; Copyright 2015 The Crashpad Authors
;
; 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.
; Detect ml64 assembling for x86_64 by checking for rax.
ifdef rax
_M_X64 equ 1
else
_M_IX86 equ 1
endif
ifdef _M_IX86
.586
.xmm
.model flat
endif
; The CONTEXT structure definitions that follow are based on those in <winnt.h>.
; Field names are prefixed (as in c_Rax) to avoid colliding with the predefined
; register names (such as Rax).
ifdef _M_IX86
CONTEXT_i386 equ 10000h
CONTEXT_CONTROL equ CONTEXT_i386 or 1h
CONTEXT_INTEGER equ CONTEXT_i386 or 2h
CONTEXT_SEGMENTS equ CONTEXT_i386 or 4h
CONTEXT_FLOATING_POINT equ CONTEXT_i386 or 8h
CONTEXT_DEBUG_REGISTERS equ CONTEXT_i386 or 10h
CONTEXT_EXTENDED_REGISTERS equ CONTEXT_i386 or 20h
CONTEXT_XSTATE equ CONTEXT_i386 or 40h
MAXIMUM_SUPPORTED_EXTENSION equ 512
CONTEXT struct
c_ContextFlags dword ?
c_Dr0 dword ?
c_Dr1 dword ?
c_Dr2 dword ?
c_Dr3 dword ?
c_Dr6 dword ?
c_Dr7 dword ?
struct c_FloatSave
f_ControlWord dword ?
f_StatusWord dword ?
f_TagWord dword ?
f_ErrorOffset dword ?
f_ErrorSelector dword ?
f_DataOffset dword ?
f_DataSelector dword ?
f_RegisterArea byte 80 dup(?)
union
f_Spare0 dword ? ; As in FLOATING_SAVE_AREA.
f_Cr0NpxState dword ? ; As in WOW64_FLOATING_SAVE_AREA.
ends
ends
c_SegGs dword ?
c_SegFs dword ?
c_SegEs dword ?
c_SegDs dword ?
c_Edi dword ?
c_Esi dword ?
c_Ebx dword ?
c_Edx dword ?
c_Ecx dword ?
c_Eax dword ?
c_Ebp dword ?
c_Eip dword ?
c_SegCs dword ?
c_EFlags dword ?
c_Esp dword ?
c_SegSs dword ?
c_ExtendedRegisters byte MAXIMUM_SUPPORTED_EXTENSION dup(?)
CONTEXT ends
elseifdef _M_X64
M128A struct 16
m_Low qword ?
m_High qword ?
M128A ends
CONTEXT_AMD64 equ 100000h
CONTEXT_CONTROL equ CONTEXT_AMD64 or 1h
CONTEXT_INTEGER equ CONTEXT_AMD64 or 2h
CONTEXT_SEGMENTS equ CONTEXT_AMD64 or 4h
CONTEXT_FLOATING_POINT equ CONTEXT_AMD64 or 8h
CONTEXT_DEBUG_REGISTERS equ CONTEXT_AMD64 or 10h
CONTEXT_XSTATE equ CONTEXT_AMD64 or 40h
CONTEXT struct 16
c_P1Home qword ?
c_P2Home qword ?
c_P3Home qword ?
c_P4Home qword ?
c_P5Home qword ?
c_P6Home qword ?
c_ContextFlags dword ?
c_MxCsr dword ?
c_SegCs word ?
c_SegDs word ?
c_SegEs word ?
c_SegFs word ?
c_SegGs word ?
c_SegSs word ?
c_EFlags dword ?
c_Dr0 qword ?
c_Dr1 qword ?
c_Dr2 qword ?
c_Dr3 qword ?
c_Dr6 qword ?
c_Dr7 qword ?
c_Rax qword ?
c_Rcx qword ?
c_Rdx qword ?
c_Rbx qword ?
c_Rsp qword ?
c_Rbp qword ?
c_Rsi qword ?
c_Rdi qword ?
c_R8 qword ?
c_R9 qword ?
c_R10 qword ?
c_R11 qword ?
c_R12 qword ?
c_R13 qword ?
c_R14 qword ?
c_R15 qword ?
c_Rip qword ?
union
struct c_FltSave
f_ControlWord word ?
f_StatusWord word ?
f_TagWord byte ?
f_Reserved1 byte ?
f_ErrorOpcode word ?
f_ErrorOffset dword ?
f_ErrorSelector word ?
f_Reserved2 word ?
f_DataOffset dword ?
f_DataSelector word ?
f_Reserved3 word ?
f_MxCsr dword ?
