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task.c
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// This file is a part of Julia. License is MIT: https://julialang.org/license
/*
task.c
lightweight processes (symmetric coroutines)
*/
// need this to get the real definition of ucontext_t,
// if we're going to use the ucontext_t implementation there
//#if defined(__APPLE__) && defined(JL_HAVE_UCONTEXT)
//#pragma push_macro("_XOPEN_SOURCE")
//#define _XOPEN_SOURCE
//#include <ucontext.h>
//#pragma pop_macro("_XOPEN_SOURCE")
//#endif
// this is needed for !COPY_STACKS to work on linux
#ifdef _FORTIFY_SOURCE
// disable __longjmp_chk validation so that we can jump between stacks
// (which would normally be invalid to do with setjmp / longjmp)
#pragma push_macro("_FORTIFY_SOURCE")
#undef _FORTIFY_SOURCE
#include <setjmp.h>
#pragma pop_macro("_FORTIFY_SOURCE")
#endif
#include "platform.h"
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include <inttypes.h>
#include "julia.h"
#include "julia_internal.h"
#include "threading.h"
#include "julia_assert.h"
#ifdef __cplusplus
extern "C" {
#endif
#if defined(JL_ASAN_ENABLED)
static inline void sanitizer_start_switch_fiber(const void* bottom, size_t size) {
__sanitizer_start_switch_fiber(NULL, bottom, size);
}
static inline void sanitizer_finish_switch_fiber(void) {
__sanitizer_finish_switch_fiber(NULL, NULL, NULL);
}
#else
static inline void sanitizer_start_switch_fiber(const void* bottom, size_t size) {}
static inline void sanitizer_finish_switch_fiber(void) {}
#endif
#if defined(JL_TSAN_ENABLED)
static inline void tsan_destroy_ctx(jl_ptls_t ptls, void *state) {
if (state != &ptls->root_task->state) {
__tsan_destroy_fiber(ctx->state);
}
ctx->state = NULL;
}
static inline void tsan_switch_to_ctx(void *state) {
__tsan_switch_to_fiber(state, 0);
}
#endif
// empirically, jl_finish_task needs about 64k stack space to infer/run
// and additionally, gc-stack reserves 64k for the guard pages
#if defined(MINSIGSTKSZ) && MINSIGSTKSZ > 131072
#define MINSTKSZ MINSIGSTKSZ
#else
#define MINSTKSZ 131072
#endif
#define ROOT_TASK_STACK_ADJUSTMENT 3000000
#ifdef JL_HAVE_ASYNCIFY
// Switching logic is implemented in JavaScript
#define STATIC_OR_JS JL_DLLEXPORT
#else
#define STATIC_OR_JS static
#endif
extern size_t jl_page_size;
static char *jl_alloc_fiber(jl_ucontext_t *t, size_t *ssize, jl_task_t *owner) JL_NOTSAFEPOINT;
STATIC_OR_JS void jl_set_fiber(jl_ucontext_t *t);
STATIC_OR_JS void jl_swap_fiber(jl_ucontext_t *lastt, jl_ucontext_t *t);
STATIC_OR_JS void jl_start_fiber_swap(jl_ucontext_t *savet, jl_ucontext_t *t);
STATIC_OR_JS void jl_start_fiber_set(jl_ucontext_t *t);
#ifdef ALWAYS_COPY_STACKS
# ifndef COPY_STACKS
# error "ALWAYS_COPY_STACKS requires COPY_STACKS"
# endif
static int always_copy_stacks = 1;
#else
static int always_copy_stacks = 0;
#endif
#ifdef COPY_STACKS
static void memcpy_a16(uint64_t *to, uint64_t *from, size_t nb)
{
memcpy((char*)jl_assume_aligned(to, 16), (char*)jl_assume_aligned(from, 16), nb);
//uint64_t *end = (uint64_t*)((char*)from + nb);
//while (from < end)
// *(to++) = *(from++);
}
static void NOINLINE save_stack(jl_ptls_t ptls, jl_task_t *lastt, jl_task_t **pt)
{
char *frame_addr = (char*)((uintptr_t)jl_get_frame_addr() & ~15);
char *stackbase = (char*)ptls->stackbase;
assert(stackbase > frame_addr);
size_t nb = stackbase - frame_addr;
void *buf;
if (lastt->bufsz < nb) {
buf = (void*)jl_gc_alloc_buf(ptls, nb);
lastt->stkbuf = buf;
lastt->bufsz = nb;
}
else {
