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
 * Copyright (C) 2014 Imagination Technologies Ltd.
 */
#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

	addiu	t1, 4			# skip to next instruction
	sw	t1, PT_EPC(sp)

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

	/*
	 * 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).
	 */
	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.
	 */

	.set    push
	.set    noreorder
	.set	nomacro

load_a4: user_lw(t5, 16(t0))		# argument #5 from usp
load_a5: user_lw(t6, 20(t0))		# argument #6 from usp
load_a6: user_lw(t7, 24(t0))		# argument #7 from usp
load_a7: user_lw(t8, 28(t0))		# argument #8 from usp
loads_done:

	sw	t5, 16(sp)		# argument #5 to ksp
	sw	t6, 20(sp)		# argument #6 to ksp
	sw	t7, 24(sp)		# argument #7 to ksp
	sw	t8, 28(sp)		# argument #8 to ksp
	.set	pop

	.section __ex_table,"a"
	PTR	load_a4, bad_stack_a4
	PTR	load_a5, bad_stack_a5
	PTR	load_a6, bad_stack_a6
	PTR	load_a7, bad_stack_a7
	.previous

	lw	t0, TI_FLAGS($28)	# syscall tracing enabled?
	li	t1, _TIF_WORK_SYSCALL_ENTRY
	and	t0, t1
	bnez	t0, syscall_trace_entry # -> yes
syscall_common:
	subu	v0, v0, __NR_O32_Linux	# check syscall number
	sltiu	t0, v0, __NR_O32_Linux_syscalls + 1
	beqz	t0, illegal_syscall

	sll	t0, v0, 2
	la	t1, sys_call_table
	addu	t1, t0
	lw	t2, (t1)		# syscall routine

	beqz	t2, illegal_syscall

	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

	lw	t1, PT_R2(sp)		# syscall number
	negu	v0			# error
	sw	t1, PT_R0(sp)		# save it for syscall restarting
1:	sw	v0, PT_R2(sp)		# result

o32_syscall_exit:
	j	syscall_exit_partial

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

syscall_trace_entry:
	SAVE_STATIC
	move	a0, sp

	/*
	 * syscall number is in v0 unless we called syscall(__NR_###)
	 * where the real syscall number is in a0
	 */
	move	a1, v0
	subu	t2, v0,  __NR_O32_Linux
	bnez	t2, 1f /* __NR_syscall at offset 0 */
	lw	a1, PT_R4(sp)

1:	jal	syscall_trace_enter

	bltz	v0, 1f			# seccomp failed? Skip syscall

	RESTORE_STATIC
	lw	v0, PT_R2(sp)		# Restore syscall (maybe modified)
	lw	a0, PT_R4(sp)		# Restore argument registers
	lw	a1, PT_R5(sp)
	lw	a2, PT_R6(sp)
	lw	a3, PT_R7(sp)
	j	syscall_common

1:	j	syscall_exit

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

	/*
	 * Our open-coded access area sanity test for the stack pointer
	 * failed. We probably should handle this case a bit more drastic.
	 */
bad_stack:
	li	v0, EFAULT
	sw	v0, PT_R2(sp)
	li	t0, 1				# set error flag
	sw	t0, PT_R7(sp)
	j	o32_syscall_exit

bad_stack_a4:
	li	t5, 0
	b	load_a5

bad_stack_a5:
	li	t6, 0
	b	load_a6

bad_stack_a6:
	li	t7, 0
	b	load_a7

bad_stack_a7:
	li	t8, 0
	b	loads_done

	/*
	 * 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(sys_syscall)
	subu	t0, a0, __NR_O32_Linux	# check syscall number
	sltiu	v0, t0, __NR_O32_Linux_syscalls + 1
	beqz	t0, einval		# do not recurse
	sll	t1, t0, 2
	beqz	v0, einval
	lw	t2, sys_call_table(t1)		# syscall routine
	sw	a0, PT_R2(sp)			# call routine directly on restart

