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[jit, exception] use shared mutex to reduce thread contention of cached code blocks in fastmem trap handler
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Signed-off-by: lizzie <lizzie@eden-emu.dev>
This commit is contained in:
lizzie 2025-08-26 10:18:17 +00:00 • committed by crueter
parent 21cd44ec04
commit 8e4bbf0d5b
1 changed files with 86 additions and 133 deletions
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219
src/dynarmic/src/dynarmic/backend/exception_handler_posix.cpp
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@ -6,8 +6,13 @@
* SPDX-License-Identifier: 0BSD
*/
#include "dynarmic/backend/exception_handler.h"
#include <cstring>
#include <functional>
#include <memory>
#include <mutex>
#include <shared_mutex>
#include <optional>
#include <sys/mman.h>
#ifdef __APPLE__
# include <signal.h>
# include <sys/ucontext.h>
@ -21,17 +26,10 @@
# endif
#endif
#include <cstring>
#include <functional>
#include <memory>
#include <mutex>
#include <optional>
#include <vector>
#include <ankerl/unordered_dense.h>
#include "dynarmic/common/assert.h"
#include <mcl/bit_cast.hpp>
#include "dynarmic/backend/exception_handler.h"
#include "dynarmic/common/common_types.h"
#if defined(MCL_ARCHITECTURE_X86_64)
# include "dynarmic/backend/x64/block_of_code.h"
#elif defined(MCL_ARCHITECTURE_ARM64)
@ -43,42 +41,79 @@
#else
# error "Invalid architecture"
#endif
#include <mcl/bit_cast.hpp>
namespace Dynarmic::Backend {
namespace {
struct CodeBlockInfo {
u64 code_begin, code_end;
u64 size;
std::function<FakeCall(u64)> cb;
};
class SigHandler {
public:
SigHandler();
~SigHandler();
void AddCodeBlock(CodeBlockInfo info);
void RemoveCodeBlock(u64 host_pc);
bool SupportsFastmem() const { return supports_fast_mem; }
private:
auto FindCodeBlockInfo(u64 host_pc) {
return std::find_if(code_block_infos.begin(), code_block_infos.end(), [&](const auto& x) { return x.code_begin <= host_pc && x.code_end > host_pc; });
auto FindCodeBlockInfo(u64 offset) noexcept {
return std::find_if(code_block_infos.begin(), code_block_infos.end(), [&](auto const& e) {
return e.first <= offset && e.first + e.second.size > offset;
});
}
static void SigAction(int sig, siginfo_t* info, void* raw_context);
bool supports_fast_mem = true;
void* signal_stack_memory = nullptr;
std::vector<CodeBlockInfo> code_block_infos;
std::mutex code_block_infos_mutex;
ankerl::unordered_dense::map<u64, CodeBlockInfo> code_block_infos;
std::shared_mutex code_block_infos_mutex;
struct sigaction old_sa_segv;
struct sigaction old_sa_bus;
static constexpr std::size_t signal_stack_size = std::max<size_t>(SIGSTKSZ, 2 * 1024 * 1024);
public:
SigHandler() noexcept {
signal_stack_memory = mmap(nullptr, signal_stack_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
static void SigAction(int sig, siginfo_t* info, void* raw_context);
stack_t signal_stack{};
signal_stack.ss_sp = signal_stack_memory;
signal_stack.ss_size = signal_stack_size;
signal_stack.ss_flags = 0;
if (sigaltstack(&signal_stack, nullptr) != 0) {
fmt::print(stderr, "dynarmic: POSIX SigHandler: init failure at sigaltstack\n");
supports_fast_mem = false;
return;
}
struct sigaction sa{};
sa.sa_handler = nullptr;
sa.sa_sigaction = &SigHandler::SigAction;
sa.sa_flags = SA_SIGINFO | SA_ONSTACK | SA_RESTART;
sigemptyset(&sa.sa_mask);
if (sigaction(SIGSEGV, &sa, &old_sa_segv) != 0) {
