signals-unix.c
// This file is a part of Julia. License is MIT: https://julialang.org/license
// Note that this file is `#include`d by "signal-handling.c"
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <pthread.h>
#include <errno.h>
#if defined(_OS_DARWIN_) && !defined(MAP_ANONYMOUS)
#define MAP_ANONYMOUS MAP_ANON
#endif
#ifdef __APPLE__
#include <AvailabilityMacros.h>
#ifdef MAC_OS_X_VERSION_10_9
#include <sys/_types/_ucontext64.h>
#else
#define __need_ucontext64_t
#include <machine/_structs.h>
#endif
#endif
// Figure out the best signals/timers to use for this platform
#ifdef __APPLE__ // Darwin's mach ports allow signal-free thread management
#define HAVE_MACH
#define HAVE_KEVENT
#elif defined(__FreeBSD__) // generic bsd
#define HAVE_ITIMER
#else // generic linux
#define HAVE_TIMER
#endif
#ifdef HAVE_KEVENT
#include <sys/event.h>
#endif
// 8M signal stack, same as default stack size and enough
// for reasonable finalizers.
// Should also be enough for parallel GC when we have it =)
#define sig_stack_size (8 * 1024 * 1024)
#include "julia_assert.h"
// helper function for returning the unw_context_t inside a ucontext_t
static bt_context_t *jl_to_bt_context(void *sigctx)
{
#ifdef __APPLE__
return (bt_context_t*)&((ucontext64_t*)sigctx)->uc_mcontext64->__ss;
#elif defined(_CPU_ARM_)
// libunwind does not use `ucontext_t` on ARM.
// `unw_context_t` is a struct of 16 `unsigned long` which should
// have the same layout as the `arm_r0` to `arm_pc` fields in `sigcontext`
ucontext_t *ctx = (ucontext_t*)sigctx;
return (bt_context_t*)&ctx->uc_mcontext.arm_r0;
#else
return (bt_context_t*)sigctx;
#endif
}
static int thread0_exit_count = 0;
static void jl_exit_thread0(int exitstate, jl_bt_element_t *bt_data, size_t bt_size);
static inline __attribute__((unused)) uintptr_t jl_get_rsp_from_ctx(const void *_ctx)
{
#if defined(_OS_LINUX_) && defined(_CPU_X86_64_)
const ucontext_t *ctx = (const ucontext_t*)_ctx;
return ctx->uc_mcontext.gregs[REG_RSP];
#elif defined(_OS_LINUX_) && defined(_CPU_X86_)
const ucontext_t *ctx = (const ucontext_t*)_ctx;
return ctx->uc_mcontext.gregs[REG_ESP];
#elif defined(_OS_LINUX_) && defined(_CPU_AARCH64_)
const ucontext_t *ctx = (const ucontext_t*)_ctx;
return ctx->uc_mcontext.sp;
#elif defined(_OS_LINUX_) && defined(_CPU_ARM_)
const ucontext_t *ctx = (const ucontext_t*)_ctx;
return ctx->uc_mcontext.arm_sp;
#elif defined(_OS_DARWIN_) && defined(_CPU_X86_64_)
const ucontext64_t *ctx = (const ucontext64_t*)_ctx;
return ctx->uc_mcontext64->__ss.__rsp;
#elif defined(_OS_DARWIN_) && defined(_CPU_AARCH64_)
const ucontext64_t *ctx = (const ucontext64_t*)_ctx;
return ctx->uc_mcontext64->__ss.__sp;
#else
// TODO Add support for FreeBSD and PowerPC(64)?
return 0;
#endif
}
static int is_addr_on_sigstack(jl_ptls_t ptls, void *ptr)
{
// One guard page for signal_stack.
return !((char*)ptr < (char*)ptls->signal_stack - jl_page_size ||
(char*)ptr > (char*)ptls->signal_stack + sig_stack_size);
}
// Modify signal context `_ctx` so that `fptr` will execute when the signal
// returns. `fptr` will execute on the signal stack, and must not return.
