aboutsummaryrefslogtreecommitdiffstats
path: root/arch/blackfin/kernel
diff options
context:
space:
mode:
Diffstat (limited to 'arch/blackfin/kernel')
-rw-r--r--arch/blackfin/kernel/Makefile3
-rw-r--r--arch/blackfin/kernel/fixed_code.S132
-rw-r--r--arch/blackfin/kernel/process.c65
-rw-r--r--arch/blackfin/kernel/setup.c22
4 files changed, 221 insertions, 1 deletions
diff --git a/arch/blackfin/kernel/Makefile b/arch/blackfin/kernel/Makefile
index 93d21406cade..b7b6de824011 100644
--- a/arch/blackfin/kernel/Makefile
+++ b/arch/blackfin/kernel/Makefile
@@ -6,7 +6,8 @@ extra-y := init_task.o vmlinux.lds
obj-y := \
entry.o process.o bfin_ksyms.o ptrace.o setup.o signal.o \
- sys_bfin.o time.o traps.o irqchip.o dma-mapping.o flat.o
+ sys_bfin.o time.o traps.o irqchip.o dma-mapping.o flat.o \
+ fixed_code.o
obj-$(CONFIG_BF53x) += bfin_gpio.o
obj-$(CONFIG_BF561) += bfin_gpio.o
diff --git a/arch/blackfin/kernel/fixed_code.S b/arch/blackfin/kernel/fixed_code.S
new file mode 100644
index 000000000000..99ea296c82c7
--- /dev/null
+++ b/arch/blackfin/kernel/fixed_code.S
@@ -0,0 +1,132 @@
+/*
+ * This file contains sequences of code that will be copied to a
+ * fixed location, defined in <asm/atomic_seq.h>. The interrupt
+ * handlers ensure that these sequences appear to be atomic when
+ * executed from userspace.
+ * These are aligned to 16 bytes, so that we have some space to replace
+ * these sequences with something else (e.g. kernel traps if we ever do
+ * BF561 SMP).
+ */
+#include <linux/linkage.h>
+#include <asm/entry.h>
+#include <asm/unistd.h>
+
+.text
+ENTRY(_fixed_code_start)
+
+.align 16
+ENTRY(_sigreturn_stub)
+ P0 = __NR_rt_sigreturn;
+ EXCPT 0;
+ /* Speculative execution paranoia. */
+0: JUMP.S 0b;
+ENDPROC (_sigreturn_stub)
+
+.align 16
+ /*
+ * Atomic swap, 8 bit.
+ * Inputs: P0: memory address to use
+ * R1: value to store
+ * Output: R0: old contents of the memory address, zero extended.
+ */
+ENTRY(_atomic_xchg32)
+ R0 = [P0];
+ [P0] = R1;
+ rts;
+ENDPROC (_atomic_xchg32)
+
+.align 16
+ /*
+ * Compare and swap, 32 bit.
+ * Inputs: P0: memory address to use
+ * R1: compare value
+ * R2: new value to store
+ * The new value is stored if the contents of the memory
+ * address is equal to the compare value.
+ * Output: R0: old contents of the memory address.
+ */
+ENTRY(_atomic_cas32)
+ R0 = [P0];
+ CC = R0 == R1;
+ IF !CC JUMP 1f;
+ [P0] = R2;
+1:
+ rts;
+ENDPROC (_atomic_cas32)
+
+.align 16
+ /*
+ * Atomic add, 32 bit.
+ * Inputs: P0: memory address to use
+ * R0: value to add
+ * Outputs: R0: new contents of the memory address.
+ * R1: previous contents of the memory address.
+ */
+ENTRY(_atomic_add32)
+ R1 = [P0];
+ R0 = R1 + R0;
+ [P0] = R0;
+ rts;
+ENDPROC (_atomic_add32)
+
+.align 16
+ /*
+ * Atomic sub, 32 bit.
+ * Inputs: P0: memory address to use
+ * R0: value to subtract
+ * Outputs: R0: new contents of the memory address.
+ * R1: previous contents of the memory address.
+ */
+ENTRY(_atomic_sub32)
+ R1 = [P0];
+ R0 = R1 - R0;
+ [P0] = R0;
+ rts;
+ENDPROC (_atomic_sub32)
+
+.align 16
+ /*
+ * Atomic ior, 32 bit.
+ * Inputs: P0: memory address to use
+ * R0: value to ior
+ * Outputs: R0: new contents of the memory address.
+ * R1: previous contents of the memory address.
+ */
+ENTRY(_atomic_ior32)
+ R1 = [P0];
+ R0 = R1 | R0;
+ [P0] = R0;
+ rts;
+ENDPROC (_atomic_ior32)
+
+.align 16
+ /*
+ * Atomic ior, 32 bit.
+ * Inputs: P0: memory address to use
+ * R0: value to ior
+ * Outputs: R0: new contents of the memory address.
+ * R1: previous contents of the memory address.
+ */
+ENTRY(_atomic_and32)
+ R1 = [P0];
+ R0 = R1 & R0;
+ [P0] = R0;
+ rts;
+ENDPROC (_atomic_ior32)
+
+.align 16
+ /*
+ * Atomic ior, 32 bit.
+ * Inputs: P0: memory address to use
+ * R0: value to ior
+ * Outputs: R0: new contents of the memory address.
+ * R1: previous contents of the memory address.
