ARM: 8224/1: Add unwinding support for memmove function

The memmove function never had unwinding annotations added.
Currently, when accessing invalid pointer by memmove occurs the
backtrace shown will stop at memmove or some completely unrelated
function. Add unwinding annotations in hopes of getting a more
useful backtrace in following cases:
1. die on accessing invalid pointer by memmove
2. kprobe trapped at any instruction within memmove
3. interrupted at any instruction within memmove

Signed-off-by: Lin Yongting <linyongting@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 28 insertions, 0 deletions

diff --git a/arch/arm/lib/memmove.S b/arch/arm/lib/memmove.S
index d1fc0c0c342c..69a9d47fc5ab 100644
--- a/arch/arm/lib/memmove.S
+++ b/arch/arm/lib/memmove.S
@@ -12,6 +12,7 @@
 
 #include <linux/linkage.h>
 #include <asm/assembler.h>
+#include <asm/unwind.h>
 
                 .text
 
@@ -27,12 +28,17 @@
  */
 
 ENTRY(memmove)
+        UNWIND( .fnstart                        )
 
                 subs    ip, r0, r1
                 cmphi   r2, ip
                 bls     memcpy
 
                 stmfd   sp!, {r0, r4, lr}
+        UNWIND( .fnend                          )
+
+        UNWIND( .fnstart                        )
+        UNWIND( .save   {r0, r4, lr}            ) @ in first stmfd block
                 add     r1, r1, r2
                 add     r0, r0, r2
                 subs    r2, r2, #4
@@ -45,6 +51,11 @@ ENTRY(memmove)
 
 1:              subs    r2, r2, #(28)
                 stmfd   sp!, {r5 - r8}
+        UNWIND( .fnend                          )
+
+        UNWIND( .fnstart                        )
+        UNWIND( .save   {r0, r4, lr}            )
+        UNWIND( .save   {r5 - r8}               ) @ in second stmfd block
                 blt     5f
 
         CALGN(  ands    ip, r0, #31             )
@@ -97,6 +108,10 @@ ENTRY(memmove)
         CALGN(  bcs     2b                      )
 
 7:              ldmfd   sp!, {r5 - r8}
+        UNWIND( .fnend                          ) @ end of second stmfd block
+
+        UNWIND( .fnstart                        )
+        UNWIND( .save   {r0, r4, lr}            ) @ still in first stmfd block
 
 8:              movs    r2, r2, lsl #31
                 ldrneb  r3, [r1, #-1]!
@@ -124,10 +139,13 @@ ENTRY(memmove)
                 ldr     r3, [r1, #0]
                 beq     17f
                 blt     18f
+        UNWIND( .fnend                          )
 
 
                 .macro  backward_copy_shift push pull
 
+        UNWIND( .fnstart                        )
+        UNWIND( .save   {r0, r4, lr}            ) @ still in first stmfd block
                 subs    r2, r2, #28
                 blt     14f
 
@@ -137,6 +155,11 @@ ENTRY(memmove)
         CALGN(  bcc     15f                     )
 
 11:             stmfd   sp!, {r5 - r9}
+        UNWIND( .fnend                          )
+
+        UNWIND( .fnstart                        )
+        UNWIND( .save   {r0, r4, lr}            )
+        UNWIND( .save   {r5 - r9}               ) @ in new second stmfd block
 
         PLD(    pld     [r1, #-4]               )
         PLD(    subs    r2, r2, #96             )
@@ -171,6 +194,10 @@ ENTRY(memmove)
         PLD(    bge     13b                     )
 
                 ldmfd   sp!, {r5 - r9}
+        UNWIND( .fnend                          ) @ end of the second stmfd block
+
+        UNWIND( .fnstart                        )
+        UNWIND( .save {r0, r4, lr}              ) @ still in first stmfd block
 
 14:             ands    ip, r2, #28
                 beq     16f
@@ -186,6 +213,7 @@ ENTRY(memmove)
 
 16:             add     r1, r1, #(\pull / 8)
                 b       8b
+        UNWIND( .fnend                          )
 
                 .endm