Revision 2f0156a6c79566bf265397641effa17a202f7ab4 authored by DilumAluthgeBot on 09 April 2021, 22:26:20 UTC, committed by GitHub on 09 April 2021, 22:26:20 UTC
Co-authored-by: Dilum Aluthge <dilum@aluthge.com>
1 parent 54c7002
signals-mach.c
// This file is a part of Julia. License is MIT: https://julialang.org/license
// Note that this file is `#include`d by "signals-unix.c"
#include <mach/clock.h>
#include <mach/clock_types.h>
#include <mach/clock_reply.h>
#include <mach/mach_traps.h>
#include <mach/task.h>
#include <mach/mig_errors.h>
#include <AvailabilityMacros.h>
#ifdef MAC_OS_X_VERSION_10_9
#include <sys/_types/_ucontext64.h>
#else
#define __need_ucontext64_t
#include <sys/_structs.h>
#endif
#include "julia_assert.h"
// private keymgr stuff
#define KEYMGR_GCC3_DW2_OBJ_LIST 302
enum {
NM_ALLOW_RECURSION = 1,
NM_RECURSION_ILLEGAL = 2
};
extern void _keymgr_set_and_unlock_processwide_ptr(unsigned int key, void *ptr);
extern int _keymgr_unlock_processwide_ptr(unsigned int key);
extern void *_keymgr_get_and_lock_processwide_ptr(unsigned int key);
extern int _keymgr_get_and_lock_processwide_ptr_2(unsigned int key, void **result);
extern int _keymgr_set_lockmode_processwide_ptr(unsigned int key, unsigned int mode);
static void attach_exception_port(thread_port_t thread, int segv_only);
// low 16 bits are the thread id, the next 8 bits are the original gc_state
static arraylist_t suspended_threads;
void jl_mach_gc_end(void)
{
// Requires the safepoint lock to be held
for (size_t i = 0; i < suspended_threads.len; i++) {
uintptr_t item = (uintptr_t)suspended_threads.items[i];
int16_t tid = (int16_t)item;
int8_t gc_state = (int8_t)(item >> 8);
jl_ptls_t ptls2 = jl_all_tls_states[tid];
jl_atomic_store_release(&ptls2->gc_state, gc_state);
thread_resume(pthread_mach_thread_np(ptls2->system_id));
}
suspended_threads.len = 0;
}
// Suspend the thread and return `1` if the GC is running.
// Otherwise return `0`
static int jl_mach_gc_wait(jl_ptls_t ptls2,
mach_port_t thread, int16_t tid)
{
jl_mutex_lock_nogc(&safepoint_lock);
if (!jl_atomic_load_relaxed(&jl_gc_running)) {
// relaxed, since gets set to zero only while the safepoint_lock was held
// this means we can tell if GC is done before we got the message or
// the safepoint was enabled for SIGINT.
jl_mutex_unlock_nogc(&safepoint_lock);
return 0;
}
// Otherwise, set the gc state of the thread, suspend and record it
int8_t gc_state = ptls2->gc_state;
jl_atomic_store_release(&ptls2->gc_state, JL_GC_STATE_WAITING);
uintptr_t item = tid | (((uintptr_t)gc_state) << 16);
arraylist_push(&suspended_threads, (void*)item);
thread_suspend(thread);
jl_mutex_unlock_nogc(&safepoint_lock);
return 1;
}
static mach_port_t segv_port = 0;
extern boolean_t exc_server(mach_msg_header_t *, mach_msg_header_t *);
#define STR(x) #x
#define XSTR(x) STR(x)
#define HANDLE_MACH_ERROR(msg, retval) \
if (retval != KERN_SUCCESS) { mach_error(msg XSTR(: __FILE__:__LINE__:), (retval)); jl_exit(1); }
void *mach_segv_listener(void *arg)
{
(void)arg;
(void)jl_get_ptls_states();
while (1) {
int ret = mach_msg_server(exc_server, 2048, segv_port, MACH_MSG_TIMEOUT_NONE);
jl_safe_printf("mach_msg_server: %s\n", mach_error_string(ret));
jl_exit(128 + SIGSEGV);
}
}
static void allocate_mach_handler()
{
// ensure KEYMGR_GCC3_DW2_OBJ_LIST is initialized, as this requires malloc
// and thus can deadlock when used without first initializing it.