f_MxCsr_Mask dword ?
f_FloatRegisters M128A 8 dup(<?>)
f_XmmRegisters M128A 16 dup(<?>)
f_Reserved4 byte 96 dup(?)
ends
struct
fx_Header M128A 2 dup(<?>)
fx_Legacy M128A 8 dup(<?>)
fx_Xmm0 M128A <?>
fx_Xmm1 M128A <?>
fx_Xmm2 M128A <?>
fx_Xmm3 M128A <?>
fx_Xmm4 M128A <?>
fx_Xmm5 M128A <?>
fx_Xmm6 M128A <?>
fx_Xmm7 M128A <?>
fx_Xmm8 M128A <?>
fx_Xmm9 M128A <?>
fx_Xmm10 M128A <?>
fx_Xmm11 M128A <?>
fx_Xmm12 M128A <?>
fx_Xmm13 M128A <?>
fx_Xmm14 M128A <?>
fx_Xmm15 M128A <?>
ends
ends
c_VectorRegister M128A 26 dup(<?>)
c_VectorControl qword ?
c_DebugControl qword ?
c_LastBranchToRip qword ?
c_LastBranchFromRip qword ?
c_LastExceptionToRip qword ?
c_LastExceptionFromRip qword ?
CONTEXT ends
endif
; namespace crashpad {
; void CaptureContext(CONTEXT* context);
; } // namespace crashpad
ifdef _M_IX86
CAPTURECONTEXT_SYMBOL equ ?CaptureContext@crashpad@@YAXPAU_CONTEXT@@@Z
elseifdef _M_X64
CAPTURECONTEXT_SYMBOL equ ?CaptureContext@crashpad@@YAXPEAU_CONTEXT@@@Z
endif
_TEXT segment
public CAPTURECONTEXT_SYMBOL
ifdef _M_IX86
CAPTURECONTEXT_SYMBOL proc
push ebp
mov ebp, esp
; pushfd first, because some instructions affect eflags. eflags will be in
; [ebp-4].
pushfd
; Save the original value of ebx, and use ebx to hold the CONTEXT* argument.
; The original value of ebx will be in [ebp-8].
push ebx
mov ebx, [ebp+8]
; General-purpose registers whose values haven’t changed can be captured
; directly.
mov [ebx.CONTEXT].c_Edi, edi
mov [ebx.CONTEXT].c_Esi, esi
mov [ebx.CONTEXT].c_Edx, edx
mov [ebx.CONTEXT].c_Ecx, ecx
mov [ebx.CONTEXT].c_Eax, eax
; Now that the original value of edx has been saved, it can be repurposed to
; hold other registers’ values.
; The original ebx was saved on the stack above.
mov edx, dword ptr [ebp-8]
mov [ebx.CONTEXT].c_Ebx, edx
; The original ebp was saved on the stack in this function’s prologue.
mov edx, dword ptr [ebp]
mov [ebx.CONTEXT].c_Ebp, edx
; eip can’t be accessed directly, but the return address saved on the stack
; by the call instruction that reached this function can be used.
mov edx, dword ptr [ebp+4]
mov [ebx.CONTEXT].c_Eip, edx
; The original eflags was saved on the stack above.
mov edx, dword ptr [ebp-4]
mov [ebx.CONTEXT].c_EFlags, edx
; esp was saved in ebp in this function’s prologue, but the caller’s esp is 8
; more than this value: 4 for the original ebp saved on the stack in this
; function’s prologue, and 4 for the return address saved on the stack by the
; call instruction that reached this function.
lea edx, [ebp+8]
mov [ebx.CONTEXT].c_Esp, edx
; The segment registers are 16 bits wide, but CONTEXT declares them as
; unsigned 32-bit values, so zero the top half.
xor edx, edx
mov dx, gs
mov [ebx.CONTEXT].c_SegGs, edx
mov dx, fs
mov [ebx.CONTEXT].c_SegFs, edx
mov dx, es
mov [ebx.CONTEXT].c_SegEs, edx
mov dx, ds
mov [ebx.CONTEXT].c_SegDs, edx
mov dx, cs
mov [ebx.CONTEXT].c_SegCs, edx
mov dx, ss
mov [ebx.CONTEXT].c_SegSs, edx
; Prepare for the string move that will populate the ExtendedRegisters area,
; or the string store that will zero it.
cld
; Use cpuid 1 to check whether fxsave is supported. If it is, perform it
; before fnsave because fxsave is a less-destructive operation.
