aboutsummaryrefslogtreecommitdiffstats
path: root/arch/riscv/net/bpf_jit_comp32.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/riscv/net/bpf_jit_comp32.c')
-rw-r--r--arch/riscv/net/bpf_jit_comp32.c103
1 files changed, 68 insertions, 35 deletions
diff --git a/arch/riscv/net/bpf_jit_comp32.c b/arch/riscv/net/bpf_jit_comp32.c
index 302934177760..b198eaa74456 100644
--- a/arch/riscv/net/bpf_jit_comp32.c
+++ b/arch/riscv/net/bpf_jit_comp32.c
@@ -13,8 +13,35 @@
#include <linux/filter.h>
#include "bpf_jit.h"
+/*
+ * Stack layout during BPF program execution:
+ *
+ * high
+ * RV32 fp => +----------+
+ * | saved ra |
+ * | saved fp | RV32 callee-saved registers
+ * | ... |
+ * +----------+ <= (fp - 4 * NR_SAVED_REGISTERS)
+ * | hi(R6) |
+ * | lo(R6) |
+ * | hi(R7) | JIT scratch space for BPF registers
+ * | lo(R7) |
+ * | ... |
+ * BPF_REG_FP => +----------+ <= (fp - 4 * NR_SAVED_REGISTERS
+ * | | - 4 * BPF_JIT_SCRATCH_REGS)
+ * | |
+ * | ... | BPF program stack
+ * | |
+ * RV32 sp => +----------+
+ * | |
+ * | ... | Function call stack
+ * | |
+ * +----------+
+ * low
+ */
+
enum {
- /* Stack layout - these are offsets from (top of stack - 4). */
+ /* Stack layout - these are offsets from top of JIT scratch space. */
BPF_R6_HI,
BPF_R6_LO,
BPF_R7_HI,
@@ -29,7 +56,11 @@ enum {
BPF_JIT_SCRATCH_REGS,
};
-#define STACK_OFFSET(k) (-4 - ((k) * 4))
+/* Number of callee-saved registers stored to stack: ra, fp, s1--s7. */
+#define NR_SAVED_REGISTERS 9
+
+/* Offset from fp for BPF registers stored on stack. */
+#define STACK_OFFSET(k) (-4 - (4 * NR_SAVED_REGISTERS) - (4 * (k)))
#define TMP_REG_1 (MAX_BPF_JIT_REG + 0)
#define TMP_REG_2 (MAX_BPF_JIT_REG + 1)
@@ -111,11 +142,9 @@ static void emit_imm64(const s8 *rd, s32 imm_hi, s32 imm_lo,
static void __build_epilogue(bool is_tail_call, struct rv_jit_context *ctx)
{
- int stack_adjust = ctx->stack_size, store_offset = stack_adjust - 4;
+ int stack_adjust = ctx->stack_size;
const s8 *r0 = bpf2rv32[BPF_REG_0];
- store_offset -= 4 * BPF_JIT_SCRATCH_REGS;
-
/* Set return value if not tail call. */
if (!is_tail_call) {
emit(rv_addi(RV_REG_A0, lo(r0), 0), ctx);
@@ -123,15 +152,15 @@ static void __build_epilogue(bool is_tail_call, struct rv_jit_context *ctx)
}
/* Restore callee-saved registers. */
- emit(rv_lw(RV_REG_RA, store_offset - 0, RV_REG_SP), ctx);
- emit(rv_lw(RV_REG_FP, store_offset - 4, RV_REG_SP), ctx);
- emit(rv_lw(RV_REG_S1, store_offset - 8, RV_REG_SP), ctx);
- emit(rv_lw(RV_REG_S2, store_offset - 12, RV_REG_SP), ctx);
- emit(rv_lw(RV_REG_S3, store_offset - 16, RV_REG_SP), ctx);
- emit(rv_lw(RV_REG_S4, store_offset - 20, RV_REG_SP), ctx);
- emit(rv_lw(RV_REG_S5, store_offset - 24, RV_REG_SP), ctx);
- emit(rv_lw(RV_REG_S6, store_offset - 28, RV_REG_SP), ctx);
- emit(rv_lw(RV_REG_S7, store_offset - 32, RV_REG_SP), ctx);
+ emit(rv_lw(RV_REG_RA, stack_adjust - 4, RV_REG_SP), ctx);
+ emit(rv_lw(RV_REG_FP, stack_adjust - 8, RV_REG_SP), ctx);
+ emit(rv_lw(RV_REG_S1, stack_adjust - 12, RV_REG_SP), ctx);
+ emit(rv_lw(RV_REG_S2, stack_adjust - 16, RV_REG_SP), ctx);
+ emit(rv_lw(RV_REG_S3, stack_adjust - 20, RV_REG_SP), ctx);
+ emit(rv_lw(RV_REG_S4, stack_adjust - 24, RV_REG_SP), ctx);
+ emit(rv_lw(RV_REG_S5, stack_adjust - 28, RV_REG_SP), ctx);
+ emit(rv_lw(RV_REG_S6, stack_adjust - 32, RV_REG_SP), ctx);
