rt: Don't switch to the C stack on the upcall_new_stack fast path
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8a145a601e
commit
6115b13dfc
3 changed files with 41 additions and 20 deletions
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@ -509,6 +509,37 @@ rust_task::free_stack(stk_seg *stk) {
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destroy_stack(&local_region, stk);
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}
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struct new_stack_args {
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rust_task *task;
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size_t requested_sz;
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};
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void
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new_stack_slow(new_stack_args *args) {
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args->task->new_stack(args->requested_sz);
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}
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// NB: This runs on the Rust stack
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// This is the new stack fast path, in which we
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// reuse the next cached stack segment
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void
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rust_task::new_stack_fast(size_t requested_sz) {
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// The minimum stack size, in bytes, of a Rust stack, excluding red zone
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size_t min_sz = thread->min_stack_size;
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// Try to reuse an existing stack segment
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if (stk != NULL && stk->prev != NULL) {
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size_t prev_sz = user_stack_size(stk->prev);
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if (min_sz <= prev_sz && requested_sz <= prev_sz) {
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stk = stk->prev;
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return;
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}
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}
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new_stack_args args = {this, requested_sz};
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call_on_c_stack(&args, (void*)new_stack_slow);
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}
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void
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rust_task::new_stack(size_t requested_sz) {
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LOG(this, mem, "creating new stack for task %" PRIxPTR, this);
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@ -572,7 +603,7 @@ rust_task::next_stack(size_t stk_sz, void *args_addr, size_t args_sz) {
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maybe_next_stack = stk->prev;
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}
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new_stack(stk_sz + args_sz);
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new_stack_fast(stk_sz + args_sz);
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A(thread, stk->end - (uintptr_t)stk->data >= stk_sz + args_sz,
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"Did not receive enough stack");
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uint8_t *new_sp = (uint8_t*)stk->end;
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@ -33,6 +33,7 @@ typedef unsigned long task_result;
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struct spawn_args;
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struct cleanup_args;
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struct reset_args;
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struct new_stack_args;
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// std::lib::task::task_notification
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//
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@ -114,7 +115,8 @@ private:
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// Called when the atomic refcount reaches zero
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void delete_this();
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void new_stack(size_t sz);
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void new_stack_fast(size_t requested_sz);
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void new_stack(size_t requested_sz);
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void free_stack(stk_seg *stk);
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size_t get_next_stack_size(size_t min, size_t current, size_t requested);
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@ -128,6 +130,7 @@ private:
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friend void task_start_wrapper(spawn_args *a);
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friend void cleanup_task(cleanup_args *a);
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friend void reset_stack_limit_on_c_stack(reset_args *a);
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friend void new_stack_slow(new_stack_args *a);
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public:
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@ -439,26 +439,13 @@ upcall_log_type(const type_desc *tydesc, uint8_t *data, uint32_t level) {
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UPCALL_SWITCH_STACK(&args, upcall_s_log_type);
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}
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struct s_new_stack_args {
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void *result;
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size_t stk_sz;
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void *args_addr;
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size_t args_sz;
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};
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extern "C" CDECL void
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upcall_s_new_stack(struct s_new_stack_args *args) {
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rust_task *task = rust_task_thread::get_task();
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args->result = task->next_stack(args->stk_sz,
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args->args_addr,
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args->args_sz);
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}
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// NB: This needs to be blazing fast. Don't switch stacks
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extern "C" CDECL void *
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upcall_new_stack(size_t stk_sz, void *args_addr, size_t args_sz) {
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s_new_stack_args args = {NULL, stk_sz, args_addr, args_sz};
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UPCALL_SWITCH_STACK(&args, upcall_s_new_stack);
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return args.result;
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rust_task *task = rust_task_thread::get_task();
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return task->next_stack(stk_sz,
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args_addr,
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args_sz);
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}
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// NB: This needs to be blazing fast. Don't switch stacks
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