mov esi, ebx
mov eax, 1
cpuid
mov ebx, esi
test edx, 01000000 ; FXSR
jnz $FXSave
; fxsave is not supported. Set ContextFlags to not include
; CONTEXT_EXTENDED_REGISTERS, and zero the ExtendedRegisters area.
mov [ebx.CONTEXT].c_ContextFlags, CONTEXT_i386 or \
CONTEXT_CONTROL or \
CONTEXT_INTEGER or \
CONTEXT_SEGMENTS or \
CONTEXT_FLOATING_POINT
lea edi, [ebx.CONTEXT].c_ExtendedRegisters
xor eax, eax
mov ecx, MAXIMUM_SUPPORTED_EXTENSION / sizeof(dword) ; 128
rep stosd
jmp $FXSaveDone
$FXSave:
; fxsave is supported. Set ContextFlags to include CONTEXT_EXTENDED_REGISTERS.
mov [ebx.CONTEXT].c_ContextFlags, CONTEXT_i386 or \
CONTEXT_CONTROL or \
CONTEXT_INTEGER or \
CONTEXT_SEGMENTS or \
CONTEXT_FLOATING_POINT or \
CONTEXT_EXTENDED_REGISTERS
; fxsave requires a 16 byte-aligned destination memory area. Nothing
; guarantees the alignment of a CONTEXT structure, so create a temporary
; aligned fxsave destination on the stack.
and esp, 0fffffff0h
sub esp, MAXIMUM_SUPPORTED_EXTENSION
; Zero out the temporary fxsave area before performing the fxsave. Some of the
; fxsave area may not be written by fxsave, and some is definitely not written
; by fxsave.
mov edi, esp
xor eax, eax
mov ecx, MAXIMUM_SUPPORTED_EXTENSION / sizeof(dword) ; 128
rep stosd
fxsave [esp]
; Copy the temporary fxsave area into the CONTEXT structure.
lea edi, [ebx.CONTEXT].c_ExtendedRegisters
mov esi, esp
mov ecx, MAXIMUM_SUPPORTED_EXTENSION / sizeof(dword) ; 128
rep movsd
; Free the stack space used for the temporary fxsave area.
lea esp, [ebp-8]
; TODO(mark): AVX/xsave support. https://crashpad.chromium.org/bug/58
$FXSaveDone:
; fnsave reinitializes the FPU with an implicit finit operation, so use frstor
; to restore the original state.
fnsave [ebx.CONTEXT].c_FloatSave
frstor [ebx.CONTEXT].c_FloatSave
; cr0 is inaccessible from user code, and this field would not be used anyway.
mov [ebx.CONTEXT].c_FloatSave.f_Cr0NpxState, 0
; The debug registers can’t be read from user code, so zero them out in the
; CONTEXT structure. context->ContextFlags doesn’t indicate that they are
; present.
mov [ebx.CONTEXT].c_Dr0, 0
mov [ebx.CONTEXT].c_Dr1, 0
mov [ebx.CONTEXT].c_Dr2, 0
mov [ebx.CONTEXT].c_Dr3, 0
mov [ebx.CONTEXT].c_Dr6, 0
mov [ebx.CONTEXT].c_Dr7, 0
; Clean up by restoring clobbered registers, even those considered volatile
; by the ABI, so that the captured context represents the state at this
; function’s exit.
mov edi, [ebx.CONTEXT].c_Edi
mov esi, [ebx.CONTEXT].c_Esi
mov edx, [ebx.CONTEXT].c_Edx
mov ecx, [ebx.CONTEXT].c_Ecx
mov eax, [ebx.CONTEXT].c_Eax
pop ebx
popfd
pop ebp
ret
CAPTURECONTEXT_SYMBOL endp
elseifdef _M_X64
CAPTURECONTEXT_SYMBOL proc frame
push rbp
.pushreg rbp
mov rbp, rsp
.setframe rbp, 0
; Note that 16-byte stack alignment is not maintained because this function
; does not call out to any other.
; pushfq first, because some instructions affect rflags. rflags will be in
; [rbp-8].
pushfq
.allocstack 8
.endprolog
mov [rcx.CONTEXT].c_ContextFlags, CONTEXT_AMD64 or \
CONTEXT_CONTROL or \
CONTEXT_INTEGER or \
CONTEXT_SEGMENTS or \
CONTEXT_FLOATING_POINT
; General-purpose registers whose values haven’t changed can be captured
; directly.
