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Build: Require attribute no_profile_instrument_function for ifunc usage.

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Using __attribute__((__no_profile_instrument_function__)) on the ifunc
resolver works around a bug in GCC -fprofile-generate:
it adds profiling code even to ifunc resolvers which can make
the ifunc resolver crash at program startup. This attribute
was not introduced until GCC 7 and Clang 13, so ifunc won't
be used with prior versions of these compilers.

This bug was brought to our attention by:

    https://bugs.gentoo.org/925415

And was reported to upstream GCC by:

    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=11411
This commit is contained in:
Jia Tan 2024-03-05 00:27:31 +08:00
parent 7eeadd279a
commit e5faaebbcf
2 changed files with 14 additions and 0 deletions
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7
CMakeLists.txt
View file

@ -1082,6 +1082,13 @@ if(USE_ATTR_IFUNC STREQUAL "auto")
#endif #endif
static void func(void) { return; } static void func(void) { return; }
/*
* The attribute __no_profile_instrument_function__ is
* needed with GCC to prevent improper instrumentation in
* the ifunc resolver.
*/
__attribute__((__no_profile_instrument_function__))
static void (*resolve_func(void)) (void) { return func; } static void (*resolve_func(void)) (void) { return func; }
void func_ifunc(void) void func_ifunc(void)
__attribute__((__ifunc__(\"resolve_func\"))); __attribute__((__ifunc__(\"resolve_func\")));

7
configure.ac
View file

@ -915,6 +915,13 @@ if test "x$enable_ifunc" = xauto ; then
#endif #endif
static void func(void) { return; } static void func(void) { return; }
/*
* The attribute __no_profile_instrument_function__ is
* needed with GCC to prevent improper instrumentation in
* the ifunc resolver.
*/
__attribute__((__no_profile_instrument_function__))
static void (*resolve_func (void)) (void) { return func; } static void (*resolve_func (void)) (void) { return func; }
void func_ifunc (void) void func_ifunc (void)
__attribute__((__ifunc__("resolve_func"))); __attribute__((__ifunc__("resolve_func")));