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arm64: Add trampoline code for kretprobes

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The trampoline code is used by kretprobes to capture a return from a probed
function.  This is done by saving the registers, calling the handler, and
restoring the registers. The code then returns to the original saved caller
return address. It is necessary to do this directly instead of using a
software breakpoint because the code used in processing that breakpoint
could itself be kprobe'd and cause a problematic reentry into the debug
exception handler.

Signed-off-by: William Cohen <wcohen@redhat.com>
Signed-off-by: David A. Long <dave.long@linaro.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
[catalin.marinas@arm.com: removed unnecessary masking of the PSTATE bits]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
William Cohen
2016-07-08 12:35:52 -04:00
committed by Catalin Marinas
parent 39a67d49ba
commit da6a91252a
5 changed files with 100 additions and 0 deletions
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11
arch/arm64/kernel/asm-offsets.c
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@@ -51,6 +51,17 @@ int main(void)
DEFINE(S_X5, offsetof(struct pt_regs, regs[5]));
DEFINE(S_X6, offsetof(struct pt_regs, regs[6]));
DEFINE(S_X7, offsetof(struct pt_regs, regs[7]));
DEFINE(S_X8, offsetof(struct pt_regs, regs[8]));
DEFINE(S_X10, offsetof(struct pt_regs, regs[10]));
DEFINE(S_X12, offsetof(struct pt_regs, regs[12]));
DEFINE(S_X14, offsetof(struct pt_regs, regs[14]));
DEFINE(S_X16, offsetof(struct pt_regs, regs[16]));
DEFINE(S_X18, offsetof(struct pt_regs, regs[18]));
DEFINE(S_X20, offsetof(struct pt_regs, regs[20]));
DEFINE(S_X22, offsetof(struct pt_regs, regs[22]));
DEFINE(S_X24, offsetof(struct pt_regs, regs[24]));
DEFINE(S_X26, offsetof(struct pt_regs, regs[26]));
DEFINE(S_X28, offsetof(struct pt_regs, regs[28]));
DEFINE(S_LR, offsetof(struct pt_regs, regs[30]));
DEFINE(S_SP, offsetof(struct pt_regs, sp));
#ifdef CONFIG_COMPAT