1 // SPDX-License-Identifier: GPL-2.0-or-later
2
3 #include <linux/context_tracking.h>
4 #include <linux/err.h>
5 #include <linux/compat.h>
6
7 #include <asm/asm-prototypes.h>
8 #include <asm/kup.h>
9 #include <asm/cputime.h>
10 #include <asm/interrupt.h>
11 #include <asm/hw_irq.h>
12 #include <asm/interrupt.h>
13 #include <asm/kprobes.h>
14 #include <asm/paca.h>
15 #include <asm/ptrace.h>
16 #include <asm/reg.h>
17 #include <asm/signal.h>
18 #include <asm/switch_to.h>
19 #include <asm/syscall.h>
20 #include <asm/time.h>
21 #include <asm/unistd.h>
22
23 #if defined(CONFIG_PPC_ADV_DEBUG_REGS) && defined(CONFIG_PPC32)
24 unsigned long global_dbcr0[NR_CPUS];
25 #endif
26
27 typedef long (*syscall_fn)(long, long, long, long, long, long);
28
29 /* Has to run notrace because it is entered not completely "reconciled" */
system_call_exception(long r3,long r4,long r5,long r6,long r7,long r8,unsigned long r0,struct pt_regs * regs)30 notrace long system_call_exception(long r3, long r4, long r5,
31 long r6, long r7, long r8,
32 unsigned long r0, struct pt_regs *regs)
33 {
34 syscall_fn f;
35
36 kuep_lock();
37
38 regs->orig_gpr3 = r3;
39
40 if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
41 BUG_ON(irq_soft_mask_return() != IRQS_ALL_DISABLED);
42
43 trace_hardirqs_off(); /* finish reconciling */
44
45 CT_WARN_ON(ct_state() == CONTEXT_KERNEL);
46 user_exit_irqoff();
47
48 if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x))
49 BUG_ON(!(regs->msr & MSR_RI));
50 BUG_ON(!(regs->msr & MSR_PR));
51 BUG_ON(arch_irq_disabled_regs(regs));
52
53 #ifdef CONFIG_PPC_PKEY
54 if (mmu_has_feature(MMU_FTR_PKEY)) {
55 unsigned long amr, iamr;
56 bool flush_needed = false;
57 /*
58 * When entering from userspace we mostly have the AMR/IAMR
59 * different from kernel default values. Hence don't compare.
60 */
61 amr = mfspr(SPRN_AMR);
62 iamr = mfspr(SPRN_IAMR);
63 regs->amr = amr;
64 regs->iamr = iamr;
65 if (mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) {
66 mtspr(SPRN_AMR, AMR_KUAP_BLOCKED);
67 flush_needed = true;
68 }
69 if (mmu_has_feature(MMU_FTR_BOOK3S_KUEP)) {
70 mtspr(SPRN_IAMR, AMR_KUEP_BLOCKED);
71 flush_needed = true;
72 }
73 if (flush_needed)
74 isync();
75 } else
76 #endif
77 kuap_assert_locked();
78
79 booke_restore_dbcr0();
80
81 account_cpu_user_entry();
82
83 account_stolen_time();
84
85 /*
86 * This is not required for the syscall exit path, but makes the
87 * stack frame look nicer. If this was initialised in the first stack
88 * frame, or if the unwinder was taught the first stack frame always
89 * returns to user with IRQS_ENABLED, this store could be avoided!
90 */
91 irq_soft_mask_regs_set_state(regs, IRQS_ENABLED);
92
93 local_irq_enable();
94
95 if (unlikely(current_thread_info()->flags & _TIF_SYSCALL_DOTRACE)) {
96 if (unlikely(trap_is_unsupported_scv(regs))) {
97 /* Unsupported scv vector */
98 _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
99 return regs->gpr[3];
100 }
101 /*
102 * We use the return value of do_syscall_trace_enter() as the
103 * syscall number. If the syscall was rejected for any reason
104 * do_syscall_trace_enter() returns an invalid syscall number
105 * and the test against NR_syscalls will fail and the return
106 * value to be used is in regs->gpr[3].
107 */
108 r0 = do_syscall_trace_enter(regs);
109 if (unlikely(r0 >= NR_syscalls))
110 return regs->gpr[3];
111 r3 = regs->gpr[3];
112 r4 = regs->gpr[4];
113 r5 = regs->gpr[5];
114 r6 = regs->gpr[6];
115 r7 = regs->gpr[7];
116 r8 = regs->gpr[8];
117
118 } else if (unlikely(r0 >= NR_syscalls)) {
119 if (unlikely(trap_is_unsupported_scv(regs))) {
120 /* Unsupported scv vector */
121 _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
122 return regs->gpr[3];
123 }
124 return -ENOSYS;
125 }
126
127 /* May be faster to do array_index_nospec? */
128 barrier_nospec();
129
130 if (unlikely(is_compat_task())) {
131 f = (void *)compat_sys_call_table[r0];
132
133 r3 &= 0x00000000ffffffffULL;
134 r4 &= 0x00000000ffffffffULL;
135 r5 &= 0x00000000ffffffffULL;
136 r6 &= 0x00000000ffffffffULL;
137 r7 &= 0x00000000ffffffffULL;
138 r8 &= 0x00000000ffffffffULL;
139
140 } else {
141 f = (void *)sys_call_table[r0];
142 }
143
144 return f(r3, r4, r5, r6, r7, r8);
145 }
146
147 /*
148 * local irqs must be disabled. Returns false if the caller must re-enable
149 * them, check for new work, and try again.
