1 /* $Id: entry.S,v 1.37 2004/06/11 13:02:46 doyu Exp $
3 * linux/arch/sh/entry.S
5 * Copyright (C) 1999, 2000, 2002 Niibe Yutaka
6 * Copyright (C) 2003 Paul Mundt
8 * This file is subject to the terms and conditions of the GNU General Public
9 * License. See the file "COPYING" in the main directory of this archive
15 ! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
16 ! to be jumped is too far, but it causes illegal slot exception.
19 * entry.S contains the system-call and fault low-level handling routines.
20 * This also contains the timer-interrupt handler, as well as all interrupts
21 * and faults that can result in a task-switch.
23 * NOTE: This code handles signal-recognition, which happens every time
24 * after a timer-interrupt and after each system call.
26 * NOTE: This code uses a convention that instructions in the delay slot
27 * of a transfer-control instruction are indented by an extra space, thus:
29 * jmp @k0 ! control-transfer instruction
30 * ldc k1, ssr ! delay slot
32 * Stack layout in 'ret_from_syscall':
33 * ptrace needs to have all regs on the stack.
34 * if the order here is changed, it needs to be
35 * updated in ptrace.c and ptrace.h
50 #if defined(CONFIG_PREEMPT)
51 # define preempt_stop() cli
53 # define preempt_stop()
54 # define resume_kernel __restore_all
57 #if defined(CONFIG_SH_STANDARD_BIOS) || defined(CONFIG_SH_KGDB)
58 ! Handle kernel debug if either kgdb (SW) or gdb-stub (FW) is present.
59 ! If both are configured, handle the debug traps (breakpoints) in SW,
60 ! but still allow BIOS traps to FW.
64 #if defined(CONFIG_SH_STANDARD_BIOS) && defined(CONFIG_SH_KGDB)
65 /* Force BIOS call to FW (debug_trap put TRA in r8) */
70 #endif /* CONFIG_SH_STANDARD_BIOS && CONFIG_SH_KGDB */
73 #if defined(CONFIG_SH_KGDB)
74 /* Jump to kgdb, pass stacked regs as arg */
80 3: .long kgdb_handle_exception
81 #endif /* CONFIG_SH_KGDB */
83 #endif /* CONFIG_SH_STANDARD_BIOS || CONFIG_SH_KGDB */
88 #if defined(CONFIG_SH_STANDARD_BIOS) || defined(CONFIG_SH_KGDB)
90 mov.l @(r0,r15), r0 ! get status register
92 shll r0 ! kernel space?
95 mov.l @r15, r0 ! Restore R0 value
101 ENTRY(exception_error)
110 1: .long break_point_trap_software
111 2: .long do_exception_error
119 mov.l @(r0,r15), r0 ! get status register
121 shll r0 ! kernel space?
122 get_current_thread_info r8, r0
123 bt resume_kernel ! Yes, it's from kernel, go back soon
125 #ifdef CONFIG_PREEMPT
129 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count
133 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
134 tst #_TIF_NEED_RESCHED, r0 ! need_resched set?
138 mov.l @(r0,r15), r0 ! get status register
139 and #0xf0, r0 ! interrupts off (exception path)?
144 mov.l r0, @(TI_PRE_COUNT,r8)
151 mov.l r0, @(TI_PRE_COUNT,r8)
161 1: .long PREEMPT_ACTIVE
165 ENTRY(resume_userspace)
166 ! r8: current_thread_info
168 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
169 tst #_TIF_WORK_MASK, r0
171 tst #_TIF_NEED_RESCHED, r0
175 ! r0: current_thread_info->flags
176 ! r8: current_thread_info
177 ! t: result of "tst #_TIF_NEED_RESCHED, r0"
179 tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0
183 mov r12, r5 ! set arg1(save_r0)
190 #ifndef CONFIG_PREEMPT
192 mov.l @(OFF_SP,r15), r0 ! get user space stack pointer
199 ! SP >= 0xc0000000 : gUSA mark
200 mov.l @(r0,r15), r2 ! get user space PC (program counter)
201 mov.l @(OFF_R0,r15), r3 ! end point
202 cmp/hs r3, r2 ! r2 >= r3?
204 add r3, r1 ! rewind point #2
205 mov.l r1, @(r0,r15) ! reset PC to rewind point #2
214 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
215 tst #_TIF_WORK_MASK, r0
218 tst #_TIF_NEED_RESCHED, r0
222 2: .long do_notify_resume
227 ! r0: current_thread_info->flags
228 ! r8: current_thread_info
229 tst #_TIF_SYSCALL_TRACE, r0
231 tst #_TIF_NEED_RESCHED, r0
233 ! XXX setup arguments...
234 mov.l 4f, r0 ! do_syscall_trace
243 ! XXX setup arguments...
244 mov.l 4f, r11 ! Call do_syscall_trace which notifies
245 jsr @r11 ! superior (will chomp R[0-7])
247 ! Reload R0-R4 from kernel stack, where the
248 ! parent may have modified them using
249 ! ptrace(POKEUSR). (Note that R0-R2 are
250 ! used by the system call handler directly
251 ! from the kernel stack anyway, so don't need
252 ! to be reloaded here.) This allows the parent
253 ! to rewrite system calls and args on the fly.
254 mov.l @(OFF_R4,r15), r4 ! arg0
255 mov.l @(OFF_R5,r15), r5
256 mov.l @(OFF_R6,r15), r6
257 mov.l @(OFF_R7,r15), r7 ! arg3
258 mov.l @(OFF_R3,r15), r3 ! syscall_nr
260 mov.l 2f, r10 ! Number of syscalls
265 mov.l r0, @(OFF_R0,r15) ! Return value
281 syscall_badsys: ! Bad syscall number
284 mov.l r0, @(OFF_R0,r15) ! Return value
291 * Arguments #0 to #3: R4--R7
292 * Arguments #4 to #6: R0, R1, R2
293 * TRA: (number of arguments + 0x10) x 4
295 * This code also handles delegating other traps to the BIOS/gdb stub
301 * 0x0-0xf old syscall ABI
302 * 0x10-0x1f new syscall ABI
303 * 0x20-0xff delegated through debug_trap to BIOS/gdb stub.
305 * Note: When we're first called, the TRA value must be shifted
306 * right 2 bits in order to get the value that was used as the "trapa"
319 1: .long schedule_tail
322 #if !defined(CONFIG_CPU_SH2)
324 mov.l @r9, r8 ! Read from TRA (Trap Address) Register
327 ! Is the trap argument >= 0x20? (TRA will be >= 0x80)
333 mov.l r8, @r9 ! set TRA value to tra
336 get_current_thread_info r8, r10
337 mov.l @(TI_FLAGS,r8), r8
338 mov #_TIF_SYSCALL_TRACE, r10
340 bf syscall_trace_entry
342 mov.l 2f, r8 ! Number of syscalls
348 mov.l 3f, r8 ! Load the address of sys_call_table
351 jsr @r8 ! jump to specific syscall handler
353 mov.l @(OFF_R0,r15), r12 ! save r0
354 mov.l r0, @(OFF_R0,r15) ! save the return value
359 get_current_thread_info r8, r0
360 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
361 tst #_TIF_ALLWORK_MASK, r0
366 #if !defined(CONFIG_CPU_SH2)
370 3: .long sys_call_table
371 4: .long do_syscall_trace