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Use weak symbols to prevent LTO if this is an option.

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Idea from Matthew Dempsky.
This commit is contained in:
Frank Denis 2014-06-20 21:09:18 -07:00
parent c7418dfd58
commit 957315035a
2 changed files with 18 additions and 0 deletions
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10
configure.ac
View File

@ -375,6 +375,16 @@ __asm__ __volatile__ ("xchgl %%ebx, %k1; cpuid; xchgl %%ebx, %k1" :
])
AC_SUBST(HAVE_CPUID_V)
AC_MSG_CHECKING(if weak symbols are supported)
AC_LINK_IFELSE([AC_LANG_PROGRAM([[
__attribute__((weak)) void __dummy(void *x) { }
void f(void *x) { __dummy(x); }
]], [[ ]]
)],
[AC_MSG_RESULT(yes)
AC_DEFINE([HAVE_WEAK_SYMBOLS], [1], [weak symbols are supported])],
[AC_MSG_RESULT(no)])
AS_CASE([$host_cpu],
[i*86 | x86_64 | powerpc* | s390*],
[AC_MSG_NOTICE([data alignment is not required on this target])],

8
src/libsodium/sodium/utils.c
View File

@ -19,6 +19,11 @@
# include <wincrypt.h>
#endif
#ifdef HAVE_WEAK_SYMBOLS
__attribute__((weak)) void
__sodium_dummy_symbol_to_prevent_lto(void * const pnt, const size_t len) { }
#endif
void
sodium_memzero(void * const pnt, const size_t len)
{
@ -30,6 +35,9 @@ sodium_memzero(void * const pnt, const size_t len)
}
#elif defined(HAVE_EXPLICIT_BZERO)
explicit_bzero(pnt, len);
#elif HAVE_WEAK_SYMBOLS
memset(pnt, 0, len);
__sodium_dummy_symbol_to_prevent_lto(pnt, len);
#else
volatile unsigned char *pnt_ = (volatile unsigned char *) pnt;
size_t i = (size_t) 0U;