	/* 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, -ENOSYS
	jr	ra
	END(sys_syscall)

	.align	2
	.type	sys_call_table, @object
EXPORT(sys_call_table)
	PTR	sys_syscall			/* 4000 */
	PTR	sys_exit
	PTR	__sys_fork
	PTR	sys_read
	PTR	sys_write
	PTR	sys_open			/* 4005 */
	PTR	sys_close
	PTR	sys_waitpid
	PTR	sys_creat
	PTR	sys_link
	PTR	sys_unlink			/* 4010 */
	PTR	sys_execve
	PTR	sys_chdir
	PTR	sys_time
	PTR	sys_mknod
	PTR	sys_chmod			/* 4015 */
	PTR	sys_lchown
	PTR	sys_ni_syscall
	PTR	sys_ni_syscall			/* was sys_stat */
	PTR	sys_lseek
	PTR	sys_getpid			/* 4020 */
	PTR	sys_mount
	PTR	sys_oldumount
	PTR	sys_setuid
	PTR	sys_getuid
	PTR	sys_stime			/* 4025 */
	PTR	sys_ptrace
	PTR	sys_alarm
	PTR	sys_ni_syscall			/* was sys_fstat */
	PTR	sys_pause
	PTR	sys_utime			/* 4030 */
	PTR	sys_ni_syscall
	PTR	sys_ni_syscall
	PTR	sys_access
	PTR	sys_nice
	PTR	sys_ni_syscall			/* 4035 */
	PTR	sys_sync
	PTR	sys_kill
	PTR	sys_rename
	PTR	sys_mkdir
	PTR	sys_rmdir			/* 4040 */
	PTR	sys_dup
	PTR	sysm_pipe
	PTR	sys_times
	PTR	sys_ni_syscall
	PTR	sys_brk				/* 4045 */
	PTR	sys_setgid
	PTR	sys_getgid
	PTR	sys_ni_syscall			/* was signal(2) */
	PTR	sys_geteuid
	PTR	sys_getegid			/* 4050 */
	PTR	sys_acct
	PTR	sys_umount
	PTR	sys_ni_syscall
	PTR	sys_ioctl
	PTR	sys_fcntl			/* 4055 */
	PTR	sys_ni_syscall
	PTR	sys_setpgid
	PTR	sys_ni_syscall
	PTR	sys_olduname
	PTR	sys_umask			/* 4060 */
	PTR	sys_chroot
	PTR	sys_ustat
	PTR	sys_dup2
	PTR	sys_getppid
	PTR	sys_getpgrp			/* 4065 */
	PTR	sys_setsid
	PTR	sys_sigaction
	PTR	sys_sgetmask
	PTR	sys_ssetmask
	PTR	sys_setreuid			/* 4070 */
	PTR	sys_setregid
	PTR	sys_sigsuspend
	PTR	sys_sigpending
	PTR	sys_sethostname
	PTR	sys_setrlimit			/* 4075 */
	PTR	sys_getrlimit
	PTR	sys_getrusage
	PTR	sys_gettimeofday
	PTR	sys_settimeofday
	PTR	sys_getgroups			/* 4080 */
	PTR	sys_setgroups
	PTR	sys_ni_syscall			/* old_select */
	PTR	sys_symlink
	PTR	sys_ni_syscall			/* was sys_lstat */
	PTR	sys_readlink			/* 4085 */
	PTR	sys_uselib
	PTR	sys_swapon
	PTR	sys_reboot
	PTR	sys_old_readdir
	PTR	sys_mips_mmap			/* 4090 */
	PTR	sys_munmap
	PTR	sys_truncate
	PTR	sys_ftruncate
	PTR	sys_fchmod
	PTR	sys_fchown			/* 4095 */
	PTR	sys_getpriority
	PTR	sys_setpriority
	PTR	sys_ni_syscall
	PTR	sys_statfs
	PTR	sys_fstatfs			/* 4100 */
	PTR	sys_ni_syscall			/*</