Improve ARM CPU info reporting.

This patch improves several things for Linux/ARM:

- Better detection of the number of CPUs on the target
  device. The content of /proc/cpuinfo only matches the
  number of "online" CPUs, which varies over time with
  recent Android devices.

- Reconstruct the CPUID and ELF hwcaps values from
  /proc/cpuinfo, this is useful to better identify
  target devices in minidumps.

- Make minidump_dump display the new information
  in useful ways.

- Write a small helper class to parse /proc/cpuinfo
  and also use it for x86/64.

- Write a small helper class to parse sysfds cpu lists.

- Add a my_memchr() implementation.

- Add unit tests.

Tested on a Nexus S (1 CPU), Galaxy Nexus (2 CPUs)
and a Nexus 4 (4 CPUs).

Review URL: https://breakpad.appspot.com/540003

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1160 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 144 insertions, 0 deletions

diff --git a/src/client/linux/minidump_writer/cpu_set.h b/src/client/linux/minidump_writer/cpu_set.h
new file mode 100644
index 00000000..1cca9aa5
--- /dev/null
+++ b/src/client/linux/minidump_writer/cpu_set.h
@@ -0,0 +1,144 @@
+// Copyright (c) 2013, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef CLIENT_LINUX_MINIDUMP_WRITER_CPU_SET_H_
+#define CLIENT_LINUX_MINIDUMP_WRITER_CPU_SET_H_
+
+#include <stdint.h>
+#include <assert.h>
+#include <string.h>
+
+#include "common/linux/linux_libc_support.h"
+#include "third_party/lss/linux_syscall_support.h"
+
+namespace google_breakpad {
+
+// Helper class used to model a set of CPUs, as read from sysfs
+// files like /sys/devices/system/cpu/present
+// See See http://www.kernel.org/doc/Documentation/cputopology.txt
+class CpuSet {
+public:
+  // The maximum number of supported CPUs.
+  static const size_t kMaxCpus = 1024;
+
+  CpuSet() {
+    my_memset(mask_, 0, sizeof(mask_));
+  }
+
+  // Parse a sysfs file to extract the corresponding CPU set.
+  bool ParseSysFile(int fd) {
+    char buffer[512];
+    int ret = sys_read(fd, buffer, sizeof(buffer)-1);
+    if (ret < 0)
+      return false;
+
+    buffer[ret] = '\0';
+
+    // Expected format: comma-separated list of items, where each
+    // item can be a decimal integer, or two decimal integers separated
+    // by a dash.
+    // E.g.:
+    //       0
+    //       0,1,2,3
+    //       0-3
+    //       1,10-23
+    const char* p = buffer;
+    const char* p_end = p + ret;
+    while (p < p_end) {
+      // Skip leading space, if any
+      while (p < p_end && my_isspace(*p))
+        p++;
+
+      // Find start and size of current item.
+      const char* item = p;
+      size_t item_len = static_cast<size_t>(p_end - p);
+      const char* item_next =
+          static_cast<const char*>(my_memchr(p, ',', item_len));
+      if (item_next != NULL) {
+        p = item_next + 1;
+        item_len = static_cast<size_t>(item_next - item);
+      } else {
+        p = p_end;
+        item_next = p_end;
+      }
+
+      // Ignore trailing spaces.
+      while (item_next > item && my_isspace(item_next[-1]))
+        item_next--;
+
+      // skip empty items.
+      if (item_next == item)
+        continue;
+
+      // read first decimal value.
+      uintptr_t start = 0;
+      const char* next = my_read_decimal_ptr(&start, item);
+      uintptr_t end = start;
+      if (*next == '-')
+        my_read_decimal_ptr(&end, next+1);
+
+      while (start <= end)
+        SetBit(start++);
+    }
+    return true;
+  }
+
+  // Intersect this CPU set with another one.
+  void IntersectWith(const CpuSet& other) {
+    for (size_t nn = 0; nn < kMaskWordCount; ++nn)
+      mask_[nn] &= other.mask_[nn];
+  }
+
+  // Return the number of CPUs in this set.
+  int GetCount() {
+    int result = 0;
+    for (size_t nn = 0; nn < kMaskWordCount; ++nn) {
+      result += __builtin_popcount(mask_[nn]);
+    }
+    return result;
+  }
+
+private:
+  void SetBit(uintptr_t index) {
+    size_t nn = static_cast<size_t>(index);
+    if (nn < kMaxCpus)
+      mask_[nn / kMaskWordBits] |= (1U << (nn % kMaskWordBits));
+  }
+
+  typedef uint32_t MaskWordType;
+  static const size_t kMaskWordBits = 8*sizeof(MaskWordType);
+  static const size_t kMaskWordCount =
+      (kMaxCpus + kMaskWordBits - 1) / kMaskWordBits;
+
+  MaskWordType mask_[kMaskWordCount];
+};
+
+}  // namespace google_breakpad
+
+#endif  // CLIENT_LINUX_MINIDUMP_WRITER_CPU_SET_H_