2 * Copyright (C) 1999, 2000, 2002 Niibe Yutaka
3 * Copyright (C) 2003 - 2008 Paul Mundt
5 * This file is subject to the terms and conditions of the GNU General Public
6 * License. See the file "COPYING" in the main directory of this archive
12 ! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
13 ! to be jumped is too far, but it causes illegal slot exception.
16 * entry.S contains the system-call and fault low-level handling routines.
17 * This also contains the timer-interrupt handler, as well as all interrupts
18 * and faults that can result in a task-switch.
20 * NOTE: This code handles signal-recognition, which happens every time
21 * after a timer-interrupt and after each system call.
23 * NOTE: This code uses a convention that instructions in the delay slot
24 * of a transfer-control instruction are indented by an extra space, thus:
26 * jmp @k0 ! control-transfer instruction
27 * ldc k1, ssr ! delay slot
29 * Stack layout in 'ret_from_syscall':
30 * ptrace needs to have all regs on the stack.
31 * if the order here is changed, it needs to be
32 * updated in ptrace.c and ptrace.h
46 #include <asm/dwarf.h>
48 #if defined(CONFIG_PREEMPT)
49 # define preempt_stop() cli ; TRACE_IRQS_OFF
51 # define preempt_stop()
52 # define resume_kernel __restore_all
57 ENTRY(exception_error)
66 1: .long do_exception_error
79 mov.l @(r0,r15), r0 ! get status register
88 mov.l @(r0,r15), r0 ! get status register
90 shll r0 ! kernel space?
91 get_current_thread_info r8, r0
92 bt resume_kernel ! Yes, it's from kernel, go back soon
99 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count
103 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
104 tst #_TIF_NEED_RESCHED, r0 ! need_resched set?
108 mov.l @(r0,r15), r0 ! get status register
109 and #0xf0, r0 ! interrupts off (exception path)?
113 jsr @r0 ! call preempt_schedule_irq
123 1: .long PREEMPT_ACTIVE
125 3: .long preempt_schedule_irq
128 ENTRY(resume_userspace)
129 ! r8: current_thread_info
132 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
133 tst #(_TIF_WORK_MASK & 0xff), r0
135 tst #_TIF_NEED_RESCHED, r0
139 ! r0: current_thread_info->flags
140 ! r8: current_thread_info
141 ! t: result of "tst #_TIF_NEED_RESCHED, r0"
143 tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0
147 mov r12, r5 ! set arg1(save_r0)
160 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
161 tst #(_TIF_WORK_MASK & 0xff), r0
164 tst #_TIF_NEED_RESCHED, r0
168 2: .long do_notify_resume
169 3: .long resume_userspace
173 ! r0: current_thread_info->flags
174 ! r8: current_thread_info
175 tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0
177 tst #_TIF_NEED_RESCHED, r0
181 mov.l 8f, r0 ! do_syscall_trace_leave
191 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies
192 jsr @r11 ! superior (will chomp R[0-7])
194 mov.l r0, @(OFF_R0,r15) ! Save return value
195 ! Reload R0-R4 from kernel stack, where the
196 ! parent may have modified them using
197 ! ptrace(POKEUSR). (Note that R0-R2 are
198 ! used by the system call handler directly
199 ! from the kernel stack anyway, so don't need
200 ! to be reloaded here.) This allows the parent
201 ! to rewrite system calls and args on the fly.
202 mov.l @(OFF_R4,r15), r4 ! arg0
203 mov.l @(OFF_R5,r15), r5
204 mov.l @(OFF_R6,r15), r6
205 mov.l @(OFF_R7,r15), r7 ! arg3
206 mov.l @(OFF_R3,r15), r3 ! syscall_nr
208 mov.l 2f, r10 ! Number of syscalls
213 mov.l r0, @(OFF_R0,r15) ! Return value
224 syscall_badsys: ! Bad syscall number
225 get_current_thread_info r8, r0
228 mov.l r0, @(OFF_R0,r15) ! Return value
231 * The main debug trap handler.
233 * r8=TRA (not the trap number!)
235 * Note: This assumes that the trapa value is left in its original
236 * form (without the shlr2 shift) so the calculation for the jump
237 * call table offset remains a simple in place mask.
252 1: .long debug_trap_table
258 * Arguments #0 to #3: R4--R7
259 * Arguments #4 to #6: R0, R1, R2
260 * TRA: (number of arguments + ABI revision) x 4
262 * This code also handles delegating other traps to the BIOS/gdb stub
268 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use).
269 * 0x10-0x1f general SH-3/4 syscall ABI.
270 * 0x20-0x2f syscall ABI for SH-2 parts.
271 * 0x30-0x3f debug traps used by the kernel.
272 * 0x40-0xff Not supported by all parts, so left unhandled.
274 * Note: When we're first called, the TRA value must be shifted
275 * right 2 bits in order to get the value that was used as the "trapa"
288 1: .long schedule_tail
291 * The poorly named main trapa decode and dispatch routine, for
292 * system calls and debug traps through their respective jump tables.
296 #if !defined(CONFIG_CPU_SH2)
298 mov.l @r9, r8 ! Read from TRA (Trap Address) Register
303 mov.l r8, @r10 ! set TRA value to tra
306 * Check the trap type
308 mov #((0x20 << 2) - 1), r9
310 bt/s debug_trap ! it's a debug trap..
317 get_current_thread_info r8, r10
318 mov.l @(TI_FLAGS,r8), r8
319 mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10
320 mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9
323 bf syscall_trace_entry
325 bf syscall_trace_entry
327 mov.l 2f, r8 ! Number of syscalls
333 mov.l 3f, r8 ! Load the address of sys_call_table
336 jsr @r8 ! jump to specific syscall handler
338 mov.l @(OFF_R0,r15), r12 ! save r0
339 mov.l r0, @(OFF_R0,r15) ! save the return value
345 get_current_thread_info r8, r0
346 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
347 tst #(_TIF_ALLWORK_MASK & 0xff), r0
348 mov #(_TIF_ALLWORK_MASK >> 8), r1
356 #if !defined(CONFIG_CPU_SH2)
360 3: .long sys_call_table
361 7: .long do_syscall_trace_enter
362 8: .long do_syscall_trace_leave