Duckstation/src/common/page_fault_handler.cpp

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#include "page_fault_handler.h"
#include "common/cpu_detect.h"
#include "common/log.h"
#include <algorithm>
#include <cstring>
#include <mutex>
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#include <vector>
Log_SetChannel(Common::PageFaultHandler);
#if defined(WIN32)
#include "common/windows_headers.h"
#elif defined(__linux__) || defined(__ANDROID__)
#include <signal.h>
#include <ucontext.h>
#include <unistd.h>
#define USE_SIGSEGV 1
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#elif defined(__APPLE__) || defined(__FreeBSD__)
#include <signal.h>
#include <unistd.h>
#define USE_SIGSEGV 1
#endif
namespace Common::PageFaultHandler {
struct RegisteredHandler
{
void* owner;
Callback callback;
};
static std::vector<RegisteredHandler> m_handlers;
static std::mutex m_handler_lock;
static thread_local bool s_in_handler;
#if defined(CPU_AARCH32)
static bool IsStoreInstruction(const void* ptr)
{
u32 bits;
std::memcpy(&bits, ptr, sizeof(bits));
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// TODO
return false;
}
#elif defined(CPU_AARCH64)
static bool IsStoreInstruction(const void* ptr)
{
u32 bits;
std::memcpy(&bits, ptr, sizeof(bits));
// Based on vixl's disassembler Instruction::IsStore().
// if (Mask(LoadStoreAnyFMask) != LoadStoreAnyFixed)
if ((bits & 0x0a000000) != 0x08000000)
return false;
// if (Mask(LoadStorePairAnyFMask) == LoadStorePairAnyFixed)
if ((bits & 0x3a000000) == 0x28000000)
{
// return Mask(LoadStorePairLBit) == 0
return (bits & (1 << 22)) == 0;
}
switch (bits & 0xC4C00000)
{
case 0x00000000: // STRB_w
case 0x40000000: // STRH_w
case 0x80000000: // STR_w
case 0xC0000000: // STR_x
case 0x04000000: // STR_b
case 0x44000000: // STR_h
case 0x84000000: // STR_s
case 0xC4000000: // STR_d
case 0x04800000: // STR_q
return true;
default:
return false;
}
}
#endif
#if defined(WIN32) && (defined(CPU_X64) || defined(CPU_AARCH64))
static PVOID s_veh_handle;
static LONG ExceptionHandler(PEXCEPTION_POINTERS exi)
{
if (exi->ExceptionRecord->ExceptionCode != EXCEPTION_ACCESS_VIOLATION || s_in_handler)
return EXCEPTION_CONTINUE_SEARCH;
s_in_handler = true;
#if defined(_M_AMD64)
void* const exception_pc = reinterpret_cast<void*>(exi->ContextRecord->Rip);
#elif defined(_M_ARM64)
void* const exception_pc = reinterpret_cast<void*>(exi->ContextRecord->Pc);
#else
void* const exception_pc = nullptr;
#endif
void* const exception_address = reinterpret_cast<void*>(exi->ExceptionRecord->ExceptionInformation[1]);
bool const is_write = exi->ExceptionRecord->ExceptionInformation[0] == 1;
std::lock_guard<std::mutex> guard(m_handler_lock);
for (const RegisteredHandler& rh : m_handlers)
{
if (rh.callback(exception_pc, exception_address, is_write) == HandlerResult::ContinueExecution)
{
s_in_handler = false;
return EXCEPTION_CONTINUE_EXECUTION;
}
}
s_in_handler = false;
return EXCEPTION_CONTINUE_SEARCH;
}
#elif defined(USE_SIGSEGV)
static struct sigaction s_old_sigsegv_action;
#if defined(__APPLE__) || defined(__aarch64__)
static struct sigaction s_old_sigbus_action;
#endif
static void SIGSEGVHandler(int sig, siginfo_t* info, void* ctx)
{
if ((info->si_code != SEGV_MAPERR && info->si_code != SEGV_ACCERR) || s_in_handler)
return;
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#if defined(__linux__) || defined(__ANDROID__)
void* const exception_address = reinterpret_cast<void*>(info->si_addr);
#if defined(CPU_X64)
void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.gregs[REG_RIP]);
const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext.gregs[REG_ERR] & 2) != 0;
#elif defined(CPU_AARCH32)
void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.arm_pc);
const bool is_write = IsStoreInstruction(exception_pc);
#elif defined(CPU_AARCH64)
void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.pc);
const bool is_write = IsStoreInstruction(exception_pc);
#else
void* const exception_pc = nullptr;
const bool is_write = false;
#endif
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#elif defined(__APPLE__)
#if defined(CPU_X64)
void* const exception_address =
reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__faultvaddr);
void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__rip);