fmt::print(stderr, "dynarmic: POSIX SigHandler: could not set SIGSEGV handler\n");
supports_fast_mem = false;
return;
}
#ifdef __APPLE__
if (sigaction(SIGBUS, &sa, &old_sa_bus) != 0) {
fmt::print(stderr, "dynarmic: POSIX SigHandler: could not set SIGBUS handler\n");
supports_fast_mem = false;
return;
}
#endif
}
~SigHandler() noexcept {
munmap(signal_stack_memory, signal_stack_size);
}
void AddCodeBlock(u64 offset, CodeBlockInfo cbi) noexcept {
std::unique_lock guard(code_block_infos_mutex);
code_block_infos.insert_or_assign(offset, cbi);
}
void RemoveCodeBlock(u64 offset) noexcept {
std::unique_lock guard(code_block_infos_mutex);
code_block_infos.erase(offset);
}
bool SupportsFastmem() const noexcept { return supports_fast_mem; }
};
std::mutex handler_lock;
@ -91,64 +126,8 @@ void RegisterHandler() {
}
}
SigHandler::SigHandler() {
const size_t signal_stack_size = std::max<size_t>(SIGSTKSZ, 2 * 1024 * 1024);
signal_stack_memory = std::malloc(signal_stack_size);
stack_t signal_stack;
signal_stack.ss_sp = signal_stack_memory;
signal_stack.ss_size = signal_stack_size;
signal_stack.ss_flags = 0;
if (sigaltstack(&signal_stack, nullptr) != 0) {
fmt::print(stderr, "dynarmic: POSIX SigHandler: init failure at sigaltstack\n");
supports_fast_mem = false;
return;
}
struct sigaction sa;
sa.sa_handler = nullptr;
sa.sa_sigaction = &SigHandler::SigAction;
sa.sa_flags = SA_SIGINFO | SA_ONSTACK | SA_RESTART;
sigemptyset(&sa.sa_mask);
if (sigaction(SIGSEGV, &sa, &old_sa_segv) != 0) {
fmt::print(stderr, "dynarmic: POSIX SigHandler: could not set SIGSEGV handler\n");
supports_fast_mem = false;
return;
}
#ifdef __APPLE__
if (sigaction(SIGBUS, &sa, &old_sa_bus) != 0) {
fmt::print(stderr, "dynarmic: POSIX SigHandler: could not set SIGBUS handler\n");
supports_fast_mem = false;
return;
}
#endif
}
SigHandler::~SigHandler() {
std::free(signal_stack_memory);
}
void SigHandler::AddCodeBlock(CodeBlockInfo cbi) {
std::lock_guard<std::mutex> guard(code_block_infos_mutex);
if (auto iter = FindCodeBlockInfo(cbi.code_begin); iter != code_block_infos.end()) {
code_block_infos.erase(iter);
}
code_block_infos.push_back(cbi);
}
void SigHandler::RemoveCodeBlock(u64 host_pc) {
std::lock_guard<std::mutex> guard(code_block_infos_mutex);
const auto iter = FindCodeBlockInfo(host_pc);
if (iter == code_block_infos.end()) {
return;
}
code_block_infos.erase(iter);
}
void SigHandler::SigAction(int sig, siginfo_t* info, void* raw_context) {
ASSERT(sig == SIGSEGV || sig == SIGBUS);
DEBUG_ASSERT(sig == SIGSEGV || sig == SIGBUS);
#ifndef MCL_ARCHITECTURE_RISCV
ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(raw_context);
#ifndef __OpenBSD__
@ -157,7 +136,6 @@ void SigHandler::SigAction(int sig, siginfo_t* info, void* raw_context) {
#endif
#if defined(MCL_ARCHITECTURE_X86_64)
# if defined(__APPLE__)
# define CTX_RIP (mctx->__ss.__rip)
# define CTX_RSP (mctx->__ss.__rsp)
@ -179,26 +157,18 @@ void SigHandler::SigAction(int sig, siginfo_t* info, void* raw_context) {
# else
# error "Unknown platform"
# endif
{
std::lock_guard<std::mutex> guard(sig_handler->code_block_infos_mutex);
const auto iter = sig_handler->FindCodeBlockInfo(CTX_RIP);
if (iter != sig_handler->code_block_infos.end()) {
FakeCall fc = iter->cb(CTX_RIP);
std::shared_lock guard(sig_handler->code_block_infos_mutex);
if (auto const iter = sig_handler->FindCodeBlockInfo(CTX_RIP); iter != sig_handler->code_block_infos.end()) {
FakeCall fc = iter->second.cb(CTX_RIP);
