[PATCH, rs6000] Fix little-endian bug in linux-unwind.h

[PATCH, rs6000] Fix little-endian bug in linux-unwind.h

[Ulrich Weigand]

Hello,

this fixes another issue related to CR unwinding, this time only on
64-bit little-endian systems.

The problem is linux-unwind.h:ppc_fallback_frame_state, which notes
that the kernel places the CR value in the low bits of a 64-bit
field in the signal handler frame; but the offset of that field
is different in little-endian.

Tested on powerpc64-linux and powerpc64le-linux.

OK for mainline?

Bye,
Ulrich


libgcc/ChangeLog:

2013-11-11  Ulrich Weigand  <Ulrich.Weigand@de.ibm.com>
	    Alan Modra  <amodra@gmail.com>

	* config/rs6000/linux-unwind.h (ppc_fallback_frame_state): Correct
	location of CR save area for 64-bit little-endian systems.

Index: gcc/libgcc/config/rs6000/linux-unwind.h
===================================================================
--- gcc.orig/libgcc/config/rs6000/linux-unwind.h
+++ gcc/libgcc/config/rs6000/linux-unwind.h
@@ -185,6 +185,7 @@ ppc_fallback_frame_state (struct _Unwind
 {
   struct gcc_regs *regs = get_regs (context);
   struct gcc_vregs *vregs;
+  long cr_offset;
   long new_cfa;
   int i;
 
@@ -206,11 +207,13 @@ ppc_fallback_frame_state (struct _Unwind
       fs->regs.reg[i].loc.offset = (long) &regs->gpr[i] - new_cfa;
     }
 
+  /* The CR is saved in the low 32 bits of regs->ccr.  */
+  cr_offset = (long) &regs->ccr - new_cfa;
+#ifndef __LITTLE_ENDIAN__
+  cr_offset += sizeof (long) - 4;
+#endif
   fs->regs.reg[R_CR2].how = REG_SAVED_OFFSET;
-  /* CR? regs are always 32-bit and PPC is big-endian, so in 64-bit
-     libgcc loc.offset needs to point to the low 32 bits of regs->ccr.  */
-  fs->regs.reg[R_CR2].loc.offset = (long) &regs->ccr - new_cfa
-				   + sizeof (long) - 4;
+  fs->regs.reg[R_CR2].loc.offset = cr_offset;
 
   fs->regs.reg[R_LR].how = REG_SAVED_OFFSET;
   fs->regs.reg[R_LR].loc.offset = (long) &regs->link - new_cfa;
-- 
  Dr. Ulrich Weigand
  GNU/Linux compilers and toolchain
  Ulrich.Weigand@de.ibm.com

Re: [PATCH, rs6000] Fix little-endian bug in linux-unwind.h

[David Edelsohn]

libgcc/ChangeLog:

2013-11-11  Ulrich Weigand  <Ulrich.Weigand@de.ibm.com>
   Alan Modra  <amodra@gmail.com>

* config/rs6000/linux-unwind.h (ppc_fallback_frame_state): Correct
location of CR save area for 64-bit little-endian systems.


Okay.

Thanks, David