diff options
author | Wang Nan <wangnan0@huawei.com> | 2015-01-09 14:37:36 +0800 |
---|---|---|
committer | Jon Medhurst <tixy@linaro.org> | 2015-01-13 16:10:17 +0000 |
commit | 0dc016dbd820260b8ea74337980735b8c88d4ef2 (patch) | |
tree | 0a6408b4181016d41858afec026cc4e93455f852 /arch/arm/probes/kprobes/core.c | |
parent | cbf6ab52add20b845f903decc973afbd5463c527 (diff) |
ARM: kprobes: enable OPTPROBES for ARM 32
This patch introduce kprobeopt for ARM 32.
Limitations:
- Currently only kernel compiled with ARM ISA is supported.
- Offset between probe point and optinsn slot must not larger than
32MiB. Masami Hiramatsu suggests replacing 2 words, it will make
things complex. Futher patch can make such optimization.
Kprobe opt on ARM is relatively simpler than kprobe opt on x86 because
ARM instruction is always 4 bytes aligned and 4 bytes long. This patch
replace probed instruction by a 'b', branch to trampoline code and then
calls optimized_callback(). optimized_callback() calls opt_pre_handler()
to execute kprobe handler. It also emulate/simulate replaced instruction.
When unregistering kprobe, the deferred manner of unoptimizer may leave
branch instruction before optimizer is called. Different from x86_64,
which only copy the probed insn after optprobe_template_end and
reexecute them, this patch call singlestep to emulate/simulate the insn
directly. Futher patch can optimize this behavior.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Will Deacon <will.deacon@arm.com>
Reviewed-by: Jon Medhurst (Tixy) <tixy@linaro.org>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
Diffstat (limited to 'arch/arm/probes/kprobes/core.c')
-rw-r--r-- | arch/arm/probes/kprobes/core.c | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c index 3a58db4cc1c6..a4ec240ee7ba 100644 --- a/arch/arm/probes/kprobes/core.c +++ b/arch/arm/probes/kprobes/core.c @@ -163,19 +163,31 @@ void __kprobes arch_arm_kprobe(struct kprobe *p) * memory. It is also needed to atomically set the two half-words of a 32-bit * Thumb breakpoint. */ -int __kprobes __arch_disarm_kprobe(void *p) -{ - struct kprobe *kp = p; - void *addr = (void *)((uintptr_t)kp->addr & ~1); - - __patch_text(addr, kp->opcode); +struct patch { + void *addr; + unsigned int insn; +}; +static int __kprobes_remove_breakpoint(void *data) +{ + struct patch *p = data; + __patch_text(p->addr, p->insn); return 0; } +void __kprobes kprobes_remove_breakpoint(void *addr, unsigned int insn) +{ + struct patch p = { + .addr = addr, + .insn = insn, + }; + stop_machine(__kprobes_remove_breakpoint, &p, cpu_online_mask); +} + void __kprobes arch_disarm_kprobe(struct kprobe *p) { - stop_machine(__arch_disarm_kprobe, p, cpu_online_mask); + kprobes_remove_breakpoint((void *)((uintptr_t)p->addr & ~1), + p->opcode); } void __kprobes arch_remove_kprobe(struct kprobe *p) |