diff options
| author | Jon Medhurst <tixy@yxit.co.uk> | 2011-07-02 15:51:03 +0100 |
|---|---|---|
| committer | Tixy <tixy@medhuaa1.miniserver.com> | 2011-07-13 17:32:43 +0000 |
| commit | a9c3c29e72cc459be0ecd597f0af11a67713175b (patch) | |
| tree | e167451c8ebfef40c75f0c52fc3c14bc97dadaea /arch/arm/kernel/kprobes-thumb.c | |
| parent | 059987ffa7f8905fada25c8af1734e254209c55d (diff) | |
ARM: kprobes: Decode 16-bit Thumb BX and BLX instructions
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Diffstat (limited to 'arch/arm/kernel/kprobes-thumb.c')
| -rw-r--r-- | arch/arm/kernel/kprobes-thumb.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c index e1cef8273126..b457da0e7397 100644 --- a/arch/arm/kernel/kprobes-thumb.c +++ b/arch/arm/kernel/kprobes-thumb.c @@ -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) { @@ -132,6 +157,18 @@ const union decode_item kprobe_decode_thumb16_table[] = { 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 */ |