2 * Copyright (C) 2012 Regents of the University of California
3 * Copyright (C) 2017 SiFive
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation, version 2.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
15 #include <linux/init.h>
16 #include <linux/linkage.h>
20 #include <asm/unistd.h>
21 #include <asm/thread_info.h>
22 #include <asm/asm-offsets.h>
28 * Prepares to enter a system call or exception by saving all registers to the
32 LOCAL _restore_kernel_tpsp
36 * If coming from userspace, preserve the user thread pointer and load
37 * the kernel thread pointer. If we came from the kernel, sscratch
38 * will contain 0, and we should continue on the current TP.
40 csrrw tp, sscratch, tp
41 bnez tp, _save_context
45 REG_S sp, TASK_TI_KERNEL_SP(tp)
47 REG_S sp, TASK_TI_USER_SP(tp)
48 REG_L sp, TASK_TI_KERNEL_SP(tp)
49 addi sp, sp, -(PT_SIZE_ON_STACK)
81 * Disable user-mode memory access as it should only be set in the
82 * actual user copy routines.
84 * Disable the FPU to detect illegal usage of floating point in kernel
89 REG_L s0, TASK_TI_USER_SP(tp)
96 REG_S s1, PT_SSTATUS(sp)
98 REG_S s3, PT_SBADADDR(sp)
99 REG_S s4, PT_SCAUSE(sp)
104 * Prepares to return from a system call or exception by restoring all
105 * registers from the stack.
108 REG_L a0, PT_SSTATUS(sp)
109 REG_L a2, PT_SEPC(sp)
137 REG_L x26, PT_S10(sp)
138 REG_L x27, PT_S11(sp)
147 ENTRY(handle_exception)
151 * Set sscratch register to 0, so that if a recursive exception
152 * occurs, the exception vector knows it came from the kernel
156 /* Load the global pointer */
159 la gp, __global_pointer$
162 la ra, ret_from_exception
164 * MSB of cause differentiates between
165 * interrupts and exceptions
169 /* Handle interrupts */
170 move a0, sp /* pt_regs */
171 move a1, s4 /* scause */
174 /* Exceptions run with interrupts enabled or disabled
175 depending on the state of sstatus.SR_SPIE */
181 /* Handle syscalls */
183 beq s4, t0, handle_syscall
185 /* Handle other exceptions */
186 slli t0, s4, RISCV_LGPTR
187 la t1, excp_vect_table
188 la t2, excp_vect_table_end
189 move a0, sp /* pt_regs */
191 /* Check if exception code lies within bounds */
199 /* save the initial A0 value (needed in signal handlers) */
200 REG_S a0, PT_ORIG_A0(sp)
202 * Advance SEPC to avoid executing the original
203 * scall instruction on sret
206 REG_S s2, PT_SEPC(sp)
207 /* Trace syscalls, but only if requested by the user. */
208 REG_L t0, TASK_TI_FLAGS(tp)
209 andi t0, t0, _TIF_SYSCALL_TRACE
210 bnez t0, handle_syscall_trace_enter
212 /* Check to make sure we don't jump to a bogus syscall number. */
214 la s0, sys_ni_syscall
215 /* Syscall number held in a7 */
217 la s0, sys_call_table
218 slli t0, a7, RISCV_LGPTR
225 /* Set user a0 to kernel a0 */
227 /* Trace syscalls, but only if requested by the user. */
228 REG_L t0, TASK_TI_FLAGS(tp)
229 andi t0, t0, _TIF_SYSCALL_TRACE
230 bnez t0, handle_syscall_trace_exit
233 REG_L s0, PT_SSTATUS(sp)
239 /* Interrupts must be disabled here so flags are checked atomically */
240 REG_L s0, TASK_TI_FLAGS(tp) /* current_thread_info->flags */
241 andi s1, s0, _TIF_WORK_MASK
242 bnez s1, work_pending
244 /* Save unwound kernel stack pointer in thread_info */
245 addi s0, sp, PT_SIZE_ON_STACK
246 REG_S s0, TASK_TI_KERNEL_SP(tp)
249 * Save TP into sscratch, so we can find the kernel data structures
259 /* Enter slow path for supplementary processing */
260 la ra, ret_from_exception
261 andi s1, s0, _TIF_NEED_RESCHED
262 bnez s1, work_resched
264 /* Handle pending signals and notify-resume requests */
265 csrs sstatus, SR_SIE /* Enable interrupts for do_notify_resume() */
266 move a0, sp /* pt_regs */
267 move a1, s0 /* current_thread_info->flags */
268 tail do_notify_resume
272 /* Slow paths for ptrace. */
273 handle_syscall_trace_enter:
275 call do_syscall_trace_enter
285 handle_syscall_trace_exit:
287 call do_syscall_trace_exit
290 END(handle_exception)
293 la ra, ret_from_exception
295 ENDPROC(ret_from_fork)
297 ENTRY(ret_from_kernel_thread)
300 la ra, ret_from_exception
303 ENDPROC(ret_from_kernel_thread)
307 * Integer register context switch
308 * The callee-saved registers must be saved and restored.
