From 809120663f9526aaea0f3345039f40bcdedf9873 Mon Sep 17 00:00:00 2001
From: Jon Medhurst <tixy@yxit.co.uk>
Date: Sat, 2 Jul 2011 15:51:03 +0100
Subject: [PATCH] --- yaml --- r: 258343 b: refs/heads/master c:
 a9c3c29e72cc459be0ecd597f0af11a67713175b h: refs/heads/master i:   258341:
 213029e2060837fd7461f8dacbb73f19a0b6cafa   258339:
 b358bac6ff062bbf7d9d511592b30d6f111c58a0   258335:
 ad50c0ac3b9d6008411b2dff1b0a022bc57d4004 v: v3

---
 [refs]                                |  2 +-
 trunk/arch/arm/kernel/kprobes-thumb.c | 37 +++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index e0286efb67fc..49ec28d14860 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 059987ffa7f8905fada25c8af1734e254209c55d
+refs/heads/master: a9c3c29e72cc459be0ecd597f0af11a67713175b
diff --git a/trunk/arch/arm/kernel/kprobes-thumb.c b/trunk/arch/arm/kernel/kprobes-thumb.c
index e1cef8273126..b457da0e7397 100644
--- a/trunk/arch/arm/kernel/kprobes-thumb.c
+++ b/trunk/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)
 {
@@ -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