const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__err & 2) != 0;
#elif defined(CPU_AARCH64)
void* const exception_address = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__far);
void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__pc);
const bool is_write = IsStoreInstruction(exception_pc);
#else
void* const exception_address = reinterpret_cast<void*>(info->si_addr);
void* const exception_pc = nullptr;
const bool is_write = false;
#endif
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#elif defined(__FreeBSD__)
#if defined(CPU_X64)
void* const exception_address = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.mc_addr);
void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.mc_rip);
const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext.mc_err & 2) != 0;
#elif defined(CPU_AARCH64)
void* const exception_address = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__far);
void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__pc);
const bool is_write = IsStoreInstruction(exception_pc);
#else
void* const exception_address = reinterpret_cast<void*>(info->si_addr);
void* const exception_pc = nullptr;
const bool is_write = false;
#endif
#endif
std::lock_guard<std::mutex> guard(m_handler_lock);
for (const RegisteredHandler& rh : m_handlers)
{
if (rh.callback(exception_pc, exception_address, is_write) == HandlerResult::ContinueExecution)
{
s_in_handler = false;
return;
}
}
// call old signal handler
#if !defined(__APPLE__) && !defined(__aarch64__)
const struct sigaction& sa = s_old_sigsegv_action;
#else
const struct sigaction& sa = (sig == SIGBUS) ? s_old_sigbus_action : s_old_sigsegv_action;
#endif
if (sa.sa_flags & SA_SIGINFO)
sa.sa_sigaction(sig, info, ctx);
else if (sa.sa_handler == SIG_DFL)
signal(sig, SIG_DFL);
else if (sa.sa_handler == SIG_IGN)
return;
else
sa.sa_handler(sig);
}
#endif
bool InstallHandler(void* owner, Callback callback)
{
bool was_empty;
{
std::lock_guard<std::mutex> guard(m_handler_lock);
if (std::find_if(m_handlers.begin(), m_handlers.end(),
[owner](const RegisteredHandler& rh) { return rh.owner == owner; }) != m_handlers.end())
{
return false;
}
was_empty = m_handlers.empty();
m_handlers.push_back(RegisteredHandler{owner, std::move(callback)});
}
if (was_empty)
{
#if defined(WIN32) && (defined(CPU_X64) || defined(CPU_AARCH64))
s_veh_handle = AddVectoredExceptionHandler(1, ExceptionHandler);
if (!s_veh_handle)
{
Log_ErrorPrint("Failed to add vectored exception handler");
return false;
}
#elif defined(USE_SIGSEGV)
#if 0
// Alternative stack - we'll need this is we ever use the host stack for branches.
stack_t signal_stack = {};
signal_stack.ss_sp = malloc(SIGSTKSZ);
signal_stack.ss_size = SIGSTKSZ;
if (sigaltstack(&signal_stack, nullptr))
{
Log_ErrorPrintf("signaltstack() failed: %d", errno);
return false;
}
#endif
struct sigaction sa = {};
sa.sa_sigaction = SIGSEGVHandler;
sa.sa_flags = SA_SIGINFO;
sigemptyset(&sa.sa_mask);
if (sigaction(SIGSEGV, &sa, &s_old_sigsegv_action) < 0)
{
Log_ErrorPrintf("sigaction(SIGSEGV) failed: %d", errno);
return false;
}
#if defined(__APPLE__) || defined(__aarch64__)
if (sigaction(SIGBUS, &sa, &s_old_sigbus_action) < 0)
{
Log_ErrorPrintf("sigaction(SIGBUS) failed: %d", errno);
return false;
}
#endif
#else
return false;
#endif
}
return true;
}
bool RemoveHandler(void* owner)
{
std::lock_guard<std::mutex> guard(m_handler_lock);
auto it = std::find_if(m_handlers.begin(), m_handlers.end(),
[owner](const RegisteredHandler& rh) { return rh.owner == owner; });
if (it == m_handlers.end())
return false;
m_handlers.erase(it);
if (m_handlers.empty())
{
#if defined(WIN32) && (defined(CPU_X64) || defined(CPU_AARCH64))
RemoveVectoredExceptionHandler(s_veh_handle);
s_veh_handle = nullptr;
#elif defined(USE_SIGSEGV)
// restore old signal handler
#if defined(__APPLE__) || defined(__aarch64__)
if (sigaction(SIGBUS, &s_old_sigbus_action, nullptr) < 0)
{
Log_ErrorPrintf("sigaction(SIGBUS) failed: %d", errno);
return false;
}
s_old_sigbus_action = {};
#endif
if (sigaction(SIGSEGV, &s_old_sigsegv_action, nullptr) < 0)
{
Log_ErrorPrintf("sigaction(SIGSEGV) failed: %d", errno);
return false;
}
s_old_sigsegv_action = {};
#else
return false;
#endif
}
return true;
}
} // namespace Common::PageFaultHandler