File ppc-tle-htm-nosc.patch of Package glibc.18276

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
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