Re: ppc soft-float regression

[Szabolcs Nagy <nsz@port70.net>]

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* Rich Felker <dalias@libc.org> [2015-05-17 12:35:21 -0400]:
> On Sun, May 17, 2015 at 10:03:21AM +0200, Waldemar Brodkorb wrote:
> > Hi,
> > 
> > as mentioned the days on IRC.
> > 1.1.9 produces a lot of segfaults on Qemu-PPC with Soft-Float.
> > 1.1.8 was fine.
> 
> Soft-float has never been a supported configuration for PowerPC, as
> you can see from the fact that there's no separate dynamic linker name
> for it. I'm surprised it ever seemed to work -- surely setjmp/longjmp
> would be broken since they save/restore FPU registers. I don't think
> it would be hard to add though, and I'd welcome patches for it. What's
> needed is basically:
> 
> - detection in configure, setting $SUBARCH there
> - dynamic linker name variants in arch/powerpc/reloc.h
> - separate subarch dir for soft-float in src/setjmp
> 
> If you add soft-float it would probably make sense to add
> little-endian variant at the same time, if that's useful to anyone,
> since once you do the subarch work there's hardly any more work to
> make an endian variant too.
> 

note that the current musl-cross powerpc patches don't do
the include reordering so the gcc includes will be the
first in the path.  this is fixed in

http://gcc.gnu.org/ml/gcc-patches/2015-04/msg01640.html

if there is a ppc soft-float abi musl may support then please
invent an abi name for it so i can update the gcc patch before
it gets committed.

(i think powerpc{el}{-sf} and powerpc64{el}{-sf} should work:
it is consistent with the naming for mips).

attached the musl dynamic linker name patch for "el" support,
similar would be needed for -sf (+setjmp.s etc updates).

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diff --git a/arch/powerpc/reloc.h b/arch/powerpc/reloc.h
index aa5f8c9..4292cea 100644
--- a/arch/powerpc/reloc.h
+++ b/arch/powerpc/reloc.h
@@ -1,4 +1,12 @@
-#define LDSO_ARCH "powerpc"
+#include <endian.h>
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define ENDIAN_SUFFIX "el"
+#else
+#define ENDIAN_SUFFIX ""
+#endif
+
+#define LDSO_ARCH "powerpc" ENDIAN_SUFFIX
 
 #define TPOFF_K (-0x7000)
 
diff --git a/configure b/configure
index 143dc92..4e1a1fe 100755
--- a/configure
+++ b/configure
@@ -491,6 +491,9 @@ fi
 test "$ARCH" = "microblaze" && trycppif __MICROBLAZEEL__ "$t" \
 && SUBARCH=${SUBARCH}el
 
+test "$ARCH" = "powerpc" && trycppif __LITTLE_ENDIAN__ "$t" \
+&& SUBARCH=${SUBARCH}el
+
 if test "$ARCH" = "sh" ; then
 trycppif __BIG_ENDIAN__ "$t" && SUBARCH=${SUBARCH}eb
 if trycppif "__SH_FPU_ANY__ || __SH4__" "$t" ; then