lkml.org 
[lkml]   [2014]   [Aug]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] ARM: probes: return directly when emulate not set
Date
When kprobe decoding instruction, original code calls instruction
specific decoder if emulate is set to false. However, instructions with
DECODE_TYPE_EMULATE are in fact don't have their decoder. What in the
action table are in fact handlers. For example:

/* LDRD (immediate) cccc 000x x1x0 xxxx xxxx xxxx 1101 xxxx */
/* STRD (immediate) cccc 000x x1x0 xxxx xxxx xxxx 1111 xxxx */
DECODE_EMULATEX (0x0e5000d0, 0x004000d0, PROBES_LDRSTRD,
REGS(NOPCWB, NOPCX, 0, 0, 0)),

and

const union decode_action kprobes_arm_actions[NUM_PROBES_ARM_ACTIONS] = {
...
[PROBES_LDRSTRD] = {.handler = emulate_ldrdstrd},
...

In this situation, original code calls 'emulate_ldrdstrd' as a decoder,
which is obviously incorrect.

This patch makes it returns INSN_GOOD directly when 'emulate' is not
true.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: "David A. Long" <dave.long@linaro.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Jon Medhurst <tixy@linaro.org>
Cc: Taras Kondratiuk <taras.kondratiuk@linaro.org>
Cc: Ben Dooks <ben.dooks@codethink.co.uk>
---
arch/arm/kernel/probes.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm/kernel/probes.c b/arch/arm/kernel/probes.c
index a8ab540..1c77b8d 100644
--- a/arch/arm/kernel/probes.c
+++ b/arch/arm/kernel/probes.c
@@ -436,8 +436,7 @@ probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
struct decode_emulate *d = (struct decode_emulate *)h;

if (!emulate)
- return actions[d->handler.action].decoder(insn,
- asi, h);
+ return INSN_GOOD;

asi->insn_handler = actions[d->handler.action].handler;
set_emulated_insn(insn, asi, thumb);
--
1.8.4


\
 
 \ /
  Last update: 2014-08-27 07:41    [W:0.036 / U:0.492 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site