 - successfully JITed an 8-byte eBPF instruction.
* >0 - successfully JITed a 16-byte eBPF instruction.
* <0 - failed to JIT.
*/
-static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
+static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
+ bool extra_pass)
{
const u8 code = insn->code;
const u8 dst = bpf2a64[insn->dst_reg];
const u8 src = bpf2a64[insn->src_reg];
const u8 tmp = bpf2a64[TMP_REG_1];
const u8 tmp2 = bpf2a64[TMP_REG_2];
- const u8 tmp3 = bpf2a64[TMP_REG_3];
+ const u8 fp = bpf2a64[BPF_REG_FP];
+ const u8 fpb = bpf2a64[FP_BOTTOM];
const s16 off = insn->off;
const s32 imm = insn->imm;
const int i = insn - ctx->prog->insnsi;
- const bool is64 = BPF_CLASS(code) == BPF_ALU64;
- const bool isdw = BPF_SIZE(code) == BPF_DW;
+ const bool is64 = BPF_CLASS(code) == BPF_ALU64 ||
+ BPF_CLASS(code) == BPF_JMP;
u8 jmp_cond;
s32 jmp_offset;
-
-#define check_imm(bits, imm) do { \
- if ((((imm) > 0) && ((imm) >> (bits))) || \
- (((imm) < 0) && (~(imm) >> (bits)))) { \
- pr_info("[%2d] imm=%d(0x%x) out of range\n", \
- i, imm, imm); \
- return -EINVAL; \
- } \
-} while (0)
-#define check_imm19(imm) check_imm(19, imm)
-#define check_imm26(imm) check_imm(26, imm)
+ u32 a64_insn;
+ u8 src_adj;
+ u8 dst_adj;
+ int off_adj;
+ int ret;
switch (code) {
/* dst = src */
@@ -374,32 +807,13 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
break;
case BPF_ALU | BPF_DIV | BPF_X:
case BPF_ALU64 | BPF_DIV | BPF_X:
+ emit(A64_UDIV(is64, dst, dst, src), ctx);
+ break;
case BPF_ALU | BPF_MOD | BPF_X:
case BPF_ALU64 | BPF_MOD | BPF_X:
- {
- const u8 r0 = bpf2a64[BPF_REG_0];
-
- /* if (src == 0) return 0 */
- jmp_offset = 3; /* skip ahead to else path */
- check_imm19(jmp_offset);
- emit(A64_CBNZ(is64, src, jmp_offset), ctx);
- emit(A64_MOVZ(1, r0, 0, 0), ctx);
- jmp_offset = epilogue_offset(ctx);
- check_imm26(jmp_offset);
- emit(A64_B(jmp_offset), ctx);
- /* else */
- switch (BPF_OP(code)) {
- case BPF_DIV:
- emit(A64_UDIV(is64, dst, dst, src), ctx);
- break;
- case BPF_MOD:
- emit(A64_UDIV(is64, tmp, dst, src), ctx);
- emit(A64_MUL(is64, tmp, tmp, src), ctx);
- emit(A64_SUB(is64, dst, dst, tmp), ctx);
- break;
- }
+ emit(A64_UDIV(is64, tmp, dst, src), ctx);
+ emit(A64_MSUB(is64, dst, dst, tmp, src), ctx);
break;
- }
case BPF_ALU | BPF_LSH | BPF_X:
case BPF_ALU64 | BPF_LSH | BPF_X:
emit(A64_LSLV(is64, dst, dst, src), ctx);
@@ -465,28 +879,55 @@ emit_bswap_uxt:
/* dst = dst OP imm */
case BPF_ALU | BPF_ADD | BPF_K:
case BPF_ALU64 | BPF_ADD | BPF_K:
- emit_a64_mov_i(is64, tmp, imm, ctx);
- emit(A64_ADD(is64, dst, dst, tmp), ctx);
+ if (is_addsub_imm(imm)) {
+ emit(A64_ADD_I(is64, dst, dst, imm), ctx);
+ } else if (is_addsub_imm(-imm)) {
+ emit(A64_SUB_I(is64, dst, dst, -imm), ctx);
+ } else {
+ emit_a64_mov_i(is64, tmp, imm, ctx);
+ emit(A64_ADD(is64, dst, dst, tmp), ctx);
+ }
break;
case BPF_ALU | BPF_SUB | BPF_K:
case BPF_ALU64 | BPF_SUB | BPF_K:
- emit_a64_mov_i(is64, tmp, imm, ctx);
- emit(A64_SUB(is64, dst, dst, tmp), ctx);
+ if (is_addsub_imm(imm)) {
+ emit(A64_SUB_I(is64, dst, dst, imm), ctx);
+ } else if (is_addsub_imm(-imm)) {
+ emit(A64_ADD_I(is64, dst, dst, -imm), ctx);
+ } else {
+ emit_a64_mov_i(is64, tmp, imm, ctx);
+ emit(A64_SUB(is64, dst, dst, tmp), ctx);
+ }
break;
case BPF_ALU | BPF_AND | BPF_K:
case BPF_ALU64 | BPF_AND | BPF_K:
- emit_a64_mov_i(is64, tmp, imm, ctx);
- emit(A64_AND(is64, dst, dst, tmp), ctx);
+ a64_insn = A64_AND_I(is64, dst, dst, imm);
+ if (a64_insn != AARCH64_BREAK_FAULT) {
+ emit(a64_insn, ctx);
+ } else {
+ emit_a64_mov_i(is64, tmp, imm, ctx);
+ emit(A64_AND(is64, dst, dst, tmp), ctx);
+ }
break;
case BPF_ALU | BPF_OR | BPF_K:
case BPF_ALU64 | BPF_OR | BPF_K:
- emit_a64_mov_i(is64, tmp, imm, ctx);
- emit(A64_ORR(is64, dst, dst, tmp), ctx);
+ a64_insn = A64_ORR_I(is64, dst, dst, imm);
+ if (a64_insn != AARCH64_BREAK_FAULT) {
+ emit(a64_insn, ctx);
+ } else {
+ emit_a64_mov_i(is64, tmp, imm, ctx);
+ emit(A64_ORR(is64, dst, dst, tmp), ctx);
+ }
break;
case BPF_ALU | BPF_XOR | BPF_K:
case BPF_ALU64 | BPF_XOR | BPF_K:
- emit_a64_mov_i(is64, tmp, imm, ctx);
- emit(A64_EOR(is64, dst, dst, tmp), ctx);
+ a64_insn = A64_EOR_I(is64, dst, dst, imm);
+ if (a64_insn != AARCH64_BREAK_FAULT) {
+ emit(a64_insn, ctx);
+ } else {
+ emit_a64_mov_i(is64, tmp, imm, ctx);
+ emit(A64_EOR(is64, dst, dst, tmp), ctx);
+ }
break;
case BPF_ALU | BPF_MUL | BPF_K:
case BPF_ALU64 | BPF_MUL | BPF_K:
@@ -502,8 +943,7 @@ emit_bswap_uxt:
case BPF_ALU64 | BPF_MOD | BPF_K:
emit_a64_mov_i(is64, tmp2, imm, ctx);
emit(A64_UDIV(is64, tmp, dst, tmp2), ctx);
- emit(A64_MUL(is64, tmp, tmp, tmp2), ctx);
- emit(A64_SUB(is64, dst, dst, tmp), ctx);
+ emit(A64_MSUB(is64, dst, dst, tmp, tmp2), ctx);
break;
case BPF_ALU | BPF_LSH | BPF_K:
case BPF_ALU64 | BPF_LSH | BPF_K:
@@ -520,7 +960,7 @@ emit_bswap_uxt:
/* JUMP off */
case BPF_JMP | BPF_JA:
- jmp_offset = bpf2a64_offset(i + off, i, ctx);
+ jmp_offset = bpf2a64_offset(i, off, ctx);
check_imm26(jmp_offset);
emit(A64_B(jmp_offset), ctx);
break;
@@ -535,9 +975,19 @@ emit_bswap_uxt:
case BPF_JMP | BPF_JSLT | BPF_X:
case BPF_JMP | BPF_JSGE | BPF_X:
case BPF_JMP | BPF_JSLE | BPF_X:
- emit(A64_CMP(1, dst, src), ctx);
+ case BPF_JMP32 | BPF_JEQ | BPF_X:
+ case BPF_JMP32 | BPF_JGT | BPF_X:
+ case BPF_JMP32 | BPF_JLT | BPF_X:
+ case BPF_JMP32 | BPF_JGE | BPF_X:
+ case BPF_JMP32 | BPF_JLE | BPF_X:
+ case BPF_JMP32 | BPF_JNE | BPF_X:
+ case BPF_JMP32 | BPF_JSGT | BPF_X:
+ case BPF_JMP32 | BPF_JSLT | BPF_X:
+ case BPF_JMP32 | BPF_JSGE | BPF_X:
+ case BPF_JMP32 | BPF_JSLE | BPF_X:
+ emit(A64_CMP(is64, dst, src), ctx);
emit_cond_jmp:
- jmp_offset = bpf2a64_offset(i + off, i, ctx);
+ jmp_offset = bpf2a64_offset(i, off, ctx);
check_imm19(jmp_offset);
switch (BPF_OP(code)) {
case BPF_JEQ:
@@ -577,7 +1027,8 @@ emit_cond_jmp:
emit(A64_B_(jmp_cond, jmp_offset), ctx);
break;
case BPF_JMP | BPF_JSET | BPF_X:
- emit(A64_TST(1, dst, src), ctx);
+ case BPF_JMP32 | BPF_JSET | BPF_X:
+ emit(A64_TST(is64, dst, src), ctx);
goto emit_cond_jmp;
/* IF (dst COND imm) JUMP off */
case BPF_JMP | BPF_JEQ | BPF_K:
@@ -590,21 +1041,47 @@ emit_cond_jmp:
case BPF_JMP | BPF_JSLT | BPF_K:
case BPF_JMP | BPF_JSGE | BPF_K:
case BPF_JMP | BPF_JSLE | BPF_K:
- emit_a64_mov_i(1, tmp, imm, ctx);
- emit(A64_CMP(1, dst, tmp), ctx);
+ case BPF_JMP32 | BPF_JEQ | BPF_K:
+ case BPF_JMP32 | BPF_JGT | BPF_K:
+ case BPF_JMP32 | BPF_JLT | BPF_K:
+ case BPF_JMP32 | BPF_JGE | BPF_K:
+ case BPF_JMP32 | BPF_JLE | BPF_K:
+ case BPF_JMP32 | BPF_JNE | BPF_K:
+ case BPF_JMP32 | BPF_JSGT | BPF_K:
+ case BPF_JMP32 | BPF_JSLT | BPF_K:
+ case BPF_JMP32 | BPF_JSGE | BPF_K:
+ case BPF_JMP32 | BPF_JSLE | BPF_K:
+ if (is_addsub_imm(imm)) {
+ emit(A64_CMP_I(is64, dst, imm), ctx);
+ } else if (is_addsub_imm(-imm)) {
+ emit(A64_CMN_I(is64, dst, -imm), ctx);
+ } else {
+ emit_a64_mov_i(is64, tmp, imm, ctx);
+ emit(A64_CMP(is64, dst, tmp), ctx);
+ }
goto emit_cond_jmp;
case BPF_JMP | BPF_JSET | BPF_K:
- emit_a64_mov_i(1, tmp, imm, ctx);
- emit(A64_TST(1, dst, tmp), ctx);
+ case BPF_JMP32 | BPF_JSET | BPF_K:
+ a64_insn = A64_TST_I(is64, dst, imm);
+ if (a64_insn != AARCH64_BREAK_FAULT) {
+ emit(a64_insn, ctx);
+ } else {
+ emit_a64_mov_i(is64, tmp, imm, ctx);
+ emit(A64_TST(is64, dst, tmp), ctx);
+ }
goto emit_cond_jmp;
/* function call */
case BPF_JMP | BPF_CALL:
{
const u8 r0 = bpf2a64[BPF_REG_0];
- const u64 func = (u64)__bpf_call_base + imm;
+ bool func_addr_fixed;
+ u64 func_addr;
- emit_a64_mov_i64(tmp, func, ctx);
- emit(A64_BLR(tmp), ctx);
+ ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass,
+ &func_addr, &func_addr_fixed);
+ if (ret < 0)
+ return ret;
+ emit_call(func_addr, ctx);
emit(A64_MOV(1, r0, A64_R(0)), ctx);
break;
}
@@ -631,7 +1108,10 @@ emit_cond_jmp:
u64 imm64;
imm64 = (u64)insn1.imm << 32 | (u32)imm;
- emit_a64_mov_i64(dst, imm64, ctx);
+ if (bpf_pseudo_func(insn))
+ emit_addr_mov_i64(dst, imm64, ctx);
+ else
+ emit_a64_mov_i64(dst, imm64, ctx);
return 1;
}
@@ -641,21 +1121,68 @@ emit_cond_jmp:
case BPF_LDX | BPF_MEM | BPF_H:
case BPF_LDX | BPF_MEM | BPF_B:
case BPF_LDX | BPF_MEM | BPF_DW:
- emit_a64_mov_i(1, tmp, off, ctx);
+ case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
+ case BPF_LDX | BPF_PROBE_MEM | BPF_W:
+ case BPF_LDX | BPF_PROBE_MEM | BPF_H:
+ case BPF_LDX | BPF_PROBE_MEM | BPF_B:
+ if (ctx->fpb_offset > 0 && src == fp) {
+ src_adj = fpb;
+ off_adj = off + ctx->fpb_offset;
+ } else {
+ src_adj = src;
+ off_adj = off;
+ }
switch (BPF_SIZE(code)) {
case BPF_W:
- emit(A64_LDR32(dst, src, tmp), ctx);
+ if (is_lsi_offset(off_adj, 2)) {
+ emit(A64_LDR32I(dst, src_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp, off, ctx);
+ emit(A64_LDR32(dst, src, tmp), ctx);
+ }
break;
case BPF_H:
- emit(A64_LDRH(dst, src, tmp), ctx);
+ if (is_lsi_offset(off_adj, 1)) {
+ emit(A64_LDRHI(dst, src_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp, off, ctx);
+ emit(A64_LDRH(dst, src, tmp), ctx);
+ }
break;
case BPF_B:
- emit(A64_LDRB(dst, src, tmp), ctx);
+ if (is_lsi_offset(off_adj, 0)) {
+ emit(A64_LDRBI(dst, src_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp, off, ctx);
+ emit(A64_LDRB(dst, src, tmp), ctx);
+ }
break;
case BPF_DW:
- emit(A64_LDR64(dst, src, tmp), ctx);
+ if (is_lsi_offset(off_adj, 3)) {
+ emit(A64_LDR64I(dst, src_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp, off, ctx);
+ emit(A64_LDR64(dst, src, tmp), ctx);
+ }
break;
}
+
+ ret = add_exception_handler(insn, ctx, dst);
+ if (ret)
+ return ret;
+ break;
+
+ /* speculation barrier */
+ case BPF_ST | BPF_NOSPEC:
+ /*
+ * Nothing required here.
