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-rw-r--r--benchmarks/unistd_benchmark.cpp11
-rw-r--r--libc/Android.mk1
-rw-r--r--libc/SYSCALLS.TXT2
-rw-r--r--libc/arch-arm/syscalls/__getpid.S (renamed from libc/arch-arm/syscalls/getpid.S)4
-rw-r--r--libc/arch-arm64/syscalls/__getpid.S (renamed from libc/arch-arm64/syscalls/getpid.S)5
-rw-r--r--libc/arch-mips/syscalls/__getpid.S (renamed from libc/arch-mips/syscalls/getpid.S)4
-rw-r--r--libc/arch-mips64/syscalls/__getpid.S (renamed from libc/arch-mips64/syscalls/getpid.S)5
-rw-r--r--libc/arch-x86/syscalls/__getpid.S (renamed from libc/arch-x86/syscalls/getpid.S)4
-rw-r--r--libc/arch-x86_64/syscalls/__getpid.S (renamed from libc/arch-x86_64/syscalls/getpid.S)5
-rw-r--r--libc/bionic/fork.cpp13
-rw-r--r--libc/bionic/getpid.cpp47
-rw-r--r--libc/bionic/libc_init_common.cpp17
-rw-r--r--libc/bionic/pthread_create.cpp3
-rw-r--r--libc/bionic/pthread_internal.h20
-rw-r--r--tests/unistd_test.cpp45
15 files changed, 163 insertions, 23 deletions
diff --git a/benchmarks/unistd_benchmark.cpp b/benchmarks/unistd_benchmark.cpp
index c35e7c3..7e2ac30 100644
--- a/benchmarks/unistd_benchmark.cpp
+++ b/benchmarks/unistd_benchmark.cpp
@@ -30,6 +30,17 @@ static void BM_unistd_getpid(int iters) {
}
BENCHMARK(BM_unistd_getpid);
+static void BM_unistd_getpid_syscall(int iters) {
+ StartBenchmarkTiming();
+
+ for (int i = 0; i < iters; ++i) {
+ syscall(__NR_getpid);
+ }
+
+ StopBenchmarkTiming();
+}
+BENCHMARK(BM_unistd_getpid_syscall);
+
// Stop GCC optimizing out our pure function.
/* Must not be static! */ pid_t (*gettid_fp)() = gettid;
diff --git a/libc/Android.mk b/libc/Android.mk
index a6298a0..002978c 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -127,6 +127,7 @@ libc_bionic_src_files := \
bionic/getauxval.cpp \
bionic/getcwd.cpp \
bionic/getpgrp.cpp \
+ bionic/getpid.cpp \
bionic/gettid.cpp \
bionic/inotify_init.cpp \
bionic/lchown.cpp \
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index 369b23c..839cfb7 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -97,7 +97,7 @@ ssize_t pread64|pread(int, void*, size_t, off_t) arm64,mips64,x86_64
ssize_t pwrite64(int, void*, size_t, off64_t) arm,mips,x86
ssize_t pwrite64|pwrite(int, void*, size_t, off_t) arm64,mips64,x86_64
int close(int) all
-pid_t getpid() all
+pid_t __getpid:getpid() all
int munmap(void*, size_t) all
void* mremap(void*, size_t, size_t, unsigned long) all
int msync(const void*, size_t, int) all
diff --git a/libc/arch-arm/syscalls/getpid.S b/libc/arch-arm/syscalls/__getpid.S
index 10bcb8e..eedc33a 100644
--- a/libc/arch-arm/syscalls/getpid.S
+++ b/libc/arch-arm/syscalls/__getpid.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(getpid)
+ENTRY(__getpid)
mov ip, r7
ldr r7, =__NR_getpid
swi #0
@@ -11,4 +11,4 @@ ENTRY(getpid)
bxls lr
neg r0, r0
b __set_errno
-END(getpid)
+END(__getpid)
diff --git a/libc/arch-arm64/syscalls/getpid.S b/libc/arch-arm64/syscalls/__getpid.S
index 1802ce8..c3003c3 100644
--- a/libc/arch-arm64/syscalls/getpid.S
+++ b/libc/arch-arm64/syscalls/__getpid.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(getpid)
+ENTRY(__getpid)
mov x8, __NR_getpid
svc #0
@@ -11,4 +11,5 @@ ENTRY(getpid)
b.hi __set_errno
ret
-END(getpid)
+END(__getpid)
+.hidden __getpid
diff --git a/libc/arch-mips/syscalls/getpid.S b/libc/arch-mips/syscalls/__getpid.S
index a053f5b..52cf6f4 100644
--- a/libc/arch-mips/syscalls/getpid.S
+++ b/libc/arch-mips/syscalls/__getpid.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(getpid)
+ENTRY(__getpid)
.set noreorder
.cpload t9
li v0, __NR_getpid
@@ -16,4 +16,4 @@ ENTRY(getpid)
j t9
nop
.set reorder
-END(getpid)
+END(__getpid)
diff --git a/libc/arch-mips64/syscalls/getpid.S b/libc/arch-mips64/syscalls/__getpid.S
