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authorJon Medhurst <tixy@yxit.co.uk>2011-07-02 15:51:03 +0100
committerTixy <tixy@medhuaa1.miniserver.com>2011-07-13 17:32:43 +0000
commita9c3c29e72cc459be0ecd597f0af11a67713175b (patch)
treee167451c8ebfef40c75f0c52fc3c14bc97dadaea /arch/arm/kernel/kprobes-thumb.c
parent059987ffa7f8905fada25c8af1734e254209c55d (diff)
downloadop-kernel-dev-a9c3c29e72cc459be0ecd597f0af11a67713175b.zip
op-kernel-dev-a9c3c29e72cc459be0ecd597f0af11a67713175b.tar.gz
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.c37
1 files changed, 37 insertions, 0 deletions
diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c
index e1cef82..b457da0 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
*/
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