// Apple caused this problem in their libunwind in 10.9 (circa keymgr-28)
// when they removed this part of the code from keymgr.
// Much thanks to Apple for providing source code, or this would probably
// have simply remained unsolved forever on their platform.
// This is similar to just calling checkKeyMgrRegisteredFDEs
// (this is quite thread-unsafe)
if (_keymgr_set_lockmode_processwide_ptr(KEYMGR_GCC3_DW2_OBJ_LIST, NM_ALLOW_RECURSION))
jl_error("_keymgr_set_lockmode_processwide_ptr failed");
arraylist_new(&suspended_threads, jl_n_threads);
pthread_t thread;
pthread_attr_t attr;
kern_return_t ret;
mach_port_t self = mach_task_self();
ret = mach_port_allocate(self, MACH_PORT_RIGHT_RECEIVE, &segv_port);
HANDLE_MACH_ERROR("mach_port_allocate",ret);
ret = mach_port_insert_right(self, segv_port, segv_port, MACH_MSG_TYPE_MAKE_SEND);
HANDLE_MACH_ERROR("mach_port_insert_right",ret);
// Alright, create a thread to serve as the listener for exceptions
if (pthread_attr_init(&attr) != 0) {
jl_error("pthread_attr_init failed");
}
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
if (pthread_create(&thread, &attr, mach_segv_listener, NULL) != 0) {
jl_error("pthread_create failed");
}
pthread_attr_destroy(&attr);
for (int16_t tid = 0; tid < jl_n_threads; tid++) {
attach_exception_port(pthread_mach_thread_np(jl_all_tls_states[tid]->system_id), 0);
}
}
#ifdef LLVMLIBUNWIND
volatile mach_port_t mach_profiler_thread = 0;
static kern_return_t profiler_segv_handler
(mach_port_t exception_port,
mach_port_t thread,
mach_port_t task,
exception_type_t exception,
exception_data_t code,
mach_msg_type_number_t code_count);
#endif
#if defined(_CPU_X86_64_)
typedef x86_thread_state64_t host_thread_state_t;
typedef x86_exception_state64_t host_exception_state_t;
#define THREAD_STATE x86_THREAD_STATE64
#define THREAD_STATE_COUNT x86_THREAD_STATE64_COUNT
#define HOST_EXCEPTION_STATE x86_EXCEPTION_STATE64
#define HOST_EXCEPTION_STATE_COUNT x86_EXCEPTION_STATE64_COUNT
#elif defined(_CPU_AARCH64_)
typedef arm_thread_state64_t host_thread_state_t;
typedef arm_exception_state64_t host_exception_state_t;
#define THREAD_STATE ARM_THREAD_STATE64
#define THREAD_STATE_COUNT ARM_THREAD_STATE64_COUNT
#define HOST_EXCEPTION_STATE ARM_EXCEPTION_STATE64
#define HOST_EXCEPTION_STATE_COUNT ARM_EXCEPTION_STATE64_COUNT
#endif
static void jl_call_in_state(jl_ptls_t ptls2, host_thread_state_t *state,
void (*fptr)(void))
{
#ifdef _CPU_X86_64_
uintptr_t rsp = state->__rsp;
#elif defined(_CPU_AARCH64_)
uintptr_t rsp = state->__sp;
#else
#error "julia: throw-in-context not supported on this platform"
#endif
if (ptls2->signal_stack == NULL || is_addr_on_sigstack(ptls2, (void*)rsp)) {
rsp = (rsp - 256) & ~(uintptr_t)15; // redzone and re-alignment
}
else {
rsp = (uintptr_t)ptls2->signal_stack + sig_stack_size;
}
assert(rsp % 16 == 0);
#ifdef _CPU_X86_64_
rsp -= sizeof(void*);
state->__rsp = rsp; // set stack pointer
state->__rip = (uint64_t)fptr; // "call" the function
#elif defined(_CPU_AARCH64_)
state->__sp = rsp;
state->__pc = (uint64_t)fptr;
state->__lr = 0;
#else
#error "julia: throw-in-context not supported on this platform"
#endif
}
#ifdef _CPU_X86_64_
int is_write_fault(host_exception_state_t exc_state) {
return exc_reg_is_write_fault(exc_state.__err);
}
