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commit 56cf2763819d2f721c98f2b8bcc04a3c673837d3
Author: Adhemerval Zanella <azanella@linux.vnet.ibm.com>
Date: Fri Nov 7 12:34:52 2014 -0500
powerpc: abort transaction in syscalls
Linux kernel powerpc documentation states issuing a syscall inside a
transaction is not recommended and may lead to undefined behavior. It
also states syscalls does not abort transactoin neither they run in
transactional state.
To avoid side-effects being visible outside transactions, GLIBC with
lock elision enabled will issue a transaction abort instruction just
before all syscalls if hardware supports hardware transactions.
Index: glibc-2.17-c758a686/nptl/sysdeps/powerpc/tcb-offsets.sym
===================================================================
--- glibc-2.17-c758a686.orig/nptl/sysdeps/powerpc/tcb-offsets.sym
+++ glibc-2.17-c758a686/nptl/sysdeps/powerpc/tcb-offsets.sym
@@ -15,6 +15,7 @@ MULTIPLE_THREADS_OFFSET thread_offsetof
PID thread_offsetof (pid)
TID thread_offsetof (tid)
POINTER_GUARD (offsetof (tcbhead_t, pointer_guard) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
+TM_CAPABLE (offsetof (tcbhead_t, tm_capable) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
#ifndef __ASSUME_PRIVATE_FUTEX
PRIVATE_FUTEX_OFFSET thread_offsetof (header.private_futex)
#endif
Index: glibc-2.17-c758a686/nptl/sysdeps/powerpc/tls.h
===================================================================
--- glibc-2.17-c758a686.orig/nptl/sysdeps/powerpc/tls.h
+++ glibc-2.17-c758a686/nptl/sysdeps/powerpc/tls.h
@@ -61,6 +61,15 @@ typedef union dtv
are private. */
typedef struct
{
+ /* Indicate if HTM capable (ISA 2.07). */
+ uint32_t tm_capable;
+ /* Reservation for AT_PLATFORM data - powerpc64. */
+#ifdef __powerpc64__
+ uint32_t at_platform;
+#endif
+ /* Reservation for Dynamic System Optimizer ABI. */
+ uintptr_t dso_slot2;
+ uintptr_t dso_slot1;
/* GCC split stack support. */
void *__private_ss;
/* Reservation for the Event-Based Branching ABI. */
@@ -123,7 +132,11 @@ register void *__thread_register __asm__
special attention since 'errno' is not yet available and if the
operation can cause a failure 'errno' must not be touched. */
# define TLS_INIT_TP(tcbp, secondcall) \
- (__thread_register = (void *) (tcbp) + TLS_TCB_OFFSET, NULL)
+ ({ \
+ __thread_register = (void *) (tcbp) + TLS_TCB_OFFSET; \
+ THREAD_SET_TM_CAPABLE (GLRO (dl_hwcap2) & PPC_FEATURE2_HAS_HTM ? 1 : 0); \
+ NULL; \
+ })
/* Return the address of the dtv for the current thread. */
# define THREAD_DTV() \
@@ -177,6 +190,13 @@ register void *__thread_register __asm__
+ TLS_PRE_TCB_SIZE))[-1].pointer_guard \
= THREAD_GET_POINTER_GUARD())
+/* tm_capable field in TCB head. */
+# define THREAD_GET_TM_CAPABLE() \
+ (((tcbhead_t *) ((char *) __thread_register \
+ - TLS_TCB_OFFSET))[-1].tm_capable)
+# define THREAD_SET_TM_CAPABLE(value) \
+ (THREAD_GET_TM_CAPABLE () = (value))
+
/* l_tls_offset == 0 is perfectly valid on PPC, so we have to use some
different value to mean unset l_tls_offset. */
# define NO_TLS_OFFSET -1
Index: glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/sysdep.h
===================================================================
--- glibc-2.17-c758a686.orig/sysdeps/powerpc/powerpc32/sysdep.h
+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/sysdep.h
@@ -89,7 +89,23 @@ GOT_LABEL: ; \
cfi_endproc; \
ASM_SIZE_DIRECTIVE(name)
+#if ! IS_IN(rtld) && defined (ENABLE_LOCK_ELISION)
+# define ABORT_TRANSACTION \
+ cmpwi 2,0; \
+ beq 1f; \
+ lwz 0,TM_CAPABLE(2); \
+ cmpwi 0,0; \
+ beq 1f; \
+ li 0,_ABORT_SYSCALL; \
+ tabort. 0; \
+ .align 4; \
+1:
+#else
+# define ABORT_TRANSACTION
+#endif
+
#define DO_CALL(syscall) \
+ ABORT_TRANSACTION \
li 0,syscall; \
sc
