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52c2f6edfc
and its test. Minidump context structures now interoperate more easily with snapshot CPUContext structures, while maintaining identical layout to before. This is facilitated by reusing the Fxsave types for the substructures which were completely identical, and by using compatible logic to initialize the minidump and snapshot structures for testing. TEST=minidump_test, snapshot_test R=rsesek@chromium.org Review URL: https://codereview.chromium.org/686353004
100 lines
3.2 KiB
C++
100 lines
3.2 KiB
C++
// Copyright 2014 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "snapshot/cpu_context.h"
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#include "base/logging.h"
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namespace crashpad {
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// static
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uint16_t CPUContextX86::FxsaveToFsaveTagWord(
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uint16_t fsw,
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uint8_t fxsave_tag,
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const CPUContextX86::X87OrMMXRegister st_mm[8]) {
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enum {
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kX87TagValid = 0,
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kX87TagZero,
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kX87TagSpecial,
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kX87TagEmpty,
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};
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// The x87 tag word (in both abridged and full form) identifies physical
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// registers, but |st_mm| is arranged in logical stack order. In order to map
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// physical tag word bits to the logical stack registers they correspond to,
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// the “stack top” value from the x87 status word is necessary.
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int stack_top = (fsw >> 11) & 0x7;
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uint16_t fsave_tag = 0;
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for (int physical_index = 0; physical_index < 8; ++physical_index) {
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bool fxsave_bit = fxsave_tag & (1 << physical_index);
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uint8_t fsave_bits;
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if (fxsave_bit) {
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int st_index = (physical_index + 8 - stack_top) % 8;
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const CPUContextX86::X87Register& st = st_mm[st_index].st;
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uint32_t exponent = ((st[9] & 0x7f) << 8) | st[8];
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if (exponent == 0x7fff) {
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// Infinity, NaN, pseudo-infinity, or pseudo-NaN. If it was important to
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// distinguish between these, the J bit and the M bit (the most
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// significant bit of |fraction|) could be consulted.
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fsave_bits = kX87TagSpecial;
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} else {
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// The integer bit the “J bit”.
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bool integer_bit = st[7] & 0x80;
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if (exponent == 0) {
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uint64_t fraction = ((static_cast<uint64_t>(st[7]) & 0x7f) << 56) |
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(static_cast<uint64_t>(st[6]) << 48) |
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(static_cast<uint64_t>(st[5]) << 40) |
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(static_cast<uint64_t>(st[4]) << 32) |
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(static_cast<uint32_t>(st[3]) << 24) |
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(st[2] << 16) | (st[1] << 8) | st[0];
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if (!integer_bit && fraction == 0) {
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fsave_bits = kX87TagZero;
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} else {
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// Denormal (if the J bit is clear) or pseudo-denormal.
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fsave_bits = kX87TagSpecial;
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}
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} else if (integer_bit) {
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fsave_bits = kX87TagValid;
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} else {
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// Unnormal.
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fsave_bits = kX87TagSpecial;
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}
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}
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} else {
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fsave_bits = kX87TagEmpty;
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}
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fsave_tag |= (fsave_bits << (physical_index * 2));
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}
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return fsave_tag;
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}
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uint64_t CPUContext::InstructionPointer() const {
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switch (architecture) {
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case kCPUArchitectureX86:
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return x86->eip;
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case kCPUArchitectureX86_64:
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return x86_64->rip;
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default:
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NOTREACHED();
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return -1;
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}
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}
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} // namespace crashpad
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