#elif defined(_CPU_AARCH64_)
int is_write_fault(host_exception_state_t exc_state) {
return exc_reg_is_write_fault(exc_state.__esr);
}
#else
#warning Implement this query for consistent PROT_NONE handling
int is_write_fault(host_exception_state_t exc_state) {
return 0;
}
#endif
static void jl_throw_in_thread(int tid, mach_port_t thread, jl_value_t *exception)
{
unsigned int count = THREAD_STATE_COUNT;
host_thread_state_t state;
kern_return_t ret = thread_get_state(thread, THREAD_STATE, (thread_state_t)&state, &count);
HANDLE_MACH_ERROR("thread_get_state", ret);
jl_ptls_t ptls2 = jl_all_tls_states[tid];
if (!ptls2->safe_restore) {
assert(exception);
ptls2->bt_size = rec_backtrace_ctx(ptls2->bt_data, JL_MAX_BT_SIZE,
(bt_context_t*)&state, ptls2->pgcstack);
ptls2->sig_exception = exception;
}
jl_call_in_state(ptls2, &state, &jl_sig_throw);
ret = thread_set_state(thread, THREAD_STATE, (thread_state_t)&state, count);
HANDLE_MACH_ERROR("thread_set_state", ret);
}
static void segv_handler(int sig, siginfo_t *info, void *context)
{
jl_ptls_t ptls = jl_get_ptls_states();
assert(sig == SIGSEGV || sig == SIGBUS);
if (ptls->safe_restore) { // restarting jl_ or jl_unwind_stepn
jl_call_in_state(ptls, (host_thread_state_t*)jl_to_bt_context(context), &jl_sig_throw);
}
else {
sigdie_handler(sig, info, context);
}
}
//exc_server uses dlsym to find symbol
JL_DLLEXPORT
kern_return_t catch_exception_raise(mach_port_t exception_port,
mach_port_t thread,
mach_port_t task,
exception_type_t exception,
exception_data_t code,
mach_msg_type_number_t code_count)
{
unsigned int exc_count = HOST_EXCEPTION_STATE_COUNT;
host_exception_state_t exc_state;
#ifdef LLVMLIBUNWIND
if (thread == mach_profiler_thread) {
return profiler_segv_handler(exception_port, thread, task, exception, code, code_count);
}
#endif
int16_t tid;
jl_ptls_t ptls2 = NULL;
for (tid = 0; tid < jl_n_threads; tid++) {
jl_ptls_t _ptls2 = jl_all_tls_states[tid];
if (pthread_mach_thread_np(_ptls2->system_id) == thread) {
ptls2 = _ptls2;
break;
}
}
if (!ptls2) {
// We don't know about this thread, let the kernel try another handler
// instead. This shouldn't actually happen since we only register the
// handler for the threads we know about.
jl_safe_printf("ERROR: Exception handler triggered on unmanaged thread.\n");
return KERN_INVALID_ARGUMENT;
}
if (exception == EXC_ARITHMETIC) {
jl_throw_in_thread(tid, thread, jl_diverror_exception);
return KERN_SUCCESS;
}
assert(exception == EXC_BAD_ACCESS);
kern_return_t ret = thread_get_state(thread, HOST_EXCEPTION_STATE, (thread_state_t)&exc_state, &exc_count);
HANDLE_MACH_ERROR("thread_get_state", ret);
#ifdef _CPU_X86_64_
uint64_t fault_addr = exc_state.__faultvaddr;
#else
uint64_t fault_addr = exc_state.__far;
#endif
if (jl_addr_is_safepoint(fault_addr)) {
if (jl_mach_gc_wait(ptls2, thread, tid))
return KERN_SUCCESS;
if (ptls2->tid != 0)
return KERN_SUCCESS;
if (ptls2->defer_signal) {
jl_safepoint_defer_sigint();
}
else if (jl_safepoint_consume_sigint()) {
jl_clear_force_sigint();
jl_throw_in_thread(tid, thread, jl_interrupt_exception);
}
return KERN_SUCCESS;
}
if (ptls2->safe_restore) {
jl_throw_in_thread(tid, thread, jl_stackovf_exception);
return KERN_SUCCESS;
}
#ifdef SEGV_EXCEPTION
if (1) {
#else
if (msync((void*)(fault_addr & ~(jl_page_size - 1)), 1, MS_ASYNC) == 0) { // check if this was a valid address