mov [rcx.CONTEXT].c_Rax, rax
mov [rcx.CONTEXT].c_Rdx, rdx
mov [rcx.CONTEXT].c_Rbx, rbx
mov [rcx.CONTEXT].c_Rsi, rsi
mov [rcx.CONTEXT].c_Rdi, rdi
mov [rcx.CONTEXT].c_R8, r8
mov [rcx.CONTEXT].c_R9, r9
mov [rcx.CONTEXT].c_R10, r10
mov [rcx.CONTEXT].c_R11, r11
mov [rcx.CONTEXT].c_R12, r12
mov [rcx.CONTEXT].c_R13, r13
mov [rcx.CONTEXT].c_R14, r14
mov [rcx.CONTEXT].c_R15, r15
; Because of the calling convention, there’s no way to recover the value of
; the caller’s rcx as it existed prior to calling this function. This
; function captures a snapshot of the register state at its return, which
; involves rcx containing a pointer to its first argument.
mov [rcx.CONTEXT].c_Rcx, rcx
; Now that the original value of rax has been saved, it can be repurposed to
; hold other registers’ values.
; Save mxcsr. This is duplicated in context->FltSave.MxCsr, saved by fxsave
; below.
stmxcsr [rcx.CONTEXT].c_MxCsr
; Segment registers.
mov [rcx.CONTEXT].c_SegCs, cs
mov [rcx.CONTEXT].c_SegDs, ds
mov [rcx.CONTEXT].c_SegEs, es
mov [rcx.CONTEXT].c_SegFs, fs
mov [rcx.CONTEXT].c_SegGs, gs
mov [rcx.CONTEXT].c_SegSs, ss
; The original rflags was saved on the stack above. Note that the CONTEXT
; structure only stores eflags, the low 32 bits. The high 32 bits in rflags
; are reserved.
mov rax, qword ptr [rbp-8]
mov [rcx.CONTEXT].c_EFlags, eax
; rsp was saved in rbp in this function’s prologue, but the caller’s rsp is
; 16 more than this value: 8 for the original rbp saved on the stack in this
; function’s prologue, and 8 for the return address saved on the stack by the
; call instruction that reached this function.
lea rax, [rbp+16]
mov [rcx.CONTEXT].c_Rsp, rax
; The original rbp was saved on the stack in this function’s prologue.
mov rax, qword ptr [rbp]
mov [rcx.CONTEXT].c_Rbp, rax
; rip can’t be accessed directly, but the return address saved on the stack by
; the call instruction that reached this function can be used.
mov rax, qword ptr [rbp+8]
mov [rcx.CONTEXT].c_Rip, rax
; Zero out the fxsave area before performing the fxsave. Some of the fxsave
; area may not be written by fxsave, and some is definitely not written by
; fxsave. This also zeroes out the rest of the CONTEXT structure to its end,
; including the unused VectorRegister and VectorControl fields, and the debug
; control register fields.
mov rbx, rcx
cld
lea rdi, [rcx.CONTEXT].c_FltSave
xor rax, rax
mov rcx, (sizeof(CONTEXT) - CONTEXT.c_FltSave) / sizeof(qword) ; 122
rep stosq
mov rcx, rbx
; Save the floating point (including SSE) state. The CONTEXT structure is
; declared as 16-byte-aligned, which is correct for this operation.
fxsave [rcx.CONTEXT].c_FltSave
; TODO(mark): AVX/xsave support. https://crashpad.chromium.org/bug/58
; The register parameter home address fields aren’t used, so zero them out.
mov [rcx.CONTEXT].c_P1Home, 0
mov [rcx.CONTEXT].c_P2Home, 0
mov [rcx.CONTEXT].c_P3Home, 0
mov [rcx.CONTEXT].c_P4Home, 0
mov [rcx.CONTEXT].c_P5Home, 0
mov [rcx.CONTEXT].c_P6Home, 0
; The debug registers can’t be read from user code, so zero them out in the
; CONTEXT structure. context->ContextFlags doesn’t indicate that they are
; present.
mov [rcx.CONTEXT].c_Dr0, 0
mov [rcx.CONTEXT].c_Dr1, 0
mov [rcx.CONTEXT].c_Dr2, 0
mov [rcx.CONTEXT].c_Dr3, 0
mov [rcx.CONTEXT].c_Dr6, 0
mov [rcx.CONTEXT].c_Dr7, 0
; Clean up by restoring clobbered registers, even those considered volatile by
; the ABI, so that the captured context represents the state at this
; function’s exit.
mov rax, [rcx.CONTEXT].c_Rax
mov rbx, [rcx.CONTEXT].c_Rbx
mov rdi, [rcx.CONTEXT].c_Rdi
popfq
pop rbp
ret
CAPTURECONTEXT_SYMBOL endp
endif
_TEXT ends
end
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