path: root/arch/ia64/kernel/fsys.S

/*
 * This file contains the light-weight system call handlers (fsyscall-handlers).
 *
 * Copyright (C) 2003 Hewlett-Packard Co
 * 	David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * 25-Sep-03 davidm	Implement fsys_rt_sigprocmask().
 * 18-Feb-03 louisk	Implement fsys_gettimeofday().
 * 28-Feb-03 davidm	Fixed several bugs in fsys_gettimeofday().  Tuned it some more,
 *			probably broke it along the way... ;-)
 * 13-Jul-04 clameter   Implement fsys_clock_gettime and revise fsys_gettimeofday to make
 *                      it capable of using memory based clocks without falling back to C code.
 */

#include <asm/asmmacro.h>
#include <asm/errno.h>
#include <asm/asm-offsets.h>
#include <asm/percpu.h>
#include <asm/thread_info.h>
#include <asm/sal.h>
#include <asm/signal.h>
#include <asm/system.h>
#include <asm/unistd.h>

#include "entry.h"

/*
 * See Documentation/ia64/fsys.txt for details on fsyscalls.
 *
 * On entry to an fsyscall handler:
 *   r10	= 0 (i.e., defaults to "successful syscall return")
 *   r11	= saved ar.pfs (a user-level value)
 *   r15	= system call number
 *   r16	= "current" task pointer (in normal kernel-mode, this is in r13)
 *   r32-r39	= system call arguments
 *   b6		= return address (a user-level value)
 *   ar.pfs	= previous frame-state (a user-level value)
 *   PSR.be	= cleared to zero (i.e., little-endian byte order is in effect)
 *   all other registers may contain values passed in from user-mode
 *
 * On return from an fsyscall handler:
 *   r11	= saved ar.pfs (as passed into the fsyscall handler)
 *   r15	= system call number (as passed into the fsyscall handler)
 *   r32-r39	= system call arguments (as passed into the fsyscall handler)
 *   b6		= return address (as passed into the fsyscall handler)
 *   ar.pfs	= previous frame-state (as passed into the fsyscall handler)
 */

ENTRY(fsys_ni_syscall)
	.prologue
	.altrp b6
	.body
	mov r8=ENOSYS
	mov r10=-1
	FSYS_RETURN
END(fsys_ni_syscall)

ENTRY(fsys_getpid)
	.prologue
	.altrp b6
	.body
	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
	;;
	ld4 r9=[r9]
	add r8=IA64_TASK_TGID_OFFSET,r16
	;;
	and r9=TIF_ALLWORK_MASK,r9
	ld4 r8=[r8]				// r8 = current->tgid
	;;
	cmp.ne p8,p0=0,r9
(p8)	br.spnt.many fsys_fallback_syscall
	FSYS_RETURN
END(fsys_getpid)

ENTRY(fsys_getppid)
	.prologue
	.altrp b6
	.body
	add r17=IA64_TASK_GROUP_LEADER_OFFSET,r16
	;;
	ld8 r17=[r17]				// r17 = current->group_leader
	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
	;;

	ld4 r9=[r9]
	add r17=IA64_TASK_REAL_PARENT_OFFSET,r17 // r17 = &current->group_leader->real_parent
	;;
	and r9=TIF_ALLWORK_MASK,r9

1:	ld8 r18=[r17]				// r18 = current->group_leader->real_parent
	;;
	cmp.ne p8,p0=0,r9
	add r8=IA64_TASK_TGID_OFFSET,r18	// r8 = &current->group_leader->real_parent->tgid
	;;

	/*
	 * The .acq is needed to ensure that the read of tgid has returned its data before
	 * we re-check "real_parent".
	 */
	ld4.acq r8=[r8]				// r8 = current->group_leader->real_parent->tgid
#ifdef CONFIG_SMP
	/*
	 * Re-read current->group_leader->real_parent.
	 */
	ld8 r19=[r17]				// r19 = current->group_leader->real_parent
(p8)	br.spnt.many fsys_fallback_syscall
	;;
	cmp.ne p6,p0=r18,r19			// did real_parent change?
	mov r19=0			// i must not leak kernel bits...
(p6)	br.cond.spnt.few 1b			// yes -> redo the read of tgid and the