1 /* SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1999, 2000, 2002 Niibe Yutaka
4 * Copyright (C) 2003 - 2008 Paul Mundt
8 ! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
9 ! to be jumped is too far, but it causes illegal slot exception.
12 * entry.S contains the system-call and fault low-level handling routines.
13 * This also contains the timer-interrupt handler, as well as all interrupts
14 * and faults that can result in a task-switch.
16 * NOTE: This code handles signal-recognition, which happens every time
17 * after a timer-interrupt and after each system call.
19 * NOTE: This code uses a convention that instructions in the delay slot
20 * of a transfer-control instruction are indented by an extra space, thus:
22 * jmp @k0 ! control-transfer instruction
23 * ldc k1, ssr ! delay slot
25 * Stack layout in 'ret_from_syscall':
26 * ptrace needs to have all regs on the stack.
27 * if the order here is changed, it needs to be
28 * updated in ptrace.c and ptrace.h
42 #include <asm/dwarf.h>
44 #if defined(CONFIG_PREEMPTION)
45 # define preempt_stop() cli ; TRACE_IRQS_OFF
47 # define preempt_stop()
48 # define resume_kernel __restore_all
53 ENTRY(exception_error)
62 1: .long do_exception_error
81 mov.l @(r0,r15), r0 ! get status register
83 shll r0 ! kernel space?
84 get_current_thread_info r8, r0
85 bt resume_kernel ! Yes, it's from kernel, go back soon
87 #ifdef CONFIG_PREEMPTION
93 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count
97 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
98 tst #_TIF_NEED_RESCHED, r0 ! need_resched set?
102 mov.l @(r0,r15), r0 ! get status register
104 and #(0xf0>>1), r0 ! interrupts off (exception path)?
105 cmp/eq #(0xf0>>1), r0
108 jsr @r0 ! call preempt_schedule_irq
118 1: .long preempt_schedule_irq
121 ENTRY(resume_userspace)
122 ! r8: current_thread_info
125 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
126 tst #(_TIF_WORK_MASK & 0xff), r0
128 tst #_TIF_NEED_RESCHED, r0
132 ! r0: current_thread_info->flags
133 ! r8: current_thread_info
134 ! t: result of "tst #_TIF_NEED_RESCHED, r0"
136 tst #(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME), r0
140 mov r12, r5 ! set arg1(save_r0)
154 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
155 tst #(_TIF_WORK_MASK & 0xff), r0
158 tst #_TIF_NEED_RESCHED, r0
162 2: .long do_notify_resume
163 3: .long resume_userspace
167 ! r0: current_thread_info->flags
168 ! r8: current_thread_info
169 tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0
171 tst #_TIF_NEED_RESCHED, r0
175 mov.l 8f, r0 ! do_syscall_trace_leave
185 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies
186 jsr @r11 ! superior (will chomp R[0-7])
188 mov.l r0, @(OFF_R0,r15) ! Save return value
189 ! Reload R0-R4 from kernel stack, where the
190 ! parent may have modified them using
191 ! ptrace(POKEUSR). (Note that R0-R2 are
192 ! reloaded from the kernel stack by syscall_call
193 ! below, so don't need to be reloaded here.)
194 ! This allows the parent to rewrite system calls
195 ! and args on the fly.
196 mov.l @(OFF_R4,r15), r4 ! arg0
197 mov.l @(OFF_R5,r15), r5
198 mov.l @(OFF_R6,r15), r6
199 mov.l @(OFF_R7,r15), r7 ! arg3
200 mov.l @(OFF_R3,r15), r3 ! syscall_nr
202 mov.l 2f, r10 ! Number of syscalls
207 mov.l r0, @(OFF_R0,r15) ! Return value
211 mov.l @(r0,r15), r0 ! get status register
231 syscall_badsys: ! Bad syscall number
232 get_current_thread_info r8, r0
235 mov.l r0, @(OFF_R0,r15) ! Return value
238 * The main debug trap handler.
240 * r8=TRA (not the trap number!)
242 * Note: This assumes that the trapa value is left in its original
243 * form (without the shlr2 shift) so the calculation for the jump
244 * call table offset remains a simple in place mask.
254 bra ret_from_exception
259 1: .long debug_trap_table
265 * Arguments #0 to #3: R4--R7
266 * Arguments #4 to #6: R0, R1, R2
267 * TRA: See following table.
271 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use).
272 * 0x10-0x1f general SH-3/4 syscall ABI.
273 * 0x1f unified SH-2/3/4 syscall ABI (preferred).
274 * 0x20-0x2f original SH-2 syscall ABI.
275 * 0x30-0x3f debug traps used by the kernel.
276 * 0x40-0xff Not supported by all parts, so left unhandled.
278 * For making system calls, any trap number in the range for the
279 * given cpu model may be used, but the unified trap number 0x1f is
280 * preferred for compatibility with all models.
282 * The low bits of the trap number were once documented as matching
283 * the number of arguments, but they were never actually used as such
284 * by the kernel. SH-2 originally used its own separate trap range
285 * because several hardware exceptions fell in the range used for the
286 * SH-3/4 syscall ABI.
288 * This code also handles delegating other traps to the BIOS/gdb stub.
290 * Note: When we're first called, the TRA value must be shifted
291 * right 2 bits in order to get the value that was used as the "trapa"
305 .globl ret_from_kernel_thread
306 ret_from_kernel_thread:
310 mov.l @(OFF_R5,r15), r5 ! fn
312 mov.l @(OFF_R4,r15), r4 ! arg
317 1: .long schedule_tail
320 * The poorly named main trapa decode and dispatch routine, for
321 * system calls and debug traps through their respective jump tables.
325 #if !defined(CONFIG_CPU_SH2)
327 mov.l @r9, r8 ! Read from TRA (Trap Address) Register
332 mov.l r8, @r10 ! set TRA value to tra
335 * Check the trap type
337 mov #((0x20 << 2) - 1), r9
339 bt/s debug_trap ! it's a debug trap..
346 get_current_thread_info r8, r10
347 mov.l @(TI_FLAGS,r8), r8
348 mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10
349 mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9
352 bf syscall_trace_entry
354 bf syscall_trace_entry
356 mov.l 2f, r8 ! Number of syscalls
362 mov.l 3f, r8 ! Load the address of sys_call_table
365 mov.l @(OFF_R2,r15), r2
366 mov.l @(OFF_R1,r15), r1
367 mov.l @(OFF_R0,r15), r0
371 jsr @r8 ! jump to specific syscall handler
374 mov.l @(OFF_R0,r15), r12 ! save r0
375 mov.l r0, @(OFF_R0,r15) ! save the return value
381 get_current_thread_info r8, r0
382 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags
383 tst #(_TIF_ALLWORK_MASK & 0xff), r0
384 mov #(_TIF_ALLWORK_MASK >> 8), r1
392 #if !defined(CONFIG_CPU_SH2)
396 3: .long sys_call_table
397 7: .long do_syscall_trace_enter
398 8: .long do_syscall_trace_leave