// jl_call_in_ctx is also currently executing on that signal stack,
// so be careful not to smash it
static void jl_call_in_ctx(jl_ptls_t ptls, void (*fptr)(void), int sig, void *_ctx)
{
// Modifying the ucontext should work but there is concern that
// sigreturn oriented programming mitigation can work against us
// by rejecting ucontext that is modified.
// The current (staged) implementation in the Linux Kernel only
// checks that the syscall is made in the signal handler and that
// the ucontext address is valid. Hopefully the value of the ucontext
// will not be part of the validation...
if (!ptls->signal_stack) {
sigset_t sset;
sigemptyset(&sset);
sigaddset(&sset, sig);
sigprocmask(SIG_UNBLOCK, &sset, NULL);
fptr();
return;
}
uintptr_t rsp = jl_get_rsp_from_ctx(_ctx);
if (is_addr_on_sigstack(ptls, (void*)rsp)) {
rsp = (rsp - 256) & ~(uintptr_t)15; // redzone and re-alignment
}
else {
rsp = (uintptr_t)ptls->signal_stack + sig_stack_size;
}
assert(rsp % 16 == 0);
#if defined(_OS_LINUX_) && defined(_CPU_X86_64_)
ucontext_t *ctx = (ucontext_t*)_ctx;
rsp -= sizeof(void*);
ctx->uc_mcontext.gregs[REG_RSP] = rsp;
ctx->uc_mcontext.gregs[REG_RIP] = (uintptr_t)fptr;
#elif defined(_OS_FREEBSD_) && defined(_CPU_X86_64_)
ucontext_t *ctx = (ucontext_t*)_ctx;
rsp -= sizeof(void*);
ctx->uc_mcontext.mc_rsp = rsp;
ctx->uc_mcontext.mc_rip = (uintptr_t)fptr;
#elif defined(_OS_LINUX_) && defined(_CPU_X86_)
ucontext_t *ctx = (ucontext_t*)_ctx;
rsp -= sizeof(void*);
ctx->uc_mcontext.gregs[REG_ESP] = rsp;
ctx->uc_mcontext.gregs[REG_EIP] = (uintptr_t)fptr;
#elif defined(_OS_FREEBSD_) && defined(_CPU_X86_)
ucontext_t *ctx = (ucontext_t*)_ctx;
rsp -= sizeof(void*);
ctx->uc_mcontext.mc_esp = rsp;
ctx->uc_mcontext.mc_eip = (uintptr_t)fptr;
#elif defined(_OS_LINUX_) && defined(_CPU_AARCH64_)
ucontext_t *ctx = (ucontext_t*)_ctx;
ctx->uc_mcontext.sp = rsp;
ctx->uc_mcontext.regs[29] = 0; // Clear link register (x29)
ctx->uc_mcontext.pc = (uintptr_t)fptr;
#elif defined(_OS_LINUX_) && defined(_CPU_ARM_)
ucontext_t *ctx = (ucontext_t*)_ctx;
uintptr_t target = (uintptr_t)fptr;
// Apparently some glibc's sigreturn target is running in thumb state.
// Mimic a `bx` instruction by setting the T(5) bit of CPSR
// depending on the target address.
uintptr_t cpsr = ctx->uc_mcontext.arm_cpsr;
// Thumb mode function pointer should have the lowest bit set
if (target & 1) {
target = target & ~((uintptr_t)1);
cpsr = cpsr | (1 << 5);
}
else {
cpsr = cpsr & ~(1 << 5);
}
ctx->uc_mcontext.arm_cpsr = cpsr;
ctx->uc_mcontext.arm_sp = rsp;
ctx->uc_mcontext.arm_lr = 0; // Clear link register
ctx->uc_mcontext.arm_pc = target;
#elif defined(_OS_DARWIN_) && (defined(_CPU_X86_64_) || defined(_CPU_AARCH64_))
// Only used for SIGFPE.
