[PATCH] powerpc/vdso: Emit GNU & SysV hashes

[PATCH] powerpc/vdso: Emit GNU & SysV hashes

[Michael Ellerman]

Andy Lutomirski says:

  Some dynamic loaders may be slightly faster if a GNU hash is
  available.

  This is unlikely to have any measurable effect on the time it takes
  to resolve vdso symbols (since there are so few of them).  In some
  contexts, it can be a win for a different reason: if every DSO has a
  GNU hash section, then libc can avoid calculating SysV hashes at
  all. Both musl and glibc appear to have this optimization.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/kernel/vdso32/Makefile | 2 +-
 arch/powerpc/kernel/vdso64/Makefile | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/vdso32/Makefile b/arch/powerpc/kernel/vdso32/Makefile
index 53e6c9b979ec..6abffb7a8cd9 100644
--- a/arch/powerpc/kernel/vdso32/Makefile
+++ b/arch/powerpc/kernel/vdso32/Makefile
@@ -18,7 +18,7 @@ GCOV_PROFILE := n
 
 ccflags-y := -shared -fno-common -fno-builtin
 ccflags-y += -nostdlib -Wl,-soname=linux-vdso32.so.1 \
-		$(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
+		$(call cc-ldoption, -Wl$(comma)--hash-style=both)
 asflags-y := -D__VDSO32__ -s
 
 obj-y += vdso32_wrapper.o
diff --git a/arch/powerpc/kernel/vdso64/Makefile b/arch/powerpc/kernel/vdso64/Makefile
index effca9404b17..8c8f2ae43935 100644
--- a/arch/powerpc/kernel/vdso64/Makefile
+++ b/arch/powerpc/kernel/vdso64/Makefile
@@ -11,7 +11,7 @@ GCOV_PROFILE := n
 
 ccflags-y := -shared -fno-common -fno-builtin
 ccflags-y += -nostdlib -Wl,-soname=linux-vdso64.so.1 \
-		$(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
+		$(call cc-ldoption, -Wl$(comma)--hash-style=both)
 asflags-y := -D__VDSO64__ -s
 
 obj-y += vdso64_wrapper.o
-- 
2.1.4

Re: powerpc/vdso: Emit GNU & SysV hashes

[Michael Ellerman]

On Fri, 2015-07-08 at 03:05:42 UTC, Michael Ellerman wrote:
> Andy Lutomirski says:
> 
>   Some dynamic loaders may be slightly faster if a GNU hash is
>   available.
> 
>   This is unlikely to have any measurable effect on the time it takes
>   to resolve vdso symbols (since there are so few of them).  In some
>   contexts, it can be a win for a different reason: if every DSO has a
>   GNU hash section, then libc can avoid calculating SysV hashes at
>   all. Both musl and glibc appear to have this optimization.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Applied to powerpc next.

https://git.kernel.org/powerpc/c/787b393c9f6300c343600d39

cheers