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/*
* Handle ABI O32 style syscalls.
*
* Copyright (C) 1997, 1998 by Ralf Baechle
*
* $Id: scall_o32.S,v 1.1 1998/03/12 19:06:20 ralf Exp $
*/
#include <asm/asm.h>
#include <linux/errno.h>
#include <asm/current.h>
#include <asm/mipsregs.h>
#include <asm/regdef.h>
#include <asm/stackframe.h>
#include <asm/unistd.h>
/* This duplicates the definition from <linux/sched.h> */
#define PF_TRACESYS 0x00000020 /* tracing system calls */
/* This duplicates the definition from <asm/signal.h> */
#define SIGILL 4 /* Illegal instruction (ANSI). */
/* Highest syscall used of any syscall flavour */
#define MAX_SYSCALL_NO __NR_Linux + __NR_Linux_syscalls
.align 5
NESTED(handle_sys, PT_SIZE, sp)
.set noat
SAVE_ALL
STI
.set at
/*
* By convention "li v0,<syscallno>" is always preceeding
* the syscall instruction. So if we're in a delay slot
* userland is screwed up.
*/
lw t0, PT_CAUSE(sp) # delay slot?
lw t1, PT_EPC(sp) # skip syscall on return
bltz t0, sigill_and_out
sltiu t0, v0, MAX_SYSCALL_NO + 1 # check syscall number
addiu t1, 4 # skip to next instruction
beqz t0, illegal_syscall
sw t1, PT_EPC(sp)
/* XXX Put both in one cacheline, should save a bit. */
sll t0, v0, 2
lw s0, sys_call_table(t0) # syscall routine
lbu s1, sys_narg_table(v0) # number of arguments
beqz s0, illegal_syscall;
subu t0, s1, 5 # 5 or more arguments?
bgezal t0, stackargs
lw s3, TASK_FLAGS($28) # syscall tracing enabled?
andi s3, PF_TRACESYS
bnez s3, trace_a_syscall
jalr s0 # 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
j ret_from_sys_call
/* ------------------------------------------------------------------------ */
trace_a_syscall:
jal syscall_trace
jalr s0 # 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
jal syscall_trace
j ret_from_sys_call
/* ------------------------------------------------------------------------ */
/*
* 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:
move s3, ra # save return address
lw t0, PT_R29(sp) # get old user stack pointer
subu s2, s1, 4
sll t1, s2, 2 # stack valid?
addu t1, t0 # end address
or t2, t0, t1
bltz t0, bad_stack # -> sp is bad
lw t0, PT_R29(sp) # get old user stack pointer
la t1, 3f # copy 1 to 2 arguments
sll s2, s2, 3
subu t1, s2
jr t1
/* Ok, copy the args from the luser stack to the kernel stack */
1: lw t1, 20(t0) # argument #6 from usp
sw t1, 20(sp)
2: lw t1, 16(t0) # argument #5 from usp
sw t1, 16(sp)
3: jr s3 # go back
.section __ex_table,"a"
PTR 1b,bad_stack
PTR 2b,bad_stack
.previous
/*
* The stackpointer for a call with more than 4 arguments is bad.
*/
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 ret_from_sys_call
/*
* 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 ret_from_sys_call
sigill_and_out:
li t0, -1 # not a sys call
REG_S t0, PT_OR2(sp)
li a0, SIGILL
move a2, $28
jal force_sig
j ret_from_sys_call
END(handle_sys)
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