Index: glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/sysdep.h
===================================================================
--- glibc-2.17-c758a686.orig/sysdeps/powerpc/powerpc64/sysdep.h
+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/sysdep.h
@@ -283,7 +283,23 @@ LT_LABELSUFFIX(name,_name_end): ; \
TRACEBACK_MASK(name,mask) \
END_2(name)
+#if !IS_IN(rtld) && defined (ENABLE_LOCK_ELISION)
+# define ABORT_TRANSACTION \
+ cmpdi 13,0; \
+ beq 1f; \
+ lwz 0,TM_CAPABLE(13); \
+ cmpwi 0,0; \
+ beq 1f; \
+ li 0,_ABORT_SYSCALL; \
+ tabort. 0; \
+ .align 4; \
+1:
+#else
+# define ABORT_TRANSACTION
+#endif
+
#define DO_CALL(syscall) \
+ ABORT_TRANSACTION \
li 0,syscall; \
sc
Index: glibc-2.17-c758a686/sysdeps/powerpc/sysdep.h
===================================================================
--- glibc-2.17-c758a686.orig/sysdeps/powerpc/sysdep.h
+++ glibc-2.17-c758a686/sysdeps/powerpc/sysdep.h
@@ -21,6 +21,10 @@
*/
#define _SYS_AUXV_H 1
#include <bits/hwcap.h>
+#ifdef ENABLE_LOCK_ELISION
+#include <tls.h>
+#include <htm.h>
+#endif
#define PPC_FEATURE_970 (PPC_FEATURE_POWER4 + PPC_FEATURE_HAS_ALTIVEC)
@@ -164,4 +168,22 @@
#define ALIGNARG(log2) log2
#define ASM_SIZE_DIRECTIVE(name) .size name,.-name
+#else
+
+/* Linux kernel powerpc documentation [1] states issuing a syscall inside a
+ transaction is not recommended and may lead to undefined behavior. It
+ also states syscalls do not abort transactions. To avoid such traps,
+ we abort transaction just before syscalls.
+
+ [1] Documentation/powerpc/transactional_memory.txt [Syscalls] */
+#if !IS_IN(rtld) && defined (ENABLE_LOCK_ELISION)
+# define ABORT_TRANSACTION \
+ ({ \
+ if (THREAD_GET_TM_CAPABLE ()) \
+ __builtin_tabort (_ABORT_SYSCALL); \
+ })
+#else
+# define ABORT_TRANSACTION
+#endif
+
#endif /* __ASSEMBLER__ */
Index: glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h
===================================================================
--- glibc-2.17-c758a686.orig/sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h
+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h
@@ -194,6 +194,7 @@
register long int r11 __asm__ ("r11"); \
register long int r12 __asm__ ("r12"); \
LOADARGS_##nr(name, args); \
+ ABORT_TRANSACTION; \
__asm__ __volatile__ \
("sc \n\t" \
"mfcr %0" \
Index: glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h
===================================================================
--- glibc-2.17-c758a686.orig/sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h
+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h
@@ -201,6 +201,7 @@
register long int r7 __asm__ ("r7"); \
register long int r8 __asm__ ("r8"); \
LOADARGS_##nr (name, ##args); \
+ ABORT_TRANSACTION; \
__asm__ __volatile__ \
("sc\n\t" \
"mfcr %0\n\t" \
Index: glibc-2.17-c758a686/nptl/sysdeps/unix/sysv/linux/powerpc/createthread.c
===================================================================
--- glibc-2.17-c758a686.orig/nptl/sysdeps/unix/sysv/linux/powerpc/createthread.c
+++ glibc-2.17-c758a686/nptl/sysdeps/unix/sysv/linux/powerpc/createthread.c
@@ -16,9 +16,16 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+/* RHEL 7-specific changes: The functions PREPARE_CREATE and TLS_VALUE
+ are used by createthread.c to override thread setup. In upstream
+ they appear in TLS_DEFINE_INIT_TP. */
+# define PREPARE_CREATE \
+ void *tp = (void *) (pd) + TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE; \
+ (((tcbhead_t *) ((char *) tp - TLS_TCB_OFFSET))[-1].tm_capable) = \
+ THREAD_GET_TM_CAPABLE ();
+
/* Value passed to 'clone' for initialization of the thread register. */
-#define TLS_VALUE ((void *) (pd) \
- + TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE)
+# define TLS_VALUE tp
/* Get the real implementation. */
#include <nptl/sysdeps/pthread/createthread.c>