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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* 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 "util/NativeStack.h"
#include "mozilla/Assertions.h" // MOZ_ASSERT, MOZ_RELEASE_ASSERT, MOZ_CRASH
#ifdef XP_WIN
# include "util/WindowsWrapper.h"
#elif defined(__wasi__)
// Nothing
#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(SOLARIS) || defined(AIX)
# include <ucontext.h>
# endif
# if defined(ANDROID) && !defined(__aarch64__)
# 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>
# define gettid() static_cast<pid_t>(syscall(__NR_gettid))
# endif
#else
# error "Unsupported platform"
#endif
#include "js/friend/StackLimits.h" // JS_STACK_GROWTH_DIRECTION
#if defined(XP_WIN)
void* js::GetNativeStackBaseImpl() {
PNT_TIB pTib = reinterpret_cast<PNT_TIB>(NtCurrentTeb());
return static_cast<void*>(pTib->StackBase);
}
#elif defined(SOLARIS)
static_assert(JS_STACK_GROWTH_DIRECTION < 0);
void* js::GetNativeStackBaseImpl() {
stack_t st;
stack_getbounds(&st);
return static_cast<char*>(st.ss_sp) + st.ss_size;
}
#elif defined(AIX)
static_assert(JS_STACK_GROWTH_DIRECTION < 0);
void* js::GetNativeStackBaseImpl() {
ucontext_t context;
getcontext(&context);
return static_cast<char*>(context.uc_stack.ss_sp) + context.uc_stack.ss_size;
}
#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 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 firefox can run in sandboxed environments where /proc may
// not be mounted.
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
}
#elif defined(__wasi__)
// Since we rearrange the layout for wasi via --stack-first flag for the linker
// the final layout is: 0x00 | <- stack | data | heap -> |.
static void* const NativeStackBase = __builtin_frame_address(0);
void* js::GetNativeStackBaseImpl() {
MOZ_ASSERT(JS_STACK_GROWTH_DIRECTION < 0);
return NativeStackBase;
}
#else // __wasi__
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) && !defined(__aarch64__)
if (gettid() == getpid()) {
// bionic's pthread_attr_getstack prior to API 21 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
rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
# endif
if (rc) {
MOZ_CRASH();
}
MOZ_ASSERT(stackBase);
pthread_attr_destroy(&sattr);
# if JS_STACK_GROWTH_DIRECTION > 0
return stackBase;
# else
return static_cast<char*>(stackBase) + stackSize;
# endif
# endif
}
#endif /* !XP_WIN */