+ emit(rv_lw(RV_REG_S7, stack_adjust - 36, RV_REG_SP), ctx);
emit(rv_addi(RV_REG_SP, RV_REG_SP, stack_adjust), ctx);
@@ -770,12 +799,13 @@ static int emit_bpf_tail_call(int insn, struct rv_jit_context *ctx)
emit_bcc(BPF_JGE, lo(idx_reg), RV_REG_T1, off, ctx);
/*
- * if ((temp_tcc = tcc - 1) < 0)
+ * temp_tcc = tcc - 1;
+ * if (tcc < 0)
* goto out;
*/
emit(rv_addi(RV_REG_T1, RV_REG_TCC, -1), ctx);
off = (tc_ninsn - (ctx->ninsns - start_insn)) << 2;
- emit_bcc(BPF_JSLT, RV_REG_T1, RV_REG_ZERO, off, ctx);
+ emit_bcc(BPF_JSLT, RV_REG_TCC, RV_REG_ZERO, off, ctx);
/*
* prog = array->ptrs[index];
@@ -1259,17 +1289,20 @@ notsupported:
void bpf_jit_build_prologue(struct rv_jit_context *ctx)
{
- /* Make space to save 9 registers: ra, fp, s1--s7. */
- int stack_adjust = 9 * sizeof(u32), store_offset, bpf_stack_adjust;
const s8 *fp = bpf2rv32[BPF_REG_FP];
const s8 *r1 = bpf2rv32[BPF_REG_1];
-
- bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
+ int stack_adjust = 0;
+ int bpf_stack_adjust =
+ round_up(ctx->prog->aux->stack_depth, STACK_ALIGN);
+
+ /* Make space for callee-saved registers. */
+ stack_adjust += NR_SAVED_REGISTERS * sizeof(u32);
+ /* Make space for BPF registers on stack. */
+ stack_adjust += BPF_JIT_SCRATCH_REGS * sizeof(u32);
+ /* Make space for BPF stack. */
stack_adjust += bpf_stack_adjust;
-
- store_offset = stack_adjust - 4;
-
- stack_adjust += 4 * BPF_JIT_SCRATCH_REGS;
+ /* Round up for stack alignment. */
+ stack_adjust = round_up(stack_adjust, STACK_ALIGN);
/*
* The first instruction sets the tail-call-counter (TCC) register.
@@ -1280,24 +1313,24 @@ void bpf_jit_build_prologue(struct rv_jit_context *ctx)
emit(rv_addi(RV_REG_SP, RV_REG_SP, -stack_adjust), ctx);
/* Save callee-save registers. */
- emit(rv_sw(RV_REG_SP, store_offset - 0, RV_REG_RA), ctx);
- emit(rv_sw(RV_REG_SP, store_offset - 4, RV_REG_FP), ctx);
- emit(rv_sw(RV_REG_SP, store_offset - 8, RV_REG_S1), ctx);
- emit(rv_sw(RV_REG_SP, store_offset - 12, RV_REG_S2), ctx);
- emit(rv_sw(RV_REG_SP, store_offset - 16, RV_REG_S3), ctx);
- emit(rv_sw(RV_REG_SP, store_offset - 20, RV_REG_S4), ctx);
- emit(rv_sw(RV_REG_SP, store_offset - 24, RV_REG_S5), ctx);
- emit(rv_sw(RV_REG_SP, store_offset - 28, RV_REG_S6), ctx);
- emit(rv_sw(RV_REG_SP, store_offset - 32, RV_REG_S7), ctx);
+ emit(rv_sw(RV_REG_SP, stack_adjust - 4, RV_REG_RA), ctx);
+ emit(rv_sw(RV_REG_SP, stack_adjust - 8, RV_REG_FP), ctx);
+ emit(rv_sw(RV_REG_SP, stack_adjust - 12, RV_REG_S1), ctx);
+ emit(rv_sw(RV_REG_SP, stack_adjust - 16, RV_REG_S2), ctx);
+ emit(rv_sw(RV_REG_SP, stack_adjust - 20, RV_REG_S3), ctx);
+ emit(rv_sw(RV_REG_SP, stack_adjust - 24, RV_REG_S4), ctx);
+ emit(rv_sw(RV_REG_SP, stack_adjust - 28, RV_REG_S5), ctx);
+ emit(rv_sw(RV_REG_SP, stack_adjust - 32, RV_REG_S6), ctx);
+ emit(rv_sw(RV_REG_SP, stack_adjust - 36, RV_REG_S7), ctx);
/* Set fp: used as the base address for stacked BPF registers. */
emit(rv_addi(RV_REG_FP, RV_REG_SP, stack_adjust), ctx);
- /* Set up BPF stack pointer. */
+ /* Set up BPF frame pointer. */
emit(rv_addi(lo(fp), RV_REG_SP, bpf_stack_adjust), ctx);
emit(rv_addi(hi(fp), RV_REG_ZERO, 0), ctx);
- /* Set up context pointer. */
+ /* Set up BPF context pointer. */
emit(rv_addi(lo(r1), RV_REG_A0, 0), ctx);
emit(rv_addi(hi(r1), RV_REG_ZERO, 0), ctx);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.