#endif
jl_value_t *excpt;
if (is_addr_on_stack(ptls2, (void*)fault_addr)) {
excpt = jl_stackovf_exception;
}
#ifdef SEGV_EXCEPTION
else if (msync((void*)(fault_addr & ~(jl_page_size - 1)), 1, MS_ASYNC) != 0) {
// no page mapped at this address
excpt = jl_segv_exception;
}
#endif
else {
if (!is_write_fault(exc_state))
return KERN_INVALID_ARGUMENT;
excpt = jl_readonlymemory_exception;
}
jl_throw_in_thread(tid, thread, excpt);
return KERN_SUCCESS;
}
else {
jl_exit_thread0(128 + SIGSEGV, NULL, 0);
return KERN_SUCCESS;
}
}
static void attach_exception_port(thread_port_t thread, int segv_only)
{
kern_return_t ret;
// http://www.opensource.apple.com/source/xnu/xnu-2782.1.97/osfmk/man/thread_set_exception_ports.html
exception_mask_t mask = EXC_MASK_BAD_ACCESS;
if (!segv_only)
mask |= EXC_MASK_ARITHMETIC;
ret = thread_set_exception_ports(thread, mask, segv_port, EXCEPTION_DEFAULT, MACHINE_THREAD_STATE);
HANDLE_MACH_ERROR("thread_set_exception_ports", ret);
}
static void jl_thread_suspend_and_get_state2(int tid, host_thread_state_t *ctx)
{
jl_ptls_t ptls2 = jl_all_tls_states[tid];
mach_port_t thread = pthread_mach_thread_np(ptls2->system_id);
kern_return_t ret = thread_suspend(thread);
HANDLE_MACH_ERROR("thread_suspend", ret);
// Do the actual sampling
unsigned int count = THREAD_STATE_COUNT;
memset(ctx, 0, sizeof(*ctx));
// Get the state of the suspended thread
ret = thread_get_state(thread, THREAD_STATE, (thread_state_t)ctx, &count);
}
static void jl_thread_suspend_and_get_state(int tid, unw_context_t **ctx)
{
static host_thread_state_t state;
jl_thread_suspend_and_get_state2(tid, &state);
*ctx = (unw_context_t*)&state;
}
static void jl_thread_resume(int tid, int sig)
{
jl_ptls_t ptls2 = jl_all_tls_states[tid];
mach_port_t thread = pthread_mach_thread_np(ptls2->system_id);
kern_return_t ret = thread_resume(thread);
HANDLE_MACH_ERROR("thread_resume", ret);
}
// Throw jl_interrupt_exception if the master thread is in a signal async region
// or if SIGINT happens too often.
static void jl_try_deliver_sigint(void)
{
jl_ptls_t ptls2 = jl_all_tls_states[0];
mach_port_t thread = pthread_mach_thread_np(ptls2->system_id);
kern_return_t ret = thread_suspend(thread);
HANDLE_MACH_ERROR("thread_suspend", ret);
// This aborts `sleep` and other syscalls.
ret = thread_abort(thread);
HANDLE_MACH_ERROR("thread_abort", ret);
jl_safepoint_enable_sigint();
int force = jl_check_force_sigint();
if (force || (!ptls2->defer_signal && ptls2->io_wait)) {
jl_safepoint_consume_sigint();
if (force)
jl_safe_printf("WARNING: Force throwing a SIGINT\n");
jl_clear_force_sigint();
jl_throw_in_thread(0, thread, jl_interrupt_exception);
}
else {
jl_wake_libuv();
}
ret = thread_resume(thread);
HANDLE_MACH_ERROR("thread_resume", ret);
}
static void JL_NORETURN jl_exit_thread0_cb(int exitstate)
{
CFI_NORETURN
jl_critical_error(exitstate - 128, NULL);
jl_exit(exitstate);
}
static void jl_exit_thread0(int exitstate, jl_bt_element_t *bt_data, size_t bt_size)
{
jl_ptls_t ptls2 = jl_all_tls_states[0];
mach_port_t thread = pthread_mach_thread_np(ptls2->system_id);
host_thread_state_t state;
jl_thread_suspend_and_get_state2(0, &state);
unw_context_t *uc = (unw_context_t*)&state;
// This aborts `sleep` and other syscalls.
