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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "jsnativestack.h"
#ifdef XP_WIN
# include "jswin.h"
#elif defined(XP_DARWIN) || defined(DARWIN) || defined(XP_UNIX)
# include <pthread.h>
# if defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
# include <pthread_np.h>
# endif
# if defined(ANDROID)
# include <sys/types.h>
# include <unistd.h>
# endif
# if defined(XP_LINUX) && !defined(ANDROID) && defined(__GLIBC__)
# include <dlfcn.h>
# include <sys/syscall.h>
# include <sys/types.h>
# include <unistd.h>
static pid_t
gettid()
{
return syscall(__NR_gettid);
}
# endif
#else
# error "Unsupported platform"
#endif
#if defined(XP_WIN)
void*
js::GetNativeStackBaseImpl()
{
# if defined(_M_IX86) && defined(_MSC_VER)
/*
* offset 0x18 from the FS segment register gives a pointer to
* the thread information block for the current thread
*/
NT_TIB* pTib;
__asm {
MOV EAX, FS:[18h]
MOV pTib, EAX
}
return static_cast<void*>(pTib->StackBase);
# elif defined(_M_X64)
PNT_TIB64 pTib = reinterpret_cast<PNT_TIB64>(NtCurrentTeb());
return reinterpret_cast<void*>(pTib->StackBase);
# elif defined(_M_ARM)
PNT_TIB pTib = reinterpret_cast<PNT_TIB>(NtCurrentTeb());
return static_cast<void*>(pTib->StackBase);
# elif defined(_WIN32) && defined(__GNUC__)
NT_TIB* pTib;
asm ("movl %%fs:0x18, %0\n" : "=r" (pTib));
return static_cast<void*>(pTib->StackBase);
# endif
}
#elif defined(XP_LINUX) && !defined(ANDROID) && defined(__GLIBC__)
void*
js::GetNativeStackBaseImpl()
{
// On the main thread, get stack base from glibc's __libc_stack_end rather than pthread APIs
// to avoid filesystem calls /proc/self/maps. Non-main threads spawned with pthreads can read
// this information directly from their pthread struct, but when using the pthreads API, the
// main thread must go parse /proc/self/maps to figure the mapped stack address space ranges.
// We want to avoid reading from /proc/ so that the application can run in restricted
// environments where /proc may not be mounted (e.g. chroot).
if (gettid() == getpid()) {
void** pLibcStackEnd = (void**)dlsym(RTLD_DEFAULT, "__libc_stack_end");
// If __libc_stack_end is not found, architecture specific frame pointer hopping will need
// to be implemented.
MOZ_RELEASE_ASSERT(pLibcStackEnd, "__libc_stack_end unavailable, unable to setup stack range for JS.");
void* stackBase = *pLibcStackEnd;
MOZ_RELEASE_ASSERT(stackBase, "Invalid stack base, unable to setup stack range for JS.");
// We don't need to fix stackBase, as it already roughly points to beginning of the stack.
return stackBase;
}
// Non-main threads have the required info stored in memory, so no filesystem calls are made.
pthread_t thread = pthread_self();
pthread_attr_t sattr;
pthread_attr_init(&sattr);
pthread_getattr_np(thread, &sattr);
// stackBase will be the *lowest* address on all architectures.
void* stackBase = nullptr;
size_t stackSize = 0;
int rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
if (rc) {
MOZ_CRASH("Call to pthread_attr_getstack failed, unable to setup stack range for JS.");
}
MOZ_RELEASE_ASSERT(stackBase, "Invalid stack base, unable to setup stack range for JS.");
pthread_attr_destroy(&sattr);
# if JS_STACK_GROWTH_DIRECTION > 0
return stackBase;
# else
return static_cast<char*>(stackBase) + stackSize;
# endif
}
#else /* XP_UNIX */
void*
js::GetNativeStackBaseImpl()
{
pthread_t thread = pthread_self();
# if defined(XP_DARWIN) || defined(DARWIN)
return pthread_get_stackaddr_np(thread);
# else
pthread_attr_t sattr;
pthread_attr_init(&sattr);
# if defined(__OpenBSD__)
stack_t ss;
# elif defined(PTHREAD_NP_H) || defined(_PTHREAD_NP_H_) || defined(NETBSD)
/* e.g. on FreeBSD 4.8 or newer, neundorf@kde.org */
pthread_attr_get_np(thread, &sattr);
# else
/*
* FIXME: this function is non-portable;
* other POSIX systems may have different np alternatives
*/
pthread_getattr_np(thread, &sattr);
# endif
void* stackBase = 0;
size_t stackSize = 0;
int rc;
# if defined(__OpenBSD__)
rc = pthread_stackseg_np(pthread_self(), &ss);
stackBase = (void*)((size_t) ss.ss_sp - ss.ss_size);
stackSize = ss.ss_size;
# elif defined(ANDROID)
if (gettid() == getpid()) {
// bionic's pthread_attr_getstack doesn't tell the truth for the main
// thread (see bug 846670). So we scan /proc/self/maps to find the
// segment which contains the stack.
rc = -1;
// Put the string on the stack, otherwise there is the danger that it
// has not been decompressed by the the on-demand linker. Bug 1165460.
//
// The volatile keyword should stop the compiler from trying to omit
// the stack copy in the future (hopefully).
volatile char path[] = "/proc/self/maps";
FILE* fs = fopen((const char*)path, "r");
if (fs) {
char line[100];
unsigned long stackAddr = (unsigned long)&sattr;
while (fgets(line, sizeof(line), fs) != nullptr) {
unsigned long stackStart;
unsigned long stackEnd;
if (sscanf(line, "%lx-%lx ", &stackStart, &stackEnd) == 2 &&
stackAddr >= stackStart && stackAddr < stackEnd) {
stackBase = (void*)stackStart;
stackSize = stackEnd - stackStart;
rc = 0;
break;
}
}
fclose(fs);
}
} else
// For non main-threads pthread allocates the stack itself so it tells
// the truth.
rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
# else
// Use the default pthread_attr_getstack() call. Note that this function
// differs between libc implementations and could imply /proc access etc.
// which may not work in restricted environments.
rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
# endif
if (rc) {
MOZ_CRASH("Call to pthread_attr_getstack failed, unable to setup stack range for JS.");
}
MOZ_RELEASE_ASSERT(stackBase, "Invalid stack base, unable to setup stack range for JS.");
pthread_attr_destroy(&sattr);
# if JS_STACK_GROWTH_DIRECTION > 0
return stackBase;
# else
return static_cast<char*>(stackBase) + stackSize;
# endif
# endif
}
#endif /* !XP_WIN */
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