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Revert "Revert "Lose the hand-written futex assembler.""

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The problem with the original patch was that using syscall(3) means that
errno can be set, but pthread_create(3) was abusing the TLS errno slot as
a pthread_mutex_t for the thread startup handshake.

There was also a mistake in the check for syscall failures --- it should
have checked against -1 instead of 0 (not just because that's the default
idiom, but also here because futex(2) can legitimately return values > 0).

This patch stops abusing the TLS errno slot and adds a pthread_mutex_t to
pthread_internal_t instead. (Note that for LP64 sizeof(pthread_mutex_t) >
sizeof(uintptr_t), so we could potentially clobber other TLS slots too.)

I've also rewritten the LP32 compatibility stubs to directly reuse the
code from the .h file.

This reverts commit 75c55ff84e.

Bug: 15195455
Change-Id: I6ffb13e5cf6a35d8f59f692d94192aae9ab4593d
This commit is contained in:
Elliott Hughes 2014-05-28 19:35:33 +00:00
parent 52f74322b1
commit b30aff405a
24 changed files with 45 additions and 455 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
libc/SYSCALLS.TXT
View File

@ -305,8 +305,6 @@ int eventfd:eventfd2(unsigned int, int) all
void _exit|_Exit:exit_group(int) all
void __exit:exit(int) all
int futex(void*, int, int, void*, void*, int) all
int inotify_init1(int) all
int inotify_add_watch(int, const char*, unsigned int) all
int inotify_rm_watch(int, unsigned int) all

1
libc/arch-arm/arm.mk
View File

@ -53,7 +53,6 @@ libc_bionic_src_files_arm += \
arch-arm/bionic/__bionic_clone.S \
arch-arm/bionic/eabi.c \
arch-arm/bionic/_exit_with_stack_teardown.S \
arch-arm/bionic/futex_arm.S \
arch-arm/bionic/__get_sp.S \
arch-arm/bionic/libgcc_compat.c \
arch-arm/bionic/memcmp16.S \

38
libc/arch-arm/bionic/futex_arm.S
View File

@ -1,38 +0,0 @@
/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <private/bionic_asm.h>
// int __futex_syscall4(volatile void* ftx, int op, int val, const struct timespec* timeout)
ENTRY_PRIVATE(__futex_syscall4)
mov ip, r7
ldr r7, =__NR_futex
swi #0
mov r7, ip
bx lr
END(__futex_syscall4)

22
libc/arch-arm/syscalls/futex.S
View File

@ -1,22 +0,0 @@
/* Generated by gensyscalls.py. Do not edit. */
#include <private/bionic_asm.h>
ENTRY(futex)
mov ip, sp
stmfd sp!, {r4, r5, r6, r7}
.cfi_def_cfa_offset 16
.cfi_rel_offset r4, 0
.cfi_rel_offset r5, 4
.cfi_rel_offset r6, 8
.cfi_rel_offset r7, 12
ldmfd ip, {r4, r5, r6}
ldr r7, =__NR_futex
swi #0
ldmfd sp!, {r4, r5, r6, r7}
.cfi_def_cfa_offset 0
cmn r0, #(MAX_ERRNO + 1)
bxls lr
neg r0, r0
b __set_errno
END(futex)

1
libc/arch-arm64/arm64.mk
View File

@ -37,7 +37,6 @@ libc_bionic_src_files_arm64 := \
arch-arm64/bionic/__bionic_clone.S \
arch-arm64/bionic/bzero_arm64.c \
arch-arm64/bionic/_exit_with_stack_teardown.S \
arch-arm64/bionic/futex_arm64.S \
arch-arm64/bionic/__get_sp.S \
arch-arm64/bionic/__rt_sigreturn.S \
arch-arm64/bionic/_setjmp.S \

47
libc/arch-arm64/bionic/futex_arm64.S
View File

@ -1,47 +0,0 @@
/*
* Copyright (C) 2013 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <private/bionic_asm.h>
// int __futex_syscall4(volatile void* ftx, int op, int val, const struct timespec* timeout)
ENTRY_PRIVATE(__futex_syscall4)
stp x29, x30, [sp, #-16]!
.cfi_def_cfa_offset 16
.cfi_rel_offset x29, 0
.cfi_rel_offset x30, 8
mov x29, sp
mov x8, __NR_futex
svc #0
ldp x29, x30, [sp], #16
.cfi_def_cfa_offset 0
.cfi_restore x29
.cfi_restore x30
ret
END(__futex_syscall4)

