ladybird/AK/StackInfo.cpp
Andrew Kaster 06b6f838d6 AK: Use MacOS pthread_get_stacksize_np to get stack size for StackInfo
Seems Rust and OpenJDK both had issues with getting accurate stack size
for the main thread with MacOS Maverick and above. Apply a variant of
their workarounds. We could probably assume 8MB in all cases just to
be safe, as the only user of AK::StackInfo right now is lib JS's heap
for determining possible pointer candidates. But, this approach should
work if userspace apps start trying to add custom guard pages, as well.
2020-12-30 11:28:50 +01:00

81 lines
3.1 KiB
C++

/*
* Copyright (c) 2020, the SerenityOS developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. 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 HOLDER 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 <AK/Assertions.h>
#include <AK/StackInfo.h>
#include <stdio.h>
#ifdef __serenity__
# include <serenity.h>
#elif defined(__linux__) or defined(__APPLE__)
# include <pthread.h>
#endif
namespace AK {
StackInfo::StackInfo()
{
#ifdef __serenity__
if (get_stack_bounds(&m_base, &m_size) < 0) {
perror("get_stack_bounds");
ASSERT_NOT_REACHED();
}
#elif __linux__
pthread_attr_t attr = {};
if (int rc = pthread_getattr_np(pthread_self(), &attr) != 0) {
fprintf(stderr, "pthread_getattr_np: %s\n", strerror(-rc));
ASSERT_NOT_REACHED();
}
if (int rc = pthread_attr_getstack(&attr, (void**)&m_base, &m_size) != 0) {
fprintf(stderr, "pthread_attr_getstack: %s\n", strerror(-rc));
ASSERT_NOT_REACHED();
}
pthread_attr_destroy(&attr);
#elif __APPLE__
// NOTE: !! On MacOS, pthread_get_stackaddr_np gives the TOP of the stack, not the bottom!
FlatPtr top_of_stack = (FlatPtr)pthread_get_stackaddr_np(pthread_self());
m_size = (size_t)pthread_get_stacksize_np(pthread_self());
// https://github.com/rust-lang/rust/issues/43347#issuecomment-316783599
// https://developer.apple.com/library/archive/qa/qa1419/_index.html
//
// MacOS seems inconsistent on what stack size is given for the main thread.
// According to the Apple docs, default for main thread is 8MB, and default for
// other threads is 512KB
constexpr size_t eight_megabytes = 0x800000;
if (pthread_main_np() == 1 && m_size < eight_megabytes) {
// Assume no one messed with stack size linker options for the main thread,
// and just set it to 8MB.
m_size = eight_megabytes;
}
m_base = top_of_stack - m_size;
#else
ASSERT_NOT_REACHED();
#endif
m_top = m_base + m_size;
}
}