From d56460c939c94a6c547abe8238f442b8de10bfbd Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Thu, 12 Nov 2015 15:50:26 -0500 Subject: unify static and dynamic linked implementations of thread-local storage this both allows removal of some of the main remaining uses of the SHARED macro and clears one obstacle to static-linked dlopen support, which may be added at some point in the future. specialized single-TLS-module versions of __copy_tls and __reset_tls are removed and replaced with code adapted from their dynamic-linked versions, capable of operating on a whole chain of TLS modules, and use of the dynamic linker's DSO chain (which contains large struct dso objects) by these functions is replaced with a new chain of struct tls_module objects containing only the information needed for implementing TLS. this may also yield some performance benefit initializing TLS for a new thread when a large number of modules without TLS have been loaded, since since there is no need to walk structures for modules without TLS. --- src/env/__init_tls.c | 71 +++++++++++++++++++++++++++++---------------------- src/env/__reset_tls.c | 23 +++++++---------- 2 files changed, 49 insertions(+), 45 deletions(-) (limited to 'src/env') diff --git a/src/env/__init_tls.c b/src/env/__init_tls.c index 73551e6c..0107a545 100644 --- a/src/env/__init_tls.c +++ b/src/env/__init_tls.c @@ -8,9 +8,6 @@ #include "atomic.h" #include "syscall.h" -#ifndef SHARED -static -#endif int __init_tp(void *p) { pthread_t td = p; @@ -24,8 +21,6 @@ int __init_tp(void *p) return 0; } -#ifndef SHARED - static struct builtin_tls { char c; struct pthread pt; @@ -33,33 +28,40 @@ static struct builtin_tls { } builtin_tls[1]; #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt) -struct tls_image { - void *image; - size_t len, size, align; -} __static_tls; - -#define T __static_tls +static struct tls_module main_tls; void *__copy_tls(unsigned char *mem) { pthread_t td; - if (!T.image) return mem; - void **dtv = (void *)mem; - dtv[0] = (void *)1; + struct tls_module *p; + size_t i; + void **dtv; + #ifdef TLS_ABOVE_TP - mem += sizeof(void *) * 2; - mem += -((uintptr_t)mem + sizeof(struct pthread)) & (T.align-1); + dtv = (void **)(mem + libc.tls_size) - (libc.tls_cnt + 1); + + mem += -((uintptr_t)mem + sizeof(struct pthread)) & (libc.tls_align-1); td = (pthread_t)mem; mem += sizeof(struct pthread); + + for (i=1, p=libc.tls_head; p; i++, p=p->next) { + dtv[i] = mem + p->offset; + memcpy(dtv[i], p->image, p->len); + } #else + dtv = (void **)mem; + mem += libc.tls_size - sizeof(struct pthread); - mem -= (uintptr_t)mem & (T.align-1); + mem -= (uintptr_t)mem & (libc.tls_align-1); td = (pthread_t)mem; - mem -= T.size; + + for (i=1, p=libc.tls_head; p; i++, p=p->next) { + dtv[i] = mem - p->offset; + memcpy(dtv[i], p->image, p->len); + } #endif + dtv[0] = (void *)libc.tls_cnt; td->dtv = td->dtv_copy = dtv; - dtv[1] = mem; - memcpy(mem, T.image, T.len); return td; } @@ -69,7 +71,7 @@ typedef Elf32_Phdr Phdr; typedef Elf64_Phdr Phdr; #endif -void __init_tls(size_t *aux) +static void static_init_tls(size_t *aux) { unsigned char *p; size_t n; @@ -86,16 +88,24 @@ void __init_tls(size_t *aux) } if (tls_phdr) { - 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; + main_tls.image = (void *)(base + tls_phdr->p_vaddr); + main_tls.len = tls_phdr->p_filesz; + main_tls.size = tls_phdr->p_memsz; + main_tls.align = tls_phdr->p_align; + libc.tls_cnt = 1; + libc.tls_head = &main_tls; } - T.size += (-T.size - (uintptr_t)T.image) & (T.align-1); - if (T.align < MIN_TLS_ALIGN) T.align = MIN_TLS_ALIGN; + main_tls.size += (-main_tls.size - (uintptr_t)main_tls.image) + & (main_tls.align-1); + if (main_tls.align < MIN_TLS_ALIGN) main_tls.align = MIN_TLS_ALIGN; +#ifndef TLS_ABOVE_TP + main_tls.offset = main_tls.size; +#endif - libc.tls_size = 2*sizeof(void *)+T.size+T.align+sizeof(struct pthread) + libc.tls_align = main_tls.align; + libc.tls_size = 2*sizeof(void *) + sizeof(struct pthread) + + main_tls.size + main_tls.align + MIN_TLS_ALIGN-1 & -MIN_TLS_ALIGN; if (libc.tls_size > sizeof builtin_tls) { @@ -117,6 +127,5 @@ void __init_tls(size_t *aux) if (__init_tp(__copy_tls(mem)) < 0) a_crash(); } -#else -void __init_tls(size_t *auxv) { } -#endif + +weak_alias(static_init_tls, __init_tls); diff --git a/src/env/__reset_tls.c b/src/env/__reset_tls.c index bd61f311..677e57f5 100644 --- a/src/env/__reset_tls.c +++ b/src/env/__reset_tls.c @@ -1,21 +1,16 @@ -#ifndef SHARED - #include #include "pthread_impl.h" - -extern struct tls_image { - void *image; - size_t len, size, align; -} __static_tls; - -#define T __static_tls +#include "libc.h" 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); + struct tls_module *p; + size_t i, n = (size_t)self->dtv[0]; + if (n) for (p=libc.tls_head, i=1; i<=n; i++, p=p->next) { + if (!self->dtv[i]) continue; + memcpy(self->dtv[i], p->image, p->len); + memset((char *)self->dtv[i]+p->len, 0, + p->size - p->len); + } } - -#endif -- cgit v1.2.1