Adding untrusted crash dump / stack trace tests.

src/untrusted/crash_dump/untrusted_crash_dump.c

+/*
+ * Copyright (c) 2012 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/untrusted/crash_dump/untrusted_crash_dump.h"
+
+#include <assert.h>
+#include <inttypes.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/nacl_syscalls.h>
+
+#ifdef __GLIBC__
+#include <elf.h>
+#include <link.h>
+#endif  /* __GLIBC__ */
+
+#include "native_client/src/untrusted/nacl/syscall_bindings_trampoline.h"
+
+
+#define CRASH_PAGE_CHUNK (64 * 1024)
+#define CRASH_STACK_SIZE (CRASH_PAGE_CHUNK * 4)
+#define CRASH_STACK_GUARD_SIZE CRASH_PAGE_CHUNK
+#define CRASH_STACK_COMPLETE_SIZE (CRASH_STACK_GUARD_SIZE + CRASH_STACK_SIZE)
+
+
+static void (*g_PrevHandler)(int prog_ctr, int stack_ptr) = 0;
+static pthread_key_t g_CrashStackKey;
+
+
+#ifdef __GLIBC__
+
+struct ProgramTableData {
+  FILE *core;
+  uintptr_t addr;

[Mark Seaborn, 2012/02/16 18:42:50]

Not used?

[bradn, 2012/02/16 20:13:10]

Done.

+  int first;
+};
+
+
+static int PrintSegmentsOne(
+    struct dl_phdr_info *info, size_t size, void *data) {
+  int i;
+  struct ProgramTableData *ptd = (struct ProgramTableData*) data;
+
+  if (ptd->first) {
+    ptd->first = 0;
+  } else {
+    fprintf(ptd->core, ",\n");
+  }
+  fprintf(ptd->core, "{\n");
+  fprintf(ptd->core, "\"dlpi_name\": \"%s\",\n", info->dlpi_name);

[Mark Seaborn, 2012/02/16 18:42:50]

Please put in a TODO for quoting special characters in the string.  There's a
chance we'll see backslashes in filenames since I believe an obscure operating
system uses them as a separator. :-)

[bradn, 2012/02/16 20:13:10]

Done.

+  fprintf(ptd->core, "\"dlpi_addr\": %"PRIuPTR",\n", info->dlpi_addr);
+  fprintf(ptd->core, "\"dlpi_phdr\": [\n");
+  for (i = 0; i < info->dlpi_phnum; i++) {
+    /* Skip non-LOAD type segments. */
+    if (info->dlpi_phdr[i].p_type != PT_LOAD) {
+      continue;
+    }
+    if (i != 0) {
+      fprintf(ptd->core, ",\n");
+    }
+    fprintf(ptd->core, "{\n");
+    fprintf(ptd->core, "\"p_vaddr\": %"PRIuPTR",\n",
+            info->dlpi_phdr[i].p_vaddr);
+    fprintf(ptd->core, "\"p_memsz\": %"PRIuPTR"\n",
+            info->dlpi_phdr[i].p_memsz);
+    fprintf(ptd->core, "}\n");
+  }
+  fprintf(ptd->core, "]\n");
+  fprintf(ptd->core, "}\n");
+  return 0;
+}
+
+static void PrintSegments(FILE *core) {
+  struct ProgramTableData data;
+  data.core = core;
+  data.first = 1;
+  dl_iterate_phdr(PrintSegmentsOne, &data);
+}
+
+#else  /* __GLIBC__ */
+
+static void PrintSegments(FILE *core) {
+}
+
+#endif  /* __GLIBC__ */
+
+uintptr_t SafeRead(uintptr_t a) {
+  /* TODO(bradnelson): use exception handling to recover from reads. */
+  return *(uintptr_t*)a;
+}
+
+static void StackWalk(FILE *core, uintptr_t ip, uintptr_t fp) {

[Mark Seaborn, 2012/02/16 18:42:50]

'fp' -> 'frame_ptr' or 'frame'?

'ip' is also rather cryptic and suggests "IP address" too much.  In the
sel_rt_*.h headers we use "prog_ctr".  How about that?

[bradn, 2012/02/16 20:13:10]

Done.