+ *
+ * In case of arm64, we rely on the firmware mitigation of
+ * Speculative Store Bypass as controlled via the ssbd kernel
+ * parameter. Whenever the mitigation is enabled, it works
+ * for all of the kernel code with no need to provide any
+ * additional instructions.
+ */
break;
/* ST: *(size *)(dst + off) = imm */
@@ -663,21 +1190,47 @@ emit_cond_jmp:
case BPF_ST | BPF_MEM | BPF_H:
case BPF_ST | BPF_MEM | BPF_B:
case BPF_ST | BPF_MEM | BPF_DW:
+ if (ctx->fpb_offset > 0 && dst == fp) {
+ dst_adj = fpb;
+ off_adj = off + ctx->fpb_offset;
+ } else {
+ dst_adj = dst;
+ off_adj = off;
+ }
/* Load imm to a register then store it */
- emit_a64_mov_i(1, tmp2, off, ctx);
emit_a64_mov_i(1, tmp, imm, ctx);
switch (BPF_SIZE(code)) {
case BPF_W:
- emit(A64_STR32(tmp, dst, tmp2), ctx);
+ if (is_lsi_offset(off_adj, 2)) {
+ emit(A64_STR32I(tmp, dst_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp2, off, ctx);
+ emit(A64_STR32(tmp, dst, tmp2), ctx);
+ }
break;
case BPF_H:
- emit(A64_STRH(tmp, dst, tmp2), ctx);
+ if (is_lsi_offset(off_adj, 1)) {
+ emit(A64_STRHI(tmp, dst_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp2, off, ctx);
+ emit(A64_STRH(tmp, dst, tmp2), ctx);
+ }
break;
case BPF_B:
- emit(A64_STRB(tmp, dst, tmp2), ctx);
+ if (is_lsi_offset(off_adj, 0)) {
+ emit(A64_STRBI(tmp, dst_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp2, off, ctx);
+ emit(A64_STRB(tmp, dst, tmp2), ctx);
+ }
break;
case BPF_DW:
- emit(A64_STR64(tmp, dst, tmp2), ctx);
+ if (is_lsi_offset(off_adj, 3)) {
+ emit(A64_STR64I(tmp, dst_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp2, off, ctx);
+ emit(A64_STR64(tmp, dst, tmp2), ctx);
+ }
break;
}
break;
@@ -687,131 +1240,177 @@ emit_cond_jmp:
case BPF_STX | BPF_MEM | BPF_H:
case BPF_STX | BPF_MEM | BPF_B:
case BPF_STX | BPF_MEM | BPF_DW:
- emit_a64_mov_i(1, tmp, off, ctx);
+ if (ctx->fpb_offset > 0 && dst == fp) {
+ dst_adj = fpb;
+ off_adj = off + ctx->fpb_offset;
+ } else {
+ dst_adj = dst;
+ off_adj = off;
+ }
switch (BPF_SIZE(code)) {
case BPF_W:
- emit(A64_STR32(src, dst, tmp), ctx);
+ if (is_lsi_offset(off_adj, 2)) {
+ emit(A64_STR32I(src, dst_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp, off, ctx);
+ emit(A64_STR32(src, dst, tmp), ctx);
+ }
break;
case BPF_H:
- emit(A64_STRH(src, dst, tmp), ctx);
+ if (is_lsi_offset(off_adj, 1)) {
+ emit(A64_STRHI(src, dst_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp, off, ctx);
+ emit(A64_STRH(src, dst, tmp), ctx);
+ }
break;
case BPF_B:
- emit(A64_STRB(src, dst, tmp), ctx);
+ if (is_lsi_offset(off_adj, 0)) {
+ emit(A64_STRBI(src, dst_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp, off, ctx);
+ emit(A64_STRB(src, dst, tmp), ctx);
+ }
break;
case BPF_DW:
- emit(A64_STR64(src, dst, tmp), ctx);
+ if (is_lsi_offset(off_adj, 3)) {
+ emit(A64_STR64I(src, dst_adj, off_adj), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp, off, ctx);
+ emit(A64_STR64(src, dst, tmp), ctx);
+ }
break;
}
break;
- /* STX XADD: lock *(u32 *)(dst + off) += src */
- case BPF_STX | BPF_XADD | BPF_W:
- /* STX XADD: lock *(u64 *)(dst + off) += src */
- case BPF_STX | BPF_XADD | BPF_DW:
- emit_a64_mov_i(1, tmp, off, ctx);
- emit(A64_ADD(1, tmp, tmp, dst), ctx);
- emit(A64_PRFM(tmp, PST, L1, STRM), ctx);
- emit(A64_LDXR(isdw, tmp2, tmp), ctx);
- emit(A64_ADD(isdw, tmp2, tmp2, src), ctx);
- emit(A64_STXR(isdw, tmp2, tmp, tmp3), ctx);
- jmp_offset = -3;
- check_imm19(jmp_offset);
- emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
+
+ case BPF_STX | BPF_ATOMIC | BPF_W:
+ case BPF_STX | BPF_ATOMIC | BPF_DW:
+ if (cpus_have_cap(ARM64_HAS_LSE_ATOMICS))
+ ret = emit_lse_atomic(insn, ctx);
+ else
+ ret = emit_ll_sc_atomic(insn, ctx);
+ if (ret)
+ return ret;
break;
- /* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + imm)) */
- case BPF_LD | BPF_ABS | BPF_W:
