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author | Rich Felker <dalias@aerifal.cx> | 2015-03-06 13:27:08 -0500 |
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committer | Rich Felker <dalias@aerifal.cx> | 2015-03-06 13:27:08 -0500 |
commit | bd67959f3ad5049c35af0a0e2f8f1a1e60577a49 (patch) | |
tree | e902b7ed8e160789cfc372d25dfd6cbaa0e1492c /src | |
parent | 2b42c8cb37a3ef115bd04de8637078e43cd72f37 (diff) | |
download | musl-bd67959f3ad5049c35af0a0e2f8f1a1e60577a49.tar.gz musl-bd67959f3ad5049c35af0a0e2f8f1a1e60577a49.tar.bz2 musl-bd67959f3ad5049c35af0a0e2f8f1a1e60577a49.tar.xz musl-bd67959f3ad5049c35af0a0e2f8f1a1e60577a49.zip |
fix over-alignment of TLS, insufficient builtin TLS on 64-bit archs
a conservative estimate of 4*sizeof(size_t) was used as the minimum
alignment for thread-local storage, despite the only requirements
being alignment suitable for struct pthread and void* (which struct
pthread already contains). additional alignment required by the
application or libraries is encoded in their headers and is already
applied.
over-alignment prevented the builtin_tls array from ever being used in
dynamic-linked programs on 64-bit archs, thereby requiring allocation
at startup even in programs with no TLS of their own.
Diffstat (limited to 'src')
-rw-r--r-- | src/env/__init_tls.c | 10 | ||||
-rw-r--r-- | src/ldso/dynlink.c | 10 |
2 files changed, 16 insertions, 4 deletions
diff --git a/src/env/__init_tls.c b/src/env/__init_tls.c index ddc2a736..b0dad429 100644 --- a/src/env/__init_tls.c +++ b/src/env/__init_tls.c @@ -2,6 +2,7 @@ #include <limits.h> #include <sys/mman.h> #include <string.h> +#include <stddef.h> #include "pthread_impl.h" #include "libc.h" #include "atomic.h" @@ -22,7 +23,12 @@ int __init_tp(void *p) #ifndef SHARED -static long long builtin_tls[(sizeof(struct pthread) + 64)/sizeof(long long)]; +static struct builtin_tls { + char c; + struct pthread pt; + void *space[16]; +} builtin_tls[1]; +#define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt) struct tls_image { void *image; @@ -86,7 +92,7 @@ void __init_tls(size_t *aux) } T.size += (-T.size - (uintptr_t)T.image) & (T.align-1); - if (T.align < 4*sizeof(size_t)) T.align = 4*sizeof(size_t); + if (T.align < MIN_TLS_ALIGN) T.align = MIN_TLS_ALIGN; libc.tls_size = 2*sizeof(void *)+T.size+T.align+sizeof(struct pthread); diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c index 0bdc988c..ca101993 100644 --- a/src/ldso/dynlink.c +++ b/src/ldso/dynlink.c @@ -122,6 +122,13 @@ void __init_libc(char **, char *); const char *__libc_get_version(void); +static struct builtin_tls { + char c; + struct pthread pt; + void *space[16]; +} builtin_tls[1]; +#define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt) + static struct dso *head, *tail, *ldso, *fini_head; static char *env_path, *sys_path; static unsigned long long gencnt; @@ -132,10 +139,9 @@ static int noload; static jmp_buf *rtld_fail; static pthread_rwlock_t lock; static struct debug debug; -static size_t tls_cnt, tls_offset, tls_align = 4*sizeof(size_t); +static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN; static size_t static_tls_cnt; static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE }; -static long long builtin_tls[(sizeof(struct pthread) + 64)/sizeof(long long)]; struct debug *_dl_debug_addr = &debug; |