25
libc/arch-arm64/syscalls/futex.S
View File

@ -1,25 +0,0 @@
/* Generated by gensyscalls.py. Do not edit. */
#include <private/bionic_asm.h>
ENTRY(futex)
stp x29, x30, [sp, #-16]!
.cfi_def_cfa_offset 16
.cfi_rel_offset x29, 0
.cfi_rel_offset x30, 8
mov x29, sp
mov x8, __NR_futex
svc #0
ldp x29, x30, [sp], #16
.cfi_def_cfa_offset 0
.cfi_restore x29
.cfi_restore x30
cmn x0, #(MAX_ERRNO + 1)
cneg x0, x0, hi
b.hi __set_errno
ret
END(futex)

50
libc/arch-mips/bionic/futex_mips.S
View File

@ -1,50 +0,0 @@
/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <private/bionic_asm.h>
// int __futex_syscall4(volatile void* ftx, int op, int val, const struct timespec* timeout)
ENTRY_PRIVATE(__futex_syscall4)
subu sp,4*6
sw $0,20(sp) /* val3 */
sw $0,16(sp) /* addr2 */
# move a3,a3 /* timespec */
# move a2,a2 /* val */
# li a1,a1 /* op */
# move a0,a0 /* ftx */
li v0,__NR_futex
syscall
.set noreorder
bnez a3, 1f /* Check for error */
neg v0 /* Negate error number if it's valid */
move v0,$0 /* Otherwise return 0 */
1:
.set reorder
addu sp,4*6
j ra
END(__futex_syscall4)

1
libc/arch-mips/mips.mk
View File

@ -58,7 +58,6 @@ libc_bionic_src_files_mips += \
arch-mips/bionic/bzero.S \
arch-mips/bionic/cacheflush.cpp \
arch-mips/bionic/_exit_with_stack_teardown.S \
arch-mips/bionic/futex_mips.S \
arch-mips/bionic/__get_sp.S \
arch-mips/bionic/memcmp16.S \
arch-mips/bionic/_setjmp.S \

19
libc/arch-mips/syscalls/futex.S
View File

@ -1,19 +0,0 @@
/* Generated by gensyscalls.py. Do not edit. */
#include <private/bionic_asm.h>
ENTRY(futex)
.set noreorder
.cpload t9
li v0, __NR_futex
syscall
bnez a3, 1f
move a0, v0
j ra
nop
1:
la t9,__set_errno
j t9
nop
.set reorder
END(futex)

64
libc/arch-mips64/bionic/futex_mips.S
View File

@ -1,64 +0,0 @@
/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <private/bionic_asm.h>
#if (_MIPS_SIM == _ABIO32) || (_MIPS_SIM == _ABI32)
FRAMESZ = MKFSIZ(NARGSAVE+2,0)
FRAME_A4 = 4*REGSZ
FRAME_A5 = 5*REGSZ
#else
FRAMESZ = 0
#endif
// int __futex_syscall4(volatile void* ftx, int op, int val, const struct timespec* timeout)
LEAF(__futex_syscall4,FRAMESZ)
#if (_MIPS_SIM == _ABIO32) || (_MIPS_SIM == _ABI32)
PTR_SUBU sp, FRAMESZ
REG_S $0,FRAME_A5(sp) /* val3 */
REG_S $0,FRAME_A4(sp) /* addr2 */
#else
move a5,$0 /* val3 */
move a4,$0 /* addr2 */
#endif
# move a3,a3 /* timespec */
# move a2,a2 /* val */
# move a1,a1 /* op */
# move a0,a0 /* ftx */
LI v0,__NR_futex
syscall
neg v0 /* Negate errno */
bnez a3,1f /* Check for error */
move v0,$0 /* Return 0 if no error */
1:
#if (_MIPS_SIM == _ABIO32) || (_MIPS_SIM == _ABI32)
PTR_ADDU sp,FRAMESZ
#endif
j ra
END(__futex_syscall4)
.hidden __futex_syscall4

1
libc/arch-mips64/mips64.mk
View File

@ -43,7 +43,6 @@ libc_bionic_src_files_mips64 := \
arch-mips64/bionic/__bionic_clone.S \
arch-mips64/bionic/bzero.S \
arch-mips64/bionic/_exit_with_stack_teardown.S \
arch-mips64/bionic/futex_mips.S \
arch-mips64/bionic/__get_sp.S \
arch-mips64/bionic/getdents.cpp \
arch-mips64/bionic/memcmp16.S \