- case BPF_LD | BPF_ABS | BPF_H:
- case BPF_LD | BPF_ABS | BPF_B:
- /* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + src + imm)) */
- case BPF_LD | BPF_IND | BPF_W:
- case BPF_LD | BPF_IND | BPF_H:
- case BPF_LD | BPF_IND | BPF_B:
- {
- const u8 r0 = bpf2a64[BPF_REG_0]; /* r0 = return value */
- const u8 r6 = bpf2a64[BPF_REG_6]; /* r6 = pointer to sk_buff */
- const u8 fp = bpf2a64[BPF_REG_FP];
- const u8 r1 = bpf2a64[BPF_REG_1]; /* r1: struct sk_buff *skb */
- const u8 r2 = bpf2a64[BPF_REG_2]; /* r2: int k */
- const u8 r3 = bpf2a64[BPF_REG_3]; /* r3: unsigned int size */
- const u8 r4 = bpf2a64[BPF_REG_4]; /* r4: void *buffer */
- const u8 r5 = bpf2a64[BPF_REG_5]; /* r5: void *(*func)(...) */
- int size;
-
- emit(A64_MOV(1, r1, r6), ctx);
- emit_a64_mov_i(0, r2, imm, ctx);
- if (BPF_MODE(code) == BPF_IND)
- emit(A64_ADD(0, r2, r2, src), ctx);
- switch (BPF_SIZE(code)) {
- case BPF_W:
- size = 4;
- break;
- case BPF_H:
- size = 2;
- break;
- case BPF_B:
- size = 1;
- break;
- default:
- return -EINVAL;
- }
- emit_a64_mov_i64(r3, size, ctx);
- emit(A64_SUB_I(1, r4, fp, ctx->stack_size), ctx);
- emit_a64_mov_i64(r5, (unsigned long)bpf_load_pointer, ctx);
- emit(A64_BLR(r5), ctx);
- emit(A64_MOV(1, r0, A64_R(0)), ctx);
+ default:
+ pr_err_once("unknown opcode %02x\n", code);
+ return -EINVAL;
+ }
- jmp_offset = epilogue_offset(ctx);
- check_imm19(jmp_offset);
- emit(A64_CBZ(1, r0, jmp_offset), ctx);
- emit(A64_MOV(1, r5, r0), ctx);
- switch (BPF_SIZE(code)) {
- case BPF_W:
- emit(A64_LDR32(r0, r5, A64_ZR), ctx);
-#ifndef CONFIG_CPU_BIG_ENDIAN
- emit(A64_REV32(0, r0, r0), ctx);
-#endif
+ return 0;
+}
+
+/*
+ * Return 0 if FP may change at runtime, otherwise find the minimum negative
+ * offset to FP, converts it to positive number, and align down to 8 bytes.
+ */
+static int find_fpb_offset(struct bpf_prog *prog)
+{
+ int i;
+ int offset = 0;
+
+ for (i = 0; i < prog->len; i++) {
+ const struct bpf_insn *insn = &prog->insnsi[i];
+ const u8 class = BPF_CLASS(insn->code);
+ const u8 mode = BPF_MODE(insn->code);
+ const u8 src = insn->src_reg;
+ const u8 dst = insn->dst_reg;
+ const s32 imm = insn->imm;
+ const s16 off = insn->off;
+
+ switch (class) {
+ case BPF_STX:
+ case BPF_ST:
+ /* fp holds atomic operation result */
+ if (class == BPF_STX && mode == BPF_ATOMIC &&
+ ((imm == BPF_XCHG ||
+ imm == (BPF_FETCH | BPF_ADD) ||
+ imm == (BPF_FETCH | BPF_AND) ||
+ imm == (BPF_FETCH | BPF_XOR) ||
+ imm == (BPF_FETCH | BPF_OR)) &&
+ src == BPF_REG_FP))
+ return 0;
+
+ if (mode == BPF_MEM && dst == BPF_REG_FP &&
+ off < offset)
+ offset = insn->off;
break;
- case BPF_H:
- emit(A64_LDRH(r0, r5, A64_ZR), ctx);
-#ifndef CONFIG_CPU_BIG_ENDIAN
- emit(A64_REV16(0, r0, r0), ctx);
-#endif
+
+ case BPF_JMP32:
+ case BPF_JMP:
break;
- case BPF_B:
- emit(A64_LDRB(r0, r5, A64_ZR), ctx);
+
+ case BPF_LDX:
+ case BPF_LD:
+ /* fp holds load result */
+ if (dst == BPF_REG_FP)
+ return 0;
+
+ if (class == BPF_LDX && mode == BPF_MEM &&
+ src == BPF_REG_FP && off < offset)
+ offset = off;
break;
+
+ case BPF_ALU:
+ case BPF_ALU64:
+ default:
+ /* fp holds ALU result */
+ if (dst == BPF_REG_FP)
+ return 0;
}
- break;
}
- default:
- pr_err_once("unknown opcode %02x\n", code);
- return -EINVAL;
+
+ if (offset < 0) {
+ /*
+ * safely be converted to a positive 'int', since insn->off
+ * is 's16'
+ */
+ offset = -offset;
+ /* align down to 8 bytes */
+ offset = ALIGN_DOWN(offset, 8);
}
- return 0;
+ return offset;
}
-static int build_body(struct jit_ctx *ctx)
+static int build_body(struct jit_ctx *ctx, bool extra_pass)
{
const struct bpf_prog *prog = ctx->prog;
int i;
+ /*
+ * - offset[0] offset of the end of prologue,
+ * start of the 1st instruction.
+ * - offset[1] - offset of the end of 1st instruction,
+ * start of the 2nd instruction
+ * [....]