buf = lastt->stkbuf;
}
*pt = NULL; // clear the gc-root for the target task before copying the stack for saving
lastt->copy_stack = nb;
lastt->sticky = 1;
memcpy_a16((uint64_t*)buf, (uint64_t*)frame_addr, nb);
// this task's stack could have been modified after
// it was marked by an incremental collection
// move the barrier back instead of walking it again here
jl_gc_wb_back(lastt);
}
static void NOINLINE JL_NORETURN restore_stack(jl_task_t *t, jl_ptls_t ptls, char *p)
{
size_t nb = t->copy_stack;
char *_x = (char*)ptls->stackbase - nb;
if (!p) {
// switch to a stackframe that's beyond the bounds of the last switch
p = _x;
if ((char*)&_x > _x) {
p = (char*)alloca((char*)&_x - _x);
}
restore_stack(t, ptls, p); // pass p to ensure the compiler can't tailcall this or avoid the alloca
}
void *_y = t->stkbuf;
assert(_x != NULL && _y != NULL);
memcpy_a16((uint64_t*)_x, (uint64_t*)_y, nb); // destroys all but the current stackframe
sanitizer_start_switch_fiber(t->stkbuf, t->bufsz);
#if defined(_OS_WINDOWS_)
jl_setcontext(&t->ctx);
#else
jl_longjmp(t->copy_stack_ctx.uc_mcontext, 1);
#endif
abort(); // unreachable
}
static void restore_stack2(jl_task_t *t, jl_ptls_t ptls, jl_task_t *lastt)
{
assert(t->copy_stack && !lastt->copy_stack);
size_t nb = t->copy_stack;
char *_x = (char*)ptls->stackbase - nb;
void *_y = t->stkbuf;
assert(_x != NULL && _y != NULL);
memcpy_a16((uint64_t*)_x, (uint64_t*)_y, nb); // destroys all but the current stackframe
#if defined(JL_HAVE_UNW_CONTEXT)
volatile int returns = 0;
int r = unw_getcontext(&lastt->ctx);
if (++returns == 2) // r is garbage after the first return
return;
if (r != 0 || returns != 1)
abort();
#elif defined(JL_HAVE_ASM) || defined(JL_HAVE_SIGALTSTACK) || defined(_OS_WINDOWS_)
if (jl_setjmp(lastt->copy_stack_ctx.uc_mcontext, 0))
return;
#else
#error COPY_STACKS is incompatible with this platform
#endif
sanitizer_start_switch_fiber(t->stkbuf, t->bufsz);
#if defined(_OS_WINDOWS_)
jl_setcontext(&t->ctx);
#else
jl_longjmp(t->copy_stack_ctx.uc_mcontext, 1);
#endif
}
#endif
/* Rooted by the base module */
static jl_function_t *task_done_hook_func JL_GLOBALLY_ROOTED = NULL;
void JL_NORETURN jl_finish_task(jl_task_t *t)
{
jl_ptls_t ptls = jl_get_ptls_states();
JL_SIGATOMIC_BEGIN();
if (t->_isexception)
jl_atomic_store_release(&t->_state, JL_TASK_STATE_FAILED);
else
jl_atomic_store_release(&t->_state, JL_TASK_STATE_DONE);
if (t->copy_stack) // early free of stkbuf
t->stkbuf = NULL;
// ensure that state is cleared
ptls->in_finalizer = 0;
ptls->in_pure_callback = 0;
jl_get_ptls_states()->world_age = jl_world_counter;
// let the runtime know this task is dead and find a new task to run
jl_function_t *done = jl_atomic_load_relaxed(&task_done_hook_func);
if (done == NULL) {
done = (jl_function_t*)jl_get_global(jl_base_module, jl_symbol("task_done_hook"));
if (done != NULL)
jl_atomic_store_release(&task_done_hook_func, done);
}
if (done != NULL) {
jl_value_t *args[2] = {done, (jl_value_t*)t};
JL_TRY {
jl_apply(args, 2);
}
JL_CATCH {
jl_no_exc_handler(jl_current_exception());
}
}
gc_debug_critical_error();
abort();
}
JL_DLLEXPORT void *jl_task_stack_buffer(jl_task_t *task, size_t *size, int *tid)
{
size_t off = 0;
#ifndef _OS_WINDOWS_
if (jl_all_tls_states[0]->root_task == task) {
// See jl_init_root_task(). The root task of the main thread
// has its buffer enlarged by an artificial 3000000 bytes, but
// that means that the start of the buffer usually points to
// inaccessible memory. We need to correct for this.
