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PageFaultHandler: Simplifications

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This commit is contained in:
Stenzek
2024-05-25 16:49:24 +10:00
parent b4b579d2b1
commit 0240ea8b49
4 changed files with 68 additions and 98 deletions
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73
src/util/page_fault_handler.cpp
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@ -4,6 +4,7 @@
#include "page_fault_handler.h"
#include "common/assert.h"
#include "common/crash_handler.h"
#include "common/error.h"
#include "common/log.h"
@ -14,7 +15,7 @@
#if defined(_WIN32)
#include "common/windows_headers.h"
#elif defined(__linux__) || defined(__ANDROID__)
#elif defined(__linux__)
#include <signal.h>
#include <ucontext.h>
#include <unistd.h>
@ -139,54 +140,11 @@ bool PageFaultHandler::Install(Error* error)
namespace PageFaultHandler {
static void SignalHandler(int sig, siginfo_t* info, void* ctx);
static void CallExistingSignalHandler(int signal, siginfo_t* siginfo, void* ctx);
static struct sigaction s_old_sigsegv_action;
#if defined(__APPLE__) || defined(__aarch64__)
static struct sigaction s_old_sigbus_action;
#endif
} // namespace PageFaultHandler
void PageFaultHandler::CallExistingSignalHandler(int signal, siginfo_t* siginfo, void* ctx)
{
#if defined(__aarch64__)
const struct sigaction& sa = (signal == SIGBUS) ? s_old_sigbus_action : s_old_sigsegv_action;
#elif defined(__APPLE__)
const struct sigaction& sa = s_old_sigbus_action;
#else
const struct sigaction& sa = s_old_sigsegv_action;
#endif
if (sa.sa_flags & SA_SIGINFO)
{
sa.sa_sigaction(signal, siginfo, ctx);
}
else if (sa.sa_handler == SIG_DFL)
{
// Re-raising the signal would just queue it, and since we'd restore the handler back to us,
// we'd end up right back here again. So just abort, because that's probably what it'd do anyway.
abort();
}
else if (sa.sa_handler != SIG_IGN)
{
sa.sa_handler(signal);
}
}
void PageFaultHandler::SignalHandler(int sig, siginfo_t* info, void* ctx)
{
// Executing the handler concurrently from multiple threads wouldn't go down well.
std::unique_lock lock(s_exception_handler_mutex);
// Prevent recursive exception filtering.
if (s_in_exception_handler)
{
lock.unlock();
CallExistingSignalHandler(sig, info, ctx);
return;
}
#if defined(__linux__) || defined(__ANDROID__)
#if defined(__linux__)
void* const exception_address = reinterpret_cast<void*>(info->si_addr);
#if defined(CPU_ARCH_X64)
@ -241,19 +199,26 @@ void PageFaultHandler::SignalHandler(int sig, siginfo_t* info, void* ctx)
#endif
s_in_exception_handler = true;
// Executing the handler concurrently from multiple threads wouldn't go down well.
s_exception_handler_mutex.lock();
const HandlerResult result = HandlePageFault(exception_pc, exception_address, is_write);
s_in_exception_handler = false;
// Prevent recursive exception filtering.
HandlerResult result = HandlerResult::ExecuteNextHandler;
if (!s_in_exception_handler)
{
s_in_exception_handler = true;
result = HandlePageFault(exception_pc, exception_address, is_write);
s_in_exception_handler = false;
}
s_exception_handler_mutex.unlock();
// Resumes execution right where we left off (re-executes instruction that caused the SIGSEGV).
if (result == HandlerResult::ContinueExecution)
return;
// Call old signal handler, which will likely dump core.
lock.unlock();
CallExistingSignalHandler(sig, info, ctx);
// We couldn't handle it. Pass it off to the crash dumper.
CrashHandler::CrashSignalHandler(sig, info, ctx);
}
bool PageFaultHandler::Install(Error* error)
@ -270,14 +235,14 @@ bool PageFaultHandler::Install(Error* error)
// Don't block the signal from executing recursively, we want to fire the original handler.
sa.sa_flags |= SA_NODEFER;
#endif
if (sigaction(SIGSEGV, &sa, &s_old_sigsegv_action) != 0)
if (sigaction(SIGSEGV, &sa, nullptr) != 0)
{
Error::SetErrno(error, "sigaction() for SIGSEGV failed: ", errno);
return false;
}
#if defined(__APPLE__) || defined(__aarch64__)
// MacOS uses SIGBUS for memory permission violations
if (sigaction(SIGBUS, &sa, &s_old_sigbus_action) != 0)
if (sigaction(SIGBUS, &sa, nullptr) != 0)
{
Error::SetErrno(error, "sigaction() for SIGBUS failed: ", errno);
return false;