[PATCH 3.10 49/70] ARM: probes: fix instruction fetch order with

Greg Kroah-Hartman
2014-11-19T21:16:49Z

From: Ben Dooks <ben.dooks@codethink.co.uk>

commit 888be25402021a425da3e85e2d5a954d7509286e upstream.

If we are running BE8, the data and instruction endianness do not
match, so use <asm/opcodes.h> to correctly translate memory accesses
into ARM instructions.

Acked-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
[taras.kondratiuk@linaro.org: fixed Thumb instruction fetch order]
Signed-off-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
[wangnan: backport to 3.10 and 3.14:
- adjust context
- backport all changes on arch/arm/kernel/probes.c to
arch/arm/kernel/kprobes-common.c since we don't have
commit c18377c303787ded44b7decd7dee694db0f205e9.
- After the above adjustments, becomes same to Taras Kondratiuk's
original patch:
http://lists.linaro.org/pipermail/linaro-kernel/2014-January/010346.html
]
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/kernel/kprobes-common.c | 19 +++++++++++--------
arch/arm/kernel/kprobes-thumb.c | 20 ++++++++++++--------
arch/arm/kernel/kprobes.c | 9 +++++----
3 files changed, 28 insertions(+), 20 deletions(-)

--- a/arch/arm/kernel/kprobes-common.c
+++ b/arch/arm/kernel/kprobes-common.c
@@ -14,6 +14,7 @@
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <asm/system_info.h>
+#include <asm/opcodes.h>

#include "kprobes.h"

@@ -305,7 +306,8 @@ kprobe_decode_ldmstm(kprobe_opcode_t ins

if (handler) {
/* We can emulate the instruction in (possibly) modified form */
- asi->insn[0] = (insn & 0xfff00000) | (rn << 16) | reglist;
+ asi->insn[0] = __opcode_to_mem_arm((insn & 0xfff00000) |
+ (rn << 16) | reglist);
asi->insn_handler = handler;
return INSN_GOOD;
}
@@ -334,13 +336,14 @@ prepare_emulated_insn(kprobe_opcode_t in
#ifdef CONFIG_THUMB2_KERNEL
if (thumb) {
u16 *thumb_insn = (u16 *)asi->insn;
- thumb_insn[1] = 0x4770; /* Thumb bx lr */
- thumb_insn[2] = 0x4770; /* Thumb bx lr */
+ /* Thumb bx lr */
+ thumb_insn[1] = __opcode_to_mem_thumb16(0x4770);
+ thumb_insn[2] = __opcode_to_mem_thumb16(0x4770);
return insn;
}
- asi->insn[1] = 0xe12fff1e; /* ARM bx lr */
+ asi->insn[1] = __opcode_to_mem_arm(0xe12fff1e); /* ARM bx lr */
#else
- asi->insn[1] = 0xe1a0f00e; /* mov pc, lr */
+ asi->insn[1] = __opcode_to_mem_arm(0xe1a0f00e); /* mov pc, lr */
#endif
/* Make an ARM instruction unconditional */
if (insn < 0xe0000000)
@@ -360,12 +363,12 @@ set_emulated_insn(kprobe_opcode_t insn,
if (thumb) {
u16 *ip = (u16 *)asi->insn;
if (is_wide_instruction(insn))
- *ip++ = insn >> 16;
- *ip++ = insn;
+ *ip++ = __opcode_to_mem_thumb16(insn >> 16);
+ *ip++ = __opcode_to_mem_thumb16(insn);
return;
}
#endif
- asi->insn[0] = insn;
+ asi->insn[0] = __opcode_to_mem_arm(insn);
}

/*
--- a/arch/arm/kernel/kprobes-thumb.c
+++ b/arch/arm/kernel/kprobes-thumb.c
@@ -163,9 +163,9 @@ t32_decode_ldmstm(kprobe_opcode_t insn,
enum kprobe_insn ret = kprobe_decode_ldmstm(insn, asi);

