[thirdparty/glibc.git] / sysdeps / unix / sysv / linux / hppa / pt-vfork.S

/* Copyright (C) 2005-2016 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>
#define _ERRNO_H        1
#include <bits/errno.h>
#include <tcb-offsets.h>

/* Clone the calling process, but without copying the whole address space.
   The calling process is suspended until the new process exits or is
   replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
   and the process ID of the new process to the old process.  */

/* Load the thread register.
   Load the saved PID value.
   Negate the value.
   Store the temporary PID. */
#define SAVE_PID							\
	mfctl %cr27, %r26				ASM_LINE_SEP	\
	ldw PID_THREAD_OFFSET(%r26),%r1			ASM_LINE_SEP    \
	sub %r0,%r1,%r1					ASM_LINE_SEP    \
	stw %r1,PID_THREAD_OFFSET(%r26)			ASM_LINE_SEP
/* If we are the parent...
   Get the thread pointer.
   Load the saved PID.
   Negate the value (got back original)
   Restore the PID. */
#define RESTORE_PID							\
	cmpb,=,n %r0,%ret0,.Lthread_start		ASM_LINE_SEP	\
	mfctl %cr27, %r26				ASM_LINE_SEP	\
	ldw PID_THREAD_OFFSET(%r26),%r1			ASM_LINE_SEP	\
	sub %r0,%r1,%r1					ASM_LINE_SEP	\
	stw %r1,PID_THREAD_OFFSET(%r26)			ASM_LINE_SEP	\
.Lthread_start:						ASM_LINE_SEP

	/* r26, r25, r24, r23 are free since vfork has no arguments */
ENTRY(__vfork)
	/* We must not create a frame. When the child unwinds to call
	   exec it will clobber the same frame that the parent
	   needs to unwind.  */

	/* Save the PIC register. */
#ifdef PIC
	copy	%r19, %r25	/* parent */
#endif

	/* Save the process PID */
	SAVE_PID

	/* Syscall saves and restores all register states */
	ble	0x100(%sr2,%r0)
	ldi	__NR_vfork,%r20

	/* Conditionally restore the PID */
	RESTORE_PID

	/* Check for error */
	ldi	-4096,%r1
	comclr,>>= %r1,%ret0,%r0        /* Note: unsigned compare. */
	b,n	.Lerror

	/* Return, and DO NOT restore rp. The child may have called
	   functions that updated the frame's rp. This works because
	   the kernel ensures rp is preserved across the vfork
	   syscall.  */
	bv,n	%r0(%rp)

.Lerror:
	/* Now we need a stack to call a function. We are assured
	   that there is no child now, so it's safe to create
	   a frame.  */
	stw	%rp, -20(%sp)
	stwm	%r3, 64(%sp)
	stw	%sp, -4(%sp)