off = ROOT_TASK_STACK_ADJUSTMENT;
}
#endif
*tid = -1;
for (int i = 0; i < jl_n_threads; i++) {
jl_ptls_t ptls = jl_all_tls_states[i];
if (ptls->current_task == task) {
*tid = i;
#ifdef COPY_STACKS
if (task->copy_stack) {
*size = ptls->stacksize;
return (char *)ptls->stackbase - *size;
}
#endif
break; // continue with normal return
}
}
*size = task->bufsz - off;
return (void *)((char *)task->stkbuf + off);
}
JL_DLLEXPORT void jl_active_task_stack(jl_task_t *task,
char **active_start, char **active_end,
char **total_start, char **total_end)
{
if (!task->started) {
*total_start = *active_start = 0;
*total_end = *active_end = 0;
return;
}
int16_t tid = task->tid;
jl_ptls_t ptls2 = (tid != -1) ? jl_all_tls_states[tid] : 0;
if (task->copy_stack && ptls2 && task == ptls2->current_task) {
*total_start = *active_start = (char*)ptls2->stackbase - ptls2->stacksize;
*total_end = *active_end = (char*)ptls2->stackbase;
}
else if (task->stkbuf) {
*total_start = *active_start = (char*)task->stkbuf;
#ifndef _OS_WINDOWS_
if (jl_all_tls_states[0]->root_task == task) {
// See jl_init_root_task(). The root task of the main thread
// has its buffer enlarged by an artificial 3000000 bytes, but
// that means that the start of the buffer usually points to
// inaccessible memory. We need to correct for this.
*active_start += ROOT_TASK_STACK_ADJUSTMENT;
*total_start += ROOT_TASK_STACK_ADJUSTMENT;
}
#endif
*total_end = *active_end = (char*)task->stkbuf + task->bufsz;
#ifdef COPY_STACKS
// save_stack stores the stack of an inactive task in stkbuf, and the
// actual number of used bytes in copy_stack.
if (task->copy_stack > 1)
*active_end = (char*)task->stkbuf + task->copy_stack;
#endif
}
else {
// no stack allocated yet
*total_start = *active_start = 0;
*total_end = *active_end = 0;
return;
}
if (task == jl_current_task) {
// scan up to current `sp` for current thread and task
*active_start = (char*)jl_get_frame_addr();
}
}
// Marked noinline so we can consistently skip the associated frame.
// `skip` is number of additional frames to skip.
NOINLINE static void record_backtrace(jl_ptls_t ptls, int skip) JL_NOTSAFEPOINT
{
// storing bt_size in ptls ensures roots in bt_data will be found
ptls->bt_size = rec_backtrace(ptls->bt_data, JL_MAX_BT_SIZE, skip + 1);
}
JL_DLLEXPORT void julia_init(JL_IMAGE_SEARCH rel)
{
_julia_init(rel);
}
JL_DLLEXPORT void jl_set_next_task(jl_task_t *task) JL_NOTSAFEPOINT
{
jl_get_ptls_states()->next_task = task;
}
JL_DLLEXPORT jl_task_t *jl_get_next_task(void) JL_NOTSAFEPOINT
{
jl_ptls_t ptls = jl_get_ptls_states();
if (ptls->next_task)
return ptls->next_task;
return ptls->current_task;
}
#ifdef JL_TSAN_ENABLED
const char tsan_state_corruption[] = "TSAN state corrupted. Exiting HARD!\n";
#endif
static void ctx_switch(jl_ptls_t ptls)
{
jl_task_t **pt = &ptls->next_task;
jl_task_t *t = *pt;
assert(t != ptls->current_task);
jl_task_t *lastt = ptls->current_task;
// none of these locks should be held across a task switch
assert(ptls->locks.len == 0);
#ifdef JL_TSAN_ENABLED
if (lastt->ctx.tsan_state != __tsan_get_current_fiber()) {
// Something went really wrong - don't even assume that we can
// use assert/abort which involve lots of signal handling that
// looks at the tsan state.