/* Fixup modified instruction to have halfwords in correct order...*/
- insn = asi->insn[0];
- ((u16 *)asi->insn)[0] = insn >> 16;
- ((u16 *)asi->insn)[1] = insn & 0xffff;
+ insn = __mem_to_opcode_arm(asi->insn[0]);
+ ((u16 *)asi->insn)[0] = __opcode_to_mem_thumb16(insn >> 16);
+ ((u16 *)asi->insn)[1] = __opcode_to_mem_thumb16(insn & 0xffff);

return ret;
}
@@ -1153,7 +1153,7 @@ t16_decode_hiregs(kprobe_opcode_t insn,
{
insn &= ~0x00ff;
insn |= 0x001; /* Set Rdn = R1 and Rm = R0 */
- ((u16 *)asi->insn)[0] = insn;
+ ((u16 *)asi->insn)[0] = __opcode_to_mem_thumb16(insn);
asi->insn_handler = t16_emulate_hiregs;
return INSN_GOOD;
}
@@ -1182,8 +1182,10 @@ t16_decode_push(kprobe_opcode_t insn, st
* and call it with R9=SP and LR in the register list represented
* by R8.
*/
- ((u16 *)asi->insn)[0] = 0xe929; /* 1st half STMDB R9!,{} */
- ((u16 *)asi->insn)[1] = insn & 0x1ff; /* 2nd half (register list) */
+ /* 1st half STMDB R9!,{} */
+ ((u16 *)asi->insn)[0] = __opcode_to_mem_thumb16(0xe929);
+ /* 2nd half (register list) */
+ ((u16 *)asi->insn)[1] = __opcode_to_mem_thumb16(insn & 0x1ff);
asi->insn_handler = t16_emulate_push;
return INSN_GOOD;
}
@@ -1232,8 +1234,10 @@ t16_decode_pop(kprobe_opcode_t insn, str
* and call it with R9=SP and PC in the register list represented
* by R8.
*/
- ((u16 *)asi->insn)[0] = 0xe8b9; /* 1st half LDMIA R9!,{} */
- ((u16 *)asi->insn)[1] = insn & 0x1ff; /* 2nd half (register list) */
+ /* 1st half LDMIA R9!,{} */
+ ((u16 *)asi->insn)[0] = __opcode_to_mem_thumb16(0xe8b9);
+ /* 2nd half (register list) */
+ ((u16 *)asi->insn)[1] = __opcode_to_mem_thumb16(insn & 0x1ff);
asi->insn_handler = insn & 0x100 ? t16_emulate_pop_pc
: t16_emulate_pop_nopc;
return INSN_GOOD;
--- a/arch/arm/kernel/kprobes.c
+++ b/arch/arm/kernel/kprobes.c
@@ -26,6 +26,7 @@
#include <linux/stop_machine.h>
#include <linux/stringify.h>
#include <asm/traps.h>
+#include <asm/opcodes.h>
#include <asm/cacheflush.h>

#include "kprobes.h"
@@ -62,10 +63,10 @@ int __kprobes arch_prepare_kprobe(struct
#ifdef CONFIG_THUMB2_KERNEL
thumb = true;
addr &= ~1; /* Bit 0 would normally be set to indicate Thumb code */
- insn = ((u16 *)addr)[0];
+ insn = __mem_to_opcode_thumb16(((u16 *)addr)[0]);
if (is_wide_instruction(insn)) {
- insn <<= 16;
- insn |= ((u16 *)addr)[1];
+ u16 inst2 = __mem_to_opcode_thumb16(((u16 *)addr)[1]);
+ insn = __opcode_thumb32_compose(insn, inst2);
decode_insn = thumb32_kprobe_decode_insn;
} else
decode_insn = thumb16_kprobe_decode_insn;
@@ -73,7 +74,7 @@ int __kprobes arch_prepare_kprobe(struct
thumb = false;
if (addr & 0x3)
return -EINVAL;
- insn = *p->addr;
+ insn = __mem_to_opcode_arm(*p->addr);
decode_insn = arm_kprobe_decode_insn;
#endif