	sub	%r0,%ret0,%r3
	SYSCALL_ERROR_HANDLER
	/* Restore the PIC register (in delay slot) on error */
#ifdef PIC
	copy	%r25, %r19    /* parent */
#else
	nop
#endif
	/* Write syscall return into errno location */
	stw	%r3, 0(%ret0)
	ldw	-84(%sp), %rp
	bv	%r0(%rp)
	ldwm	-64(%sp), %r3
PSEUDO_END (__vfork)
libc_hidden_def (__vfork)
weak_alias (__vfork, vfork)
Commit	Line	Data
f7a9f785	1	/* Copyright (C) 2005-2016 Free Software Foundation, Inc.
da1ea0f0 CD	2	This file is part of the GNU C Library.
	3
	4	The GNU C Library is free software; you can redistribute it and/or
	5	modify it under the terms of the GNU Lesser General Public
	6	License as published by the Free Software Foundation; either
	7	version 2.1 of the License, or (at your option) any later version.
	8
	9	The GNU C Library is distributed in the hope that it will be useful,
	10	but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	12	Lesser General Public License for more details.
	13
	14	You should have received a copy of the GNU Lesser General Public
ab84e3ff PE	15	License along with the GNU C Library. If not, see
ab84e3ff PE	16	<http://www.gnu.org/licenses/>. */
da1ea0f0 CD	17
	18	#include <sysdep.h>
	19	#define _ERRNO_H 1
	20	#include <bits/errno.h>
	21	#include <tcb-offsets.h>
	22
	23	/* Clone the calling process, but without copying the whole address space.
	24	The calling process is suspended until the new process exits or is
	25	replaced by a call to `execve'. Return -1 for errors, 0 to the new process,
	26	and the process ID of the new process to the old process. */
	27
	28	/* Load the thread register.
	29	Load the saved PID value.
	30	Negate the value.
	31	Store the temporary PID. */
	32	#define SAVE_PID \
	33	mfctl %cr27, %r26 ASM_LINE_SEP \
	34	ldw PID_THREAD_OFFSET(%r26),%r1 ASM_LINE_SEP \
	35	sub %r0,%r1,%r1 ASM_LINE_SEP \
	36	stw %r1,PID_THREAD_OFFSET(%r26) ASM_LINE_SEP
	37	/* If we are the parent...
	38	Get the thread pointer.
	39	Load the saved PID.
	40	Negate the value (got back original)
	41	Restore the PID. */
	42	#define RESTORE_PID \
	43	cmpb,=,n %r0,%ret0,.Lthread_start ASM_LINE_SEP \
	44	mfctl %cr27, %r26 ASM_LINE_SEP \
	45	ldw PID_THREAD_OFFSET(%r26),%r1 ASM_LINE_SEP \
	46	sub %r0,%r1,%r1 ASM_LINE_SEP \
	47	stw %r1,PID_THREAD_OFFSET(%r26) ASM_LINE_SEP \
	48	.Lthread_start: ASM_LINE_SEP
	49
	50	/* r26, r25, r24, r23 are free since vfork has no arguments */
	51	ENTRY(__vfork)
5556231d	52	/* We must not create a frame. When the child unwinds to call
3680f14a CD	53	exec it will clobber the same frame that the parent
3680f14a CD	54	needs to unwind. */
da1ea0f0 CD	55
	56	/* Save the PIC register. */
	57	#ifdef PIC
	58	copy %r19, %r25 /* parent */
	59	#endif
	60
	61	/* Save the process PID */
	62	SAVE_PID
	63
	64	/* Syscall saves and restores all register states */
	65	ble 0x100(%sr2,%r0)
	66	ldi __NR_vfork,%r20
	67
	68	/* Conditionally restore the PID */
	69	RESTORE_PID
	70
	71	/* Check for error */
	72	ldi -4096,%r1
	73	comclr,>>= %r1,%ret0,%r0 /* Note: unsigned compare. */
	74	b,n .Lerror
	75
3680f14a CD	76	/* Return, and DO NOT restore rp. The child may have called
3680f14a CD	77	functions that updated the frame's rp. This works because
5556231d	78	the kernel ensures rp is preserved across the vfork
3680f14a CD	79	syscall. */
3680f14a CD	80	bv,n %r0(%rp)
da1ea0f0 CD	81
da1ea0f0 CD	82	.Lerror:
3680f14a CD	83	/* Now we need a stack to call a function. We are assured
	84	that there is no child now, so it's safe to create
	85	a frame. */
	86	stw %rp, -20(%sp)
	87	stwm %r3, 64(%sp)
	88	stw %sp, -4(%sp)
	89
0daa0500	90	sub %r0,%ret0,%r3
da1ea0f0 CD	91	SYSCALL_ERROR_HANDLER
	92	/* Restore the PIC register (in delay slot) on error */
	93	#ifdef PIC
	94	copy %r25, %r19 /* parent */
	95	#else
	96	nop
	97	#endif
0daa0500 CD	98	/* Write syscall return into errno location */
	99	stw %r3, 0(%ret0)
	100	ldw -84(%sp), %rp
	101	bv %r0(%rp)
	102	ldwm -64(%sp), %r3
da1ea0f0 CD	103	PSEUDO_END (__vfork)
	104	libc_hidden_def (__vfork)
	105	weak_alias (__vfork, vfork)