File ppc-tle-htm-nosc.patch of Package glibc.22972
2018-09-21 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* sysdeps/powerpc/nptl/tcb-offsets.sym (TM_CAPABLE): Remove.
* sysdeps/powerpc/nptl/tls.h (tcbhead_t): Rename tm_capable to
__ununsed1.
(TLS_INIT_TP, TLS_DEFINE_INIT_TP): Remove tm_capable setup.
(THREAD_GET_TM_CAPABLE, THREAD_SET_TM_CAPABLE): Remove macros.
* sysdeps/powerpc/powerpc32/sysdep.h,
sysdeps/powerpc/powerpc64/sysdep.h (ABORT_TRANSACTION): Remove macro.
* sysdeps/powerpc/sysdep.h (ABORT_TRANSACTION): Likewise.
* sysdeps/unix/sysv/linux/powerpc/elision-conf.c (elision_init): Set
__pthread_force_elision iff PPC_FEATURE2_HTM_NOSC is set.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h,
sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h
sysdeps/unix/sysv/linux/powerpc/syscall.S (ABORT_TRANSACTION): Remove
usage.
Index: glibc-2.26/sysdeps/powerpc/nptl/tcb-offsets.sym
===================================================================
--- glibc-2.26.orig/sysdeps/powerpc/nptl/tcb-offsets.sym
+++ glibc-2.26/sysdeps/powerpc/nptl/tcb-offsets.sym
@@ -21,7 +21,6 @@ DSO_SLOT2 (offsetof (tcbhead_t, dso_sl
#ifdef __powerpc64__
TCB_AT_PLATFORM (offsetof (tcbhead_t, at_platform) - TLS_TCB_OFFSET - sizeof(tcbhead_t))
#endif
-TM_CAPABLE (offsetof (tcbhead_t, tm_capable) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
#ifndef __powerpc64__
TCB_AT_PLATFORM (offsetof (tcbhead_t, at_platform) - TLS_TCB_OFFSET - sizeof(tcbhead_t))
PADDING (offsetof (tcbhead_t, padding) - TLS_TCB_OFFSET - sizeof(tcbhead_t))
Index: glibc-2.26/sysdeps/powerpc/nptl/tls.h
===================================================================
--- glibc-2.26.orig/sysdeps/powerpc/nptl/tls.h
+++ glibc-2.26/sysdeps/powerpc/nptl/tls.h
@@ -67,8 +67,7 @@ typedef struct
uint32_t padding;
uint32_t at_platform;
#endif
- /* Indicate if HTM capable (ISA 2.07). */
- uint32_t tm_capable;
+ uint32_t __unused;
/* Reservation for AT_PLATFORM data - powerpc64. */
#ifdef __powerpc64__
uint32_t at_platform;
@@ -142,7 +141,6 @@ register void *__thread_register __asm__
# define TLS_INIT_TP(tcbp) \
({ \
__thread_register = (void *) (tcbp) + TLS_TCB_OFFSET; \
- THREAD_SET_TM_CAPABLE (__tcb_hwcap & PPC_FEATURE2_HAS_HTM ? 1 : 0); \
THREAD_SET_HWCAP (__tcb_hwcap); \
THREAD_SET_AT_PLATFORM (__tcb_platform); \
NULL; \
@@ -151,8 +149,6 @@ register void *__thread_register __asm__
/* Value passed to 'clone' for initialization of the thread register. */
# define TLS_DEFINE_INIT_TP(tp, pd) \
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 (); \
(((tcbhead_t *) ((char *) tp - TLS_TCB_OFFSET))[-1].hwcap) = \
THREAD_GET_HWCAP (); \
(((tcbhead_t *) ((char *) tp - TLS_TCB_OFFSET))[-1].at_platform) = \
@@ -210,13 +206,6 @@ 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))
-
/* hwcap field in TCB head. */
# define THREAD_GET_HWCAP() \
(((tcbhead_t *) ((char *) __thread_register \
Index: glibc-2.26/sysdeps/powerpc/powerpc32/sysdep.h
===================================================================
--- glibc-2.26.orig/sysdeps/powerpc/powerpc32/sysdep.h
+++ glibc-2.26/sysdeps/powerpc/powerpc32/sysdep.h
@@ -90,23 +90,7 @@ 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 11,_ABORT_SYSCALL; \
- tabort. 11; \
- .align 4; \
-1:
-#else
-# define ABORT_TRANSACTION
-#endif
-
#define DO_CALL(syscall) \
- ABORT_TRANSACTION \
li 0,syscall; \
sc
Index: glibc-2.26/sysdeps/powerpc/powerpc64/sysdep.h
