From 7dfe8a35215a019f552f117d907eca294225c121 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Wed, 12 Jun 2013 10:21:22 -0500 Subject: [PATCH 35/42] Fix unsafe compiler optimization GCC 4.8 enables -ftree-loop-distribute-patterns at -O3 by default and this optimization may transform loops into memset/memmove calls. Without proper handling this may generate unexpected PLT calls on GLIBC. This patch fixes by create memset/memmove alias to internal GLIBC __GI_memset/__GI_memmove symbols. (cherry picked from commit 6a97b62a5b4f18aea849d6f4d8de58d1469d2521) --- sysdeps/generic/symbol-hacks.h | 7 ++++++- sysdeps/wordsize-32/symbol-hacks.h | 2 ++ 3 files changed, 16 insertions(+), 1 deletion(-) diff --git glibc-2.17-c758a686/sysdeps/generic/symbol-hacks.h glibc-2.17-c758a686/sysdeps/generic/symbol-hacks.h index bc7b4c4..9eaf014 100644 --- glibc-2.17-c758a686/sysdeps/generic/symbol-hacks.h +++ glibc-2.17-c758a686/sysdeps/generic/symbol-hacks.h @@ -1 +1,6 @@ -/* Fortunately nothing to do. */ +/* Some compiler optimizations may transform loops into memset/memmove + calls and without proper declaration it may generate PLT calls. */ +#if !defined __ASSEMBLER__ && !defined NOT_IN_libc && defined SHARED +asm ("memmove = __GI_memmove"); +asm ("memset = __GI_memset"); +#endif diff --git glibc-2.17-c758a686/sysdeps/wordsize-32/symbol-hacks.h glibc-2.17-c758a686/sysdeps/wordsize-32/symbol-hacks.h index 52a14fc..ad5b231 100644 --- glibc-2.17-c758a686/sysdeps/wordsize-32/symbol-hacks.h +++ glibc-2.17-c758a686/sysdeps/wordsize-32/symbol-hacks.h @@ -16,6 +16,8 @@ License along with the GNU C Library; if not, see . */ +#include_next "symbol-hacks.h" + /* A very dirty trick: gcc emits references to __divdi3, __udivdi3, __moddi3, and __umoddi3. These functions are exported and therefore we get PLTs. Unnecessarily so. Changing gcc is a big -- 1.7.11.7