Non-SFI mode: Add Linux asynchronous signal support

src/nonsfi/irt/irt_interfaces.c

 /*
  * Copyright (c) 2013 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "native_client/src/nonsfi/irt/irt_interfaces.h"
 
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <pthread.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
 #if defined(__linux__)
 # include <linux/futex.h>
 # include <sys/syscall.h>
 #endif
 
 #include "native_client/src/include/elf32.h"
 #include "native_client/src/include/elf_auxv.h"
 #include "native_client/src/include/nacl/nacl_exception.h"
+#include "native_client/src/include/nacl/nacl_signal.h"
 #include "native_client/src/include/nacl_macros.h"
 #include "native_client/src/public/irt_core.h"
-#include "native_client/src/public/nonsfi/irt_exception_handling.h"
+#include "native_client/src/public/nonsfi/irt_signal_handling.h"
 #include "native_client/src/trusted/service_runtime/include/machine/_types.h"
 #include "native_client/src/trusted/service_runtime/include/sys/mman.h"
 #include "native_client/src/trusted/service_runtime/include/sys/stat.h"
 #include "native_client/src/trusted/service_runtime/include/sys/time.h"
 #include "native_client/src/trusted/service_runtime/include/sys/unistd.h"
 #include "native_client/src/untrusted/irt/irt.h"
 #include "native_client/src/untrusted/irt/irt_dev.h"
 #include "native_client/src/untrusted/irt/irt_interfaces.h"
 #include "native_client/src/untrusted/nacl/nacl_random.h"
+#include "native_client/src/untrusted/pthread/pthread_types.h"

[Mark Seaborn, 2015/06/26 18:31:59]

Not used?  irt_interfaces.c shouldn't depend on src/untrusted/pthread/ anyway.

Oh, I see you are depending on this for "tid->native_tid" below...

[Luis Héctor Chávez, 2015/07/06 23:44:59]

Removed.

 
 #if defined(__native_client__) && defined(__arm__)
 #include "native_client/src/nonsfi/irt/irt_icache.h"
 #endif
 
 /*
  * This is an implementation of NaCl's IRT interfaces that runs
  * outside of the NaCl sandbox.
  *
  * This allows PNaCl to be used as a portability layer without the
@@ skipping 295 matching lines @@
 
 static void *start_thread(void *arg) {
   struct thread_args args = *(struct thread_args *) arg;
   free(arg);
   g_tls_value = args.thread_ptr;
   args.start_func();
   abort();
 }
 
 static int thread_create(void (*start_func)(void), void *stack,
-                         void *thread_ptr) {
+                         void *thread_ptr, nacl_irt_tid_t *child_tid) {
   /*
    * For now, we ignore the stack that user code provides and just use
    * the stack that the host libpthread allocates.
    */
   pthread_attr_t attr;
   int error = pthread_attr_init(&attr);
   if (error != 0)
     return error;
   error = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
   if (error != 0)
     return error;
   struct thread_args *args = malloc(sizeof(struct thread_args));
   if (args == NULL) {
     error = ENOMEM;
     goto cleanup;
   }
   args->start_func = start_func;
   args->thread_ptr = thread_ptr;
   pthread_t tid;
   error = pthread_create(&tid, &attr, start_thread, args);
-  if (error != 0)
+  if (error != 0) {
     free(args);
+  } else if (child_tid != NULL) {
+    *child_tid = tid->native_tid;

[Mark Seaborn, 2015/06/26 18:31:59]

This creates an unfortunate dependency on libpthread's internals.  (And adding
tid->native_tid to libpthread has problems -- see other comment.)

This would fail when compiling irt_interfaces.c for Linux or Mac (rather than
for Non-SFI mode) -- which we test on the PNaCl toolchain trybots for "PNaCl
unsandboxed mode".

What I would recommend here is:

Change src/nonsfi/linux/linux_pthread_private.c to export a user_thread_create()
function (or nacl_irt_thread structs).  In irt_interfaces.c, when
__native_client__ is #defined, we can then use that user_thread_create() instead
of calling pthread_create().

Note that this user_thread_create() would need to do more than the existing
nacl_irt_thread_create() in linux_pthread_private.c, because it would need to
initialise the IRT's pthread state for the new thread.  See
nacl_irt_thread_create() and irt_start_thread() in
src/untrusted/irt/irt_thread.c for how to do that.

This is admittedly a bit fiddly, so you could do it as a separate refactoring
change.  But it does have the benefit that we would no longer be allocating two
stacks for every thread.  Currently, when a Bare Metal Mode app creates a
thread, it allocates a stack and passes it to thread_create(), but the IRT
ignores that stack and uses one it allocates itself (allocated by the IRT's
internal pthread_create()).  This refactoring would fix that:  the IRT would
start using the stack that the app passes to thread_create().

[Luis Héctor Chávez, 2015/07/06 23:44:59]

Split that off into https://codereview.chromium.org/1222753005/ that can be
applied before.