+ * - offset[3] - offset of the end of 3rd instruction,
+ * start of 4th instruction
+ */
for (i = 0; i < prog->len; i++) {
const struct bpf_insn *insn = &prog->insnsi[i];
int ret;
- ret = build_insn(insn, ctx);
+ if (ctx->image == NULL)
+ ctx->offset[i] = ctx->idx;
+ ret = build_insn(insn, ctx, extra_pass);
if (ret > 0) {
i++;
if (ctx->image == NULL)
ctx->offset[i] = ctx->idx;
continue;
}
- if (ctx->image == NULL)
- ctx->offset[i] = ctx->idx;
if (ret)
return ret;
}
+ /*
+ * offset is allocated with prog->len + 1 so fill in
+ * the last element with the offset after the last
+ * instruction (end of program)
+ */
+ if (ctx->image == NULL)
+ ctx->offset[i] = ctx->idx;
return 0;
}
@@ -826,6 +1425,16 @@ static int validate_code(struct jit_ctx *ctx)
if (a64_insn == AARCH64_BREAK_FAULT)
return -1;
}
+ return 0;
+}
+
+static int validate_ctx(struct jit_ctx *ctx)
+{
+ if (validate_code(ctx))
+ return -1;
+
+ if (WARN_ON_ONCE(ctx->exentry_idx != ctx->prog->aux->num_exentries))
+ return -1;
return 0;
}
@@ -835,16 +1444,25 @@ static inline void bpf_flush_icache(void *start, void *end)
flush_icache_range((unsigned long)start, (unsigned long)end);
}
+struct arm64_jit_data {
+ struct bpf_binary_header *header;
+ u8 *image;
+ struct jit_ctx ctx;
+};
+
struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
{
+ int image_size, prog_size, extable_size, extable_align, extable_offset;
struct bpf_prog *tmp, *orig_prog = prog;
struct bpf_binary_header *header;
+ struct arm64_jit_data *jit_data;
+ bool was_classic = bpf_prog_was_classic(prog);
bool tmp_blinded = false;
+ bool extra_pass = false;
struct jit_ctx ctx;
- int image_size;
u8 *image_ptr;
- if (!bpf_jit_enable)
+ if (!prog->jit_requested)
return orig_prog;
tmp = bpf_jit_blind_constants(prog);
@@ -858,33 +1476,63 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
prog = tmp;
}
+ jit_data = prog->aux->jit_data;
+ if (!jit_data) {
+ jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
+ if (!jit_data) {
+ prog = orig_prog;
+ goto out;
+ }
+ prog->aux->jit_data = jit_data;
+ }
+ if (jit_data->ctx.offset) {
+ ctx = jit_data->ctx;
+ image_ptr = jit_data->image;
+ header = jit_data->header;
+ extra_pass = true;
+ prog_size = sizeof(u32) * ctx.idx;
+ goto skip_init_ctx;
+ }
memset(&ctx, 0, sizeof(ctx));
ctx.prog = prog;
- ctx.offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL);
+ ctx.offset = kvcalloc(prog->len + 1, sizeof(int), GFP_KERNEL);
if (ctx.offset == NULL) {
prog = orig_prog;
- goto out;
+ goto out_off;
}
- /* 1. Initial fake pass to compute ctx->idx. */
+ ctx.fpb_offset = find_fpb_offset(prog);
- /* Fake pass to fill in ctx->offset. */
- if (build_body(&ctx)) {
+ /*
+ * 1. Initial fake pass to compute ctx->idx and ctx->offset.
+ *
+ * BPF line info needs ctx->offset[i] to be the offset of
+ * instruction[i] in jited image, so build prologue first.
+ */
+ if (build_prologue(&ctx, was_classic)) {
prog = orig_prog;
goto out_off;
}
- if (build_prologue(&ctx)) {
+ if (build_body(&ctx, extra_pass)) {
prog = orig_prog;
goto out_off;
}
ctx.epilogue_offset = ctx.idx;
build_epilogue(&ctx);
+ build_plt(&ctx);
+
+ extable_align = __alignof__(struct exception_table_entry);
+ extable_size = prog->aux->num_exentries *
+ sizeof(struct exception_table_entry);
/* Now we know the actual image size. */
- image_size = sizeof(u32) * ctx.idx;
+ prog_size = sizeof(u32) * ctx.idx;
+ /* also allocate space for plt target */
+ extable_offset = round_up(prog_size + PLT_TARGET_SIZE, extable_align);
+ image_size = extable_offset + extable_size;
header = bpf_jit_binary_alloc(image_size, &image_ptr,
sizeof(u32), jit_fill_hole);
if (header == NULL) {
@@ -895,20 +1543,25 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
/* 2. Now, the actual pass. */
ctx.image = (__le32 *)image_ptr;
+ if (extable_size)
+ prog->aux->extable = (void *)image_ptr + extable_offset;
+skip_init_ctx:
ctx.idx = 0;
+ ctx.exentry_idx = 0;
- build_prologue(&ctx);
+ build_prologue(&ctx, was_classic);
- if (build_body(&ctx)) {
+ if (build_body(&ctx, extra_pass)) {
bpf_jit_binary_free(header);
prog = orig_prog;
goto out_off;
}
build_epilogue(&ctx);
+ build_plt(&ctx);
/* 3. Extra pass to validate JITed code. */
- if (validate_code(&ctx)) {
+ if (validate_ctx(&ctx)) {
bpf_jit_binary_free(header);
prog = orig_prog;
goto out_off;
@@ -916,20 +1569,658 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
/* And we're done. */
if (bpf_jit_enable > 1)
- bpf_jit_dump(prog->len, image_size, 2, ctx.image);
+ bpf_jit_dump(prog->len, prog_size, 2, ctx.image);
bpf_flush_icache(header, ctx.image + ctx.idx);
- bpf_jit_binary_lock_ro(header);
+ if (!prog->is_func || extra_pass) {
+ if (extra_pass && ctx.idx != jit_data->ctx.idx) {
+ pr_err_once("multi-func JIT bug %d != %d\n",
+ ctx.idx, jit_data->ctx.idx);
+ bpf_jit_binary_free(header);
+ prog->bpf_func = NULL;
+ prog->jited = 0;
+ prog->jited_len = 0;
+ goto out_off;
+ }
+ bpf_jit_binary_lock_ro(header);
+ } else {
+ jit_data->ctx = ctx;
+ jit_data->image = image_ptr;
+ jit_data->header = header;
+ }
prog->bpf_func = (void *)ctx.image;
prog->jited = 1;
- prog->jited_len = image_size;
+ prog->jited_len = prog_size;
+
+ if (!prog->is_func || extra_pass) {
+ int i;
+ /* offset[prog->len] is the size of program */
+ for (i = 0; i <= prog->len; i++)
+ ctx.offset[i] *= AARCH64_INSN_SIZE;
+ bpf_prog_fill_jited_linfo(prog, ctx.offset + 1);
out_off:
- kfree(ctx.offset);
+ kvfree(ctx.offset);
+ kfree(jit_data);
+ prog->aux->jit_data = NULL;
+ }
out:
if (tmp_blinded)
bpf_jit_prog_release_other(prog, prog == orig_prog ?
tmp : orig_prog);
return prog;
}
+
+bool bpf_jit_supports_kfunc_call(void)
+{
+ return true;
+}
+
+u64 bpf_jit_alloc_exec_limit(void)
+{
+ return VMALLOC_END - VMALLOC_START;
+}
+
+void *bpf_jit_alloc_exec(unsigned long size)
+{
+ /* Memory is intended to be executable, reset the pointer tag. */
+ return kasan_reset_tag(vmalloc(size));
+}
+
+void bpf_jit_free_exec(void *addr)
+{
+ return vfree(addr);
+}
+
+/* Indicate the JIT backend supports mixing bpf2bpf and tailcalls. */
+bool bpf_jit_supports_subprog_tailcalls(void)
+{
+ return true;
+}
+
+static void invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l,
+ int args_off, int retval_off, int run_ctx_off,
+ bool save_ret)
+{
+ __le32 *branch;
+ u64 enter_prog;
+ u64 exit_prog;
+ struct bpf_prog *p = l->link.prog;
+ int cookie_off = offsetof(struct bpf_tramp_run_ctx, bpf_cookie);
+
+ if (p->aux->sleepable) {
+ enter_prog = (u64)__bpf_prog_enter_sleepable;
+ exit_prog = (u64)__bpf_prog_exit_sleepable;
+ } else {
+ enter_prog = (u64)__bpf_prog_enter;
+ exit_prog = (u64)__bpf_prog_exit;
+ }
+
+ if (l->cookie == 0) {
+ /* if cookie is zero, one instruction is enough to store it */
+ emit(A64_STR64I(A64_ZR, A64_SP, run_ctx_off + cookie_off), ctx);
+ } else {
+ emit_a64_mov_i64(A64_R(10), l->cookie, ctx);
+ emit(A64_STR64I(A64_R(10), A64_SP, run_ctx_off + cookie_off),
+ ctx);
+ }
+
+ /* save p to callee saved register x19 to avoid loading p with mov_i64
+ * each time.
