Commit-ID: 6b7e26547fad7ace3dcb27a5babd2317fb9d1e12 Gitweb: http://git.kernel.org/tip/6b7e26547fad7ace3dcb27a5babd2317fb9d1e12 Author: Andy Lutomirski <luto@xxxxxxxxxxxxxx> AuthorDate: Thu, 6 Aug 2015 14:45:45 -0700 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Sat, 8 Aug 2015 10:42:07 +0200 x86/vdso: Emit a GNU hash Some dynamic loaders may be slightly faster if a GNU hash is available. Strangely, this seems to have no effect at all on the vdso size. 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. It's plausible that this breaks some ancient glibc version. If so, then, depending on what glibc versions break, we could either require COMPAT_VDSO for them or consider reverting. Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Isaac Dunham <ibid.ag@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Nathan Lynch <nathan_lynch@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Rich Felker <dalias@xxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: musl@xxxxxxxxxxxxxxxxxx <musl@xxxxxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/fd56cc057a2d62ab31c56a48d04fccb435b3fd4f.1438897382.git.luto@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/entry/vdso/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 96c0617..a3d0767 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -175,7 +175,7 @@ quiet_cmd_vdso = VDSO $@ -Wl,-T,$(filter %.lds,$^) $(filter %.o,$^) && \ sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@' -VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) \ +VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=both) \ $(call cc-ldoption, -Wl$(comma)--build-id) -Wl,-Bsymbolic $(LTO_CFLAGS) GCOV_PROFILE := n -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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