// This doesn't seems to be reliable when the SIGFPE is generated
// from a divide-by-zero exception, which is now handled by
// `catch_exception_raise`. It works fine when a signal is received
// due to `kill`/`raise` though.
ucontext64_t *ctx = (ucontext64_t*)_ctx;
#if defined(_CPU_X86_64_)
rsp -= sizeof(void*);
ctx->uc_mcontext64->__ss.__rsp = rsp;
ctx->uc_mcontext64->__ss.__rip = (uintptr_t)fptr;
#else
ctx->uc_mcontext64->__ss.__sp = rsp;
ctx->uc_mcontext64->__ss.__pc = (uintptr_t)fptr;
ctx->uc_mcontext64->__ss.__lr = 0;
#endif
#else
#warning "julia: throw-in-context not supported on this platform"
// TODO Add support for PowerPC(64)?
sigset_t sset;
sigemptyset(&sset);
sigaddset(&sset, sig);
sigprocmask(SIG_UNBLOCK, &sset, NULL);
fptr();
#endif
}
static void jl_throw_in_ctx(jl_ptls_t ptls, jl_value_t *e, int sig, void *sigctx)
{
if (!ptls->safe_restore)
ptls->bt_size = rec_backtrace_ctx(ptls->bt_data, JL_MAX_BT_SIZE,
jl_to_bt_context(sigctx), ptls->pgcstack);
ptls->sig_exception = e;
jl_call_in_ctx(ptls, &jl_sig_throw, sig, sigctx);
}
static pthread_t signals_thread;
static int is_addr_on_stack(jl_ptls_t ptls, void *addr)
{
jl_task_t *t = ptls->current_task;
if (t->copy_stack)
return ((char*)addr > (char*)ptls->stackbase - ptls->stacksize &&
(char*)addr < (char*)ptls->stackbase);
else
return ((char*)addr > (char*)t->stkbuf &&
(char*)addr < (char*)t->stkbuf + t->bufsz);
}
static void sigdie_handler(int sig, siginfo_t *info, void *context)
{
signal(sig, SIG_DFL);
uv_tty_reset_mode();
if (sig == SIGILL)
jl_show_sigill(context);
jl_critical_error(sig, jl_to_bt_context(context));
if (sig != SIGSEGV &&
sig != SIGBUS &&
sig != SIGILL) {
raise(sig);
}
// fall-through return to re-execute faulting statement (but without the error handler)
}
#if defined(_CPU_X86_64_) || defined(_CPU_X86_)
enum x86_trap_flags {
USER_MODE = 0x4,
WRITE_FAULT = 0x2,
PAGE_PRESENT = 0x1
};
int exc_reg_is_write_fault(uintptr_t err) {
return err & WRITE_FAULT;
}
#elif defined(_CPU_AARCH64_)
enum aarch64_esr_layout {
EC_MASK = ((uint32_t)0b111111) << 26,
EC_DATA_ABORT = ((uint32_t)0b100100) << 26,
ISR_DA_WnR = ((uint32_t)1) << 6
};
int exc_reg_is_write_fault(uintptr_t esr) {
return (esr & EC_MASK) == EC_DATA_ABORT && (esr & ISR_DA_WnR);
}
#endif
#if defined(HAVE_MACH)
#include "signals-mach.c"
#else
#if defined(_OS_LINUX_) && (defined(_CPU_X86_64_) || defined(_CPU_X86_))
int is_write_fault(void *context) {
ucontext_t *ctx = (ucontext_t*)context;
return exc_reg_is_write_fault(ctx->uc_mcontext.gregs[REG_ERR]);
}
#elif defined(_OS_LINUX_) && defined(_CPU_AARCH64_)
struct linux_aarch64_ctx_header {
uint32_t magic;
uint32_t size;
};
const uint32_t linux_esr_magic = 0x45535201;
int is_write_fault(void *context) {
ucontext_t *ctx = (ucontext_t*)context;
struct linux_aarch64_ctx_header *extra =
(struct linux_aarch64_ctx_header *)ctx->uc_mcontext.__reserved;
while (extra->magic != 0) {
if (extra->magic == linux_esr_magic) {
return exc_reg_is_write_fault(*(uint64_t*)&extra[1]);
}
extra = (struct linux_aarch64_ctx_header *)
(((uint8_t*)extra) + extra->size);
}
return 0;
}
#elif defined(_OS_FREEBSD_) && (defined(_CPU_X86_64_) || defined(_CPU_X86_))
int is_write_fault(void *context) {
ucontext_t *ctx = (ucontext_t*)context;