kern_return_t ret = thread_abort(thread);
HANDLE_MACH_ERROR("thread_abort", ret);
if (bt_data == NULL) {
// Must avoid extended backtrace frames here unless we're sure bt_data
// is properly rooted.
ptls2->bt_size = rec_backtrace_ctx(ptls2->bt_data, JL_MAX_BT_SIZE, uc, NULL);
}
else {
ptls2->bt_size = bt_size; // <= JL_MAX_BT_SIZE
memcpy(ptls2->bt_data, bt_data, ptls2->bt_size * sizeof(bt_data[0]));
}
void (*exit_func)(int) = &_exit;
if (thread0_exit_count <= 1) {
exit_func = &jl_exit_thread0_cb;
}
else if (thread0_exit_count == 2) {
exit_func = &exit;
}
else {
exit_func = &_exit;
}
#ifdef _CPU_X86_64_
// First integer argument. Not portable but good enough =)
state.__rdi = exitstate;
#elif defined(_CPU_AARCH64_)
state.__x[0] = exitstate;
#else
#error Fill in first integer argument here
#endif
jl_call_in_state(ptls2, &state, (void (*)(void))exit_func);
unsigned int count = THREAD_STATE_COUNT;
ret = thread_set_state(thread, THREAD_STATE, (thread_state_t)&state, count);
HANDLE_MACH_ERROR("thread_set_state", ret);
ret = thread_resume(thread);
HANDLE_MACH_ERROR("thread_resume", ret);
}
static int profile_started = 0;
mach_timespec_t timerprof;
static pthread_t profiler_thread;
clock_serv_t clk;
static mach_port_t profile_port = 0;
#ifdef LLVMLIBUNWIND
volatile static int forceDwarf = -2;
static unw_context_t profiler_uc;
static kern_return_t profiler_segv_handler
(mach_port_t exception_port,
mach_port_t thread,
mach_port_t task,
exception_type_t exception,
exception_data_t code,
mach_msg_type_number_t code_count)
{
assert(thread == mach_profiler_thread);
host_thread_state_t state;
// Not currently unwinding. Raise regular segfault
if (forceDwarf == -2)
return KERN_INVALID_ARGUMENT;
if (forceDwarf == 0)
forceDwarf = 1;
else
forceDwarf = -1;
unsigned int count = THREAD_STATE_COUNT;
thread_get_state(thread, THREAD_STATE, (thread_state_t)&state, &count);
#ifdef _CPU_X86_64_
// don't change cs fs gs rflags
uint64_t cs = state.__cs;
uint64_t fs = state.__fs;
uint64_t gs = state.__gs;
uint64_t rflags = state.__rflags;
#elif defined(_CPU_AARCH64_)
uint64_t cpsr = state.__cpsr;
#else
#error Unknown CPU
#endif
memcpy(&state, &profiler_uc, sizeof(state));
#ifdef _CPU_X86_64_
state.__cs = cs;
state.__fs = fs;
state.__gs = gs;
state.__rflags = rflags;
#else
state.__cpsr = cpsr;
#endif
kern_return_t ret = thread_set_state(thread, THREAD_STATE, (thread_state_t)&state, count);
HANDLE_MACH_ERROR("thread_set_state", ret);
return KERN_SUCCESS;
}
#endif
void *mach_profile_listener(void *arg)
{
(void)arg;
int i;
const int max_size = 512;
attach_exception_port(mach_thread_self(), 1);
#ifdef LLVMLIBUNWIND
mach_profiler_thread = mach_thread_self();
#endif
mig_reply_error_t *bufRequest = (mig_reply_error_t*)malloc_s(max_size);
while (1) {
kern_return_t ret = mach_msg(&bufRequest->Head, MACH_RCV_MSG,
0, max_size, profile_port,
MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
HANDLE_MACH_ERROR("mach_msg", ret);
// sample each thread, round-robin style in reverse order
// (so that thread zero gets notified last)
jl_lock_profile();
void *unused = NULL;
int keymgr_locked = _keymgr_get_and_lock_processwide_ptr_2(KEYMGR_GCC3_DW2_OBJ_LIST, &unused) == 0;
for (i = jl_n_threads; i-- > 0; ) {
// if there is no space left, break early
if (jl_profile_is_buffer_full()) {
jl_profile_stop_timer();
break;
}
host_thread_state_t state;
jl_thread_suspend_and_get_state2(i, &state);
unw_context_t *uc = (unw_context_t*)&state;
if (running) {
#ifdef LLVMLIBUNWIND
/*
* Unfortunately compact unwind info is incorrectly generated for quite a number of
* libraries by quite a large number of compilers. We can fall back to DWARF unwind info
* in some cases, but in quite a number of cases (especially libraries not compiled in debug
* mode, only the compact unwind info may be available). Even more unfortunately, there is no
* way to detect such bogus compact unwind info (other than noticing the resulting segfault).
