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ARM: kprobes: Decode 16-bit Thumb BX and BLX instructions

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Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
This commit is contained in:
Jon Medhurst 2011-07-02 15:51:03 +01:00 committed by Tixy
parent 059987ffa7
commit a9c3c29e72
1 changed files with 37 additions and 0 deletions
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37
arch/arm/kernel/kprobes-thumb.c
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@ -26,6 +26,31 @@
*/
#define current_cond(cpsr) ((cpsr >> 12) & 0xf)
/*
* Return the PC value for a probe in thumb code.
* This is the address of the probed instruction plus 4.
* We subtract one because the address will have bit zero set to indicate
* a pointer to thumb code.
*/
static inline unsigned long __kprobes thumb_probe_pc(struct kprobe *p)
{
return (unsigned long)p->addr - 1 + 4;
}
static void __kprobes
t16_simulate_bxblx(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long pc = thumb_probe_pc(p);
int rm = (insn >> 3) & 0xf;
unsigned long rmv = (rm == 15) ? pc : regs->uregs[rm];
if (insn & (1 << 7)) /* BLX ? */
regs->ARM_lr = (unsigned long)p->addr + 2;
bx_write_pc(rmv, regs);
}
static unsigned long __kprobes
t16_emulate_loregs(struct kprobe *p, struct pt_regs *regs)
{
@ -131,6 +156,18 @@ const union decode_item kprobe_decode_thumb16_table[] = {
/* MVN (register) 0100 0011 10xx xxxx */
DECODE_EMULATE (0xfc00, 0x4000, t16_emulate_loregs_noitrwflags),
/*
* Special data instructions and branch and exchange
* 0100 01xx xxxx xxxx
*/
/* BLX pc 0100 0111 1111 1xxx */
DECODE_REJECT (0xfff8, 0x47f8),
/* BX (register) 0100 0111 0xxx xxxx */
/* BLX (register) 0100 0111 1xxx xxxx */
DECODE_SIMULATE (0xff00, 0x4700, t16_simulate_bxblx),
/*
* Miscellaneous 16-bit instructions
* 1011 xxxx xxxx xxxx