/* Save current context.

   Copyright (C) 2002-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Andreas Jaeger <aj@suse.de>, 2002.

   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 <asm/prctl.h>

#include "ucontext_i.h"

/*  int __getcontext (ucontext_t *ucp)

  Saves the machine context in UCP such that when it is activated,

  it appears as if __getcontext() returned again.

  This implementation is intended to be used for *synchronous* context

  switches only.  Therefore, it does not have to save anything

  other than the PRESERVED state.  */

ENTRY(__getcontext)

	/* Save the preserved registers, the registers used for passing

	   args, and the return address.  */

	movq	%rbx, oRBX(%rdi)

	movq	%rbp, oRBP(%rdi)

	movq	%r12, oR12(%rdi)

	movq	%r13, oR13(%rdi)

	movq	%r14, oR14(%rdi)

	movq	%r15, oR15(%rdi)

	movq	%rdi, oRDI(%rdi)

	movq	%rsi, oRSI(%rdi)

	movq	%rdx, oRDX(%rdi)

	movq	%rcx, oRCX(%rdi)

	movq	%r8, oR8(%rdi)

	movq	%r9, oR9(%rdi)

	movq	(%rsp), %rcx

	movq	%rcx, oRIP(%rdi)

	leaq	8(%rsp), %rcx		/* Exclude the return address.  */

	movq	%rcx, oRSP(%rdi)

#if SHSTK_ENABLED

	/* Check if shadow stack is enabled.  */

	testl	$X86_FEATURE_1_SHSTK, %fs:FEATURE_1_OFFSET

	jz	L(no_shstk)

	/* Save RDI in RDX which won't be clobbered by syscall.  */

	movq	%rdi, %rdx

	xorl	%eax, %eax

	cmpq	%fs:SSP_BASE_OFFSET, %rax

	jnz	L(shadow_stack_bound_recorded)

	/* Get the base address and size of the default shadow stack

	   which must be the current shadow stack since nothing has

	   been recorded yet.  */

	sub	$24, %RSP_LP

	mov	%RSP_LP, %RSI_LP

	movl	$ARCH_CET_STATUS, %edi

	movl	$__NR_arch_prctl, %eax

	syscall

	testq	%rax, %rax

	jz	L(continue_no_err)

	/* This should never happen.  */

	hlt

L(continue_no_err):

	/* Record the base of the current shadow stack.  */

	movq	8(%rsp), %rax

	movq	%rax, %fs:SSP_BASE_OFFSET

	add	$24, %RSP_LP

	/* Restore RDI.  */

	movq	%rdx, %rdi

L(shadow_stack_bound_recorded):

	/* Get the current shadow stack pointer.  */

	rdsspq	%rax

	/* NB: Save the caller's shadow stack so that we can jump back

	   to the caller directly.  */

	addq	$8, %rax

	movq	%rax, oSSP(%rdx)

	/* Save the current shadow stack base in ucontext.  */

	movq	%fs:SSP_BASE_OFFSET, %rax

	movq	%rax, (oSSP + 8)(%rdi)

L(no_shstk):

#endif

	/* We have separate floating-point register content memory on the

	   stack.  We use the __fpregs_mem block in the context.  Set the

	   links up correctly.  */

	leaq	oFPREGSMEM(%rdi), %rcx

	movq	%rcx, oFPREGS(%rdi)

	/* Save the floating-point environment.  */

	fnstenv	(%rcx)

	fldenv	(%rcx)

	stmxcsr oMXCSR(%rdi)

	/* Save the current signal mask with

	   rt_sigprocmask (SIG_BLOCK, NULL, set,_NSIG/8).  */

	leaq	oSIGMASK(%rdi), %rdx

	xorl	%esi,%esi

#if SIG_BLOCK == 0

	xorl	%edi, %edi

#else

	movl	$SIG_BLOCK, %edi

#endif

	movl	$_NSIG8,%r10d

	movl	$__NR_rt_sigprocmask, %eax

	syscall

	cmpq	$-4095, %rax		/* Check %rax for error.  */

	jae	SYSCALL_ERROR_LABEL	/* Jump to error handler if error.  */

	/* All done, return 0 for success.  */

	xorl	%eax, %eax

	ret

PSEUDO_END(__getcontext)

weak_alias (__getcontext, getcontext)