3 files changed, 27 insertions, 26 deletions

diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 312d10877bd..d484871698d 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -200,6 +200,14 @@ extern unsigned long profile_pc(struct pt_regs *regs);
 #define PREDICATE_ALWAYS        0xe0000000
 
 /*
+ * True if instr is a 32-bit thumb instruction. This works if instr
+ * is the first or only half-word of a thumb instruction. It also works
+ * when instr holds all 32-bits of a wide thumb instruction if stored
+ * in the form (first_half<<16)|(second_half)
+ */
+#define is_wide_instruction(instr)      ((unsigned)(instr) >= 0xe800)
+
+/*
  * kprobe-based event tracer support
  */
 #include <linux/stddef.h>
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 97260060bf2..897ade059f5 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -228,34 +228,12 @@ static struct undef_hook thumb_break_hook = {
         .fn             = break_trap,
 };
 
-static int thumb2_break_trap(struct pt_regs *regs, unsigned int instr)
-{
-        unsigned int instr2;
-        void __user *pc;
-
-        /* Check the second half of the instruction.  */
-        pc = (void __user *)(instruction_pointer(regs) + 2);
-
-        if (processor_mode(regs) == SVC_MODE) {
-                instr2 = *(u16 *) pc;
-        } else {
-                get_user(instr2, (u16 __user *)pc);
-        }
-
-        if (instr2 == 0xa000) {
-                ptrace_break(current, regs);
-                return 0;
-        } else {
-                return 1;
-        }
-}
-
 static struct undef_hook thumb2_break_hook = {
-        .instr_mask     = 0xffff,
-        .instr_val      = 0xf7f0,
+        .instr_mask     = 0xffffffff,
+        .instr_val      = 0xf7f0a000,
         .cpsr_mask      = PSR_T_BIT,
         .cpsr_val       = PSR_T_BIT,
-        .fn             = thumb2_break_trap,
+        .fn             = break_trap,
 };
 
 static int __init ptrace_break_init(void)
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 6807cb1e76d..2d3436e9f71 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -355,9 +355,24 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
         pc = (void __user *)instruction_pointer(regs);
 
         if (processor_mode(regs) == SVC_MODE) {
-                instr = *(u32 *) pc;
+#ifdef CONFIG_THUMB2_KERNEL
+                if (thumb_mode(regs)) {
+                        instr = ((u16 *)pc)[0];
+                        if (is_wide_instruction(instr)) {
+                                instr <<= 16;
+                                instr |= ((u16 *)pc)[1];
+                        }
+                } else
+#endif
+                        instr = *(u32 *) pc;
         } else if (thumb_mode(regs)) {
                 get_user(instr, (u16 __user *)pc);
+                if (is_wide_instruction(instr)) {
+                        unsigned int instr2;
+                        get_user(instr2, (u16 __user *)pc+1);
+                        instr <<= 16;
+                        instr |= instr2;
+                }
         } else {
                 get_user(instr, (u32 __user *)pc);
         }