* What we do here is ugly, but necessary until the compact unwind info situation improves.
* We try to use the compact unwind info and if that results in a segfault, we retry with DWARF info.
* Note that in a small number of cases this may result in bogus stack traces, but at least the topmost
* entry will always be correct, and the number of cases in which this is an issue is rather small.
* Other than that, this implementation is not incorrect as the other thread is paused while we are profiling
* and during stack unwinding we only ever read memory, but never write it.
*/
forceDwarf = 0;
unw_getcontext(&profiler_uc); // will resume from this point if the next lines segfault at any point
if (forceDwarf == 0) {
// Save the backtrace
bt_size_cur += rec_backtrace_ctx((jl_bt_element_t*)bt_data_prof + bt_size_cur, bt_size_max - bt_size_cur - 1, uc, NULL);
}
else if (forceDwarf == 1) {
bt_size_cur += rec_backtrace_ctx_dwarf((jl_bt_element_t*)bt_data_prof + bt_size_cur, bt_size_max - bt_size_cur - 1, uc, NULL);
}
else if (forceDwarf == -1) {
jl_safe_printf("WARNING: profiler attempt to access an invalid memory location\n");
}
forceDwarf = -2;
#else
bt_size_cur += rec_backtrace_ctx((jl_bt_element_t*)bt_data_prof + bt_size_cur, bt_size_max - bt_size_cur - 1, uc, NULL);
#endif
// Mark the end of this block with 0
bt_data_prof[bt_size_cur++].uintptr = 0;
}
// We're done! Resume the thread.
jl_thread_resume(i, 0);
}
if (keymgr_locked)
_keymgr_unlock_processwide_ptr(KEYMGR_GCC3_DW2_OBJ_LIST);
jl_unlock_profile();
if (running) {
// Reset the alarm
kern_return_t ret = clock_alarm(clk, TIME_RELATIVE, timerprof, profile_port);
HANDLE_MACH_ERROR("clock_alarm", ret)
}
}
}
JL_DLLEXPORT int jl_profile_start_timer(void)
{
kern_return_t ret;
if (!profile_started) {
mach_port_t self = mach_task_self();
ret = host_get_clock_service(mach_host_self(), SYSTEM_CLOCK, (clock_serv_t *)&clk);
HANDLE_MACH_ERROR("host_get_clock_service", ret);
ret = mach_port_allocate(self, MACH_PORT_RIGHT_RECEIVE, &profile_port);
HANDLE_MACH_ERROR("mach_port_allocate", ret);
// Alright, create a thread to serve as the listener for exceptions
pthread_attr_t attr;
if (pthread_attr_init(&attr) != 0) {
jl_error("pthread_attr_init failed");
}
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
if (pthread_create(&profiler_thread, &attr, mach_profile_listener, NULL) != 0) {
jl_error("pthread_create failed");
}
pthread_attr_destroy(&attr);
profile_started = 1;
}
timerprof.tv_sec = nsecprof/GIGA;
timerprof.tv_nsec = nsecprof%GIGA;
running = 1;
// ensure the alarm is running
ret = clock_alarm(clk, TIME_RELATIVE, timerprof, profile_port);
HANDLE_MACH_ERROR("clock_alarm", ret);
return 0;
}
JL_DLLEXPORT void jl_profile_stop_timer(void)
{
running = 0;
}
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