From 7c6c290695cb8726e876ff4fb8413913f661fc0b Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sat, 3 Aug 2013 16:27:30 -0400 Subject: [PATCH] add system for resetting TLS to initial values this is needed for reused threads in the SIGEV_THREAD timer notification system, and could be reused elsewhere in the future if needed, though it should be refactored for such use. for static linking, __init_tls.c is simply modified to export the TLS info in a structure with external linkage, rather than using statics. this perhaps makes the code more clear, since the statics were poorly named for statics. the new __reset_tls.c is only linked if it is used. for dynamic linking, the code is in dynlink.c. sharing code with __copy_tls is not practical since __reset_tls must also re-zero thread-local bss. --- src/env/__init_tls.c | 32 ++++++++++++++++++-------------- src/env/__reset_tls.c | 22 ++++++++++++++++++++++ src/ldso/dynlink.c | 13 +++++++++++++ src/time/timer_create.c | 3 +++ 4 files changed, 56 insertions(+), 14 deletions(-) create mode 100644 src/env/__reset_tls.c diff --git a/src/env/__init_tls.c b/src/env/__init_tls.c index a4704f06..5c176811 100644 --- a/src/env/__init_tls.c +++ b/src/env/__init_tls.c @@ -8,29 +8,33 @@ #ifndef SHARED -static void *image; -static size_t len, size, align; +struct tls_image { + void *image; + size_t len, size, align; +} __static_tls ATTR_LIBC_VISIBILITY; + +#define T __static_tls void *__copy_tls(unsigned char *mem) { pthread_t td; - if (!image) return mem; + if (!T.image) return mem; void **dtv = (void *)mem; dtv[0] = (void *)1; #ifdef TLS_ABOVE_TP mem += sizeof(void *) * 2; - mem += -((uintptr_t)mem + sizeof(struct pthread)) & (align-1); + mem += -((uintptr_t)mem + sizeof(struct pthread)) & (T.align-1); td = (pthread_t)mem; mem += sizeof(struct pthread); #else mem += libc.tls_size - sizeof(struct pthread); - mem -= (uintptr_t)mem & (align-1); + mem -= (uintptr_t)mem & (T.align-1); td = (pthread_t)mem; - mem -= size; + mem -= T.size; #endif td->dtv = dtv; dtv[1] = mem; - memcpy(mem, image, len); + memcpy(mem, T.image, T.len); return td; } @@ -73,15 +77,15 @@ void __init_tls(size_t *aux) } if (!tls_phdr) return; - image = (void *)(base + tls_phdr->p_vaddr); - len = tls_phdr->p_filesz; - size = tls_phdr->p_memsz; - align = tls_phdr->p_align; + T.image = (void *)(base + tls_phdr->p_vaddr); + T.len = tls_phdr->p_filesz; + T.size = tls_phdr->p_memsz; + T.align = tls_phdr->p_align; - size += (-size - (uintptr_t)image) & (align-1); - if (align < 4*sizeof(size_t)) align = 4*sizeof(size_t); + T.size += (-T.size - (uintptr_t)T.image) & (T.align-1); + if (T.align < 4*sizeof(size_t)) T.align = 4*sizeof(size_t); - libc.tls_size = 2*sizeof(void *)+size+align+sizeof(struct pthread); + libc.tls_size = 2*sizeof(void *)+T.size+T.align+sizeof(struct pthread); mem = __mmap(0, libc.tls_size, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); diff --git a/src/env/__reset_tls.c b/src/env/__reset_tls.c new file mode 100644 index 00000000..28c4405e --- /dev/null +++ b/src/env/__reset_tls.c @@ -0,0 +1,22 @@ +#ifndef SHARED + +#include +#include "pthread_impl.h" +#include "libc.h" + +extern struct tls_image { + void *image; + size_t len, size, align; +} __static_tls ATTR_LIBC_VISIBILITY; + +#define T __static_tls + +void __reset_tls() +{ + if (!T.size) return; + pthread_t self = __pthread_self(); + memcpy(self->dtv[1], T.image, T.len); + memset((char *)self->dtv[1]+T.len, 0, T.size-T.len); +} + +#endif diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c index d689f96e..fa5ad004 100644 --- a/src/ldso/dynlink.c +++ b/src/ldso/dynlink.c @@ -783,6 +783,19 @@ void _dl_debug_state(void) { } +void __reset_tls() +{ + pthread_t self = __pthread_self(); + struct dso *p; + for (p=head; p; p=p->next) { + if (!p->tls_id || !self->dtv[p->tls_id]) continue; + memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len); + memset((char *)self->dtv[p->tls_id]+p->tls_len, 0, + p->tls_size - p->tls_len); + if (p->tls_id == (size_t)self->dtv[0]) break; + } +} + void *__copy_tls(unsigned char *mem) { pthread_t td; diff --git a/src/time/timer_create.c b/src/time/timer_create.c index 2b4619d4..ee6a9c9d 100644 --- a/src/time/timer_create.c +++ b/src/time/timer_create.c @@ -19,6 +19,8 @@ static void dummy_1(pthread_t self) } weak_alias(dummy_1, __pthread_tsd_run_dtors); +void __reset_tls(); + static void cleanup_fromsig(void *p) { pthread_t self = __pthread_self(); @@ -28,6 +30,7 @@ static void cleanup_fromsig(void *p) self->canceldisable = 0; self->cancelasync = 0; self->unblock_cancel = 0; + __reset_tls(); longjmp(p, 1); } -- 2.25.1