index 3b457b5..0977ff0 100644
--- a/libc/arch-mips64/syscalls/getpid.S
+++ b/libc/arch-mips64/syscalls/__getpid.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(getpid)
+ENTRY(__getpid)
.set push
.set noreorder
li v0, __NR_getpid
@@ -22,4 +22,5 @@ ENTRY(getpid)
j t9
move ra, t0
.set pop
-END(getpid)
+END(__getpid)
+.hidden __getpid
diff --git a/libc/arch-x86/syscalls/getpid.S b/libc/arch-x86/syscalls/__getpid.S
index 0e12d5a..f138d2f 100644
--- a/libc/arch-x86/syscalls/getpid.S
+++ b/libc/arch-x86/syscalls/__getpid.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(getpid)
+ENTRY(__getpid)
movl $__NR_getpid, %eax
int $0x80
cmpl $-MAX_ERRNO, %eax
@@ -13,4 +13,4 @@ ENTRY(getpid)
addl $4, %esp
1:
ret
-END(getpid)
+END(__getpid)
diff --git a/libc/arch-x86_64/syscalls/getpid.S b/libc/arch-x86_64/syscalls/__getpid.S
index a2d732c..bd1bf1e 100644
--- a/libc/arch-x86_64/syscalls/getpid.S
+++ b/libc/arch-x86_64/syscalls/__getpid.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(getpid)
+ENTRY(__getpid)
movl $__NR_getpid, %eax
syscall
cmpq $-MAX_ERRNO, %rax
@@ -12,4 +12,5 @@ ENTRY(getpid)
call __set_errno
1:
ret
-END(getpid)
+END(__getpid)
+.hidden __getpid
diff --git a/libc/bionic/fork.cpp b/libc/bionic/fork.cpp
index a0f98e4..6cfc736 100644
--- a/libc/bionic/fork.cpp
+++ b/libc/bionic/fork.cpp
@@ -31,19 +31,26 @@
#include "pthread_internal.h"
+#define FORK_FLAGS (CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD)
+
int fork() {
__bionic_atfork_run_prepare();
pthread_internal_t* self = __get_thread();
- int flags = CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD;
+
+ // Remember the parent pid and invalidate the cached value while we fork.
+ pid_t parent_pid = self->invalidate_cached_pid();
+
#if defined(__x86_64__) // sys_clone's last two arguments are flipped on x86-64.
- int result = syscall(__NR_clone, flags, NULL, NULL, &(self->tid), NULL);
+ int result = syscall(__NR_clone, FORK_FLAGS, NULL, NULL, &(self->tid), NULL);
#else
- int result = syscall(__NR_clone, flags, NULL, NULL, NULL, &(self->tid));
+ int result = syscall(__NR_clone, FORK_FLAGS, NULL, NULL, NULL, &(self->tid));
#endif
if (result == 0) {
+ self->set_cached_pid(gettid());
__bionic_atfork_run_child();
} else {
+ self->set_cached_pid(parent_pid);
__bionic_atfork_run_parent();
}
return result;
diff --git a/libc/bionic/getpid.cpp b/libc/bionic/getpid.cpp
new file mode 100644
index 0000000..a3d5b35
--- /dev/null
+++ b/libc/bionic/getpid.cpp
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2014 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 <unistd.h>
+
+#include "pthread_internal.h"
+
+extern "C" pid_t __getpid();
+
+pid_t getpid() {
+ pthread_internal_t* self = __get_thread();
+
+ // Do we have a valid cached pid?
+ pid_t cached_pid;
+ if (__predict_true(self->get_cached_pid(&cached_pid))) {
+ return cached_pid;
+ }
+
+ // We're still in the dynamic linker or we're in the middle of forking, so ask the kernel.
+ // We don't know whether it's safe to update the cached value, so don't try.
+ return __getpid();
+}
diff --git a/libc/bionic/libc_init_common.cpp b/libc/bionic/libc_init_common.cpp
index abf2d36..fa61c3c 100644
--- a/libc/bionic/libc_init_common.cpp
+++ b/libc/bionic/libc_init_common.cpp
@@ -86,21 +86,24 @@ static size_t get_main_thread_stack_size() {
void __libc_init_tls(KernelArgumentBlock& args) {
__libc_auxv = args.auxv;
- uintptr_t stack_top = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
- size_t stack_size = get_main_thread_stack_size();
- uintptr_t stack_bottom = stack_top - stack_size;
-
static void* tls[BIONIC_TLS_SLOTS];
static pthread_internal_t main_thread;
main_thread.tls = tls;
// Tell the kernel to clear our tid field when we exit, so we're like any other pthread.
