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authorRich Felker <dalias@aerifal.cx>2012-10-15 18:51:53 -0400
committerRich Felker <dalias@aerifal.cx>2012-10-15 18:51:53 -0400
commit9ec4283b28cf676292fd5c6f681bef1e90e30c18 (patch)
tree2897be56744c39158a3e53adfc4e3569b3f8547d /src/env
parentd5304147b983f309ed0c9050e3b8b6f2c9f87f43 (diff)
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add support for TLS variant I, presently needed for arm and mips
despite documentation that makes it sound a lot different, the only
ABI-constraint difference between TLS variants II and I seems to be
that variant II stores the initial TLS segment immediately below the
thread pointer (i.e. the thread pointer points to the end of it) and
variant I stores the initial TLS segment above the thread pointer,
requiring the thread descriptor to be stored below. the actual value
stored in the thread pointer register also tends to have per-arch
random offsets applied to it for silly micro-optimization purposes.

with these changes applied, TLS should be basically working on all
supported archs except microblaze. I'm still working on getting the
necessary information and a working toolchain that can build TLS
binaries for microblaze, but in theory, static-linked programs with
TLS and dynamic-linked programs where only the main executable uses
TLS should already work on microblaze.

alignment constraints have not yet been heavily tested, so it's
possible that this code does not always align TLS segments correctly
on archs that need TLS variant I.
Diffstat (limited to 'src/env')
-rw-r--r--src/env/__init_tls.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/src/env/__init_tls.c b/src/env/__init_tls.c
index e70025d7..ab5992ce 100644
--- a/src/env/__init_tls.c
+++ b/src/env/__init_tls.c
@@ -15,11 +15,18 @@ void *__copy_tls(unsigned char *mem)
 	if (!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);
+	td = (pthread_t)mem;
+	mem += sizeof(struct pthread);
+#else
 	mem += __libc.tls_size - sizeof(struct pthread);
 	mem -= (uintptr_t)mem & (align-1);
 	td = (pthread_t)mem;
 	td->dtv = dtv;
 	mem -= size;
+#endif
 	dtv[1] = mem;
 	memcpy(mem, image, len);
 	return td;
@@ -33,7 +40,7 @@ void *__tls_get_addr(size_t *v)
 static void *simple(void *p)
 {
 	*(void **)p = p;
-	return __set_thread_area(p) ? 0 : p;
+	return __set_thread_area(TP_ADJ(p)) ? 0 : p;
 }
 
 weak_alias(simple, __install_initial_tls);