write(STDERR_FILENO, tsan_state_corruption, sizeof(tsan_state_corruption) - 1);
_exit(1);
}
#endif
int killed = lastt->_state != JL_TASK_STATE_RUNNABLE;
if (!t->started && !t->copy_stack) {
// may need to allocate the stack
if (t->stkbuf == NULL) {
t->stkbuf = jl_alloc_fiber(&t->ctx, &t->bufsz, t);
if (t->stkbuf == NULL) {
#ifdef COPY_STACKS
// fall back to stack copying if mmap fails
t->copy_stack = 1;
t->sticky = 1;
t->bufsz = 0;
if (always_copy_stacks)
memcpy(&t->copy_stack_ctx, &ptls->copy_stack_ctx, sizeof(t->copy_stack_ctx));
else
memcpy(&t->ctx, &ptls->base_ctx, sizeof(t->ctx));
#else
jl_throw(jl_memory_exception);
#endif
}
}
}
if (killed) {
*pt = NULL; // can't fail after here: clear the gc-root for the target task now
lastt->gcstack = NULL;
if (!lastt->copy_stack && lastt->stkbuf) {
// early free of stkbuf back to the pool
jl_release_task_stack(ptls, lastt);
}
}
else {
#ifdef COPY_STACKS
if (lastt->copy_stack) { // save the old copy-stack
save_stack(ptls, lastt, pt); // allocates (gc-safepoint, and can also fail)
if (jl_setjmp(lastt->copy_stack_ctx.uc_mcontext, 0)) {
sanitizer_finish_switch_fiber();
// TODO: mutex unlock the thread we just switched from
return;
}
}
else
#endif
*pt = NULL; // can't fail after here: clear the gc-root for the target task now
lastt->gcstack = ptls->pgcstack;
}
// set up global state for new task
ptls->pgcstack = t->gcstack;
ptls->world_age = 0;
t->gcstack = NULL;
#ifdef MIGRATE_TASKS
ptls->previous_task = lastt;
#endif
ptls->current_task = t;
#if defined(JL_TSAN_ENABLED)
tsan_switch_to_ctx(&t->tsan_state);
if (killed)
tsan_destroy_ctx(ptls, &lastt->tsan_state);
#endif
if (t->started) {
#ifdef COPY_STACKS
if (t->copy_stack) {
if (!killed && !lastt->copy_stack)
restore_stack2(t, ptls, lastt);
else if (lastt->copy_stack) {
restore_stack(t, ptls, NULL); // (doesn't return)
}
else {
restore_stack(t, ptls, (char*)1); // (doesn't return)
}
}
else
#endif
{
sanitizer_start_switch_fiber(t->stkbuf, t->bufsz);
if (killed) {
jl_set_fiber(&t->ctx); // (doesn't return)
abort(); // unreachable
}
else {
if (lastt->copy_stack) {
// Resume at the jl_setjmp earlier in this function,
// don't do a full task swap
jl_set_fiber(&t->ctx); // (doesn't return)
}
else {
jl_swap_fiber(&lastt->ctx, &t->ctx);
}
}
}
}
else {
sanitizer_start_switch_fiber(t->stkbuf, t->bufsz);
if (t->copy_stack && always_copy_stacks) {
#ifdef COPY_STACKS
#if defined(_OS_WINDOWS_)
jl_setcontext(&t->ctx);
#else
jl_longjmp(t->copy_stack_ctx.uc_mcontext, 1);
#endif
#endif
abort(); // unreachable
}
else {
if (killed) {
jl_start_fiber_set(&t->ctx); // (doesn't return)
abort();
}
else if (lastt->copy_stack) {
// Resume at the jl_setjmp earlier in this function
jl_start_fiber_set(&t->ctx); // (doesn't return)
abort();
}
else {
jl_start_fiber_swap(&lastt->ctx, &t->ctx);
}
}
}
sanitizer_finish_switch_fiber();
}
static jl_ptls_t NOINLINE refetch_ptls(void)
{
return jl_get_ptls_states();
}
JL_DLLEXPORT void jl_switch(void)
{
jl_ptls_t ptls = jl_get_ptls_states();
jl_task_t *t = ptls->next_task;
jl_task_t *ct = ptls->current_task;
if (t == ct) {
return;
}
if (t->_state != JL_TASK_STATE_RUNNABLE || (t->started && t->stkbuf == NULL)) {
