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authorRich Felker <dalias@aerifal.cx>2015-11-12 15:50:26 -0500
committerRich Felker <dalias@aerifal.cx>2015-11-12 16:07:00 -0500
commitd56460c939c94a6c547abe8238f442b8de10bfbd (patch)
treeaaba49b1834dfdaafabb371d39bf4e1111935d18 /src/env
parentad1cd43a86645ba2d4f7c8747240452a349d6bc1 (diff)
downloadmusl-d56460c939c94a6c547abe8238f442b8de10bfbd.tar.gz
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.
Diffstat (limited to 'src/env')
-rw-r--r--src/env/__init_tls.c71
-rw-r--r--src/env/__reset_tls.c23
2 files changed, 49 insertions, 45 deletions
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 <string.h>
#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