===================================================================
--- glibc-2.26.orig/sysdeps/powerpc/powerpc64/sysdep.h
+++ glibc-2.26/sysdeps/powerpc/powerpc64/sysdep.h
@@ -263,23 +263,7 @@ 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 11,_ABORT_SYSCALL; \
- tabort. 11; \
- .p2align 4; \
-1:
-#else
-# define ABORT_TRANSACTION
-#endif
-
#define DO_CALL(syscall) \
- ABORT_TRANSACTION \
li 0,syscall; \
sc
Index: glibc-2.26/sysdeps/powerpc/sysdep.h
===================================================================
--- glibc-2.26.orig/sysdeps/powerpc/sysdep.h
+++ glibc-2.26/sysdeps/powerpc/sysdep.h
@@ -21,10 +21,6 @@
*/
#define _SYSDEPS_SYSDEP_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)
@@ -168,22 +164,4 @@
#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 ()) \
- __libc_tabort (_ABORT_SYSCALL); \
- })
-#else
-# define ABORT_TRANSACTION
-#endif
-
#endif /* __ASSEMBLER__ */
Index: glibc-2.26/sysdeps/unix/sysv/linux/powerpc/elision-conf.c
===================================================================
--- glibc-2.26.orig/sysdeps/unix/sysv/linux/powerpc/elision-conf.c
+++ glibc-2.26/sysdeps/unix/sysv/linux/powerpc/elision-conf.c
@@ -75,6 +75,27 @@ elision_init (int argc __attribute__ ((u
}
}
#endif
+
+ /* Linux from 3.9 through 4.2 do not abort HTM transaction on syscalls,
+ instead it suspends the transaction and resumes it when returning to
+ usercode. The side-effects of the syscall will always remain visible,
+ even if the transaction is aborted. This is an issue when a transaction
+ is used along with futex syscall, on pthread_cond_wait for instance,
+ where futex might succeed but the transaction is rolled back leading
+ the condition variable object in an inconsistent state.
+
+ Glibc used to prevent it by always aborting a transaction before issuing
+ a syscall. Linux 4.2 also decided to abort active transaction in
+ syscalls which makes the glibc workaround superflours. Worse, glibc
+ transaction abortions leads to a performance issues on recent kernels.
+
+ So Lock Elision is just enabled when it has been explict set (either
+ by tunables of by a configure switch) and if kernel aborts HTM
+ transactions on syscalls (PPC_FEATURE2_HTM_NOSC) */
+
+ __pthread_force_elision = (__pthread_force_elision
+ && GLRO (dl_hwcap2) & PPC_FEATURE2_HTM_NOSC);
+
if (!__pthread_force_elision)
/* Disable elision on rwlocks. */
__elision_aconf.try_tbegin = 0;
Index: glibc-2.26/sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h
===================================================================
--- glibc-2.26.orig/sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h
+++ glibc-2.26/sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h
@@ -109,7 +109,6 @@
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-2.26/sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h
===================================================================
--- glibc-2.26.orig/sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h
+++ glibc-2.26/sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h
@@ -131,7 +131,6 @@
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-2.26/sysdeps/unix/sysv/linux/powerpc/syscall.S
===================================================================
--- glibc-2.26.orig/sysdeps/unix/sysv/linux/powerpc/syscall.S
+++ glibc-2.26/sysdeps/unix/sysv/linux/powerpc/syscall.S
@@ -18,7 +18,6 @@
#include <sysdep.h>
ENTRY (syscall)
- ABORT_TRANSACTION
mr r0,r3
mr r3,r4
mr r4,r5