return exc_reg_is_write_fault(ctx->uc_mcontext.mc_err);
}
#else
#warning Implement this query for consistent PROT_NONE handling
int is_write_fault(void *context) {
return 0;
}
#endif
static int jl_is_on_sigstack(jl_ptls_t ptls, void *ptr, void *context)
{
return (is_addr_on_sigstack(ptls, ptr) &&
is_addr_on_sigstack(ptls, (void*)jl_get_rsp_from_ctx(context)));
}
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 (jl_addr_is_safepoint((uintptr_t)info->si_addr)) {
jl_set_gc_and_wait();
// Do not raise sigint on worker thread
if (ptls->tid != 0)
return;
if (ptls->defer_signal) {
jl_safepoint_defer_sigint();
}
else if (jl_safepoint_consume_sigint()) {
jl_clear_force_sigint();
jl_throw_in_ctx(ptls, jl_interrupt_exception, sig, context);
}
return;
}
if (ptls->safe_restore || is_addr_on_stack(ptls, info->si_addr)) { // stack overflow, or restarting jl_
jl_throw_in_ctx(ptls, jl_stackovf_exception, sig, context);
}
else if (jl_is_on_sigstack(ptls, info->si_addr, context)) {
// This mainly happens when one of the finalizers during final cleanup
// on the signal stack has a deep/infinite recursion.
// There isn't anything more we can do
// (we are already corrupting that stack running this function)
// so just call `_exit` to terminate immediately.
jl_safe_printf("ERROR: Signal stack overflow, exit\n");
_exit(sig + 128);
}
else if (sig == SIGSEGV && info->si_code == SEGV_ACCERR && is_write_fault(context)) { // writing to read-only memory (e.g., mmap)
jl_throw_in_ctx(ptls, jl_readonlymemory_exception, sig, context);
}
else {
#ifdef SEGV_EXCEPTION
jl_throw_in_ctx(ptls, jl_segv_exception, sig, context);
#else
sigdie_handler(sig, info, context);
#endif
}
}
#if !defined(JL_DISABLE_LIBUNWIND)
static unw_context_t *volatile signal_context;
static pthread_mutex_t in_signal_lock;
static pthread_cond_t exit_signal_cond;
static pthread_cond_t signal_caught_cond;
static void jl_thread_suspend_and_get_state(int tid, unw_context_t **ctx)
{
pthread_mutex_lock(&in_signal_lock);
jl_ptls_t ptls2 = jl_all_tls_states[tid];
jl_atomic_store_release(&ptls2->signal_request, 1);
pthread_kill(ptls2->system_id, SIGUSR2);
pthread_cond_wait(&signal_caught_cond, &in_signal_lock); // wait for thread to acknowledge
assert(jl_atomic_load_acquire(&ptls2->signal_request) == 0);
*ctx = signal_context;
}
static void jl_thread_resume(int tid, int sig)
{
jl_ptls_t ptls2 = jl_all_tls_states[tid];
jl_atomic_store_release(&ptls2->signal_request, sig == -1 ? 3 : 1);
pthread_cond_broadcast(&exit_signal_cond);
pthread_cond_wait(&signal_caught_cond, &in_signal_lock); // wait for thread to acknowledge
assert(jl_atomic_load_acquire(&ptls2->signal_request) == 0);
pthread_mutex_unlock(&in_signal_lock);
}
#endif
// 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];
jl_safepoint_enable_sigint();
jl_wake_libuv();
jl_atomic_store_release(&ptls2->signal_request, 2);
// This also makes sure `sleep` is aborted.
pthread_kill(ptls2->system_id, SIGUSR2);
}
// Write only by signal handling thread, read only by main thread
// no sync necessary.
static int thread0_exit_state = 0;
static void JL_NORETURN jl_exit_thread0_cb(void)
{
CFI_NORETURN
// This can get stuck if it happens at an unfortunate spot
// (unavoidable due to its async nature).
