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5069c2903a
chromium's implicit_cast is going to be removed so stop using it. BUG=529769,472900 R=mark@chromium.org Review URL: https://codereview.chromium.org/1335353002 .
102 lines
3.3 KiB
C++
102 lines
3.3 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/basictypes.h"
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#include "base/logging.h"
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#include "util/misc/implicit_cast.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 = ((implicit_cast<uint64_t>(st[7]) & 0x7f) << 56) |
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(implicit_cast<uint64_t>(st[6]) << 48) |
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(implicit_cast<uint64_t>(st[5]) << 40) |
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(implicit_cast<uint64_t>(st[4]) << 32) |
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(implicit_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 ~0ull;
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}
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}
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} // namespace crashpad
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