[PATCHv3] ARM: extract out code patch function from kprobes
Rabin Vincent
rabin at rab.in
Tue Feb 7 11:07:28 EST 2012
Extract out the code patching code from kprobes so that it can be used
from the jump label code. Additionally, the separated code:
- Uses the IS_ENABLED() macros instead of the #ifdefs for THUMB2
support
- Unifies the two separate functions in kprobes, providing one function
that uses stop_machine() internally, and one that can be called from
stop_machine() directly
- Patches the text on all CPUs only on processors requiring software
broadcasting of cache operations
Acked-by: Jon Medhurst <tixy at yxit.co.uk>
Tested-by: Jon Medhurst <tixy at yxit.co.uk>
Signed-off-by: Rabin Vincent <rabin at rab.in>
---
v3: add missing __opcode_to_mem_thumb16 for the split thumb2 case
arch/arm/kernel/Makefile | 3 +-
arch/arm/kernel/kprobes.c | 86 ++++++++++++--------------------------------
arch/arm/kernel/patch.c | 75 +++++++++++++++++++++++++++++++++++++++
arch/arm/kernel/patch.h | 7 ++++
4 files changed, 108 insertions(+), 63 deletions(-)
create mode 100644 arch/arm/kernel/patch.c
create mode 100644 arch/arm/kernel/patch.h
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index dd3d5f1..8c63ee8 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -8,6 +8,7 @@ AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_ftrace.o = -pg
CFLAGS_REMOVE_insn.o = -pg
+CFLAGS_REMOVE_patch.o = -pg
endif
CFLAGS_REMOVE_return_address.o = -pg
@@ -38,7 +39,7 @@ obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o
obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o insn.o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o insn.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
-obj-$(CONFIG_KPROBES) += kprobes.o kprobes-common.o
+obj-$(CONFIG_KPROBES) += kprobes.o kprobes-common.o patch.o
ifdef CONFIG_THUMB2_KERNEL
obj-$(CONFIG_KPROBES) += kprobes-thumb.o
else
diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c
index 129c116..ab1869d 100644
--- a/arch/arm/kernel/kprobes.c
+++ b/arch/arm/kernel/kprobes.c
@@ -29,6 +29,7 @@
#include <asm/cacheflush.h>
#include "kprobes.h"
+#include "patch.h"
#define MIN_STACK_SIZE(addr) \
min((unsigned long)MAX_STACK_SIZE, \
@@ -103,57 +104,33 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
return 0;
}
-#ifdef CONFIG_THUMB2_KERNEL
-
-/*
- * For a 32-bit Thumb breakpoint spanning two memory words we need to take
- * special precautions to insert the breakpoint atomically, especially on SMP
- * systems. This is achieved by calling this arming function using stop_machine.
- */
-static int __kprobes set_t32_breakpoint(void *addr)
-{
- ((u16 *)addr)[0] = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION >> 16;
- ((u16 *)addr)[1] = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION & 0xffff;
- flush_insns(addr, 2*sizeof(u16));
- return 0;
-}
-
void __kprobes arch_arm_kprobe(struct kprobe *p)
{
- uintptr_t addr = (uintptr_t)p->addr & ~1; /* Remove any Thumb flag */
-
- if (!is_wide_instruction(p->opcode)) {
- *(u16 *)addr = KPROBE_THUMB16_BREAKPOINT_INSTRUCTION;
- flush_insns(addr, sizeof(u16));
- } else if (addr & 2) {
- /* A 32-bit instruction spanning two words needs special care */
- stop_machine(set_t32_breakpoint, (void *)addr, &cpu_online_map);
+ unsigned int brkp;
+ void *addr;
+
+ if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
+ /* Remove any Thumb flag */
+ addr = (void *)((uintptr_t)p->addr & ~1);
+
+ if (is_wide_instruction(p->opcode))
+ brkp = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION;
+ else
+ brkp = KPROBE_THUMB16_BREAKPOINT_INSTRUCTION;
} else {
- /* Word aligned 32-bit instruction can be written atomically */
- u32 bkp = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION;
-#ifndef __ARMEB__ /* Swap halfwords for little-endian */