// Try harder to exit each time if we get multiple exit requests.
if (thread0_exit_count <= 1) {
jl_critical_error(thread0_exit_state - 128, NULL);
jl_exit(thread0_exit_state);
}
else if (thread0_exit_count == 2) {
exit(thread0_exit_state);
}
else {
_exit(thread0_exit_state);
}
}
static void jl_exit_thread0(int state, jl_bt_element_t *bt_data, size_t bt_size)
{
jl_ptls_t ptls2 = jl_all_tls_states[0];
if (thread0_exit_count <= 1) {
unw_context_t *signal_context;
jl_thread_suspend_and_get_state(0, &signal_context);
thread0_exit_state = state;
ptls2->bt_size = bt_size; // <= JL_MAX_BT_SIZE
memcpy(ptls2->bt_data, bt_data, ptls2->bt_size * sizeof(bt_data[0]));
jl_thread_resume(0, -1);
}
else {
thread0_exit_state = state;
jl_atomic_store_release(&ptls2->signal_request, 3);
// This also makes sure `sleep` is aborted.
pthread_kill(ptls2->system_id, SIGUSR2);
}
}
// request:
// 0: nothing
// 1: get state
// 2: throw sigint if `!defer_signal && io_wait` or if force throw threshold
// is reached
// 3: exit with `thread0_exit_state`
void usr2_handler(int sig, siginfo_t *info, void *ctx)
{
jl_ptls_t ptls = jl_get_ptls_states();
int errno_save = errno;
sig_atomic_t request = jl_atomic_exchange(&ptls->signal_request, 0);
#if !defined(JL_DISABLE_LIBUNWIND)
if (request == 1) {
signal_context = jl_to_bt_context(ctx);
pthread_mutex_lock(&in_signal_lock);
pthread_cond_broadcast(&signal_caught_cond);
pthread_cond_wait(&exit_signal_cond, &in_signal_lock);
request = jl_atomic_exchange(&ptls->signal_request, 0);
assert(request == 1 || request == 3);
pthread_cond_broadcast(&signal_caught_cond);
pthread_mutex_unlock(&in_signal_lock);
}
#endif
if (request == 2) {
int force = jl_check_force_sigint();
if (force || (!ptls->defer_signal && ptls->io_wait)) {
jl_safepoint_consume_sigint();
if (force)
jl_safe_printf("WARNING: Force throwing a SIGINT\n");
// Force a throw
jl_clear_force_sigint();
jl_throw_in_ctx(ptls, jl_interrupt_exception, sig, ctx);
}
}
else if (request == 3) {
jl_call_in_ctx(ptls, jl_exit_thread0_cb, sig, ctx);
}
errno = errno_save;
}
#if defined(HAVE_TIMER)
// Linux-style
#include <time.h>
#include <string.h> // for memset
static timer_t timerprof;
static struct itimerspec itsprof;
JL_DLLEXPORT int jl_profile_start_timer(void)
{
struct sigevent sigprof;
// Establish the signal event
memset(&sigprof, 0, sizeof(struct sigevent));
sigprof.sigev_notify = SIGEV_SIGNAL;
sigprof.sigev_signo = SIGUSR1;
sigprof.sigev_value.sival_ptr = &timerprof;
if (timer_create(CLOCK_REALTIME, &sigprof, &timerprof) == -1)
return -2;
// Start the timer
itsprof.it_interval.tv_sec = 0;
itsprof.it_interval.tv_nsec = 0;
itsprof.it_value.tv_sec = nsecprof / GIGA;
itsprof.it_value.tv_nsec = nsecprof % GIGA;
if (timer_settime(timerprof, 0, &itsprof, NULL) == -1)
