From a988eb00e19e0365bdcb8b3be9ee8d4f6c2c6fbb Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Fri, 7 Nov 2014 12:34:52 -0500 Subject: 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 enable issues a transaction abort instruction just before all syscalls if hardware supports hardware transactions. --- ChangeLog | 17 +++++++++++++++++ sysdeps/powerpc/nptl/tcb-offsets.sym | 1 + sysdeps/powerpc/nptl/tls.h | 19 +++++++++++++++++-- sysdeps/powerpc/powerpc32/sysdep.h | 16 ++++++++++++++++ sysdeps/powerpc/powerpc64/sysdep.h | 16 ++++++++++++++++ sysdeps/powerpc/sysdep.h | 21 +++++++++++++++++++++ sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h | 1 + sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h | 1 + 8 files changed, 90 insertions(+), 2 deletions(-) diff --git a/ChangeLog b/ChangeLog index 615c845967..490112d6bc 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,22 @@ 2014-11-10 Adhemerval Zanella + * sysdeps/powerpc/nptl/tls.h (tcbhead_t): Add tm_capable field. + (TLS_INIT_TP): Add tm_capable initialization. + (TLS_DEFINE_INIT_TP): Likewise. + (THREAD_GET_TM_CAPABLE): New file: get tm_capable field value from + TCB. + (THREAD_SET_TM_CAPABLE): New file: set tm_capable field value in TCB. + * sysdeps/powerpc/nptl/tcb-offsets.sym (TM_CAPABLE): Add field offset + calculation. + * sysdeps/powerpc/powerpc32/sysdep.h (DO_CALL): Abort hardware + transactoion is lock elision is built and TCB tm_capable is set. + * sysdeps/powerpc/powerpc64/sysdep.h (DO_CALL): Likewise. + * sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h + (INTERNAL_SYSCALL_NCS): Likewise. + * sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h + (INTERNAL_SYSCALL_NCS): Likewise. + * sysdeps/powerpc/sysdep.h (ABORT_TRANSACTION): New define. + * sysdeps/powerpc/nptl/elide.h: New file: generic lock elision support for powerpc. * sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h diff --git a/sysdeps/powerpc/nptl/tcb-offsets.sym b/sysdeps/powerpc/nptl/tcb-offsets.sym index f996759027..d955142aff 100644 --- a/sysdeps/powerpc/nptl/tcb-offsets.sym +++ b/sysdeps/powerpc/nptl/tcb-offsets.sym @@ -19,6 +19,7 @@ POINTER_GUARD (offsetof (tcbhead_t, pointer_guard) - TLS_TCB_OFFSET - sizeof ( TAR_SAVE (offsetof (tcbhead_t, tar_save) - TLS_TCB_OFFSET - sizeof (tcbhead_t)) DSO_SLOT1 (offsetof (tcbhead_t, dso_slot1) - TLS_TCB_OFFSET - sizeof (tcbhead_t)) DSO_SLOT2 (offsetof (tcbhead_t, dso_slot2) - 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 diff --git a/sysdeps/powerpc/nptl/tls.h b/sysdeps/powerpc/nptl/tls.h index b80a5fbf54..37280d2fec 100644 --- a/sysdeps/powerpc/nptl/tls.h +++ b/sysdeps/powerpc/nptl/tls.h @@ -63,6 +63,8 @@ typedef union dtv are private. */ typedef struct { + /* Indicate if hwcap2 has PPC_FEATURE2_HAS_HTM capability. */ + int tm_capable; /* Reservation for Dynamic System Optimizer ABI. */ uintptr_t dso_slot2; uintptr_t dso_slot1; @@ -130,11 +132,17 @@ register void *__thread_register __asm__ ("r13"); 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) \ - (__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; \ + }) /* 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 + 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 (); /* Return the address of the dtv for the current thread. */ # define THREAD_DTV() \ @@ -188,6 +196,13 @@ register void *__thread_register __asm__ ("r13"); + 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 diff --git a/sysdeps/powerpc/powerpc32/sysdep.h b/sysdeps/powerpc/powerpc32/sysdep.h index c8a56aadbf..c4b3ca8696 100644 --- a/sysdeps/powerpc/powerpc32/sysdep.h +++ b/sysdeps/powerpc/powerpc32/sysdep.h @@ -88,7 +88,23 @@ GOT_LABEL: ; \ cfi_endproc; \ ASM_SIZE_DIRECTIVE(name) +#if !defined 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 diff --git a/sysdeps/powerpc/powerpc64/sysdep.h b/sysdeps/powerpc/powerpc64/sysdep.h index b28fb9d8aa..78722c6873 100644 --- a/sysdeps/powerpc/powerpc64/sysdep.h +++ b/sysdeps/powerpc/powerpc64/sysdep.h @@ -283,7 +283,23 @@ LT_LABELSUFFIX(name,_name_end): ; \ TRACEBACK_MASK(name,mask) \ END_2(name) +#if !defined 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 diff --git a/sysdeps/powerpc/sysdep.h b/sysdeps/powerpc/sysdep.h index e6627c071f..c683066673 100644 --- a/sysdeps/powerpc/sysdep.h +++ b/sysdeps/powerpc/sysdep.h @@ -21,6 +21,10 @@ */ #define _SYSDEPS_SYSDEP_H 1 #include +#ifdef ENABLE_LOCK_ELISION +#include +#include +#endif #define PPC_FEATURE_970 (PPC_FEATURE_POWER4 + PPC_FEATURE_HAS_ALTIVEC) @@ -164,4 +168,21 @@ #define ALIGNARG(log2) log2 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name +#else + +/* 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 run in + transactional state. To avoid such traps, we abort transaction just + before syscalls. */ +#if !defined 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__ */ diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h b/sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h index 1a5e37a1d9..0947ca34a6 100644 --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h +++ b/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" \ diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h b/sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h index 93e454e902..a3cc3025e0 100644 --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h +++ b/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" \ -- cgit v1.2.1