ct->_isexception = t->_isexception;
ct->result = t->result;
jl_gc_wb(ct, ct->result);
return;
}
if (ptls->in_finalizer)
jl_error("task switch not allowed from inside gc finalizer");
if (ptls->in_pure_callback)
jl_error("task switch not allowed from inside staged nor pure functions");
if (t->sticky && jl_atomic_load_acquire(&t->tid) == -1) {
// manually yielding to a task
if (jl_atomic_compare_exchange(&t->tid, -1, ptls->tid) != -1)
jl_error("cannot switch to task running on another thread");
}
else if (t->tid != ptls->tid) {
jl_error("cannot switch to task running on another thread");
}
// Store old values on the stack and reset
sig_atomic_t defer_signal = ptls->defer_signal;
int8_t gc_state = jl_gc_unsafe_enter(ptls);
size_t world_age = ptls->world_age;
int finalizers_inhibited = ptls->finalizers_inhibited;
ptls->world_age = 0;
ptls->finalizers_inhibited = 0;
#ifdef ENABLE_TIMINGS
jl_timing_block_t *blk = ptls->timing_stack;
if (blk)
jl_timing_block_stop(blk);
ptls->timing_stack = NULL;
#endif
ctx_switch(ptls);
#ifdef MIGRATE_TASKS
ptls = refetch_ptls();
t = ptls->previous_task;
assert(t->tid == ptls->tid);
if (!t->sticky && !t->copy_stack)
t->tid = -1;
#elif defined(NDEBUG)
(void)refetch_ptls();
#else
assert(ptls == refetch_ptls());
#endif
// Pop old values back off the stack
assert(ct == ptls->current_task &&
0 == ptls->world_age &&
0 == ptls->finalizers_inhibited);
ptls->world_age = world_age;
ptls->finalizers_inhibited = finalizers_inhibited;
#ifdef ENABLE_TIMINGS
assert(ptls->timing_stack == NULL);
ptls->timing_stack = blk;
if (blk)
jl_timing_block_start(blk);
#else
(void)ct;
#endif
jl_gc_unsafe_leave(ptls, gc_state);
sig_atomic_t other_defer_signal = ptls->defer_signal;
ptls->defer_signal = defer_signal;
if (other_defer_signal && !defer_signal)
jl_sigint_safepoint(ptls);
}
JL_DLLEXPORT void jl_switchto(jl_task_t **pt)
{
jl_set_next_task(*pt);
jl_switch();
}
JL_DLLEXPORT JL_NORETURN void jl_no_exc_handler(jl_value_t *e)
{
// NULL exception objects are used when rethrowing. we don't have a handler to process
// the exception stack, so at least report the exception at the top of the stack.
if (!e)
e = jl_current_exception();
jl_printf((JL_STREAM*)STDERR_FILENO, "fatal: error thrown and no exception handler available.\n");
jl_static_show((JL_STREAM*)STDERR_FILENO, e);
jl_printf((JL_STREAM*)STDERR_FILENO, "\n");
jlbacktrace(); // written to STDERR_FILENO
jl_exit(1);
}
// yield to exception handler
static void JL_NORETURN throw_internal(jl_value_t *exception JL_MAYBE_UNROOTED)
{
jl_ptls_t ptls = jl_get_ptls_states();
ptls->io_wait = 0;
// @time needs its compile timer disabled on error,
// and cannot use a try-finally as it would break scope for assignments
jl_measure_compile_time[ptls->tid] = 0;
if (ptls->safe_restore)
jl_longjmp(*ptls->safe_restore, 1);
// During startup
if (!ptls->current_task)
jl_no_exc_handler(exception);
JL_GC_PUSH1(&exception);
jl_gc_unsafe_enter(ptls);
if (exception) {
// The temporary ptls->bt_data is rooted by special purpose code in the
// GC. This exists only for the purpose of preserving bt_data until we
// set ptls->bt_size=0 below.
