path: root/arch/mips/kernel/scall32-o32.S

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1995-99, 2000- 02, 06 Ralf Baechle <ralf@linux-mips.org>
 * Copyright (C) 2001 MIPS Technologies, Inc.
 * Copyright (C) 2004 Thiemo Seufer
 */
#include <linux/errno.h>
#include <asm/asm.h>
#include <asm/asmmacro.h>
#include <asm/irqflags.h>
#include <asm/mipsregs.h>
#include <asm/regdef.h>
#include <asm/stackframe.h>
#include <asm/isadep.h>
#include <asm/sysmips.h>
#include <asm/thread_info.h>
#include <asm/unistd.h>
#include <asm/war.h>
#include <asm/asm-offsets.h>

/* Highest syscall used of any syscall flavour */
#define MAX_SYSCALL_NO	__NR_O32_Linux + __NR_O32_Linux_syscalls

	.align  5
NESTED(handle_sys, PT_SIZE, sp)
	.set	noat
	SAVE_SOME
	TRACE_IRQS_ON_RELOAD
	STI
	.set	at

	lw	t1, PT_EPC(sp)		# skip syscall on return

#if defined(CONFIG_BINFMT_IRIX)
	sltiu	t0, v0, MAX_SYSCALL_NO + 1 # check syscall number
#else
	subu	v0, v0, __NR_O32_Linux	# check syscall number
	sltiu	t0, v0, __NR_O32_Linux_syscalls + 1
#endif
	addiu	t1, 4			# skip to next instruction
	sw	t1, PT_EPC(sp)
	beqz	t0, illegal_syscall

	sll	t0, v0, 3
	la	t1, sys_call_table
	addu	t1, t0
	lw	t2, (t1)		# syscall routine
	lw	t3, 4(t1)		# >= 0 if we need stack arguments
	beqz	t2, illegal_syscall

	sw	a3, PT_R26(sp)		# save a3 for syscall restarting
	bgez	t3, stackargs

stack_done:
	lw	t0, TI_FLAGS($28)	# syscall tracing enabled?
	li	t1, _TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT
	and	t0, t1
	bnez	t0, syscall_trace_entry	# -> yes

	jalr	t2			# Do The Real Thing (TM)

	li	t0, -EMAXERRNO - 1	# error?
	sltu	t0, t0, v0
	sw	t0, PT_R7(sp)		# set error flag
	beqz	t0, 1f

	negu	v0			# error
	sw	v0, PT_R0(sp)		# set flag for syscall
					# restarting
1:	sw	v0, PT_R2(sp)		# result

o32_syscall_exit:
	local_irq_disable		# make sure need_resched and
					# signals dont change between
					# sampling and return
	lw	a2, TI_FLAGS($28)	# current->work
	li	t0, _TIF_ALLWORK_MASK
	and	t0, a2
	bnez	t0, o32_syscall_exit_work

	j	restore_partial

o32_syscall_exit_work:
	j	syscall_exit_work_partial

/* ------------------------------------------------------------------------ */

syscall_trace_entry:
	SAVE_STATIC
	move	s0, t2
	move	a0, sp
	li	a1, 0
	jal	do_syscall_trace

	move	t0, s0
	RESTORE_STATIC
	lw	a0, PT_R4(sp)		# Restore argument registers
	lw	a1, PT_R5(sp)
	lw	a2, PT_R6(sp)
	lw	a3, PT_R7(sp)
	jalr	t0

	li	t0, -EMAXERRNO - 1	# error?
	sltu	t0, t0, v0
	sw	t0, PT_R7(sp)		# set error flag
	beqz	t0, 1f

	negu	v0			# error
	sw	v0, PT_R0(sp)		# set flag for syscall
					# restarting
1:	sw	v0, PT_R2(sp)		# result

	j	syscall_exit

/* ------------------------------------------------------------------------ */

	/*
	 * More than four arguments.  Try to deal with it by copying the
	 * stack arguments from the user stack to the kernel stack.
	 * This Sucks (TM).
	 */
stackargs:
	lw	t0, PT_R29(sp)		# get old user stack pointer

	/*
	 * We intentionally keep the kernel stack a little below the top of
	 * userspace so we don't have to do a slower byte accurate check here.
	 */
	lw	t5, TI_ADDR_LIMIT($28)
	addu	t4, t0, 32
	and	t5, t4
	bltz	t5, bad_stack		# -> sp is bad

	/* Ok, copy the args from the luser stack to the kernel stack.
	 * t3 is the precomputed number of instruction bytes needed to
	 * load or store arguments 6-8.
	 */

	la	t1, 5f			# load up to 3 arguments
	subu	t1, t3
1:	lw	t5, 16(t0)		# argument #5 from usp
	.set    push
	.set    noreorder
	.set	nomacro
	jr	t1
	 addiu	t1, 6f - 5f