+ // As a side-effect, this tells us our pid (which is the same as the main thread's tid).
main_thread.tid = __set_tid_address(&main_thread.tid);
+ main_thread.set_cached_pid(main_thread.tid);
+
+ // Work out the extent of the main thread's stack.
+ uintptr_t stack_top = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
+ size_t stack_size = get_main_thread_stack_size();
+ void* stack_bottom = reinterpret_cast<void*>(stack_top - stack_size);
- // We already have a stack, and we don't want to free it up on exit (because things like
- // environment variables with global scope live on it).
+ // We don't want to free the main thread's stack even when the main thread exits
+ // because things like environment variables with global scope live on it.
pthread_attr_init(&main_thread.attr);
- pthread_attr_setstack(&main_thread.attr, (void*) stack_bottom, stack_size);
+ pthread_attr_setstack(&main_thread.attr, stack_bottom, stack_size);
main_thread.attr.flags = PTHREAD_ATTR_FLAG_USER_ALLOCATED_STACK | PTHREAD_ATTR_FLAG_MAIN_THREAD;
__init_thread(&main_thread, false);
diff --git a/libc/bionic/pthread_create.cpp b/libc/bionic/pthread_create.cpp
index c83b5a0..2ded22b 100644
--- a/libc/bionic/pthread_create.cpp
+++ b/libc/bionic/pthread_create.cpp
@@ -30,6 +30,7 @@
#include <errno.h>
#include <sys/mman.h>
+#include <unistd.h>
#include "pthread_internal.h"
@@ -220,6 +221,8 @@ int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr,
thread->start_routine = start_routine;
thread->start_routine_arg = arg;
+ thread->set_cached_pid(getpid());
+
int flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID;
void* tls = thread->tls;
diff --git a/libc/bionic/pthread_internal.h b/libc/bionic/pthread_internal.h
index 490ae86..e05d15c 100644
--- a/libc/bionic/pthread_internal.h
+++ b/libc/bionic/pthread_internal.h
@@ -36,6 +36,26 @@ struct pthread_internal_t {
pid_t tid;
+ private:
+ pid_t cached_pid_;
+
+ public:
+ pid_t invalidate_cached_pid() {
+ pid_t old_value;
+ get_cached_pid(&old_value);
+ set_cached_pid(0);
+ return old_value;
+ }
+
+ void set_cached_pid(pid_t value) {
+ cached_pid_ = value;
+ }
+
+ bool get_cached_pid(pid_t* cached_pid) {
+ *cached_pid = cached_pid_;
+ return (*cached_pid != 0);
+ }
+
void** tls;
pthread_attr_t attr;
diff --git a/tests/unistd_test.cpp b/tests/unistd_test.cpp
index 6aa259a..95e63b3 100644
--- a/tests/unistd_test.cpp
+++ b/tests/unistd_test.cpp
@@ -22,6 +22,7 @@
#include <fcntl.h>
#include <stdint.h>
#include <unistd.h>
+#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
@@ -379,3 +380,47 @@ TEST(unistd, fdatasync) {
TEST(unistd, fsync) {
TestFsyncFunction(fsync);
}
+
+TEST(unistd, getpid_caching_and_fork) {
+ pid_t parent_pid = getpid();
+ ASSERT_EQ(syscall(__NR_getpid), parent_pid);
+
+ pid_t fork_result = fork();
+ ASSERT_NE(fork_result, -1);
+ if (fork_result == 0) {
+ // We're the child.
+ ASSERT_EQ(syscall(__NR_getpid), getpid());
+ ASSERT_EQ(parent_pid, getppid());
+ _exit(123);
+ } else {
+ // We're the parent.
+ ASSERT_EQ(parent_pid, getpid());
+
+ int status;
+ ASSERT_EQ(fork_result, waitpid(fork_result, &status, 0));
+ ASSERT_TRUE(WIFEXITED(status));
+ ASSERT_EQ(123, WEXITSTATUS(status));
+ }
+}
+
+static void GetPidCachingHelperHelper() {
+ ASSERT_EQ(syscall(__NR_getpid), getpid());
+}
+
+static void* GetPidCachingHelper(void*) {
+ GetPidCachingHelperHelper(); // Can't assert in a non-void function.
+ return NULL;
+}
+
+TEST(unistd, getpid_caching_and_pthread_create) {
+ pid_t parent_pid = getpid();
+
+ pthread_t t;
+ ASSERT_EQ(0, pthread_create(&t, NULL, GetPidCachingHelper, NULL));
+
+ ASSERT_EQ(parent_pid, getpid());
+
+ void* result;
+ ASSERT_EQ(0, pthread_join(t, &result));
+ ASSERT_EQ(NULL, result);
+}
generated by cgit v1.1 at 2024-12-22 13:18:40 +0000