+ */
+ emit_addr_mov_i64(A64_R(19), (const u64)p, ctx);
+
+ /* arg1: prog */
+ emit(A64_MOV(1, A64_R(0), A64_R(19)), ctx);
+ /* arg2: &run_ctx */
+ emit(A64_ADD_I(1, A64_R(1), A64_SP, run_ctx_off), ctx);
+
+ emit_call(enter_prog, ctx);
+
+ /* if (__bpf_prog_enter(prog) == 0)
+ * goto skip_exec_of_prog;
+ */
+ branch = ctx->image + ctx->idx;
+ emit(A64_NOP, ctx);
+
+ /* save return value to callee saved register x20 */
+ emit(A64_MOV(1, A64_R(20), A64_R(0)), ctx);
+
+ emit(A64_ADD_I(1, A64_R(0), A64_SP, args_off), ctx);
+ if (!p->jited)
+ emit_addr_mov_i64(A64_R(1), (const u64)p->insnsi, ctx);
+
+ emit_call((const u64)p->bpf_func, ctx);
+
+ if (save_ret)
+ emit(A64_STR64I(A64_R(0), A64_SP, retval_off), ctx);
+
+ if (ctx->image) {
+ int offset = &ctx->image[ctx->idx] - branch;
+ *branch = cpu_to_le32(A64_CBZ(1, A64_R(0), offset));
+ }
+
+ /* arg1: prog */
+ emit(A64_MOV(1, A64_R(0), A64_R(19)), ctx);
+ /* arg2: start time */
+ emit(A64_MOV(1, A64_R(1), A64_R(20)), ctx);
+ /* arg3: &run_ctx */
+ emit(A64_ADD_I(1, A64_R(2), A64_SP, run_ctx_off), ctx);
+
+ emit_call(exit_prog, ctx);
+}
+
+static void invoke_bpf_mod_ret(struct jit_ctx *ctx, struct bpf_tramp_links *tl,
+ int args_off, int retval_off, int run_ctx_off,
+ __le32 **branches)
+{
+ int i;
+
+ /* The first fmod_ret program will receive a garbage return value.
+ * Set this to 0 to avoid confusing the program.
+ */
+ emit(A64_STR64I(A64_ZR, A64_SP, retval_off), ctx);
+ for (i = 0; i < tl->nr_links; i++) {
+ invoke_bpf_prog(ctx, tl->links[i], args_off, retval_off,
+ run_ctx_off, true);
+ /* if (*(u64 *)(sp + retval_off) != 0)
+ * goto do_fexit;
+ */
+ emit(A64_LDR64I(A64_R(10), A64_SP, retval_off), ctx);
+ /* Save the location of branch, and generate a nop.
+ * This nop will be replaced with a cbnz later.
+ */
+ branches[i] = ctx->image + ctx->idx;
+ emit(A64_NOP, ctx);
+ }
+}
+
+static void save_args(struct jit_ctx *ctx, int args_off, int nargs)
+{
+ int i;
+
+ for (i = 0; i < nargs; i++) {
+ emit(A64_STR64I(i, A64_SP, args_off), ctx);
+ args_off += 8;
+ }
+}
+
+static void restore_args(struct jit_ctx *ctx, int args_off, int nargs)
+{
+ int i;
+
+ for (i = 0; i < nargs; i++) {
+ emit(A64_LDR64I(i, A64_SP, args_off), ctx);
+ args_off += 8;
+ }
+}
+
+/* Based on the x86's implementation of arch_prepare_bpf_trampoline().
+ *
+ * bpf prog and function entry before bpf trampoline hooked:
+ * mov x9, lr
+ * nop
+ *
+ * bpf prog and function entry after bpf trampoline hooked:
+ * mov x9, lr
+ * bl <bpf_trampoline or plt>
+ *
+ */
+static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im,
+ struct bpf_tramp_links *tlinks, void *orig_call,
+ int nargs, u32 flags)
+{
+ int i;
+ int stack_size;
+ int retaddr_off;
+ int regs_off;
+ int retval_off;
+ int args_off;
+ int nargs_off;
+ int ip_off;
+ int run_ctx_off;
+ struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
+ struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
+ struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN];
+ bool save_ret;
+ __le32 **branches = NULL;
+
+ /* trampoline stack layout:
+ * [ parent ip ]
+ * [ FP ]
+ * SP + retaddr_off [ self ip ]
+ * [ FP ]
+ *
+ * [ padding ] align SP to multiples of 16
+ *
+ * [ x20 ] callee saved reg x20
+ * SP + regs_off [ x19 ] callee saved reg x19
+ *
+ * SP + retval_off [ return value ] BPF_TRAMP_F_CALL_ORIG or
+ * BPF_TRAMP_F_RET_FENTRY_RET
+ *
+ * [ argN ]
+ * [ ... ]
+ * SP + args_off [ arg1 ]
+ *
+ * SP + nargs_off [ args count ]
+ *
+ * SP + ip_off [ traced function ] BPF_TRAMP_F_IP_ARG flag
+ *
+ * SP + run_ctx_off [ bpf_tramp_run_ctx ]
+ */
+
+ stack_size = 0;
+ run_ctx_off = stack_size;
+ /* room for bpf_tramp_run_ctx */
+ stack_size += round_up(sizeof(struct bpf_tramp_run_ctx), 8);
+
+ ip_off = stack_size;
+ /* room for IP address argument */
+ if (flags & BPF_TRAMP_F_IP_ARG)
+ stack_size += 8;
+
+ nargs_off = stack_size;
+ /* room for args count */
+ stack_size += 8;
+
+ args_off = stack_size;
+ /* room for args */
+ stack_size += nargs * 8;
+
+ /* room for return value */
+ retval_off = stack_size;
+ save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET);
+ if (save_ret)
+ stack_size += 8;
+
+ /* room for callee saved registers, currently x19 and x20 are used */
+ regs_off = stack_size;
+ stack_size += 16;
+
+ /* round up to multiples of 16 to avoid SPAlignmentFault */
+ stack_size = round_up(stack_size, 16);
+
+ /* return address locates above FP */
+ retaddr_off = stack_size + 8;
+
+ /* bpf trampoline may be invoked by 3 instruction types:
+ * 1. bl, attached to bpf prog or kernel function via short jump
+ * 2. br, attached to bpf prog or kernel function via long jump
+ * 3. blr, working as a function pointer, used by struct_ops.