return -3;
running = 1;
return 0;
}
JL_DLLEXPORT void jl_profile_stop_timer(void)
{
if (running)
timer_delete(timerprof);
running = 0;
}
#elif defined(HAVE_ITIMER)
// BSD-style timers
#include <string.h>
#include <sys/time.h>
struct itimerval timerprof;
JL_DLLEXPORT int jl_profile_start_timer(void)
{
timerprof.it_interval.tv_sec = 0;
timerprof.it_interval.tv_usec = 0;
timerprof.it_value.tv_sec = nsecprof / GIGA;
timerprof.it_value.tv_usec = ((nsecprof % GIGA) + 999) / 1000;
if (setitimer(ITIMER_PROF, &timerprof, NULL) == -1)
return -3;
running = 1;
return 0;
}
JL_DLLEXPORT void jl_profile_stop_timer(void)
{
if (running) {
running = 0;
memset(&timerprof, 0, sizeof(timerprof));
setitimer(ITIMER_PROF, &timerprof, NULL);
}
}
#else
#error no profile tools available
#endif
#endif // HAVE_MACH
static void allocate_segv_handler(void)
{
struct sigaction act;
memset(&act, 0, sizeof(struct sigaction));
sigemptyset(&act.sa_mask);
act.sa_sigaction = segv_handler;
act.sa_flags = SA_ONSTACK | SA_SIGINFO;
if (sigaction(SIGSEGV, &act, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
// On AArch64, stack overflow triggers a SIGBUS
if (sigaction(SIGBUS, &act, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
}
static void *alloc_sigstack(size_t *ssize)
{
void *stk = jl_malloc_stack(ssize, NULL);
if (stk == MAP_FAILED)
jl_errorf("fatal error allocating signal stack: mmap: %s", strerror(errno));
return stk;
}
void jl_install_thread_signal_handler(jl_ptls_t ptls)
{
size_t ssize = sig_stack_size;
void *signal_stack = alloc_sigstack(&ssize);
ptls->signal_stack = signal_stack;
stack_t ss;
ss.ss_flags = 0;
ss.ss_size = ssize - 16;
ss.ss_sp = signal_stack;
if (sigaltstack(&ss, NULL) < 0) {
jl_errorf("fatal error: sigaltstack: %s", strerror(errno));
}
}
static void jl_sigsetset(sigset_t *sset)
{
sigemptyset(sset);
sigaddset(sset, SIGINT);
sigaddset(sset, SIGTERM);
sigaddset(sset, SIGABRT);
sigaddset(sset, SIGQUIT);
#ifdef SIGINFO
sigaddset(sset, SIGINFO);
#else
sigaddset(sset, SIGUSR1);
#endif
#if defined(HAVE_TIMER)
sigaddset(sset, SIGUSR1);
#elif defined(HAVE_ITIMER)
sigaddset(sset, SIGPROF);
#endif
}
#ifdef HAVE_KEVENT
static void kqueue_signal(int *sigqueue, struct kevent *ev, int sig)
{
if (*sigqueue == -1)
return;
EV_SET(ev, sig, EVFILT_SIGNAL, EV_ADD, 0, 0, 0);
if (kevent(*sigqueue, ev, 1, NULL, 0, NULL)) {
perror("signal kevent");
close(*sigqueue);
*sigqueue = -1;
}
else {
signal(sig, SIG_IGN);
}
}
#endif
static void *signal_listener(void *arg)
{
static jl_bt_element_t bt_data[JL_MAX_BT_SIZE + 1];
static size_t bt_size = 0;
sigset_t sset;
int sig, critical, profile;
jl_sigsetset(&sset);
#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 199309L
siginfo_t info;
#endif
