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authorTulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>2015-12-28 12:24:43 -0200
committerTulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>2016-01-08 17:47:33 -0200
commit42bf1c897170ff951c7fd0ee9da25f97ff787396 (patch)
tree3e69cd2d5201944482407b86b4854fe75ab34f12
parentbc49a7afd38c1bd00f0ad9fd6592a5959d5ba72e (diff)
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powerpc: Enforce compiler barriers on hardware transactions
Work around a GCC behavior with hardware transactional memory built-ins. GCC doesn't treat the PowerPC transactional built-ins as compiler barriers, moving instructions past the transaction boundaries and altering their atomicity.
-rw-r--r--ChangeLog12
-rw-r--r--sysdeps/powerpc/nptl/elide.h8
-rw-r--r--sysdeps/powerpc/sysdep.h2
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/elision-lock.c4
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/elision-trylock.c6
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/elision-unlock.c2
-rw-r--r--sysdeps/unix/sysv/linux/powerpc/htm.h39
7 files changed, 58 insertions, 15 deletions
diff --git a/ChangeLog b/ChangeLog
index 704c80fca72..515d173402b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2016-01-08 Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>
+
+ * sysdeps/unix/sysv/linux/powerpc/htm.h (__libc_tbegin,
+ __libc_tabort, __libc_tend): New wrappers that enforce compiler
+ barriers to their respective compiler built-ins.
+ * sysdeps/powerpc/nptl/elide.h (__get_new_count, ELIDE_LOCK,
+ ELIDE_TRYLOCK, __elide_unlock): Use the new wrappers.
+ * sysdeps/powerpc/sysdep.h: Likewise.
+ * sysdeps/unix/sysv/linux/powerpc/elision-lock.c: Likewise.
+ * sysdeps/unix/sysv/linux/powerpc/elision-trylock.c: Likewise.
+ * sysdeps/unix/sysv/linux/powerpc/elision-unlock.c: Likewise.
+
2016-01-08 Marko Myllynen <myllynen@redhat.com>
* scripts/config.guess: Revert previous shebang change.
diff --git a/sysdeps/powerpc/nptl/elide.h b/sysdeps/powerpc/nptl/elide.h
index c7374649012..77bd82ecba0 100644
--- a/sysdeps/powerpc/nptl/elide.h
+++ b/sysdeps/powerpc/nptl/elide.h
@@ -68,14 +68,14 @@ __get_new_count (uint8_t *adapt_count, int attempt)
else \
for (int i = __elision_aconf.try_tbegin; i > 0; i--) \
{ \
- if (__builtin_tbegin (0)) \
+ if (__libc_tbegin (0)) \
{ \
if (is_lock_free) \
{ \
ret = 1; \
break; \
} \
- __builtin_tabort (_ABORT_LOCK_BUSY); \
+ __libc_tabort (_ABORT_LOCK_BUSY); \
} \
else \
if (!__get_new_count (&adapt_count,i)) \
@@ -90,7 +90,7 @@ __get_new_count (uint8_t *adapt_count, int attempt)
if (__elision_aconf.try_tbegin > 0) \
{ \
if (write) \
- __builtin_tabort (_ABORT_NESTED_TRYLOCK); \
+ __libc_tabort (_ABORT_NESTED_TRYLOCK); \
ret = ELIDE_LOCK (adapt_count, is_lock_free); \
} \
ret; \
@@ -102,7 +102,7 @@ __elide_unlock (int is_lock_free)
{
if (is_lock_free)
{
- __builtin_tend (0);
+ __libc_tend (0);
return true;
}
return false;
diff --git a/sysdeps/powerpc/sysdep.h b/sysdeps/powerpc/sysdep.h
index def54f08a29..800623af37c 100644
--- a/sysdeps/powerpc/sysdep.h
+++ b/sysdeps/powerpc/sysdep.h
@@ -180,7 +180,7 @@
# define ABORT_TRANSACTION \
({ \
if (THREAD_GET_TM_CAPABLE ()) \
- __builtin_tabort (_ABORT_SYSCALL); \
+ __libc_tabort (_ABORT_SYSCALL); \
})
#else
# define ABORT_TRANSACTION
diff --git a/sysdeps/unix/sysv/linux/powerpc/elision-lock.c b/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
index 830d2ccfe1c..dd1e4c3b17a 100644
--- a/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
+++ b/sysdeps/unix/sysv/linux/powerpc/elision-lock.c
@@ -52,12 +52,12 @@ __lll_lock_elision (int *lock, short *adapt_count, EXTRAARG int pshared)
for (int i = aconf.try_tbegin; i > 0; i--)
{
- if (__builtin_tbegin (0))
+ if (__libc_tbegin (0))
{
if (*lock == 0)
return 0;
/* Lock was busy. Fall back to normal locking. */
- __builtin_tabort (_ABORT_LOCK_BUSY);
+ __libc_tabort (_ABORT_LOCK_BUSY);
}
else
{
diff --git a/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c b/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c
index 9263f1d1b8e..0807a6a4323 100644
--- a/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c
+++ b/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c
@@ -31,7 +31,7 @@ int
__lll_trylock_elision (int *futex, short *adapt_count)
{
/* Implement POSIX semantics by forbiding nesting elided trylocks. */
- __builtin_tabort (_ABORT_NESTED_TRYLOCK);
+ __libc_tabort (_ABORT_NESTED_TRYLOCK);
/* Only try a transaction if it's worth it. */
if (*adapt_count > 0)
@@ -39,14 +39,14 @@ __lll_trylock_elision (int *futex, short *adapt_count)
goto use_lock;
}
- if (__builtin_tbegin (0))
+ if (__libc_tbegin (0))
{
if (*futex == 0)
return 0;
/* Lock was busy. This is never a nested transaction.