+ * So BTI_JC should used here to support both br and blr.
+ */
+ emit_bti(A64_BTI_JC, ctx);
+
+ /* frame for parent function */
+ emit(A64_PUSH(A64_FP, A64_R(9), A64_SP), ctx);
+ emit(A64_MOV(1, A64_FP, A64_SP), ctx);
+
+ /* frame for patched function */
+ emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
+ emit(A64_MOV(1, A64_FP, A64_SP), ctx);
+
+ /* allocate stack space */
+ emit(A64_SUB_I(1, A64_SP, A64_SP, stack_size), ctx);
+
+ if (flags & BPF_TRAMP_F_IP_ARG) {
+ /* save ip address of the traced function */
+ emit_addr_mov_i64(A64_R(10), (const u64)orig_call, ctx);
+ emit(A64_STR64I(A64_R(10), A64_SP, ip_off), ctx);
+ }
+
+ /* save args count*/
+ emit(A64_MOVZ(1, A64_R(10), nargs, 0), ctx);
+ emit(A64_STR64I(A64_R(10), A64_SP, nargs_off), ctx);
+
+ /* save args */
+ save_args(ctx, args_off, nargs);
+
+ /* save callee saved registers */
+ emit(A64_STR64I(A64_R(19), A64_SP, regs_off), ctx);
+ emit(A64_STR64I(A64_R(20), A64_SP, regs_off + 8), ctx);
+
+ if (flags & BPF_TRAMP_F_CALL_ORIG) {
+ emit_addr_mov_i64(A64_R(0), (const u64)im, ctx);
+ emit_call((const u64)__bpf_tramp_enter, ctx);
+ }
+
+ for (i = 0; i < fentry->nr_links; i++)
+ invoke_bpf_prog(ctx, fentry->links[i], args_off,
+ retval_off, run_ctx_off,
+ flags & BPF_TRAMP_F_RET_FENTRY_RET);
+
+ if (fmod_ret->nr_links) {
+ branches = kcalloc(fmod_ret->nr_links, sizeof(__le32 *),
+ GFP_KERNEL);
+ if (!branches)
+ return -ENOMEM;
+
+ invoke_bpf_mod_ret(ctx, fmod_ret, args_off, retval_off,
+ run_ctx_off, branches);
+ }
+
+ if (flags & BPF_TRAMP_F_CALL_ORIG) {
+ restore_args(ctx, args_off, nargs);
+ /* call original func */
+ emit(A64_LDR64I(A64_R(10), A64_SP, retaddr_off), ctx);
+ emit(A64_BLR(A64_R(10)), ctx);
+ /* store return value */
+ emit(A64_STR64I(A64_R(0), A64_SP, retval_off), ctx);
+ /* reserve a nop for bpf_tramp_image_put */
+ im->ip_after_call = ctx->image + ctx->idx;
+ emit(A64_NOP, ctx);
+ }
+
+ /* update the branches saved in invoke_bpf_mod_ret with cbnz */
+ for (i = 0; i < fmod_ret->nr_links && ctx->image != NULL; i++) {
+ int offset = &ctx->image[ctx->idx] - branches[i];
+ *branches[i] = cpu_to_le32(A64_CBNZ(1, A64_R(10), offset));
+ }
+
+ for (i = 0; i < fexit->nr_links; i++)
+ invoke_bpf_prog(ctx, fexit->links[i], args_off, retval_off,
+ run_ctx_off, false);
+
+ if (flags & BPF_TRAMP_F_CALL_ORIG) {
+ im->ip_epilogue = ctx->image + ctx->idx;
+ emit_addr_mov_i64(A64_R(0), (const u64)im, ctx);
+ emit_call((const u64)__bpf_tramp_exit, ctx);
+ }
+
+ if (flags & BPF_TRAMP_F_RESTORE_REGS)
+ restore_args(ctx, args_off, nargs);
+
+ /* restore callee saved register x19 and x20 */
+ emit(A64_LDR64I(A64_R(19), A64_SP, regs_off), ctx);
+ emit(A64_LDR64I(A64_R(20), A64_SP, regs_off + 8), ctx);
+
+ if (save_ret)
+ emit(A64_LDR64I(A64_R(0), A64_SP, retval_off), ctx);
+
+ /* reset SP */
+ emit(A64_MOV(1, A64_SP, A64_FP), ctx);
+
+ /* pop frames */
+ emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx);
+ emit(A64_POP(A64_FP, A64_R(9), A64_SP), ctx);
+
+ if (flags & BPF_TRAMP_F_SKIP_FRAME) {
+ /* skip patched function, return to parent */
+ emit(A64_MOV(1, A64_LR, A64_R(9)), ctx);
+ emit(A64_RET(A64_R(9)), ctx);
+ } else {
+ /* return to patched function */
+ emit(A64_MOV(1, A64_R(10), A64_LR), ctx);
+ emit(A64_MOV(1, A64_LR, A64_R(9)), ctx);
+ emit(A64_RET(A64_R(10)), ctx);
+ }
+
+ if (ctx->image)
+ bpf_flush_icache(ctx->image, ctx->image + ctx->idx);
+
+ kfree(branches);
+
+ return ctx->idx;
+}
+
+int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image,
+ void *image_end, const struct btf_func_model *m,
+ u32 flags, struct bpf_tramp_links *tlinks,
+ void *orig_call)
+{
+ int i, ret;
+ int nargs = m->nr_args;
+ int max_insns = ((long)image_end - (long)image) / AARCH64_INSN_SIZE;
+ struct jit_ctx ctx = {
+ .image = NULL,
+ .idx = 0,
+ };
+
+ /* the first 8 arguments are passed by registers */
+ if (nargs > 8)
+ return -ENOTSUPP;
+
+ /* don't support struct argument */
+ for (i = 0; i < MAX_BPF_FUNC_ARGS; i++) {
+ if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG)
+ return -ENOTSUPP;
+ }
+
+ ret = prepare_trampoline(&ctx, im, tlinks, orig_call, nargs, flags);
+ if (ret < 0)
+ return ret;
+
+ if (ret > max_insns)
+ return -EFBIG;
+
+ ctx.image = image;
+ ctx.idx = 0;
+
+ jit_fill_hole(image, (unsigned int)(image_end - image));
+ ret = prepare_trampoline(&ctx, im, tlinks, orig_call, nargs, flags);
+
+ if (ret > 0 && validate_code(&ctx) < 0)
+ ret = -EINVAL;
+
+ if (ret > 0)
+ ret *= AARCH64_INSN_SIZE;
+
+ return ret;
+}
+
+static bool is_long_jump(void *ip, void *target)
+{
+ long offset;
+
+ /* NULL target means this is a NOP */
+ if (!target)
+ return false;
+
+ offset = (long)target - (long)ip;
+ return offset < -SZ_128M || offset >= SZ_128M;
+}
+
+static int gen_branch_or_nop(enum aarch64_insn_branch_type type, void *ip,
+ void *addr, void *plt, u32 *insn)
+{
+ void *target;
+
+ if (!addr) {
+ *insn = aarch64_insn_gen_nop();
+ return 0;
+ }
+
+ if (is_long_jump(ip, addr))
+ target = plt;
+ else
+ target = addr;
+
+ *insn = aarch64_insn_gen_branch_imm((unsigned long)ip,
+ (unsigned long)target,
+ type);
+
+ return *insn != AARCH64_BREAK_FAULT ? 0 : -EFAULT;
+}
+
+/* Replace the branch instruction from @ip to @old_addr in a bpf prog or a bpf
+ * trampoline with the branch instruction from @ip to @new_addr. If @old_addr
+ * or @new_addr is NULL, the old or new instruction is NOP.
