crashpad::CPUContextX86 Struct Reference

A context structure carrying 32-bit x86 CPU state. More...

`#include "snapshot/cpu_context.h"`

## Classes

struct | Fsave
struct | Fxsave
union | X87OrMMXRegister

## Public Types

using | X87Register = uint8_t[10]
using | XMMRegister = uint8_t[16]

## Static Public Member Functions

static void | FxsaveToFsave (const Fxsave &fxsave, Fsave *fsave)
| Converts an `fxsave` area to an `fsave` area. More...
static void | FsaveToFxsave (const Fsave &fsave, Fxsave *fxsave)
| Converts an `fsave` area to an `fxsave` area. More...
static uint16_t | FxsaveToFsaveTagWord (uint16_t fsw, uint8_t fxsave_tag, const X87OrMMXRegister st_mm[8])
| Converts x87 floating-point tag words from `fxsave` (abridged, 8-bit) to `fsave` (full, 16-bit) form. More...
static uint8_t | FsaveToFxsaveTagWord (uint16_t fsave_tag)
| Converts x87 floating-point tag words from `fsave` (full, 16-bit) to `fxsave` (abridged, 8-bit) form. More...

## Public Attributes

uint32_t | eax
uint32_t | ebx
uint32_t | ecx
uint32_t | edx
uint32_t | edi
uint32_t | esi
uint32_t | ebp
uint32_t | esp
uint32_t | eip
uint32_t | eflags
uint16_t | cs
uint16_t | ds
uint16_t | es
uint16_t | fs
uint16_t | gs
uint16_t | ss
Fxsave | fxsave
uint32_t | dr0
uint32_t | dr1
uint32_t | dr2
uint32_t | dr3
uint32_t | dr4
uint32_t | dr5
uint32_t | dr6
uint32_t | dr7

## Detailed Description

A context structure carrying 32-bit x86 CPU state.

## Member Function Documentation

## FsaveToFxsave()

void crashpad::CPUContextX86::FsaveToFxsave | ( | const Fsave & | fsave,
|  | Fxsave * | fxsave
| ) |  |

static

Converts an `fsave` area to an `fxsave` area.

`fsave` state is restricted to the x87 FPU, while `fxsave` state includes state related to the x87 FPU as well as state specific to SSE.

As the `fsave` format is a subset of the `fxsave` format, this operation cannot fully populate the `fxsave` area. Fields in fxsave that have no equivalent in fsave are set to `0`, including Fxsave::mxcsr, Fxsave::mxcsr_mask, Fxsave::xmm, and Fxsave::available. FsaveToFxsaveTagWord() is used to derive Fxsave::ftw from the full 16-bit form used by `fsave`. Reserved fields in fxsave are set to `0`.

Parameters

  [in] | fsave | The `fsave` area to convert.
  [out] | fxsave | The `fxsave` area to populate.

See also
  FxsaveToFsave()

## FsaveToFxsaveTagWord()

uint8_t crashpad::CPUContextX86::FsaveToFxsaveTagWord | ( | uint16_t | fsave_tag | ) |

static

Converts x87 floating-point tag words from `fsave` (full, 16-bit) to `fxsave` (abridged, 8-bit) form.

This function performs the inverse operation of FxsaveToFsaveTagWord().

Parameters

  [in] | fsave_tag | The full FPU tag word.

Returns
  The abridged FPU tag word.

## FxsaveToFsave()

void crashpad::CPUContextX86::FxsaveToFsave | ( | const Fxsave & | fxsave,
|  | Fsave * | fsave
| ) |  |

static

Converts an `fxsave` area to an `fsave` area.

`fsave` state is restricted to the x87 FPU, while `fxsave` state includes state related to the x87 FPU as well as state specific to SSE.

As the `fxsave` format is a superset of the `fsave` format, this operation fully populates the `fsave` area. `fsave` uses the full 16-bit form for the x87 floating-point tag word, so FxsaveToFsaveTagWord() is used to derive Fsave::ftw from the abridged 8-bit form used by `fxsave`. Reserved fields in fsave are set to `0`.

Parameters

  [in] | fxsave | The `fxsave` area to convert.
  [out] | fsave | The `fsave` area to populate.

See also
  FsaveToFxsave()

## FxsaveToFsaveTagWord()

uint16_t crashpad::CPUContextX86::FxsaveToFsaveTagWord | ( | uint16_t | fsw,
|  | uint8_t | fxsave_tag,
|  | const X87OrMMXRegister | st_mm[8]
| ) |  |

static

Converts x87 floating-point tag words from `fxsave` (abridged, 8-bit) to `fsave` (full, 16-bit) form.

`fxsave` stores the x87 floating-point tag word in abridged 8-bit form, and `fsave` stores it in full 16-bit form. Some users, notably CPUContextX86::Fsave::ftw, require the full 16-bit form, where most other contemporary code uses `fxsave` and thus the abridged 8-bit form found in CPUContextX86::Fxsave::ftw.

This function converts an abridged tag word to the full version by using the abridged tag word and the contents of the registers it describes. See Intel Software Developer’s Manual, Volume 2A: Instruction Set Reference A-M (253666-052), 3.2 “FXSAVE”, specifically, the notes on the abridged FTW and recreating the FSAVE format, and AMD Architecture Programmer’s Manual, Volume 2: System Programming (24593-3.24), “FXSAVE Format for x87 Tag Word”.

See also
  FsaveToFxsaveTagWord()

Parameters

  [in] | fsw | The FPU status word, used to map logical st_mm registers to their physical counterparts. This can be taken from CPUContextX86::Fxsave::fsw.
  [in] | fxsave_tag | The abridged FPU tag word. This can be taken from CPUContextX86::Fxsave::ftw.
  [in] | st_mm | The floating-point registers in logical order. This can be taken from CPUContextX86::Fxsave::st_mm.

Returns
  The full FPU tag word.

The documentation for this struct was generated from the following files:

- snapshot/cpu_context.h
- snapshot/cpu_context.cc