/* longjmp for i386.

   Copyright (C) 1995-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <sysdep.h>

#include <jmpbuf-offsets.h>

#include <jmp_buf-ssp.h>

#include <asm-syntax.h>

#include <stap-probe.h>

/* Don't restore shadow stack register if

   1. Shadow stack isn't enabled.  Or

   2. __longjmp is defined for __longjmp_cancel.

 */

#if !SHSTK_ENABLED || defined __longjmp

# undef SHADOW_STACK_POINTER_OFFSET

#endif

	.text

ENTRY (__longjmp)

#ifdef PTR_DEMANGLE

	movl 4(%esp), %eax	/* User's jmp_buf in %eax.  */

# ifdef SHADOW_STACK_POINTER_OFFSET

#  if IS_IN (libc) && defined SHARED && defined FEATURE_1_OFFSET

	/* Check if Shadow Stack is enabled.  */

	testl $X86_FEATURE_1_SHSTK, %gs:FEATURE_1_OFFSET

	jz L(skip_ssp)

#  else

	xorl %edx, %edx

#  endif

	/* Check and adjust the Shadow-Stack-Pointer.  */

	rdsspd %edx

	/* And compare it with the saved ssp value.  */

	subl SHADOW_STACK_POINTER_OFFSET(%eax), %edx

	je L(skip_ssp)

	/* Count the number of frames to adjust and adjust it

	   with incssp instruction.  The instruction can adjust

	   the ssp by [0..255] value only thus use a loop if

	   the number of frames is bigger than 255.  */

	negl %edx

	shrl $2, %edx

	/* NB: We saved Shadow-Stack-Pointer of setjmp.  Since we are

	       restoring Shadow-Stack-Pointer of setjmp's caller, we

	       need to unwind shadow stack by one more frame.  */

	addl $1, %edx

	movl	$255, %ebx

L(loop):

	cmpl	%ebx, %edx

	cmovb	%edx, %ebx

	incsspd	%ebx

	subl	%ebx, %edx

	ja	L(loop)

L(skip_ssp):

# endif

	/* Save the return address now.  */

	movl (JB_PC*4)(%eax), %edx

	/* Get the stack pointer.  */

	movl (JB_SP*4)(%eax), %ecx

	PTR_DEMANGLE (%edx)

	PTR_DEMANGLE (%ecx)

	LIBC_PROBE (longjmp, 3, 4@%eax, -4@8(%esp), 4@%edx)

	cfi_def_cfa(%eax, 0)

	cfi_register(%eip, %edx)

	cfi_register(%esp, %ecx)

	cfi_offset(%ebx, JB_BX*4)

	cfi_offset(%esi, JB_SI*4)

	cfi_offset(%edi, JB_DI*4)

	cfi_offset(%ebp, JB_BP*4)

	/* Restore registers.  */

	movl (JB_BX*4)(%eax), %ebx

	movl (JB_SI*4)(%eax), %esi

	movl (JB_DI*4)(%eax), %edi

	movl (JB_BP*4)(%eax), %ebp

	cfi_restore(%ebx)

	cfi_restore(%esi)

	cfi_restore(%edi)

	cfi_restore(%ebp)

	LIBC_PROBE (longjmp_target, 3, 4@%eax, -4@8(%esp), 4@%edx)

	movl 8(%esp), %eax	/* Second argument is return value.  */

	movl %ecx, %esp

#else

	movl 4(%esp), %ecx	/* User's jmp_buf in %ecx.  */

	movl 8(%esp), %eax	/* Second argument is return value.  */

# ifdef SHADOW_STACK_POINTER_OFFSET

#  if IS_IN (libc) && defined SHARED

	/* Check if Shadow Stack is enabled.  */

	testl $X86_FEATURE_1_SHSTK, %gs:FEATURE_1_OFFSET

	jz L(skip_ssp)

#  endif

	/* Check and adjust the Shadow-Stack-Pointer.  */

	xorl %edx, %edx

	/* Get the current ssp.  */

	rdsspd	%edx

	/* And compare it with the saved ssp value.  */

	subl SHADOW_STACK_POINTER_OFFSET(%ecx), %edx

	je L(skip_ssp)

	/* Count the number of frames to adjust and adjust it

	   with incssp instruction.  The instruction can adjust

	   the ssp by [0..255] value only thus use a loop if

	   the number of frames is bigger than 255.  */

	negl %edx

	shrl $2, %edx

	/* NB: We saved Shadow-Stack-Pointer of setjmp.  Since we are

	       restoring Shadow-Stack-Pointer of setjmp's caller, we

	       need to unwind shadow stack by one more frame.  */

	addl $1, %edx

	movl	$255, %ebx

L(loop):

	cmpl	%ebx, %edx

	cmovb	%edx, %ebx

	incsspd	%ebx

	subl	%ebx, %edx

	ja	L(loop)

L(skip_ssp):

# endif

	/* Save the return address now.  */

	movl (JB_PC*4)(%ecx), %edx

	LIBC_PROBE (longjmp, 3, 4@%ecx, -4@%eax, 4@%edx)

	/* Restore registers.  */

	movl (JB_BX*4)(%ecx), %ebx

	movl (JB_SI*4)(%ecx), %esi

	movl (JB_DI*4)(%ecx), %edi

	movl (JB_BP*4)(%ecx), %ebp

	movl (JB_SP*4)(%ecx), %esp

	LIBC_PROBE (longjmp_target, 3, 4@%ecx, -4@%ecx, 4@%edx)

#endif

	/* Jump to saved PC.  */

	jmp *%edx

END (__longjmp)