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[PATCH][BZ #16214] Fix TLS access on S390 with -march=z10
- From: Siddhesh Poyarekar <siddhesh at redhat dot com>
- To: libc-alpha at sourceware dot org
- Cc: carlos at redhat dot com, Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>
- Date: Mon, 25 Nov 2013 11:20:09 +0530
- Subject: [PATCH][BZ #16214] Fix TLS access on S390 with -march=z10
- Authentication-results: sourceware.org; auth=none
Hi,
-march=z10 eliminates GOT pointer loads for static variables whenever
it can, which exposes a bug in the TLS implementation in s390x. The
TLS implementation assumes that the compiler will load the GOT pointer
(%r12) and implements __tls_get_offset with that assumption. This
however is true only in cases where the compiler sets up TLS for a
__thread. For cases where we call TLS_GET_ADDR directly (like in
dl-sym.c and in some test cases), we have to explicitly ensure that
%r12 is set up.
Attached patch does this for s390 and s390x. It wasn't needed on
s390, but I did it anyway to prevent a possible breakage in future.
Tested and verified that the test cases are fixed and no new
regressions were seen. OK to commit?
Siddhesh
[BZ #16214]
* sysdeps/s390/dl-tls.h (LOAD_R12): New macro.
(__TLS_GET_ADDR): Use it.
* sysdeps/s390/s390-32/tls-macros.h [PIC] (TLS_IE): Load GOT
pointer.
* sysdeps/s390/s390-64/tls-macros.h [PIC] (TLS_IE): Likewise.
diff --git a/sysdeps/s390/dl-tls.h b/sysdeps/s390/dl-tls.h
index 68a5af4..92c32e6 100644
--- a/sysdeps/s390/dl-tls.h
+++ b/sysdeps/s390/dl-tls.h
@@ -65,13 +65,24 @@ __tls_get_offset:\n\
# endif
# endif
+# ifdef __s390x__
+# define LOAD_R12(r12) asm ("lgr %0,%%r12" : "=r" (r12) ::)
+# elif defined __s390__
+# define LOAD_R12(r12) asm ("lr %0,%%r12" : "=r" (r12) ::)
+# endif
+
# define GET_ADDR_OFFSET \
(ti->ti_offset - (unsigned long) __builtin_thread_pointer ())
+/* Subtract contents of r12 from __TI. We don't really care if this is the
+ GOT pointer. */
# define __TLS_GET_ADDR(__ti) \
- ({ extern char _GLOBAL_OFFSET_TABLE_[] attribute_hidden; \
- (void *) __tls_get_offset ((char *) (__ti) - _GLOBAL_OFFSET_TABLE_) \
- + (unsigned long) __builtin_thread_pointer (); })
+({ \
+ unsigned long int r12; \
+ LOAD_R12 (r12); \
+ ((void *) __tls_get_offset ((unsigned long int) (__ti) - r12) \
+ + (unsigned long) __builtin_thread_pointer ()); \
+})
#endif
diff --git a/sysdeps/s390/s390-32/tls-macros.h b/sysdeps/s390/s390-32/tls-macros.h
index 8a0ad58..0a11998 100644
--- a/sysdeps/s390/s390-32/tls-macros.h
+++ b/sysdeps/s390/s390-32/tls-macros.h
@@ -8,12 +8,17 @@
#ifdef PIC
# define TLS_IE(x) \
- ({ unsigned long __offset; \
+ ({ unsigned long __offset, __save; \
asm ("bras %0,1f\n" \
- "0:\t.long " #x "@gotntpoff\n" \
- "1:\tl %0,0(%0)\n\t" \
- "l %0,0(%0,%%r12):tls_load:" #x \
- : "=&a" (__offset) : : "cc" ); \
+ "0:\t.long _GLOBAL_OFFSET_TABLE_-0b\n\t" \
+ ".long " #x "@gotntpoff\n" \
+ "1:\tlr %1,%%r12\n\t" \
+ "l %%r12,0(%0)\n\t" \
+ "la %%r12,0(%%r12,%0)\n\t" \
+ "l %0,4(%0)\n\t" \
+ "l %0,0(%0,%%r12):tls_load:" #x "\n\t" \
+ "lr %%r12, %1\n" \
+ : "=&a" (__offset), "=&a" (__save) : : "cc" ); \
(int *) (__builtin_thread_pointer() + __offset); })
#else
# define TLS_IE(x) \
diff --git a/sysdeps/s390/s390-64/tls-macros.h b/sysdeps/s390/s390-64/tls-macros.h
index be8aa6c..a65047c 100644
--- a/sysdeps/s390/s390-64/tls-macros.h
+++ b/sysdeps/s390/s390-64/tls-macros.h
@@ -8,12 +8,15 @@
#ifdef PIC
# define TLS_IE(x) \
- ({ unsigned long __offset; \
+ ({ unsigned long __offset, __save; \
asm ("bras %0,1f\n" \
"0:\t.quad " #x "@gotntpoff\n" \
- "1:\tlg %0,0(%0)\n\t" \
- "lg %0,0(%0,%%r12):tls_load:" #x \
- : "=&a" (__offset) : : "cc" ); \
+ "1:\tlgr %1,%%r12\n\t" \
+ "larl %%r12,_GLOBAL_OFFSET_TABLE_\n\t" \
+ "lg %0,0(%0)\n\t" \
+ "lg %0,0(%0,%%r12):tls_load:" #x "\n\t" \
+ "lgr %%r12,%1" \
+ : "=&a" (__offset), "=&a" (__save) : : "cc" ); \
(int *) (__builtin_thread_pointer() + __offset); })
#else
# define TLS_IE(x) \