assert(ptls->current_task);
jl_push_excstack(&ptls->current_task->excstack, exception,
ptls->bt_data, ptls->bt_size);
ptls->bt_size = 0;
}
assert(ptls->current_task->excstack && ptls->current_task->excstack->top);
jl_handler_t *eh = ptls->current_task->eh;
if (eh != NULL) {
#ifdef ENABLE_TIMINGS
jl_timing_block_t *cur_block = ptls->timing_stack;
while (cur_block && eh->timing_stack != cur_block) {
cur_block = jl_pop_timing_block(cur_block);
}
assert(cur_block == eh->timing_stack);
#endif
jl_longjmp(eh->eh_ctx, 1);
}
else {
jl_no_exc_handler(exception);
}
assert(0);
}
// record backtrace and raise an error
JL_DLLEXPORT void jl_throw(jl_value_t *e JL_MAYBE_UNROOTED)
{
jl_ptls_t ptls = jl_get_ptls_states();
assert(e != NULL);
if (ptls->safe_restore)
throw_internal(NULL);
record_backtrace(ptls, 1);
throw_internal(e);
}
// rethrow with current excstack state
JL_DLLEXPORT void jl_rethrow(void)
{
jl_excstack_t *excstack = jl_get_ptls_states()->current_task->excstack;
if (!excstack || excstack->top == 0)
jl_error("rethrow() not allowed outside a catch block");
throw_internal(NULL);
}
// Special case throw for errors detected inside signal handlers. This is not
// (cannot be) called directly in the signal handler itself, but is returned to
// after the signal handler exits.
JL_DLLEXPORT void jl_sig_throw(void)
{
jl_ptls_t ptls = jl_get_ptls_states();
jl_value_t *e = ptls->sig_exception;
ptls->sig_exception = NULL;
throw_internal(e);
}
JL_DLLEXPORT void jl_rethrow_other(jl_value_t *e JL_MAYBE_UNROOTED)
{
// TODO: Should uses of `rethrow(exc)` be replaced with a normal throw, now
// that exception stacks allow root cause analysis?
jl_excstack_t *excstack = jl_get_ptls_states()->current_task->excstack;
if (!excstack || excstack->top == 0)
jl_error("rethrow(exc) not allowed outside a catch block");
// overwrite exception on top of stack. see jl_excstack_exception
jl_excstack_raw(excstack)[excstack->top-1].jlvalue = e;
JL_GC_PROMISE_ROOTED(e);
throw_internal(NULL);
}
JL_DLLEXPORT jl_task_t *jl_new_task(jl_function_t *start, jl_value_t *completion_future, size_t ssize)
{
jl_ptls_t ptls = jl_get_ptls_states();
jl_task_t *t = (jl_task_t*)jl_gc_alloc(ptls, sizeof(jl_task_t), jl_task_type);
t->copy_stack = 0;
if (ssize == 0) {
// stack size unspecified; use default
if (always_copy_stacks) {
t->copy_stack = 1;
t->bufsz = 0;
}
else {
t->bufsz = JL_STACK_SIZE;
}
t->stkbuf = NULL;
}
else {
// user requested dedicated stack of a certain size
if (ssize < MINSTKSZ)
ssize = MINSTKSZ;
t->bufsz = ssize;
t->stkbuf = jl_alloc_fiber(&t->ctx, &t->bufsz, t);
if (t->stkbuf == NULL)
jl_throw(jl_memory_exception);
}
t->next = jl_nothing;
t->queue = jl_nothing;
t->tls = jl_nothing;
t->_state = JL_TASK_STATE_RUNNABLE;
t->start = start;
t->result = jl_nothing;
t->donenotify = completion_future;
t->_isexception = 0;
// Inherit logger state from parent task
t->logstate = ptls->current_task->logstate;
// there is no active exception handler available on this stack yet
t->eh = NULL;
t->sticky = 1;
t->gcstack = NULL;
t->excstack = NULL;
t->started = 0;
t->prio = -1;
t->tid = -1;
#if defined(JL_DEBUG_BUILD)
if (!t->copy_stack)
memset(&t->ctx, 0, sizeof(t->ctx));
#endif
#ifdef COPY_STACKS
if (always_copy_stacks)
memcpy(&t->copy_stack_ctx, &ptls->copy_stack_ctx, sizeof(t->copy_stack_ctx));
else if (t->copy_stack)
memcpy(&t->ctx, &ptls->base_ctx, sizeof(t->ctx));
#endif