25
libc/arch-mips64/syscalls/futex.S
View File

@ -1,25 +0,0 @@
/* Generated by gensyscalls.py. Do not edit. */
#include <private/bionic_asm.h>
ENTRY(futex)
.set push
.set noreorder
li v0, __NR_futex
syscall
bnez a3, 1f
move a0, v0
j ra
nop
1:
move t0, ra
bal 2f
nop
2:
.cpsetup ra, t1, 2b
LA t9,__set_errno
.cpreturn
j t9
move ra, t0
.set pop
END(futex)

16
libc/arch-x86/bionic/futex_x86.S
View File

@ -1,16 +0,0 @@
#include <private/bionic_asm.h>
// int __futex_syscall4(volatile void* ftx, int op, int val, const struct timespec* timeout)
ENTRY_PRIVATE(__futex_syscall4)
pushl %ebx
pushl %esi
movl 12(%esp), %ebx /* ftx */
movl 16(%esp), %ecx /* op */
movl 20(%esp), %edx /* val */
movl 24(%esp), %esi /* timeout */
movl $__NR_futex, %eax
int $0x80
popl %esi
popl %ebx
ret
END(__futex_syscall4)

42
libc/arch-x86/syscalls/futex.S
View File

@ -1,42 +0,0 @@
/* Generated by gensyscalls.py. Do not edit. */
#include <private/bionic_asm.h>
ENTRY(futex)
pushl %ebx
pushl %ecx
pushl %edx
pushl %esi
pushl %edi
pushl %ebp
.cfi_def_cfa_offset 24
.cfi_rel_offset ebx, 0
.cfi_rel_offset ecx, 4
.cfi_rel_offset edx, 8
.cfi_rel_offset esi, 12
.cfi_rel_offset edi, 16
.cfi_rel_offset ebp, 20
mov 28(%esp), %ebx
mov 32(%esp), %ecx
mov 36(%esp), %edx
mov 40(%esp), %esi
mov 44(%esp), %edi
mov 48(%esp), %ebp
movl $__NR_futex, %eax
int $0x80
cmpl $-MAX_ERRNO, %eax
jb 1f
negl %eax
pushl %eax
call __set_errno
addl $4, %esp
orl $-1, %eax
1:
popl %ebp
popl %edi
popl %esi
popl %edx
popl %ecx
popl %ebx
ret
END(futex)

1
libc/arch-x86/x86.mk
View File

@ -23,7 +23,6 @@ libc_bionic_src_files_x86 := \
libc_bionic_src_files_x86 += \
arch-x86/bionic/__bionic_clone.S \
arch-x86/bionic/_exit_with_stack_teardown.S \
arch-x86/bionic/futex_x86.S \
arch-x86/bionic/__get_sp.S \
arch-x86/bionic/_setjmp.S \
arch-x86/bionic/setjmp.S \

37
libc/arch-x86_64/bionic/futex_x86_64.S
View File

@ -1,37 +0,0 @@
/*
* Copyright (C) 2013 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <private/bionic_asm.h>
// int __futex_syscall4(volatile void* ftx, int op, int val, const struct timespec* timeout)
ENTRY_PRIVATE(__futex_syscall4)
mov %rcx, %r10 /* timeout */
mov $__NR_futex, %eax
syscall
ret
END(__futex_syscall4)

17
libc/arch-x86_64/syscalls/futex.S
View File

@ -1,17 +0,0 @@
/* Generated by gensyscalls.py. Do not edit. */
#include <private/bionic_asm.h>
ENTRY(futex)
movq %rcx, %r10
movl $__NR_futex, %eax
syscall
cmpq $-MAX_ERRNO, %rax
jb 1f
negl %eax
movl %eax, %edi
call __set_errno
orq $-1, %rax
1:
ret
END(futex)

1
libc/arch-x86_64/x86_64.mk
View File

@ -30,7 +30,6 @@ libc_common_src_files_x86_64 += \
libc_bionic_src_files_x86_64 := \
arch-x86_64/bionic/__bionic_clone.S \
arch-x86_64/bionic/_exit_with_stack_teardown.S \
arch-x86_64/bionic/futex_x86_64.S \
arch-x86_64/bionic/__get_sp.S \
arch-x86_64/bionic/__rt_sigreturn.S \
arch-x86_64/bionic/_setjmp.S \