310 * a0: previous task_struct (must be preserved across the switch)
311 * a1: next task_struct
313 * The value of a0 and a1 must be preserved by this function, as that's how
314 * arguments are passed to schedule_tail.
317 /* Save context into prev->thread */
318 li a4, TASK_THREAD_RA
321 REG_S ra, TASK_THREAD_RA_RA(a3)
322 REG_S sp, TASK_THREAD_SP_RA(a3)
323 REG_S s0, TASK_THREAD_S0_RA(a3)
324 REG_S s1, TASK_THREAD_S1_RA(a3)
325 REG_S s2, TASK_THREAD_S2_RA(a3)
326 REG_S s3, TASK_THREAD_S3_RA(a3)
327 REG_S s4, TASK_THREAD_S4_RA(a3)
328 REG_S s5, TASK_THREAD_S5_RA(a3)
329 REG_S s6, TASK_THREAD_S6_RA(a3)
330 REG_S s7, TASK_THREAD_S7_RA(a3)
331 REG_S s8, TASK_THREAD_S8_RA(a3)
332 REG_S s9, TASK_THREAD_S9_RA(a3)
333 REG_S s10, TASK_THREAD_S10_RA(a3)
334 REG_S s11, TASK_THREAD_S11_RA(a3)
335 /* Restore context from next->thread */
336 REG_L ra, TASK_THREAD_RA_RA(a4)
337 REG_L sp, TASK_THREAD_SP_RA(a4)
338 REG_L s0, TASK_THREAD_S0_RA(a4)
339 REG_L s1, TASK_THREAD_S1_RA(a4)
340 REG_L s2, TASK_THREAD_S2_RA(a4)
341 REG_L s3, TASK_THREAD_S3_RA(a4)
342 REG_L s4, TASK_THREAD_S4_RA(a4)
343 REG_L s5, TASK_THREAD_S5_RA(a4)
344 REG_L s6, TASK_THREAD_S6_RA(a4)
345 REG_L s7, TASK_THREAD_S7_RA(a4)
346 REG_L s8, TASK_THREAD_S8_RA(a4)
347 REG_L s9, TASK_THREAD_S9_RA(a4)
348 REG_L s10, TASK_THREAD_S10_RA(a4)
349 REG_L s11, TASK_THREAD_S11_RA(a4)
350 /* Swap the CPU entry around. */
351 lw a3, TASK_TI_CPU(a0)
352 lw a4, TASK_TI_CPU(a1)
353 sw a3, TASK_TI_CPU(a1)
354 sw a4, TASK_TI_CPU(a0)
356 #error "TASK_TI != 0: tp will contain a 'struct thread_info', not a 'struct task_struct' so get_current() won't work."