#ifdef JL_TSAN_ENABLED
t->tsan_state = __tsan_create_fiber(0);
#endif
return t;
}
JL_DLLEXPORT jl_value_t *jl_get_current_task(void)
{
jl_ptls_t ptls = jl_get_ptls_states();
return (jl_value_t*)ptls->current_task;
}
JL_DLLEXPORT jl_jmp_buf *jl_get_safe_restore(void)
{
jl_ptls_t ptls = jl_get_ptls_states();
return ptls->safe_restore;
}
JL_DLLEXPORT void jl_set_safe_restore(jl_jmp_buf *sr)
{
jl_ptls_t ptls = jl_get_ptls_states();
ptls->safe_restore = sr;
}
#ifdef JL_HAVE_ASYNCIFY
JL_DLLEXPORT jl_ucontext_t *task_ctx_ptr(jl_task_t *t)
{
return &t->ctx;
}
JL_DLLEXPORT jl_value_t *jl_get_root_task(void)
{
jl_ptls_t ptls = jl_get_ptls_states();
return (jl_value_t*)ptls->root_task;
}
JL_DLLEXPORT void jl_task_wait()
{
static jl_function_t *wait_func = NULL;
if (!wait_func) {
wait_func = (jl_function_t*)jl_get_global(jl_base_module, jl_symbol("wait"));
}
size_t last_age = jl_get_ptls_states()->world_age;
jl_get_ptls_states()->world_age = jl_get_world_counter();
jl_apply(&wait_func, 1);
jl_get_ptls_states()->world_age = last_age;
}
JL_DLLEXPORT void jl_schedule_task(jl_task_t *task)
{
static jl_function_t *sched_func = NULL;
if (!sched_func) {
sched_func = (jl_function_t*)jl_get_global(jl_base_module, jl_symbol("schedule"));
}
size_t last_age = jl_get_ptls_states()->world_age;
jl_get_ptls_states()->world_age = jl_get_world_counter();
jl_value_t *args[] = {(jl_value_t*)sched_func, (jl_value_t*)task};
jl_apply(args, 2);
jl_get_ptls_states()->world_age = last_age;
}
#endif
// Do one-time initializations for task system
void jl_init_tasks(void) JL_GC_DISABLED
{
char *acs = getenv("JULIA_COPY_STACKS");
if (acs) {
if (!strcmp(acs, "1") || !strcmp(acs, "yes"))
always_copy_stacks = 1;
else if (!strcmp(acs, "0") || !strcmp(acs, "no"))
always_copy_stacks = 0;
else {
jl_safe_printf("invalid JULIA_COPY_STACKS value: %s\n", acs);
exit(1);
}
}
#ifndef COPY_STACKS
if (always_copy_stacks) {
jl_safe_printf("Julia built without COPY_STACKS support");
exit(1);
}
#endif
}
STATIC_OR_JS void NOINLINE JL_NORETURN start_task(void)
{
#ifdef _OS_WINDOWS_
#if defined(_CPU_X86_64_)
// install the unhandled exception handler at the top of our stack
// to call directly into our personality handler
asm volatile ("\t.seh_handler __julia_personality, @except\n\t.text");
#endif
#else
// wipe out the call-stack unwind capability beyond this function
// (we are noreturn, so it is not a total lie)
#if defined(_CPU_X86_64_)
// per nongnu libunwind: "x86_64 ABI specifies that end of call-chain is marked with a NULL RBP or undefined return address"
// so we do all 3, to be extra certain of it
asm volatile ("\t.cfi_undefined rip");
asm volatile ("\t.cfi_undefined rbp");
asm volatile ("\t.cfi_return_column rbp");
#else
// per nongnu libunwind: "DWARF spec says undefined return address location means end of stack"
// we use whatever happens to be register 1 on this platform for this
asm volatile ("\t.cfi_undefined 1");
asm volatile ("\t.cfi_return_column 1");
#endif
#endif
// this runs the first time we switch to a task
sanitizer_finish_switch_fiber();
jl_ptls_t ptls = jl_get_ptls_states();
jl_task_t *t = ptls->current_task;
jl_value_t *res;
assert(ptls->finalizers_inhibited == 0);
#ifdef MIGRATE_TASKS
jl_task_t *pt = ptls->previous_task;
if (!pt->sticky && !pt->copy_stack)
pt->tid = -1;
#endif
t->started = 1;
if (t->_isexception) {
record_backtrace(ptls, 0);
jl_push_excstack(&t->excstack, t->result,
