diff options
| author | Florian Weimer <fweimer@redhat.com> | 2018-05-23 13:13:05 +0200 |
|---|---|---|
| committer | Florian Weimer <fw@gcc.gnu.org> | 2018-05-23 13:13:05 +0200 |
| commit | cb3c90cc4253cc236a4d5669a893562b202570e5 (patch) | |
| tree | f949dbb7958ca1eeed9204b05d8ea39418b7ac22 /libatomic/config | |
| parent | 159440699bf6f97dccc94377d9d69e540a1904dc (diff) | |
| download | gcc-cb3c90cc4253cc236a4d5669a893562b202570e5.zip gcc-cb3c90cc4253cc236a4d5669a893562b202570e5.tar.gz gcc-cb3c90cc4253cc236a4d5669a893562b202570e5.tar.bz2 | |
x86: libatomic: Do not assume ELF constructors run before IFUNC resolvers
PR libgcc/60790
x86: Do not assume ELF constructors run before IFUNC resolvers.
* config/x86/host-config.h (libat_feat1_ecx, libat_feat1_edx):
Remove declarations.
(__libat_feat1, __libat_feat1_init): Declare.
(FEAT1_REGISTER): Define.
(load_feat1): New function.
(IFUNC_COND_1): Adjust.
* config/x86/init.c (libat_feat1_ecx, libat_feat1_edx)
(init_cpuid): Remove definitions.
(__libat_feat1): New variable.
(__libat_feat1_init): New function.
From-SVN: r260603
Diffstat (limited to 'libatomic/config')
| -rw-r--r-- | libatomic/config/x86/host-config.h | 34 | ||||
| -rw-r--r-- | libatomic/config/x86/init.c | 14 |
2 files changed, 39 insertions, 9 deletions
diff --git a/libatomic/config/x86/host-config.h b/libatomic/config/x86/host-config.h index 4a9ab4a..0b6c338 100644 --- a/libatomic/config/x86/host-config.h +++ b/libatomic/config/x86/host-config.h @@ -25,13 +25,39 @@ #if HAVE_IFUNC #include <cpuid.h> -extern unsigned int libat_feat1_ecx HIDDEN; -extern unsigned int libat_feat1_edx HIDDEN; +#ifdef __x86_64__ +# define FEAT1_REGISTER ecx +#else +# define FEAT1_REGISTER edx +#endif + +/* Value of the CPUID feature register FEAT1_REGISTER for the cmpxchg + bit for IFUNC_COND1 below. */ +extern unsigned int __libat_feat1 HIDDEN; + +/* Initialize libat_feat1 and return its value. */ +unsigned int __libat_feat1_init (void) HIDDEN; + +/* Return the value of the relevant feature register for the relevant + cmpxchg bit, or 0 if there is no CPUID support. */ +static inline unsigned int +__attribute__ ((const)) +load_feat1 (void) +{ + /* See the store in __libat_feat1_init. */ + unsigned int feat1 = __atomic_load_n (&__libat_feat1, __ATOMIC_RELAXED); + if (feat1 == 0) + /* Assume that initialization has not happened yet. This may get + called repeatedly if the CPU does not have any feature bits at + all. */ + feat1 = __libat_feat1_init (); + return feat1; +} #ifdef __x86_64__ -# define IFUNC_COND_1 (libat_feat1_ecx & bit_CMPXCHG16B) +# define IFUNC_COND_1 (load_feat1 () & bit_CMPXCHG16B) #else -# define IFUNC_COND_1 (libat_feat1_edx & bit_CMPXCHG8B) +# define IFUNC_COND_1 (load_feat1 () & bit_CMPXCHG8B) #endif #ifdef __x86_64__ diff --git a/libatomic/config/x86/init.c b/libatomic/config/x86/init.c index 8b9ccd3..5a4cf8b 100644 --- a/libatomic/config/x86/init.c +++ b/libatomic/config/x86/init.c @@ -26,13 +26,17 @@ #if HAVE_IFUNC -unsigned int libat_feat1_ecx, libat_feat1_edx; +unsigned int __libat_feat1; -static void __attribute__((constructor)) -init_cpuid (void) +unsigned int +__libat_feat1_init (void) { - unsigned int eax, ebx; - __get_cpuid (1, &eax, &ebx, &libat_feat1_ecx, &libat_feat1_edx); + unsigned int eax, ebx, ecx, edx; + FEAT1_REGISTER = 0; + __get_cpuid (1, &eax, &ebx, &ecx, &edx); + /* See the load in load_feat1. */ + __atomic_store_n (&__libat_feat1, FEAT1_REGISTER, __ATOMIC_RELAXED); + return FEAT1_REGISTER; } #endif /* HAVE_IFUNC */ |