+ *
+ * When @ip is the bpf prog entry, a bpf trampoline is being attached or
+ * detached. Since bpf trampoline and bpf prog are allocated separately with
+ * vmalloc, the address distance may exceed 128MB, the maximum branch range.
+ * So long jump should be handled.
+ *
+ * When a bpf prog is constructed, a plt pointing to empty trampoline
+ * dummy_tramp is placed at the end:
+ *
+ * bpf_prog:
+ * mov x9, lr
+ * nop // patchsite
+ * ...
+ * ret
+ *
+ * plt:
+ * ldr x10, target
+ * br x10
+ * target:
+ * .quad dummy_tramp // plt target
+ *
+ * This is also the state when no trampoline is attached.
+ *
+ * When a short-jump bpf trampoline is attached, the patchsite is patched
+ * to a bl instruction to the trampoline directly:
+ *
+ * bpf_prog:
+ * mov x9, lr
+ * bl <short-jump bpf trampoline address> // patchsite
+ * ...
+ * ret
+ *
+ * plt:
+ * ldr x10, target
+ * br x10
+ * target:
+ * .quad dummy_tramp // plt target
+ *
+ * When a long-jump bpf trampoline is attached, the plt target is filled with
+ * the trampoline address and the patchsite is patched to a bl instruction to
+ * the plt:
+ *
+ * bpf_prog:
+ * mov x9, lr
+ * bl plt // patchsite
+ * ...
+ * ret
+ *
+ * plt:
+ * ldr x10, target
+ * br x10
+ * target:
+ * .quad <long-jump bpf trampoline address> // plt target
+ *
+ * The dummy_tramp is used to prevent another CPU from jumping to unknown
+ * locations during the patching process, making the patching process easier.
+ */
+int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type,
+ void *old_addr, void *new_addr)
+{
+ int ret;
+ u32 old_insn;
+ u32 new_insn;
+ u32 replaced;
+ struct bpf_plt *plt = NULL;
+ unsigned long size = 0UL;
+ unsigned long offset = ~0UL;
+ enum aarch64_insn_branch_type branch_type;
+ char namebuf[KSYM_NAME_LEN];
+ void *image = NULL;
+ u64 plt_target = 0ULL;
+ bool poking_bpf_entry;
+
+ if (!__bpf_address_lookup((unsigned long)ip, &size, &offset, namebuf))
+ /* Only poking bpf text is supported. Since kernel function
+ * entry is set up by ftrace, we reply on ftrace to poke kernel
+ * functions.
+ */
+ return -ENOTSUPP;
+
+ image = ip - offset;
+ /* zero offset means we're poking bpf prog entry */
+ poking_bpf_entry = (offset == 0UL);
+
+ /* bpf prog entry, find plt and the real patchsite */
+ if (poking_bpf_entry) {
+ /* plt locates at the end of bpf prog */
+ plt = image + size - PLT_TARGET_OFFSET;
+
+ /* skip to the nop instruction in bpf prog entry:
+ * bti c // if BTI enabled
+ * mov x9, x30
+ * nop
+ */
+ ip = image + POKE_OFFSET * AARCH64_INSN_SIZE;
+ }
+
+ /* long jump is only possible at bpf prog entry */
+ if (WARN_ON((is_long_jump(ip, new_addr) || is_long_jump(ip, old_addr)) &&
+ !poking_bpf_entry))
+ return -EINVAL;
+
+ if (poke_type == BPF_MOD_CALL)
+ branch_type = AARCH64_INSN_BRANCH_LINK;
+ else
+ branch_type = AARCH64_INSN_BRANCH_NOLINK;
+
+ if (gen_branch_or_nop(branch_type, ip, old_addr, plt, &old_insn) < 0)
+ return -EFAULT;
+
+ if (gen_branch_or_nop(branch_type, ip, new_addr, plt, &new_insn) < 0)
+ return -EFAULT;
+
+ if (is_long_jump(ip, new_addr))
+ plt_target = (u64)new_addr;
+ else if (is_long_jump(ip, old_addr))
+ /* if the old target is a long jump and the new target is not,
+ * restore the plt target to dummy_tramp, so there is always a
+ * legal and harmless address stored in plt target, and we'll
+ * never jump from plt to an unknown place.
+ */
+ plt_target = (u64)&dummy_tramp;
+
+ if (plt_target) {
+ /* non-zero plt_target indicates we're patching a bpf prog,
+ * which is read only.
+ */
+ if (set_memory_rw(PAGE_MASK & ((uintptr_t)&plt->target), 1))
+ return -EFAULT;
+ WRITE_ONCE(plt->target, plt_target);
+ set_memory_ro(PAGE_MASK & ((uintptr_t)&plt->target), 1);
+ /* since plt target points to either the new trampoline
+ * or dummy_tramp, even if another CPU reads the old plt
+ * target value before fetching the bl instruction to plt,
+ * it will be brought back by dummy_tramp, so no barrier is
+ * required here.
+ */
+ }
+
+ /* if the old target and the new target are both long jumps, no
+ * patching is required
+ */
+ if (old_insn == new_insn)
+ return 0;
+
+ mutex_lock(&text_mutex);
+ if (aarch64_insn_read(ip, &replaced)) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ if (replaced != old_insn) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ /* We call aarch64_insn_patch_text_nosync() to replace instruction
+ * atomically, so no other CPUs will fetch a half-new and half-old
+ * instruction. But there is chance that another CPU executes the
+ * old instruction after the patching operation finishes (e.g.,
+ * pipeline not flushed, or icache not synchronized yet).
+ *
+ * 1. when a new trampoline is attached, it is not a problem for
+ * different CPUs to jump to different trampolines temporarily.
+ *
+ * 2. when an old trampoline is freed, we should wait for all other
+ * CPUs to exit the trampoline and make sure the trampoline is no
+ * longer reachable, since bpf_tramp_image_put() function already
+ * uses percpu_ref and task-based rcu to do the sync, no need to call
+ * the sync version here, see bpf_tramp_image_put() for details.
+ */
+ ret = aarch64_insn_patch_text_nosync(ip, new_insn);
+out:
+ mutex_unlock(&text_mutex);
+
+ return ret;
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.