From 1769608794096c835095826559c0ba1555f43fc0 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Tue, 2 Jun 2015 20:24:25 +0000 Subject: Use libc_hidden_proto / libc_hidden_def with __strnlen. Various code in glibc uses __strnlen instead of strnlen for namespace reasons. However, __strnlen does not use libc_hidden_proto / libc_hidden_def (as is normally done for any function defined and called within the same library, whether or not exported from the library and whatever namespace it is in), so the compiler does not know that those calls are to a function within libc. This patch uses libc_hidden_proto / libc_hidden_def with __strnlen. On x86_64, it makes no difference to the installed stripped shared libraries. On 32-bit x86, it causes __strnlen calls to go to the same place as strnlen calls (the fallback strnlen implementation), rather than through a PLT entry for the strnlen IFUNC; I'm not sure of the logic behind when calls from within libc should use IFUNCs versus when they should go direct to a particular function implementation, but clearly it doesn't make sense for strnlen and __strnlen to be handled differently in this regard. Tested for x86_64 and x86 (testsuite, and comparison of installed shared libraries as described above). * string/strnlen.c [!STRNLEN] (__strnlen): Use libc_hidden_def. * include/string.h (__strnlen): Use libc_hidden_proto. * sysdeps/aarch64/strnlen.S (__strnlen): Use libc_hidden_def. * sysdeps/i386/i686/multiarch/strnlen-c.c [SHARED] (libc_hidden_def): Define __GI___strnlen as well as __GI_strnlen. * sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-power7.S (libc_hidden_def): Undefine and redefine. * sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c [SHARED] (libc_hidden_def): Define __GI___strnlen as well as __GI_strnlen. * sysdeps/powerpc/powerpc32/power7/strnlen.S (__strnlen): Use libc_hidden_def. * sysdeps/tile/tilegx/strnlen.c (__strnlen): Likewise. --- sysdeps/i386/i686/multiarch/strnlen-c.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'sysdeps/i386/i686/multiarch') diff --git a/sysdeps/i386/i686/multiarch/strnlen-c.c b/sysdeps/i386/i686/multiarch/strnlen-c.c index f02465d6a4..351e939a93 100644 --- a/sysdeps/i386/i686/multiarch/strnlen-c.c +++ b/sysdeps/i386/i686/multiarch/strnlen-c.c @@ -2,7 +2,9 @@ #ifdef SHARED # undef libc_hidden_def # define libc_hidden_def(name) \ - __hidden_ver1 (__strnlen_ia32, __GI_strnlen, __strnlen_ia32); + __hidden_ver1 (__strnlen_ia32, __GI_strnlen, __strnlen_ia32); \ + strong_alias (__strnlen_ia32, __strnlen_ia32_1); \ + __hidden_ver1 (__strnlen_ia32_1, __GI___strnlen, __strnlen_ia32_1); #endif #include "string/strnlen.c" -- cgit 1.4.1