+  }
  cleanup:
   pthread_attr_destroy(&attr);
   return error;
 }
 
+static int thread_create_v0_1(void (*start_func)(void), void *stack,
+                              void *thread_ptr) {
+  return thread_create(start_func, stack, thread_ptr, NULL);
+}
+
 static void thread_exit(int32_t *stack_flag) {
   *stack_flag = 0;  /* Indicate that the user code's stack can be freed. */
   pthread_exit(NULL);
 }
 
 static int thread_nice(const int nice) {
   return 0;
 }
 
 /*
@@ skipping 184 matching lines @@
   irt_munmap,
   irt_mprotect,
 };
 
 const struct nacl_irt_tls nacl_irt_tls = {
   tls_init,
   tls_get,
 };
 
 const struct nacl_irt_thread nacl_irt_thread = {
+  thread_create_v0_1,
+  thread_exit,
+  thread_nice,
+};
+
+const struct nacl_irt_thread_v0_2 nacl_irt_thread_v0_2 = {
   thread_create,
   thread_exit,
   thread_nice,
 };
 
 #if defined(__linux__)
 const struct nacl_irt_futex nacl_irt_futex = {
   futex_wait_abs,
   futex_wake,
 };
@@ skipping 45 matching lines @@
  * The following condition is true when building for Non-SFI Mode,
  * when we're calling Linux syscalls directly.  (Counter-intuitively,
  * "__linux__" is not #defined in this case.)
  */
 #if defined(__native_client__)
 const struct nacl_irt_exception_handling nacl_irt_exception_handling = {
   nacl_exception_get_and_set_handler,
   nacl_exception_set_stack,
   nacl_exception_clear_flag,
 };
+
+const struct nacl_irt_signal_handling nacl_irt_signal_handling = {
+  nacl_signal_set_handler,
+  nacl_signal_send_async_signal,
+};
 #endif
 
 #if defined(__native_client__) && defined(__arm__)
 const struct nacl_irt_icache nacl_irt_icache = {
   irt_clear_cache,
 };
 #endif
 
 static int g_allow_dev_interfaces = 0;
 
 void nacl_irt_nonsfi_allow_dev_interfaces() {
   g_allow_dev_interfaces = 1;
 }
 
 static int irt_dev_filter(void) {
   return g_allow_dev_interfaces;
 }
 
 static const struct nacl_irt_interface irt_interfaces[] = {
   { NACL_IRT_BASIC_v0_1, &nacl_irt_basic, sizeof(nacl_irt_basic), NULL },
   { NACL_IRT_FDIO_v0_1, &nacl_irt_fdio, sizeof(nacl_irt_fdio), NULL },
   { NACL_IRT_MEMORY_v0_3, &nacl_irt_memory, sizeof(nacl_irt_memory), NULL },
   { NACL_IRT_TLS_v0_1, &nacl_irt_tls, sizeof(nacl_irt_tls), NULL },
   { NACL_IRT_THREAD_v0_1, &nacl_irt_thread, sizeof(nacl_irt_thread), NULL },
+  { NACL_IRT_THREAD_v0_2, &nacl_irt_thread_v0_2,
+    sizeof(nacl_irt_thread_v0_2), NULL },
   { NACL_IRT_FUTEX_v0_1, &nacl_irt_futex, sizeof(nacl_irt_futex), NULL },
   { NACL_IRT_RANDOM_v0_1, &nacl_irt_random, sizeof(nacl_irt_random), NULL },
 #if defined(__linux__) || defined(__native_client__)
   { NACL_IRT_CLOCK_v0_1, &nacl_irt_clock, sizeof(nacl_irt_clock), NULL },
 #endif
   { NACL_IRT_DEV_FILENAME_v0_3, &nacl_irt_dev_filename,
     sizeof(nacl_irt_dev_filename), irt_dev_filter },
   { NACL_IRT_DEV_GETPID_v0_1, &nacl_irt_dev_getpid,
     sizeof(nacl_irt_dev_getpid), irt_dev_filter },
 #if defined(__native_client__)
   { NACL_IRT_EXCEPTION_HANDLING_v0_1, &nacl_irt_exception_handling,
     sizeof(nacl_irt_exception_handling), NULL },
+  { NACL_IRT_SIGNAL_HANDLING_v0_1, &nacl_irt_signal_handling,
+    sizeof(nacl_irt_signal_handling), NULL },
 #endif
 #if defined(__native_client__) && defined(__arm__)
   { NACL_IRT_ICACHE_v0_1, &nacl_irt_icache, sizeof(nacl_irt_icache), NULL },
 #endif
 };
 
 size_t nacl_irt_query_core(const char *interface_ident,
                            void *table, size_t tablesize) {
   return nacl_irt_query_list(interface_ident, table, tablesize,
                              irt_interfaces, sizeof(irt_interfaces));
@@ skipping 54 matching lines @@
   nacl_entry_func_t entry_func =
 #if defined(__APPLE__)
     _start;
 #else
     _user_start;
 #endif
 
   return nacl_irt_nonsfi_entry(argc, argv, environ, entry_func);
 }
 #endif