365 li a2, TASK_THREAD_F0
370 fsd f0, TASK_THREAD_F0_F0(a0)
371 fsd f1, TASK_THREAD_F1_F0(a0)
372 fsd f2, TASK_THREAD_F2_F0(a0)
373 fsd f3, TASK_THREAD_F3_F0(a0)
374 fsd f4, TASK_THREAD_F4_F0(a0)
375 fsd f5, TASK_THREAD_F5_F0(a0)
376 fsd f6, TASK_THREAD_F6_F0(a0)
377 fsd f7, TASK_THREAD_F7_F0(a0)
378 fsd f8, TASK_THREAD_F8_F0(a0)
379 fsd f9, TASK_THREAD_F9_F0(a0)
380 fsd f10, TASK_THREAD_F10_F0(a0)
381 fsd f11, TASK_THREAD_F11_F0(a0)
382 fsd f12, TASK_THREAD_F12_F0(a0)
383 fsd f13, TASK_THREAD_F13_F0(a0)
384 fsd f14, TASK_THREAD_F14_F0(a0)
385 fsd f15, TASK_THREAD_F15_F0(a0)
386 fsd f16, TASK_THREAD_F16_F0(a0)
387 fsd f17, TASK_THREAD_F17_F0(a0)
388 fsd f18, TASK_THREAD_F18_F0(a0)
389 fsd f19, TASK_THREAD_F19_F0(a0)
390 fsd f20, TASK_THREAD_F20_F0(a0)
391 fsd f21, TASK_THREAD_F21_F0(a0)
392 fsd f22, TASK_THREAD_F22_F0(a0)
393 fsd f23, TASK_THREAD_F23_F0(a0)
394 fsd f24, TASK_THREAD_F24_F0(a0)
395 fsd f25, TASK_THREAD_F25_F0(a0)
396 fsd f26, TASK_THREAD_F26_F0(a0)
397 fsd f27, TASK_THREAD_F27_F0(a0)
398 fsd f28, TASK_THREAD_F28_F0(a0)
399 fsd f29, TASK_THREAD_F29_F0(a0)
400 fsd f30, TASK_THREAD_F30_F0(a0)
401 fsd f31, TASK_THREAD_F31_F0(a0)
402 sw t0, TASK_THREAD_FCSR_F0(a0)
405 ENDPROC(__fstate_save)
407 ENTRY(__fstate_restore)
408 li a2, TASK_THREAD_F0
411 lw t0, TASK_THREAD_FCSR_F0(a0)
413 fld f0, TASK_THREAD_F0_F0(a0)
414 fld f1, TASK_THREAD_F1_F0(a0)
415 fld f2, TASK_THREAD_F2_F0(a0)
416 fld f3, TASK_THREAD_F3_F0(a0)
417 fld f4, TASK_THREAD_F4_F0(a0)
418 fld f5, TASK_THREAD_F5_F0(a0)
419 fld f6, TASK_THREAD_F6_F0(a0)
420 fld f7, TASK_THREAD_F7_F0(a0)
421 fld f8, TASK_THREAD_F8_F0(a0)
422 fld f9, TASK_THREAD_F9_F0(a0)
423 fld f10, TASK_THREAD_F10_F0(a0)
424 fld f11, TASK_THREAD_F11_F0(a0)
425 fld f12, TASK_THREAD_F12_F0(a0)
426 fld f13, TASK_THREAD_F13_F0(a0)
427 fld f14, TASK_THREAD_F14_F0(a0)
428 fld f15, TASK_THREAD_F15_F0(a0)
429 fld f16, TASK_THREAD_F16_F0(a0)
430 fld f17, TASK_THREAD_F17_F0(a0)
431 fld f18, TASK_THREAD_F18_F0(a0)
432 fld f19, TASK_THREAD_F19_F0(a0)
433 fld f20, TASK_THREAD_F20_F0(a0)
434 fld f21, TASK_THREAD_F21_F0(a0)
435 fld f22, TASK_THREAD_F22_F0(a0)
436 fld f23, TASK_THREAD_F23_F0(a0)
437 fld f24, TASK_THREAD_F24_F0(a0)
438 fld f25, TASK_THREAD_F25_F0(a0)
439 fld f26, TASK_THREAD_F26_F0(a0)
440 fld f27, TASK_THREAD_F27_F0(a0)
441 fld f28, TASK_THREAD_F28_F0(a0)
442 fld f29, TASK_THREAD_F29_F0(a0)
443 fld f30, TASK_THREAD_F30_F0(a0)
444 fld f31, TASK_THREAD_F31_F0(a0)
448 ENDPROC(__fstate_restore)
453 /* Exception vector table */
454 ENTRY(excp_vect_table)
455 RISCV_PTR do_trap_insn_misaligned
456 RISCV_PTR do_trap_insn_fault
457 RISCV_PTR do_trap_insn_illegal
458 RISCV_PTR do_trap_break
459 RISCV_PTR do_trap_load_misaligned
460 RISCV_PTR do_trap_load_fault
461 RISCV_PTR do_trap_store_misaligned
462 RISCV_PTR do_trap_store_fault
463 RISCV_PTR do_trap_ecall_u /* system call, gets intercepted */
464 RISCV_PTR do_trap_ecall_s
465 RISCV_PTR do_trap_unknown
466 RISCV_PTR do_trap_ecall_m
467 RISCV_PTR do_page_fault /* instruction page fault */
468 RISCV_PTR do_page_fault /* load page fault */
469 RISCV_PTR do_trap_unknown
470 RISCV_PTR do_page_fault /* store page fault */