MdePkg: Replace BSD License with BSD+Patent License

[mirror_edk2.git] / MdePkg / Library / BaseLib / Ia32 / SetJump.c

/** @file\r
  Implementation of SetJump() on IA-32.\r
\r
  Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\r
\r
**/\r
\r
\r
#include "BaseLibInternals.h"\r
\r
/**\r
  Worker function that checks ASSERT condition for JumpBuffer\r
\r
  Checks ASSERT condition for JumpBuffer.\r
\r
  If JumpBuffer is NULL, then ASSERT().\r
  For IPF CPUs, if JumpBuffer is not aligned on a 16-byte boundary, then ASSERT().\r
\r
  @param  JumpBuffer    A pointer to CPU context buffer.\r
\r
**/\r
VOID\r
EFIAPI\r
InternalAssertJumpBuffer (\r
  IN      BASE_LIBRARY_JUMP_BUFFER  *JumpBuffer\r
  );\r
\r
/**\r
  Saves the current CPU context that can be restored with a call to LongJump()\r
  and returns 0.\r
\r
  Saves the current CPU context in the buffer specified by JumpBuffer and\r
  returns 0. The initial call to SetJump() must always return 0. Subsequent\r
  calls to LongJump() cause a non-zero value to be returned by SetJump().\r
\r
  If JumpBuffer is NULL, then ASSERT().\r
  For IPF CPUs, if JumpBuffer is not aligned on a 16-byte boundary, then ASSERT().\r
\r
  @param  JumpBuffer  A pointer to CPU context buffer.\r
\r
  @retval 0 Indicates a return from SetJump().\r
\r
**/\r
_declspec (naked)\r
RETURNS_TWICE\r
UINTN\r
EFIAPI\r
SetJump (\r
  OUT     BASE_LIBRARY_JUMP_BUFFER  *JumpBuffer\r
  )\r
{\r
  _asm {\r
    push    [esp + 4]\r
    call    InternalAssertJumpBuffer\r
    pop     ecx\r
    pop     ecx\r
    mov     edx, [esp]\r
\r
    xor     eax, eax\r
    mov     [edx + 24], eax        ; save 0 to SSP\r
\r
    mov     eax, [PcdGet32 (PcdControlFlowEnforcementPropertyMask)]\r
    test    eax, eax\r
    jz      CetDone\r
    _emit      0x0F\r
    _emit      0x20\r
    _emit      0xE0                ; mov     eax, cr4\r
    bt      eax, 23                ; check if CET is enabled\r
    jnc     CetDone\r
\r
    mov     eax, 1\r
    _emit      0xF3\r
    _emit      0x0F\r
    _emit      0xAE\r
    _emit      0xE8                ; INCSSP EAX to read original SSP\r
    _emit      0xF3\r
    _emit      0x0F\r
    _emit      0x1E\r
    _emit      0xC8                ; READSSP EAX\r
    mov     [edx + 0x24], eax      ; save SSP\r
\r
CetDone:\r
\r
    mov     [edx], ebx\r
    mov     [edx + 4], esi\r
    mov     [edx + 8], edi\r
    mov     [edx + 12], ebp\r
    mov     [edx + 16], esp\r
    mov     [edx + 20], ecx\r
    xor     eax, eax\r
    jmp     ecx\r
  }\r
}\r
\r