ptls->bt_data, ptls->bt_size);
res = t->result;
}
else {
JL_TRY {
if (ptls->defer_signal) {
ptls->defer_signal = 0;
jl_sigint_safepoint(ptls);
}
JL_TIMING(ROOT);
ptls->world_age = jl_world_counter;
res = jl_apply(&t->start, 1);
}
JL_CATCH {
res = jl_current_exception();
t->_isexception = 1;
goto skip_pop_exception;
}
skip_pop_exception:;
}
t->result = res;
jl_gc_wb(t, t->result);
jl_finish_task(t);
gc_debug_critical_error();
abort();
}
#if defined(JL_HAVE_UCONTEXT)
#ifdef _OS_WINDOWS_
#define setcontext jl_setcontext
#define swapcontext jl_swapcontext
#define makecontext jl_makecontext
#endif
static char *jl_alloc_fiber(jl_ucontext_t *t, size_t *ssize, jl_task_t *owner) JL_NOTSAFEPOINT
{
#ifndef _OS_WINDOWS_
int r = getcontext(t);
if (r != 0)
jl_error("getcontext failed");
#endif
void *stk = jl_malloc_stack(ssize, owner);
if (stk == NULL)
return NULL;
t->uc_stack.ss_sp = stk;
t->uc_stack.ss_size = *ssize;
#ifdef _OS_WINDOWS_
makecontext(t, &start_task);
#else
t->uc_link = NULL;
makecontext(t, &start_task, 0);
#endif
return (char*)stk;
}
static void jl_start_fiber_set(jl_ucontext_t *t)
{
setcontext(t);
}
static void jl_start_fiber_swap(jl_ucontext_t *lastt, jl_ucontext_t *t)
{
assert(lastt);
swapcontext(lastt, t);
}
static void jl_swap_fiber(jl_ucontext_t *lastt, jl_ucontext_t *t)
{
swapcontext(lastt, t);
}
static void jl_set_fiber(jl_ucontext_t *t)
{
setcontext(t);
}
#endif
#if defined(JL_HAVE_UNW_CONTEXT) || defined(JL_HAVE_ASM)
static char *jl_alloc_fiber(jl_ucontext_t *t, size_t *ssize, jl_task_t *owner)
{
char *stkbuf = (char*)jl_malloc_stack(ssize, owner);
if (stkbuf == NULL)
return NULL;
#ifndef __clang_analyzer__
((char**)t)[0] = stkbuf; // stash the stack pointer somewhere for start_fiber
((size_t*)t)[1] = *ssize; // stash the stack size somewhere for start_fiber
#endif
return stkbuf;
}
#endif
#if defined(JL_HAVE_UNW_CONTEXT)
static inline void jl_unw_swapcontext(unw_context_t *old, unw_cursor_t *c)
{
volatile int returns = 0;
int r = unw_getcontext(old);
if (++returns == 2) // r is garbage after the first return
return;
if (r != 0 || returns != 1)
abort();
unw_resume(c);
}
static void jl_swap_fiber(jl_ucontext_t *lastt, jl_ucontext_t *t)
{
unw_cursor_t c;
int r = unw_init_local(&c, t);
if (r < 0)
abort();
jl_unw_swapcontext(lastt, &c);
}
static void jl_set_fiber(unw_context_t *t)
{
unw_cursor_t c;
int r = unw_init_local(&c, t);
if (r < 0)
abort();
unw_resume(&c);
}
#elif defined(JL_HAVE_ASM)
static void jl_swap_fiber(jl_ucontext_t *lastt, jl_ucontext_t *t)
{
if (jl_setjmp(lastt->uc_mcontext, 0))
return;
jl_set_fiber(t); // doesn't return
}
static void jl_set_fiber(jl_ucontext_t *t)
{
jl_longjmp(t->uc_mcontext, 1);
}
#endif
#if defined(JL_HAVE_UNW_CONTEXT) && !defined(JL_HAVE_ASM)
#if defined(_CPU_X86_) || defined(_CPU_X86_64_)
#define PUSH_RET(ctx, stk) \
do { \
stk -= sizeof(uintptr_t); \
*(uintptr_t*)stk = 0; /* push null RIP/EIP onto the stack */ \
} while (0)
#elif defined(_CPU_ARM_)
#define PUSH_RET(ctx, stk) \
if (unw_set_reg(ctx, UNW_ARM_R14, 0)) /* put NULL into the LR */ \
abort();
#else
#error please define how to simulate a CALL on this platform
#endif
static void jl_start_fiber_set(unw_context_t *t)
{
unw_cursor_t c;
char *stk = ((char**)t)[0];
size_t ssize = ((size_t*)t)[1];
uintptr_t fn = (uintptr_t)&start_task;
stk += ssize;
int r = unw_getcontext(t);
if (r)
abort();
if (unw_init_local(&c, t))
abort();