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Unified Diff: third_party/crashpad/crashpad/snapshot/cpu_context.cc

Issue 1505213004: Copy Crashpad into the Chrome tree instead of importing it via DEPS (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Address review comments, update README.chromium Created 5 years ago
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Index: third_party/crashpad/crashpad/snapshot/cpu_context.cc
diff --git a/third_party/crashpad/crashpad/snapshot/cpu_context.cc b/third_party/crashpad/crashpad/snapshot/cpu_context.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1ff2b459242eff8cc4574ac97be65bd2ad310f07
--- /dev/null
+++ b/third_party/crashpad/crashpad/snapshot/cpu_context.cc
@@ -0,0 +1,101 @@
+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "snapshot/cpu_context.h"
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "util/misc/implicit_cast.h"
+
+namespace crashpad {
+
+// static
+uint16_t CPUContextX86::FxsaveToFsaveTagWord(
+ uint16_t fsw,
+ uint8_t fxsave_tag,
+ const CPUContextX86::X87OrMMXRegister st_mm[8]) {
+ enum {
+ kX87TagValid = 0,
+ kX87TagZero,
+ kX87TagSpecial,
+ kX87TagEmpty,
+ };
+
+ // The x87 tag word (in both abridged and full form) identifies physical
+ // registers, but |st_mm| is arranged in logical stack order. In order to map
+ // physical tag word bits to the logical stack registers they correspond to,
+ // the “stack top” value from the x87 status word is necessary.
+ int stack_top = (fsw >> 11) & 0x7;
+
+ uint16_t fsave_tag = 0;
+ for (int physical_index = 0; physical_index < 8; ++physical_index) {
+ bool fxsave_bit = (fxsave_tag & (1 << physical_index)) != 0;
+ uint8_t fsave_bits;
+
+ if (fxsave_bit) {
+ int st_index = (physical_index + 8 - stack_top) % 8;
+ const CPUContextX86::X87Register& st = st_mm[st_index].st;
+
+ uint32_t exponent = ((st[9] & 0x7f) << 8) | st[8];
+ if (exponent == 0x7fff) {
+ // Infinity, NaN, pseudo-infinity, or pseudo-NaN. If it was important to
+ // distinguish between these, the J bit and the M bit (the most
+ // significant bit of |fraction|) could be consulted.
+ fsave_bits = kX87TagSpecial;
+ } else {
+ // The integer bit the “J bit”.
+ bool integer_bit = (st[7] & 0x80) != 0;
+ if (exponent == 0) {
+ uint64_t fraction = ((implicit_cast<uint64_t>(st[7]) & 0x7f) << 56) |
+ (implicit_cast<uint64_t>(st[6]) << 48) |
+ (implicit_cast<uint64_t>(st[5]) << 40) |
+ (implicit_cast<uint64_t>(st[4]) << 32) |
+ (implicit_cast<uint32_t>(st[3]) << 24) |
+ (st[2] << 16) | (st[1] << 8) | st[0];
+ if (!integer_bit && fraction == 0) {
+ fsave_bits = kX87TagZero;
+ } else {
+ // Denormal (if the J bit is clear) or pseudo-denormal.
+ fsave_bits = kX87TagSpecial;
+ }
+ } else if (integer_bit) {
+ fsave_bits = kX87TagValid;
+ } else {
+ // Unnormal.
+ fsave_bits = kX87TagSpecial;
+ }
+ }
+ } else {
+ fsave_bits = kX87TagEmpty;
+ }
+
+ fsave_tag |= (fsave_bits << (physical_index * 2));
+ }
+
+ return fsave_tag;
+}
+
+uint64_t CPUContext::InstructionPointer() const {
+ switch (architecture) {
+ case kCPUArchitectureX86:
+ return x86->eip;
+ case kCPUArchitectureX86_64:
+ return x86_64->rip;
+ default:
+ NOTREACHED();
+ return ~0ull;
+ }
+}
+
+} // namespace crashpad

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