[POWERPC] Fix 64 bits vDSO DWARF info for CR register

The current DWARF info for CR are incorrect, causing the gcc unwinder to
go to lunch if we take a segfault in the vdso.  This fixes it.

Problem identified by Andrew Haley, and fix provided by Jakub Jelinek
(thanks !).

Unfortunately, a bug in gcc cause it to not quite work either, but that
is being fixed separately with something around the lines of:

linux-unwind.h:

     fs->regs.reg[R_CR2].loc.offset = (long) &regs->ccr - new_cfa;
+    /* CR? regs are just 32-bit and PPC is big-endian.  */
+    fs->regs.reg[R_CR2].loc.offset += sizeof (long) - 4;

(According to Jakub)

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/arch/powerpc/kernel/vdso64/sigtramp.S b/arch/powerpc/kernel/vdso64/sigtramp.S
index 17a83fa6dc5..59eb59bb408 100644
--- a/arch/powerpc/kernel/vdso64/sigtramp.S
+++ b/arch/powerpc/kernel/vdso64/sigtramp.S
@@ -134,13 +134,16 @@ V_FUNCTION_END(__kernel_sigtramp_rt64)
 9:
 
 /* This is where the pt_regs pointer can be found on the stack.  */
-#define PTREGS 128+168+56
+#define PTREGS  128+168+56
 
 /* Size of regs.  */
-#define RSIZE 8
+#define RSIZE   8
+
+/* Size of CR reg in DWARF unwind info. */
+#define CRSIZE  4
 
 /* This is the offset of the VMX reg pointer.  */
-#define VREGS 48*RSIZE+33*8
+#define VREGS   48*RSIZE+33*8
 
 /* Describe where general purpose regs are saved.  */
 #define EH_FRAME_GEN \
@@ -178,7 +181,7 @@ V_FUNCTION_END(__kernel_sigtramp_rt64)
   rsave (31, 31*RSIZE);                                                 \
   rsave (67, 32*RSIZE);         /* ap, used as temp for nip */          \
   rsave (65, 36*RSIZE);         /* lr */                                \
-  rsave (70, 38*RSIZE)          /* cr */
+  rsave (70, 38*RSIZE + (RSIZE - CRSIZE)) /* cr */
 
 /* Describe where the FP regs are saved.  */
 #define EH_FRAME_FP \