/* Copyright (C) 2001-2018 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 shadow stack isn't enabled.  */

#if !SHSTK_ENABLED

# undef SHADOW_STACK_POINTER_OFFSET

#endif

	.section .rodata.str1.1,"aMS",@progbits,1

	.type	longjmp_msg,@object

longjmp_msg:

	.string "longjmp causes uninitialized stack frame"

	.size	longjmp_msg, .-longjmp_msg

#ifdef PIC

# define CALL_FAIL	movl	%ebx, %ecx;				      \

			cfi_register(%ebx,%ecx);			      \

			LOAD_PIC_REG (bx);				      \

			leal	longjmp_msg@GOTOFF(%ebx), %eax;		      \

			movl	%eax, (%esp);				      \

			call	HIDDEN_JUMPTARGET(__fortify_fail)

#else

# define CALL_FAIL	movl	$longjmp_msg, %eax;			      \

			movl	%eax, (%esp);				      \

			call	HIDDEN_JUMPTARGET(__fortify_fail)

#endif

	.text

ENTRY (____longjmp_chk)

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

#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(%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

	/* Get the stack pointer.  */

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

	cfi_undefined(%edi)

	PTR_DEMANGLE (%edx)

	PTR_DEMANGLE (%edi)

	cmpl	%edi, %esp

	jbe	.Lok

	subl	$12, %esp

	cfi_adjust_cfa_offset(12)

	xorl	%ebx, %ebx

	movl	%esp, %ecx

	movl	$__NR_sigaltstack, %eax

	ENTER_KERNEL

	/* Without working sigaltstack we cannot perform the test.  */

	test	%eax, %eax

	jne	.Lok2

	testl	$1, 4(%esp)

	jz	.Lfail

	movl	(%esp), %eax

	addl	8(%esp), %eax

	subl	%edi, %eax

	cmpl	8(%esp), %eax

	jae	.Lok2

.Lfail:	CALL_FAIL

.Lok2:	addl	$12, %esp

	cfi_adjust_cfa_offset(-12)

	movl	4(%esp), %ecx

.Lok:

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

	/* We add unwind information for the target here.  */

	cfi_def_cfa(%ecx, 0)

	cfi_register(%eip, %edx)

	cfi_register(%esp, %edi)

	cfi_offset(%ebx, JB_BX*4)

	cfi_offset(%esi, JB_SI*4)

	cfi_offset(%edi, JB_DI*4)

	cfi_offset(%ebp, JB_BP*4)

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

	movl	%edi, %esp

	/* 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

	cfi_restore(%ebx)

	cfi_restore(%esi)

	cfi_restore(%edi)

	cfi_restore(%ebp)

	/* Jump to saved PC.  */

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

	jmp	*%edx

END (____longjmp_chk)