+ */
+ENTRY(_atomic_xor32)
+ R1 = [P0];
+ R0 = R1 ^ R0;
+ [P0] = R0;
+ rts;
+ENDPROC (_atomic_ior32)
+
+ENTRY(_fixed_code_end)
diff --git a/arch/blackfin/kernel/process.c b/arch/blackfin/kernel/process.c
index 3eff7439d8d3..6b7a94ab96c2 100644
--- a/arch/blackfin/kernel/process.c
+++ b/arch/blackfin/kernel/process.c
@@ -35,6 +35,7 @@
#include <asm/blackfin.h>
#include <asm/uaccess.h>
+#include <asm/fixed_code.h>
#define LED_ON 0
#define LED_OFF 1
@@ -350,6 +351,70 @@ unsigned long get_wchan(struct task_struct *p)
return 0;
}
+void finish_atomic_sections (struct pt_regs *regs)
+{
+ if (regs->pc < ATOMIC_SEQS_START || regs->pc >= ATOMIC_SEQS_END)
+ return;
+
+ switch (regs->pc) {
+ case ATOMIC_XCHG32 + 2:
+ put_user(regs->r1, (int *)regs->p0);
+ regs->pc += 2;
+ break;
+
+ case ATOMIC_CAS32 + 2:
+ case ATOMIC_CAS32 + 4:
+ if (regs->r0 == regs->r1)
+ put_user(regs->r2, (int *)regs->p0);
+ regs->pc = ATOMIC_CAS32 + 8;
+ break;
+ case ATOMIC_CAS32 + 6:
+ put_user(regs->r2, (int *)regs->p0);
+ regs->pc += 2;
+ break;
+
+ case ATOMIC_ADD32 + 2:
+ regs->r0 = regs->r1 + regs->r0;
+ /* fall through */
+ case ATOMIC_ADD32 + 4:
+ put_user(regs->r0, (int *)regs->p0);
+ regs->pc = ATOMIC_ADD32 + 6;
+ break;
+
+ case ATOMIC_SUB32 + 2:
+ regs->r0 = regs->r1 - regs->r0;
+ /* fall through */
+ case ATOMIC_SUB32 + 4:
+ put_user(regs->r0, (int *)regs->p0);
+ regs->pc = ATOMIC_SUB32 + 6;
+ break;
+
+ case ATOMIC_IOR32 + 2:
+ regs->r0 = regs->r1 | regs->r0;
+ /* fall through */
+ case ATOMIC_IOR32 + 4:
+ put_user(regs->r0, (int *)regs->p0);
+ regs->pc = ATOMIC_IOR32 + 6;
+ break;
+
+ case ATOMIC_AND32 + 2:
+ regs->r0 = regs->r1 & regs->r0;
+ /* fall through */
+ case ATOMIC_AND32 + 4:
+ put_user(regs->r0, (int *)regs->p0);
+ regs->pc = ATOMIC_AND32 + 6;
+ break;
+
+ case ATOMIC_XOR32 + 2:
+ regs->r0 = regs->r1 ^ regs->r0;
+ /* fall through */
+ case ATOMIC_XOR32 + 4:
+ put_user(regs->r0, (int *)regs->p0);
+ regs->pc = ATOMIC_XOR32 + 6;
+ break;
+ }
+}
+
#if defined(CONFIG_ACCESS_CHECK)
int _access_ok(unsigned long addr, unsigned long size)
{
diff --git a/arch/blackfin/kernel/setup.c b/arch/blackfin/kernel/setup.c
index 76bf2cea61d7..534227f4da30 100644
--- a/arch/blackfin/kernel/setup.c
+++ b/arch/blackfin/kernel/setup.c
@@ -42,6 +42,7 @@
#include <asm/cacheflush.h>
#include <asm/blackfin.h>
#include <asm/cplbinit.h>
+#include <asm/fixed_code.h>
u16 _bfin_swrst;
@@ -404,6 +405,27 @@ void __init setup_arch(char **cmdline_p)
printk(KERN_INFO "Hardware Trace Enabled\n");
bfin_write_TBUFCTL(0x03);
+
+ /* Copy atomic sequences to their fixed location, and sanity check that
+ these locations are the ones that we advertise to userspace. */
+ memcpy((void *)FIXED_CODE_START, &fixed_code_start,
+ FIXED_CODE_END - FIXED_CODE_START);
+ BUG_ON((char *)&sigreturn_stub - (char *)&fixed_code_start
+ != SIGRETURN_STUB - FIXED_CODE_START);
+ BUG_ON((char *)&atomic_xchg32 - (char *)&fixed_code_start
+ != ATOMIC_XCHG32 - FIXED_CODE_START);
+ BUG_ON((char *)&atomic_cas32 - (char *)&fixed_code_start
+ != ATOMIC_CAS32 - FIXED_CODE_START);
+ BUG_ON((char *)&atomic_add32 - (char *)&fixed_code_start
+ != ATOMIC_ADD32 - FIXED_CODE_START);
+ BUG_ON((char *)&atomic_sub32 - (char *)&fixed_code_start
+ != ATOMIC_SUB32 - FIXED_CODE_START);
+ BUG_ON((char *)&atomic_ior32 - (char *)&fixed_code_start
+ != ATOMIC_IOR32 - FIXED_CODE_START);
+ BUG_ON((char *)&atomic_and32 - (char *)&fixed_code_start
+ != ATOMIC_AND32 - FIXED_CODE_START);
+ BUG_ON((char *)&atomic_xor32 - (char *)&fixed_code_start
+ != ATOMIC_XOR32 - FIXED_CODE_START);
}
static int __init topology_init(void)
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.