End it, and set the adapt count. */
- __builtin_tend (0);
+ __libc_tend (0);
if (aconf.skip_lock_busy > 0)
*adapt_count = aconf.skip_lock_busy;
diff --git a/sysdeps/unix/sysv/linux/powerpc/elision-unlock.c b/sysdeps/unix/sysv/linux/powerpc/elision-unlock.c
index 2561b1dca2d..43c5a67df2a 100644
--- a/sysdeps/unix/sysv/linux/powerpc/elision-unlock.c
+++ b/sysdeps/unix/sysv/linux/powerpc/elision-unlock.c
@@ -25,7 +25,7 @@ __lll_unlock_elision (int *lock, short *adapt_count, int pshared)
{
/* When the lock was free we're in a transaction. */
if (*lock == 0)
- __builtin_tend (0);
+ __libc_tend (0);
else
{
lll_unlock ((*lock), pshared);
diff --git a/sysdeps/unix/sysv/linux/powerpc/htm.h b/sysdeps/unix/sysv/linux/powerpc/htm.h
index b18b47ee67f..16b2237fccf 100644
--- a/sysdeps/unix/sysv/linux/powerpc/htm.h
+++ b/sysdeps/unix/sysv/linux/powerpc/htm.h
@@ -118,13 +118,44 @@
__ret; \
})
-#define __builtin_tbegin(tdb) _tbegin ()
-#define __builtin_tend(nested) _tend ()
-#define __builtin_tabort(abortcode) _tabort (abortcode)
-#define __builtin_get_texasru() _texasru ()
+#define __libc_tbegin(tdb) _tbegin ()
+#define __libc_tend(nested) _tend ()
+#define __libc_tabort(abortcode) _tabort (abortcode)
+#define __builtin_get_texasru() _texasru ()
#else
# include <htmintrin.h>
+
+# ifdef __TM_FENCE__
+ /* New GCC behavior. */
+# define __libc_tbegin(R) __builtin_tbegin (R);
+# define __libc_tend(R) __builtin_tend (R);
+# define __libc_tabort(R) __builtin_tabort (R);
+# else
+ /* Workaround an old GCC behavior. Earlier releases of GCC 4.9 and 5.0,
+ didn't use to treat __builtin_tbegin, __builtin_tend and
+ __builtin_tabort as compiler barriers, moving instructions into and
+ out the transaction.
+ Remove this when glibc drops support for GCC 5.0. */
+# define __libc_tbegin(R) \
+ ({ __asm__ volatile("" ::: "memory"); \
+ unsigned int __ret = __builtin_tbegin (R); \
+ __asm__ volatile("" ::: "memory"); \
+ __ret; \
+ })
+# define __libc_tabort(R) \
+ ({ __asm__ volatile("" ::: "memory"); \
+ unsigned int __ret = __builtin_tabort (R); \
+ __asm__ volatile("" ::: "memory"); \
+ __ret; \
+ })
+# define __libc_tend(R) \
+ ({ __asm__ volatile("" ::: "memory"); \
+ unsigned int __ret = __builtin_tend (R); \
+ __asm__ volatile("" ::: "memory"); \
+ __ret; \
+ })
+# endif /* __TM_FENCE__ */
#endif /* __HTM__ */
#endif /* __ASSEMBLER__ */