#ifdef HAVE_KEVENT
struct kevent ev;
int sigqueue = kqueue();
if (sigqueue == -1) {
perror("signal kqueue");
}
else {
kqueue_signal(&sigqueue, &ev, SIGINT);
kqueue_signal(&sigqueue, &ev, SIGTERM);
kqueue_signal(&sigqueue, &ev, SIGABRT);
kqueue_signal(&sigqueue, &ev, SIGQUIT);
#ifdef SIGINFO
kqueue_signal(&sigqueue, &ev, SIGINFO);
#else
kqueue_signal(&sigqueue, &ev, SIGUSR1);
#endif
#if defined(HAVE_TIMER)
kqueue_signal(&sigqueue, &ev, SIGUSR1);
#elif defined(HAVE_ITIMER)
kqueue_signal(&sigqueue, &ev, SIGPROF);
#endif
}
#endif
while (1) {
sig = 0;
errno = 0;
#ifdef HAVE_KEVENT
if (sigqueue != -1) {
int nevents = kevent(sigqueue, NULL, 0, &ev, 1, NULL);
if (nevents == -1) {
if (errno == EINTR)
continue;
perror("signal kevent");
}
if (nevents != 1) {
close(sigqueue);
sigqueue = -1;
continue;
}
sig = ev.ident;
}
else
#endif
#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 199309L
sig = sigwaitinfo(&sset, &info);
#else
if (sigwait(&sset, &sig))
sig = -1;
#endif
if (sig == -1) {
if (errno == EINTR)
continue;
sig = SIGABRT; // this branch can't occur, unless we had stack memory corruption of sset
}
profile = 0;
#ifndef HAVE_MACH
#if defined(HAVE_TIMER)
profile = (sig == SIGUSR1);
#if _POSIX_C_SOURCE >= 199309L
if (profile && !(info.si_code == SI_TIMER &&
info.si_value.sival_ptr == &timerprof))
profile = 0;
#endif
#elif defined(HAVE_ITIMER)
profile = (sig == SIGPROF);
#endif
#endif
if (sig == SIGINT) {
if (jl_ignore_sigint()) {
continue;
}
else if (exit_on_sigint) {
critical = 1;
}
else {
jl_try_deliver_sigint();
continue;
}
}
else {
critical = 0;
}
critical |= (sig == SIGTERM);
critical |= (sig == SIGABRT);
critical |= (sig == SIGQUIT);
#ifdef SIGINFO
critical |= (sig == SIGINFO);
#else
critical |= (sig == SIGUSR1 && !profile);
#endif
int doexit = critical;
#ifdef SIGINFO
if (sig == SIGINFO)
doexit = 0;
#else
if (sig == SIGUSR1)
doexit = 0;
#endif
bt_size = 0;
#if !defined(JL_DISABLE_LIBUNWIND)
unw_context_t *signal_context;
// sample each thread, round-robin style in reverse order
// (so that thread zero gets notified last)
if (critical || profile)
jl_lock_profile();
for (int i = jl_n_threads; i-- > 0; ) {
// notify thread to stop
jl_thread_suspend_and_get_state(i, &signal_context);
// do backtrace on thread contexts for critical signals
// this part must be signal-handler safe
if (critical) {
bt_size += rec_backtrace_ctx(bt_data + bt_size,
JL_MAX_BT_SIZE / jl_n_threads - 1,
signal_context, NULL);
bt_data[bt_size++].uintptr = 0;
}
// do backtrace for profiler
if (profile && running) {
if (jl_profile_is_buffer_full()) {
// Buffer full: Delete the timer
jl_profile_stop_timer();
}
else {
// unwinding can fail, so keep track of the current state
// and restore from the SEGV handler if anything happens.