+  uintptr_t next;
+  uintptr_t i;
+  int first = 1;
+
+  fprintf(core, "\"frames\": [\n");
+  for (;;) {
+    next = SafeRead(fp);
+    if (next <= fp || next == 0) {
+      break;
+    }
+    if (first) {
+      first = 0;
+    } else {
+      fprintf(core, ",");
+    }
+    fprintf(core, "{\n");
+    fprintf(core, "\"fp\": %"PRIuPTR",\n", fp);
+    fprintf(core, "\"ip\": %"PRIuPTR",\n", ip);
+    fprintf(core, "\"data\": [\n");
+    for (i = fp + 8; i < next; i += 4) {
+      if (i != fp + 8) {
+        fprintf(core, ",");
+      }
+      fprintf(core, "%"PRIuPTR"\n", SafeRead(i));
+    }
+    fprintf(core, "]\n");
+    fprintf(core, "}\n");
+
+    ip = SafeRead(fp + 4);
+    fp = next;
+  }
+
+  fprintf(core, "]\n");
+}
+
+void CrashHandlerWrapper(int prog_ctr, int stack_ptr);
+asm(".pushsection .text, \"ax\", @progbits\n"
+    ".p2align NACLENTRYALIGN\n"
+    "CrashHandlerWrapper:\n"
+    "popl %eax\n"
+    "pushl %ebp\n"
+    "call CrashHandler\n"
+    ".popsection\n");
+
+void CrashHandler(int frame_ptr, int prog_ctr, int stack_ptr) {
+  FILE *core;
+  const char *core_filename;
+
+  /* Pick core file name. */
+  core_filename = getenv("NACLCOREFILE");
+  if (core_filename == NULL) {
+    core_filename = "naclcore.json";
+  }
+
+  /* Attempt to open core file, otherwise use stdout. */
+  core = fopen(core_filename, "w");
+  if (core == NULL) {
+    core = stdout;
+  }
+
+  fprintf(core, "{\n");
+
+  fprintf(core, "\"segments\": [");
+  PrintSegments(core);
+  fprintf(core, "],\n");
+
+  fprintf(core, "\"handler\": {\n");
+  fprintf(core, "\"prog_ctr\": %"PRIuPTR",\n", prog_ctr);
+  fprintf(core, "\"stack_ptr\": %"PRIuPTR",\n", stack_ptr);
+  fprintf(core, "\"frame_ptr\": %"PRIuPTR"\n", frame_ptr);
+  fprintf(core, "},\n");
+
+  StackWalk(core, (uintptr_t) prog_ctr, (uintptr_t) frame_ptr);
+
+  fprintf(core, "}\n");
+
+  if (core != stdout) {
+    fclose(core);
+  }
+
+  exit(166);
+}
+
+void NaClCrashDumpThreadDestructor(void *arg) {
+  munmap(arg, CRASH_STACK_COMPLETE_SIZE);
+}
+
+void NaClCrashDumpInit(void) {
+  int result;
+  result = pthread_key_create(&g_CrashStackKey, NaClCrashDumpThreadDestructor);
+  assert(result == 0);
+  result = NACL_SYSCALL(exception_handler)(CrashHandlerWrapper,
+                                           &g_PrevHandler);

[Mark Seaborn, 2012/02/16 18:42:50]

Could use NULL instead of &g_PrevHandler now

[bradn, 2012/02/16 20:13:10]

Done.

+  assert(result == 0);
+  NaClCrashDumpInitThread();
+}
+
+void NaClCrashDumpInitThread(void) {
+  void *stack;
+  void *guard;
+  int result;
+  /*
+   * NOTE: Setting up a per thread stack is only particularly interesting
+   *       for stack overflow.
+   */
+  stack = mmap(NULL, CRASH_STACK_COMPLETE_SIZE,
+               PROT_READ | PROT_WRITE,
+               MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  assert(stack != MAP_FAILED);
+  guard = mmap(stack, CRASH_STACK_GUARD_SIZE,
+               PROT_NONE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  assert(guard == stack);
+  pthread_setspecific(g_CrashStackKey, stack);
+  result = NACL_SYSCALL(exception_stack)(stack, CRASH_STACK_COMPLETE_SIZE);
+  assert(result == 0);
+}