CTX_RSP -= sizeof(u64);
*mcl::bit_cast<u64*>(CTX_RSP) = fc.ret_rip;
CTX_RIP = fc.call_rip;
return;
}
}
fmt::print(stderr, "Unhandled {} at rip {:#018x}\n", sig == SIGSEGV ? "SIGSEGV" : "SIGBUS", CTX_RIP);
#elif defined(MCL_ARCHITECTURE_ARM64)
# if defined(__APPLE__)
# define CTX_PC (mctx->__ss.__pc)
# define CTX_SP (mctx->__ss.__sp)
@ -240,30 +210,19 @@ void SigHandler::SigAction(int sig, siginfo_t* info, void* raw_context) {
# else
# error "Unknown platform"
# endif
{
std::lock_guard<std::mutex> guard(sig_handler->code_block_infos_mutex);
const auto iter = sig_handler->FindCodeBlockInfo(CTX_PC);
if (iter != sig_handler->code_block_infos.end()) {
FakeCall fc = iter->cb(CTX_PC);
std::shared_lock guard(sig_handler->code_block_infos_mutex);
if (const auto iter = sig_handler->FindCodeBlockInfo(CTX_PC); iter != sig_handler->code_block_infos.end()) {
FakeCall fc = iter->second.cb(CTX_PC);
CTX_PC = fc.call_pc;
return;
}
}
fmt::print(stderr, "Unhandled {} at pc {:#018x}\n", sig == SIGSEGV ? "SIGSEGV" : "SIGBUS", CTX_PC);
#elif defined(MCL_ARCHITECTURE_RISCV)
ASSERT_FALSE("Unimplemented");
#else
# error "Invalid architecture"
#endif
struct sigaction* retry_sa = sig == SIGSEGV ? &sig_handler->old_sa_segv : &sig_handler->old_sa_bus;
@ -284,26 +243,26 @@ void SigHandler::SigAction(int sig, siginfo_t* info, void* raw_context) {
} // anonymous namespace
struct ExceptionHandler::Impl final {
Impl(u64 code_begin_, u64 code_end_)
: code_begin(code_begin_)
, code_end(code_end_) {
Impl(u64 offset_, u64 size_)
: offset(offset_)
, size(size_) {
RegisterHandler();
}
void SetCallback(std::function<FakeCall(u64)> cb) {
CodeBlockInfo cbi;
cbi.code_begin = code_begin;
cbi.code_end = code_end;
cbi.cb = cb;
sig_handler->AddCodeBlock(cbi);
sig_handler->AddCodeBlock(offset, CodeBlockInfo{
.size = size,
.cb = cb
});
}
~Impl() {
sig_handler->RemoveCodeBlock(code_begin);
sig_handler->RemoveCodeBlock(offset);
}
private:
u64 code_begin, code_end;
u64 offset;
u64 size;
};
ExceptionHandler::ExceptionHandler() = default;
@ -311,28 +270,22 @@ ExceptionHandler::~ExceptionHandler() = default;
#if defined(MCL_ARCHITECTURE_X86_64)
void ExceptionHandler::Register(X64::BlockOfCode& code) {
const u64 code_begin = mcl::bit_cast<u64>(code.getCode());
const u64 code_end = code_begin + code.GetTotalCodeSize();
impl = std::make_unique<Impl>(code_begin, code_end);
impl = std::make_unique<Impl>(mcl::bit_cast<u64>(code.getCode()), code.GetTotalCodeSize());
}
#elif defined(MCL_ARCHITECTURE_ARM64)
void ExceptionHandler::Register(oaknut::CodeBlock& mem, std::size_t size) {
const u64 code_begin = mcl::bit_cast<u64>(mem.ptr());
const u64 code_end = code_begin + size;
impl = std::make_unique<Impl>(code_begin, code_end);
impl = std::make_unique<Impl>(mcl::bit_cast<u64>(mem.ptr()), size);
}
#elif defined(MCL_ARCHITECTURE_RISCV)
void ExceptionHandler::Register(RV64::CodeBlock& mem, std::size_t size) {
const u64 code_begin = mcl::bit_cast<u64>(mem.ptr<u64>());
const u64 code_end = code_begin + size;
impl = std::make_unique<Impl>(code_begin, code_end);
impl = std::make_unique<Impl>(mcl::bit_cast<u64>(mem.ptr<u64>()), size);
}
#else
# error "Invalid architecture"
#endif
bool ExceptionHandler::SupportsFastmem() const noexcept {
return static_cast<bool>(impl) && sig_handler->SupportsFastmem();
return bool(impl) && sig_handler->SupportsFastmem();
}
void ExceptionHandler::SetFastmemCallback(std::function<FakeCall(u64)> cb) {