jl_ptls_t ptls = jl_get_ptls_states();
jl_jmp_buf *old_buf = ptls->safe_restore;
jl_jmp_buf buf;
ptls->safe_restore = &buf;
if (jl_setjmp(buf, 0)) {
jl_safe_printf("WARNING: profiler attempt to access an invalid memory location\n");
} else {
// Get backtrace data
bt_size_cur += rec_backtrace_ctx((jl_bt_element_t*)bt_data_prof + bt_size_cur,
bt_size_max - bt_size_cur - 1, signal_context, NULL);
}
ptls->safe_restore = old_buf;
// Mark the end of this block with 0
bt_data_prof[bt_size_cur++].uintptr = 0;
}
}
// notify thread to resume
jl_thread_resume(i, sig);
}
if (critical || profile)
jl_unlock_profile();
#ifndef HAVE_MACH
if (profile && running) {
#if defined(HAVE_TIMER)
timer_settime(timerprof, 0, &itsprof, NULL);
#elif defined(HAVE_ITIMER)
setitimer(ITIMER_PROF, &timerprof, NULL);
#endif
}
#endif
#endif
// this part is async with the running of the rest of the program
// and must be thread-safe, but not necessarily signal-handler safe
if (critical) {
if (doexit) {
thread0_exit_count++;
jl_exit_thread0(128 + sig, bt_data, bt_size);
}
else {
jl_safe_printf("\nsignal (%d): %s\n", sig, strsignal(sig));
size_t i;
for (i = 0; i < bt_size; i += jl_bt_entry_size(bt_data + i)) {
jl_print_bt_entry_codeloc(bt_data + i);
}
}
}
}
return NULL;
}
void restore_signals(void)
{
sigemptyset(&jl_sigint_sset);
sigaddset(&jl_sigint_sset, SIGINT);
sigset_t sset;
jl_sigsetset(&sset);
sigprocmask(SIG_SETMASK, &sset, 0);
#if !defined(HAVE_MACH) && !defined(JL_DISABLE_LIBUNWIND)
if (pthread_mutex_init(&in_signal_lock, NULL) != 0 ||
pthread_cond_init(&exit_signal_cond, NULL) != 0 ||
pthread_cond_init(&signal_caught_cond, NULL) != 0) {
jl_error("SIGUSR pthread init failed");
}
#endif
if (pthread_create(&signals_thread, NULL, signal_listener, NULL) != 0) {
jl_error("pthread_create(signal_listener) failed");
}
}
static void fpe_handler(int sig, siginfo_t *info, void *context)
{
(void)info;
jl_ptls_t ptls = jl_get_ptls_states();
jl_throw_in_ctx(ptls, jl_diverror_exception, sig, context);
}
static void sigint_handler(int sig)
{
jl_sigint_passed = 1;
}
void jl_install_default_signal_handlers(void)
{
struct sigaction actf;
memset(&actf, 0, sizeof(struct sigaction));
sigemptyset(&actf.sa_mask);
actf.sa_sigaction = fpe_handler;
actf.sa_flags = SA_ONSTACK | SA_SIGINFO;
if (sigaction(SIGFPE, &actf, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
struct sigaction actint;
memset(&actint, 0, sizeof(struct sigaction));
sigemptyset(&actint.sa_mask);
actint.sa_handler = sigint_handler;
actint.sa_flags = 0;
if (sigaction(SIGINT, &actint, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
if (signal(SIGPIPE, SIG_IGN) == SIG_ERR) {
jl_error("fatal error: Couldn't set SIGPIPE");
}
if (signal(SIGTRAP, SIG_IGN) == SIG_ERR) {
jl_error("fatal error: Couldn't set SIGTRAP");
}
#if defined(HAVE_MACH)
allocate_mach_handler();
#else
struct sigaction act;
memset(&act, 0, sizeof(struct sigaction));
sigemptyset(&act.sa_mask);
act.sa_sigaction = usr2_handler;
act.sa_flags = SA_ONSTACK | SA_SIGINFO | SA_RESTART;
if (sigaction(SIGUSR2, &act, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
#endif
allocate_segv_handler();
struct sigaction act_die;
memset(&act_die, 0, sizeof(struct sigaction));
sigemptyset(&act_die.sa_mask);
act_die.sa_sigaction = sigdie_handler;
act_die.sa_flags = SA_SIGINFO | SA_RESETHAND;
if (sigaction(SIGILL, &act_die, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
if (sigaction(SIGABRT, &act_die, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
if (sigaction(SIGSYS, &act_die, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
// need to ensure the following signals are not SIG_IGN, even though they will be blocked
act_die.sa_flags = SA_SIGINFO | SA_RESTART | SA_RESETHAND;
#if defined(HAVE_ITIMER)
if (sigaction(SIGPROF, &act_die, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
#endif
#ifdef SIGINFO
if (sigaction(SIGINFO, &act_die, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
#else
if (sigaction(SIGUSR1, &act_die, NULL) < 0) {
jl_errorf("fatal error: sigaction: %s", strerror(errno));
}
#endif
}
JL_DLLEXPORT void jl_install_sigint_handler(void)
{
// TODO: ?
}
JL_DLLEXPORT int jl_repl_raise_sigtstp(void)
{
return raise(SIGTSTP);
}