2:	lw	t8, 28(t0)		# argument #8 from usp
3:	lw	t7, 24(t0)		# argument #7 from usp
4:	lw	t6, 20(t0)		# argument #6 from usp
5:	jr	t1
	 sw	t5, 16(sp)		# argument #5 to ksp

	sw	t8, 28(sp)		# argument #8 to ksp
	sw	t7, 24(sp)		# argument #7 to ksp
	sw	t6, 20(sp)		# argument #6 to ksp
6:	j	stack_done		# go back
	 nop
	.set	pop

	.section __ex_table,"a"
	PTR	1b,bad_stack
	PTR	2b,bad_stack
	PTR	3b,bad_stack
	PTR	4b,bad_stack
	.previous

	/*
	 * The stackpointer for a call with more than 4 arguments is bad.
	 * We probably should handle this case a bit more drastic.
	 */
bad_stack:
	negu	v0				# error
	sw	v0, PT_R0(sp)
	sw	v0, PT_R2(sp)
	li	t0, 1				# set error flag
	sw	t0, PT_R7(sp)
	j	o32_syscall_exit

	/*
	 * The system call does not exist in this kernel
	 */
illegal_syscall:
	li	v0, -ENOSYS			# error
	sw	v0, PT_R2(sp)
	li	t0, 1				# set error flag
	sw	t0, PT_R7(sp)
	j	o32_syscall_exit
	END(handle_sys)

	LEAF(mips_atomic_set)
	andi	v0, a1, 3			# must be word aligned
	bnez	v0, bad_alignment

	lw	v1, TI_ADDR_LIMIT($28)		# in legal address range?
	addiu	a0, a1, 4
	or	a0, a0, a1
	and	a0, a0, v1
	bltz	a0, bad_address

#ifdef CONFIG_CPU_HAS_LLSC
	/* Ok, this is the ll/sc case.  World is sane :-)  */
1:	ll	v0, (a1)
	move	a0, a2
2:	sc	a0, (a1)
#if R10000_LLSC_WAR
	beqzl	a0, 1b
#else
	beqz	a0, 1b
#endif

	.section __ex_table,"a"
	PTR	1b, bad_stack
	PTR	2b, bad_stack
	.previous
#else
	sw	a1, 16(sp)
	sw	a2, 20(sp)

	move	a0, sp
	move	a2, a1
	li	a1, 1
	jal	do_page_fault

	lw	a1, 16(sp)
	lw	a2, 20(sp)

	/*
	 * At this point the page should be readable and writable unless
	 * there was no more memory available.
	 */
1:	lw	v0, (a1)
2:	sw	a2, (a1)

	.section __ex_table,"a"
	PTR	1b, no_mem
	PTR	2b, no_mem
	.previous
#endif

	sw	zero, PT_R7(sp)		# success
	sw	v0, PT_R2(sp)		# result

	j	o32_syscall_exit	# continue like a normal syscall

no_mem:	li	v0, -ENOMEM
	jr	ra

bad_address:
	li	v0, -EFAULT
	jr	ra

bad_alignment:
	li	v0, -EINVAL
	jr	ra
	END(mips_atomic_set)

	LEAF(sys_sysmips)
	beq	a0, MIPS_ATOMIC_SET, mips_atomic_set
	j	_sys_sysmips
	END(sys_sysmips)

	LEAF(sys_syscall)
#if defined(CONFIG_BINFMT_IRIX)
	sltiu	v0, a0, MAX_SYSCALL_NO + 1 # check syscall number
#else
	subu	t0, a0, __NR_O32_Linux	# check syscall number
	sltiu	v0, t0, __NR_O32_Linux_syscalls + 1
#endif
	sll	t1, t0, 3
	beqz	v0, einval

	lw	t2, sys_call_table(t1)		# syscall routine

#if defined(CONFIG_BINFMT_IRIX)
	li	v1, 4000			# nr of sys_syscall
#else
	li	v1, 4000 - __NR_O32_Linux	# index of sys_syscall
#endif
	beq	t0, v1, einval			# do not recurse

	/* Some syscalls like execve get their arguments from struct pt_regs
	   and claim zero arguments in the syscall table. Thus we have to
	   assume the worst case and shuffle around all potential arguments.
	   If you want performance, don't use indirect syscalls. */

	move	a0, a1				# shift argument registers
	move	a1, a2
	move	a2, a3
	lw	a3, 16(sp)
	lw	t4, 20(sp)
	lw	t5, 24(sp)
	lw	t6, 28(sp)
	sw	t4, 16(sp)
	sw	t5, 20(sp)
	sw	t6, 24(sp)
	sw	a0, PT_R4(sp)			# .. and push back a0 - a3, some
	sw	a1, PT_R5(sp)			# syscalls expect them there
	sw	a2, PT_R6(sp)
	sw	a3, PT_R7(sp)
	sw	a3, PT_R26(sp)			# update a3 for syscall restarting
	jr	t2
	/* Unreached */

einval:	li	v0, -EINVAL
	jr	ra
	END(sys_syscall)

	.macro	fifty ptr, nargs, from=1, to=50
	sys	\ptr		\nargs