ARM: kprobes: Move find_str_pc_offset into kprobes-common.c

Move str_pc_offset into kprobes-common.c as it will be needed by common
code later.

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/arch/arm/kernel/kprobes-common.c b/arch/arm/kernel/kprobes-common.c
index 794827ec27d7..e18576cca6cf 100644
--- a/arch/arm/kernel/kprobes-common.c
+++ b/arch/arm/kernel/kprobes-common.c
@@ -3,6 +3,9 @@
  *
  * Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>.
  *
+ * Some contents moved here from arch/arm/include/asm/kprobes-arm.c which is
+ * Copyright (C) 2006, 2007 Motorola Inc.
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -14,6 +17,36 @@
 #include "kprobes.h"
 
 
+/*
+ * For STR and STM instructions, an ARM core may choose to use either
+ * a +8 or a +12 displacement from the current instruction's address.
+ * Whichever value is chosen for a given core, it must be the same for
+ * both instructions and may not change.  This function measures it.
+ */
+
+int str_pc_offset;
+
+void __init find_str_pc_offset(void)
+{
+        int addr, scratch, ret;
+
+        __asm__ (
+                "sub    %[ret], pc, #4          \n\t"
+                "str    pc, %[addr]             \n\t"
+                "ldr    %[scr], %[addr]         \n\t"
+                "sub    %[ret], %[scr], %[ret]  \n\t"
+                : [ret] "=r" (ret), [scr] "=r" (scratch), [addr] "+m" (addr));
+
+        str_pc_offset = ret;
+}
+
+
+void __init arm_kprobe_decode_init(void)
+{
+        find_str_pc_offset();
+}
+
+
 static unsigned long __kprobes __check_eq(unsigned long cpsr)
 {
         return cpsr & PSR_Z_BIT;