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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.
This commit is contained in:
Adhemerval Zanella
parent
4b45943a6f
commit
56cf276381
17
ChangeLog
17
ChangeLog
@ -1,5 +1,22 @@
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2014-01-12 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
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* sysdeps/powerpc/nptl/tls.h (tcbhead_t): Add tm_capable field.
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(TLS_INIT_TP): Add tm_capable initialization.
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(TLS_DEFINE_INIT_TP): Likewise.
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(THREAD_GET_TM_CAPABLE): New file: get tm_capable field value from
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TCB.
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(THREAD_SET_TM_CAPABLE): New file: set tm_capable field value in TCB.
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* sysdeps/powerpc/nptl/tcb-offsets.sym (TM_CAPABLE): Add field offset
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calculation.
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* sysdeps/powerpc/powerpc32/sysdep.h (DO_CALL): Abort hardware
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transactoion is lock elision is built and TCB tm_capable is set.
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* sysdeps/powerpc/powerpc64/sysdep.h (DO_CALL): Likewise.
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* sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h
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(INTERNAL_SYSCALL_NCS): Likewise.
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* sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h
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(INTERNAL_SYSCALL_NCS): Likewise.
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* sysdeps/powerpc/sysdep.h (ABORT_TRANSACTION): New define.
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* sysdeps/powerpc/nptl/elide.h: New file: generic lock elision support
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for powerpc.
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* sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h
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@ -19,6 +19,7 @@ POINTER_GUARD (offsetof (tcbhead_t, pointer_guard) - TLS_TCB_OFFSET - sizeof (
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TAR_SAVE (offsetof (tcbhead_t, tar_save) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
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DSO_SLOT1 (offsetof (tcbhead_t, dso_slot1) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
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DSO_SLOT2 (offsetof (tcbhead_t, dso_slot2) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
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TM_CAPABLE (offsetof (tcbhead_t, tm_capable) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
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#ifndef __ASSUME_PRIVATE_FUTEX
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PRIVATE_FUTEX_OFFSET thread_offsetof (header.private_futex)
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#endif
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@ -63,6 +63,8 @@ typedef union dtv
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are private. */
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typedef struct
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{
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/* Indicate if HTM capable (ISA 2.07). */
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int tm_capable;
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/* Reservation for Dynamic System Optimizer ABI. */
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uintptr_t dso_slot2;
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uintptr_t dso_slot1;
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@ -130,11 +132,17 @@ register void *__thread_register __asm__ ("r13");
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special attention since 'errno' is not yet available and if the
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operation can cause a failure 'errno' must not be touched. */
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# define TLS_INIT_TP(tcbp) \
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(__thread_register = (void *) (tcbp) + TLS_TCB_OFFSET, NULL)
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({ \
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__thread_register = (void *) (tcbp) + TLS_TCB_OFFSET; \
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THREAD_SET_TM_CAPABLE (GLRO (dl_hwcap2) & PPC_FEATURE2_HAS_HTM ? 1 : 0); \
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NULL; \
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})
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/* Value passed to 'clone' for initialization of the thread register. */
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# define TLS_DEFINE_INIT_TP(tp, pd) \
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void *tp = (void *) (pd) + TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE
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void *tp = (void *) (pd) + TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE; \
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(((tcbhead_t *) ((char *) tp - TLS_TCB_OFFSET))[-1].tm_capable) = \
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THREAD_GET_TM_CAPABLE ();
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/* Return the address of the dtv for the current thread. */
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# define THREAD_DTV() \
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@ -188,6 +196,13 @@ register void *__thread_register __asm__ ("r13");
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+ TLS_PRE_TCB_SIZE))[-1].pointer_guard \
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= THREAD_GET_POINTER_GUARD())
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/* tm_capable field in TCB head. */
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# define THREAD_GET_TM_CAPABLE() \
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(((tcbhead_t *) ((char *) __thread_register \
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- TLS_TCB_OFFSET))[-1].tm_capable)
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# define THREAD_SET_TM_CAPABLE(value) \
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(THREAD_GET_TM_CAPABLE () = (value))
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/* l_tls_offset == 0 is perfectly valid on PPC, so we have to use some
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different value to mean unset l_tls_offset. */
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# define NO_TLS_OFFSET -1
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@ -88,7 +88,23 @@ GOT_LABEL: ; \
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cfi_endproc; \
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ASM_SIZE_DIRECTIVE(name)
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#if ! IS_IN(rtld) && defined (ENABLE_LOCK_ELISION)
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# define ABORT_TRANSACTION \
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cmpwi 2,0; \
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beq 1f; \
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lwz 0,TM_CAPABLE(2); \
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cmpwi 0,0; \
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beq 1f; \
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li 0,_ABORT_SYSCALL; \
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tabort. 0; \
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.align 4; \
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1:
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#else
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# define ABORT_TRANSACTION
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#endif
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#define DO_CALL(syscall) \
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ABORT_TRANSACTION \
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li 0,syscall; \
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sc
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@ -283,7 +283,23 @@ LT_LABELSUFFIX(name,_name_end): ; \
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TRACEBACK_MASK(name,mask) \
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END_2(name)
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#if !IS_IN(rtld) && defined (ENABLE_LOCK_ELISION)
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# define ABORT_TRANSACTION \
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cmpdi 13,0; \
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beq 1f; \
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lwz 0,TM_CAPABLE(13); \
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cmpwi 0,0; \
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beq 1f; \
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li 0,_ABORT_SYSCALL; \
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tabort. 0; \
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.align 4; \
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1:
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#else
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# define ABORT_TRANSACTION
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#endif
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#define DO_CALL(syscall) \
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ABORT_TRANSACTION \
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li 0,syscall; \
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sc
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@ -21,6 +21,10 @@
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*/
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#define _SYSDEPS_SYSDEP_H 1
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#include <bits/hwcap.h>
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#ifdef ENABLE_LOCK_ELISION
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#include <tls.h>
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#include <htm.h>
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#endif
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#define PPC_FEATURE_970 (PPC_FEATURE_POWER4 + PPC_FEATURE_HAS_ALTIVEC)
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@ -164,4 +168,22 @@
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#define ALIGNARG(log2) log2
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#define ASM_SIZE_DIRECTIVE(name) .size name,.-name
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#else
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/* Linux kernel powerpc documentation [1] states issuing a syscall inside a
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transaction is not recommended and may lead to undefined behavior. It
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also states syscalls do not abort transactions. To avoid such traps,
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we abort transaction just before syscalls.
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[1] Documentation/powerpc/transactional_memory.txt [Syscalls] */
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#if !IS_IN(rtld) && defined (ENABLE_LOCK_ELISION)
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# define ABORT_TRANSACTION \
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({ \
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if (THREAD_GET_TM_CAPABLE ()) \
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__builtin_tabort (_ABORT_SYSCALL); \
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})
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#else
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# define ABORT_TRANSACTION
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#endif
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#endif /* __ASSEMBLER__ */
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@ -194,6 +194,7 @@
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register long int r11 __asm__ ("r11"); \
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register long int r12 __asm__ ("r12"); \
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LOADARGS_##nr(name, args); \
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ABORT_TRANSACTION; \
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__asm__ __volatile__ \
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("sc \n\t" \
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"mfcr %0" \
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@ -201,6 +201,7 @@
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register long int r7 __asm__ ("r7"); \
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register long int r8 __asm__ ("r8"); \
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LOADARGS_##nr (name, ##args); \
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ABORT_TRANSACTION; \
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__asm__ __volatile__ \
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("sc\n\t" \
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"mfcr %0\n\t" \
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