- bkp = (bkp >> 16) | (bkp << 16);
-#endif
- *(u32 *)addr = bkp;
- flush_insns(addr, sizeof(u32));
- }
-}
+ kprobe_opcode_t insn = p->opcode;
-#else /* !CONFIG_THUMB2_KERNEL */
+ addr = p->addr;
+ brkp = KPROBE_ARM_BREAKPOINT_INSTRUCTION;
-void __kprobes arch_arm_kprobe(struct kprobe *p)
-{
- kprobe_opcode_t insn = p->opcode;
- kprobe_opcode_t brkp = KPROBE_ARM_BREAKPOINT_INSTRUCTION;
- if (insn >= 0xe0000000)
- brkp |= 0xe0000000; /* Unconditional instruction */
- else
- brkp |= insn & 0xf0000000; /* Copy condition from insn */
- *p->addr = brkp;
- flush_insns(p->addr, sizeof(p->addr[0]));
-}
+ if (insn >= 0xe0000000)
+ brkp |= 0xe0000000; /* Unconditional instruction */
+ else
+ brkp |= insn & 0xf0000000; /* Copy condition from insn */
+ }
-#endif /* !CONFIG_THUMB2_KERNEL */
+ patch_text(addr, brkp);
+}
/*
* The actual disarming is done here on each CPU and synchronized using
@@ -166,25 +143,10 @@ void __kprobes arch_arm_kprobe(struct kprobe *p)
int __kprobes __arch_disarm_kprobe(void *p)
{
struct kprobe *kp = p;
-#ifdef CONFIG_THUMB2_KERNEL
- u16 *addr = (u16 *)((uintptr_t)kp->addr & ~1);
- kprobe_opcode_t insn = kp->opcode;
- unsigned int len;
+ void *addr = (void *)((uintptr_t)kp->addr & ~1);
- if (is_wide_instruction(insn)) {
- ((u16 *)addr)[0] = insn>>16;
- ((u16 *)addr)[1] = insn;
- len = 2*sizeof(u16);
- } else {
- ((u16 *)addr)[0] = insn;
- len = sizeof(u16);
- }
- flush_insns(addr, len);
+ __patch_text(addr, kp->opcode);
-#else /* !CONFIG_THUMB2_KERNEL */
- *kp->addr = kp->opcode;
- flush_insns(kp->addr, sizeof(kp->addr[0]));
-#endif
return 0;
}
diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
new file mode 100644
index 0000000..07314af
--- /dev/null
+++ b/arch/arm/kernel/patch.c
@@ -0,0 +1,75 @@
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/stop_machine.h>
+
+#include <asm/cacheflush.h>
+#include <asm/smp_plat.h>
+#include <asm/opcodes.h>
+
+#include "patch.h"
+
+struct patch {
+ void *addr;
+ unsigned int insn;
+};
+
+void __kprobes __patch_text(void *addr, unsigned int insn)
+{
+ bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
+ int size;
+
+ if (thumb2 && __opcode_is_thumb16(insn)) {
+ *(u16 *)addr = __opcode_to_mem_thumb16(insn);
+ size = sizeof(u16);
+ } else if (thumb2 && ((uintptr_t)addr & 2)) {
+ u16 first = __opcode_thumb32_first(insn);
+ u16 second = __opcode_thumb32_second(insn);
+ u16 *addrh = addr;
+
+ addrh[0] = __opcode_to_mem_thumb16(first);
+ addrh[1] = __opcode_to_mem_thumb16(second);
+
+ size = sizeof(u32);
+ } else {
+ if (thumb2)
+ insn = __opcode_to_mem_thumb32(insn);
+ else
+ insn = __opcode_to_mem_arm(insn);
+
+ *(u32 *)addr = insn;
+ size = sizeof(u32);
+ }
+
+ flush_icache_range((uintptr_t)(addr),
+ (uintptr_t)(addr) + size);
+}
+
+static int __kprobes patch_text_stop_machine(void *data)
+{
+ struct patch *patch = data;
+
+ __patch_text(patch->addr, patch->insn);
+
+ return 0;
+}
+
+void __kprobes patch_text(void *addr, unsigned int insn)
+{
+ struct patch patch = {
+ .addr = addr,
+ .insn = insn,
+ };
+
+ if (cache_ops_need_broadcast()) {
+ stop_machine(patch_text_stop_machine, &patch, cpu_online_mask);
+ } else {
+ bool straddles_word = IS_ENABLED(CONFIG_THUMB2_KERNEL)
+ && __opcode_is_thumb32(insn)
+ && ((uintptr_t)addr & 2);
+
+ if (straddles_word)
+ stop_machine(patch_text_stop_machine, &patch, NULL);
+ else
+ __patch_text(addr, insn);
+ }
+}
diff --git a/arch/arm/kernel/patch.h b/arch/arm/kernel/patch.h
new file mode 100644
index 0000000..b4731f2
--- /dev/null
+++ b/arch/arm/kernel/patch.h
@@ -0,0 +1,7 @@
+#ifndef _ARM_KERNEL_PATCH_H
+#define _ARM_KERNEL_PATCH_H
+
+void patch_text(void *addr, unsigned int insn);
+void __patch_text(void *addr, unsigned int insn);
+
+#endif
--
1.7.9
More information about the linux-arm-kernel
mailing list