20
libc/bionic/ndk_cruft.cpp
View File

@ -31,7 +31,6 @@
#include <ctype.h>
#include <inttypes.h>
#include <linux/futex.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
@ -201,25 +200,20 @@ extern "C" int vfdprintf(int fd, const char* fmt, va_list ap) {
return vdprintf(fd, fmt, ap);
}
static inline int __futex(volatile void* ftx, int op, int value, const struct timespec* timeout) {
// Our generated syscall assembler sets errno, but our callers (pthread functions) don't want to.
int saved_errno = errno;
if (syscall(__NR_futex, ftx, op, value, timeout) == 0) {
return 0;
}
int result = -errno;
errno = saved_errno;
return result;
}
#define __futex_wake __real_futex_wake
#define __futex_wait __real_futex_wait
#include "private/bionic_futex.h"
#undef __futex_wake
#undef __futex_wait
// This used to be in <sys/atomics.h>.
extern "C" int __futex_wake(volatile void* ftx, int count) {
return __futex(ftx, FUTEX_WAKE, count, NULL);
return __real_futex_wake(ftx, count);
}
// This used to be in <sys/atomics.h>.
extern "C" int __futex_wait(volatile void* ftx, int value, const struct timespec* timeout) {
return __futex(ftx, FUTEX_WAIT, value, timeout);
return __real_futex_wait(ftx, value, timeout);
}
// Unity's libmono uses this.

20
libc/bionic/pthread_create.cpp
View File

@ -144,10 +144,8 @@ static int __pthread_start(void* arg) {
// notify gdb about this thread before we start doing anything.
// This also provides the memory barrier needed to ensure that all memory
// accesses previously made by the creating thread are visible to us.
pthread_mutex_t* start_mutex = (pthread_mutex_t*) &thread->tls[TLS_SLOT_START_MUTEX];
pthread_mutex_lock(start_mutex);
pthread_mutex_destroy(start_mutex);
thread->tls[TLS_SLOT_START_MUTEX] = NULL;
pthread_mutex_lock(&thread->startup_handshake_mutex);
pthread_mutex_destroy(&thread->startup_handshake_mutex);
__init_alternate_signal_stack(thread);
@ -204,7 +202,8 @@ int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr,
// The child stack is the same address, just growing in the opposite direction.
// At offsets >= 0, we have the TLS slots.
// At offsets < 0, we have the child stack.
thread->tls = (void**)((uint8_t*)(thread->attr.stack_base) + thread->attr.stack_size - BIONIC_TLS_SLOTS * sizeof(void*));
thread->tls = reinterpret_cast<void**>(reinterpret_cast<uint8_t*>(thread->attr.stack_base) +
thread->attr.stack_size - BIONIC_TLS_SLOTS * sizeof(void*));
void* child_stack = thread->tls;
__init_tls(thread);
@ -214,9 +213,8 @@ int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr,
// This also provides the memory barrier we need to ensure that all
// memory accesses previously performed by this thread are visible to
// the new thread.
pthread_mutex_t* start_mutex = (pthread_mutex_t*) &thread->tls[TLS_SLOT_START_MUTEX];
pthread_mutex_init(start_mutex, NULL);
pthread_mutex_lock(start_mutex);
pthread_mutex_init(&thread->startup_handshake_mutex, NULL);
pthread_mutex_lock(&thread->startup_handshake_mutex);
thread->start_routine = start_routine;
thread->start_routine_arg = arg;
@ -237,7 +235,7 @@ int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr,
// We don't have to unlock the mutex at all because clone(2) failed so there's no child waiting to
// be unblocked, but we're about to unmap the memory the mutex is stored in, so this serves as a
// reminder that you can't rewrite this function to use a ScopedPthreadMutexLocker.
pthread_mutex_unlock(start_mutex);
pthread_mutex_unlock(&thread->startup_handshake_mutex);
if ((thread->attr.flags & PTHREAD_ATTR_FLAG_USER_ALLOCATED_STACK) == 0) {
munmap(thread->attr.stack_base, thread->attr.stack_size);
}
@ -252,7 +250,7 @@ int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr,
// Letting the thread run is the easiest way to clean up its resources.
thread->attr.flags |= PTHREAD_ATTR_FLAG_DETACHED;
thread->start_routine = __do_nothing;
pthread_mutex_unlock(start_mutex);
pthread_mutex_unlock(&thread->startup_handshake_mutex);
return init_errno;
}
@ -264,7 +262,7 @@ int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr,
// Publish the pthread_t and unlock the mutex to let the new thread start running.
*thread_out = reinterpret_cast<pthread_t>(thread);
pthread_mutex_unlock(start_mutex);
pthread_mutex_unlock(&thread->startup_handshake_mutex);
return 0;
}

2
libc/bionic/pthread_internal.h
View File

@ -48,6 +48,8 @@ struct pthread_internal_t {
void* alternate_signal_stack;
pthread_mutex_t startup_handshake_mutex;
/*
* The dynamic linker implements dlerror(3), which makes it hard for us to implement this
* per-thread buffer by simply using malloc(3) and free(3).

23
libc/private/bionic_futex.h
View File

@ -28,31 +28,42 @@
#ifndef _BIONIC_FUTEX_H
#define _BIONIC_FUTEX_H
#include <errno.h>
#include <linux/futex.h>
#include <sys/cdefs.h>
#include <stdbool.h>
#include <stddef.h>
#include <sys/cdefs.h>
#include <sys/syscall.h>
__BEGIN_DECLS
struct timespec;
extern int __futex_syscall4(volatile void* ftx, int op, int value, const struct timespec* timeout);
static inline __always_inline int __futex(volatile void* ftx, int op, int value, const struct timespec* timeout) {
// Our generated syscall assembler sets errno, but our callers (pthread functions) don't want to.
int saved_errno = errno;
if (__predict_false(syscall(__NR_futex, ftx, op, value, timeout) == -1)) {
int result = -errno;
errno = saved_errno;
return result;
}
return 0;
}
static inline int __futex_wake(volatile void* ftx, int count) {
return __futex_syscall4(ftx, FUTEX_WAKE, count, NULL);
return __futex(ftx, FUTEX_WAKE, count, NULL);
}
static inline int __futex_wake_ex(volatile void* ftx, bool shared, int count) {
return __futex_syscall4(ftx, shared ? FUTEX_WAKE : FUTEX_WAKE_PRIVATE, count, NULL);
return __futex(ftx, shared ? FUTEX_WAKE : FUTEX_WAKE_PRIVATE, count, NULL);
}
static inline int __futex_wait(volatile void* ftx, int value, const struct timespec* timeout) {
return __futex_syscall4(ftx, FUTEX_WAIT, value, timeout);
return __futex(ftx, FUTEX_WAIT, value, timeout);
}
static inline int __futex_wait_ex(volatile void* ftx, bool shared, int value, const struct timespec* timeout) {
return __futex_syscall4(ftx, shared ? FUTEX_WAIT : FUTEX_WAIT_PRIVATE, value, timeout);
return __futex(ftx, shared ? FUTEX_WAIT : FUTEX_WAIT_PRIVATE, value, timeout);
}
__END_DECLS

25
libc/private/bionic_tls.h
View File

@ -46,32 +46,27 @@ __BEGIN_DECLS
** pre-allocated slot directly for performance reason).
**/
/* Well-known TLS slots. What data goes in which slot is arbitrary unless otherwise noted. */
// Well-known TLS slots. What data goes in which slot is arbitrary unless otherwise noted.
enum {
TLS_SLOT_SELF = 0, /* The kernel requires this specific slot for x86. */
TLS_SLOT_SELF = 0, // The kernel requires this specific slot for x86.
TLS_SLOT_THREAD_ID,
TLS_SLOT_ERRNO,
/* This slot in the child's TLS is used to synchronize the parent and child
* during thread initialization. The child finishes with this mutex before
* running any code that can set errno, so we can reuse the errno slot. */
TLS_SLOT_START_MUTEX = TLS_SLOT_ERRNO,
/* These two aren't used by bionic itself, but allow the graphics code to
* access TLS directly rather than using the pthread API. */
// These two aren't used by bionic itself, but allow the graphics code to
// access TLS directly rather than using the pthread API.
TLS_SLOT_OPENGL_API = 3,
TLS_SLOT_OPENGL = 4,
/* This slot is only used to pass information from the dynamic linker to
* libc.so when the C library is loaded in to memory. The C runtime init
* function will then clear it. Since its use is extremely temporary,
* we reuse an existing location that isn't needed during libc startup. */
// This slot is only used to pass information from the dynamic linker to
// libc.so when the C library is loaded in to memory. The C runtime init
// function will then clear it. Since its use is extremely temporary,
// we reuse an existing location that isn't needed during libc startup.
TLS_SLOT_BIONIC_PREINIT = TLS_SLOT_OPENGL_API,
TLS_SLOT_STACK_GUARD = 5, /* GCC requires this specific slot for x86. */
TLS_SLOT_STACK_GUARD = 5, // GCC requires this specific slot for x86.
TLS_SLOT_DLERROR,
TLS_SLOT_FIRST_USER_SLOT /* Must come last! */
TLS_SLOT_FIRST_USER_SLOT // Must come last!
};
/*