150 *
151 * This should be called with local irqs disabled, but if they were previously
152 * enabled when the interrupt handler returns (indicating a process-context /
153 * synchronous interrupt) then irqs_enabled should be true.
154 */
__prep_irq_for_enabled_exit(bool clear_ri)155 static notrace __always_inline bool __prep_irq_for_enabled_exit(bool clear_ri)
156 {
157 /* This must be done with RI=1 because tracing may touch vmaps */
158 trace_hardirqs_on();
159
160 /* This pattern matches prep_irq_for_idle */
161 if (clear_ri)
162 __hard_EE_RI_disable();
163 else
164 __hard_irq_disable();
165 #ifdef CONFIG_PPC64
166 if (unlikely(lazy_irq_pending_nocheck())) {
167 /* Took an interrupt, may have more exit work to do. */
168 if (clear_ri)
169 __hard_RI_enable();
170 trace_hardirqs_off();
171 local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
172
173 return false;
174 }
175 local_paca->irq_happened = 0;
176 irq_soft_mask_set(IRQS_ENABLED);
177 #endif
178 return true;
179 }
180
prep_irq_for_enabled_exit(bool clear_ri,bool irqs_enabled)181 static notrace inline bool prep_irq_for_enabled_exit(bool clear_ri, bool irqs_enabled)
182 {
183 if (__prep_irq_for_enabled_exit(clear_ri))
184 return true;
185
186 /*
187 * Must replay pending soft-masked interrupts now. Don't just
188 * local_irq_enabe(); local_irq_disable(); because if we are
189 * returning from an asynchronous interrupt here, another one
190 * might hit after irqs are enabled, and it would exit via this
191 * same path allowing another to fire, and so on unbounded.
192 *
193 * If interrupts were enabled when this interrupt exited,
194 * indicating a process context (synchronous) interrupt,
195 * local_irq_enable/disable can be used, which will enable
196 * interrupts rather than keeping them masked (unclear how
197 * much benefit this is over just replaying for all cases,
198 * because we immediately disable again, so all we're really
199 * doing is allowing hard interrupts to execute directly for
200 * a very small time, rather than being masked and replayed).
201 */
202 if (irqs_enabled) {
203 local_irq_enable();
204 local_irq_disable();
205 } else {
206 replay_soft_interrupts();
207 }
208
209 return false;
210 }
211
booke_load_dbcr0(void)212 static notrace void booke_load_dbcr0(void)
213 {
214 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
215 unsigned long dbcr0 = current->thread.debug.dbcr0;
216
217 if (likely(!(dbcr0 & DBCR0_IDM)))
218 return;
219
220 /*
221 * Check to see if the dbcr0 register is set up to debug.
222 * Use the internal debug mode bit to do this.
223 */
224 mtmsr(mfmsr() & ~MSR_DE);
225 if (IS_ENABLED(CONFIG_PPC32)) {
226 isync();
227 global_dbcr0[smp_processor_id()] = mfspr(SPRN_DBCR0);
228 }
229 mtspr(SPRN_DBCR0, dbcr0);
230 mtspr(SPRN_DBSR, -1);
231 #endif
232 }
233
234 /*
235 * This should be called after a syscall returns, with r3 the return value
236 * from the syscall. If this function returns non-zero, the system call
237 * exit assembly should additionally load all GPR registers and CTR and XER
238 * from the interrupt frame.
239 *
240 * The function graph tracer can not trace the return side of this function,
241 * because RI=0 and soft mask state is "unreconciled", so it is marked notrace.
242 */
syscall_exit_prepare(unsigned long r3,struct pt_regs * regs,long scv)243 notrace unsigned long syscall_exit_prepare(unsigned long r3,
244 struct pt_regs *regs,
245 long scv)
246 {
247 unsigned long ti_flags;
248 unsigned long ret = 0;
249 bool is_not_scv = !IS_ENABLED(CONFIG_PPC_BOOK3S_64) || !scv;
250
251 CT_WARN_ON(ct_state() == CONTEXT_USER);
252
253 kuap_assert_locked();
254
255 regs->result = r3;
256
257 /* Check whether the syscall is issued inside a restartable sequence */
258 rseq_syscall(regs);
259
260 ti_flags = current_thread_info()->flags;
261
262 if (unlikely(r3 >= (unsigned long)-MAX_ERRNO) && is_not_scv) {
263 if (likely(!(ti_flags & (_TIF_NOERROR | _TIF_RESTOREALL)))) {
264 r3 = -r3;
265 regs->ccr |= 0x10000000; /* Set SO bit in CR */
266 }
267 }
268
269 if (unlikely(ti_flags & _TIF_PERSYSCALL_MASK)) {
270 if (ti_flags & _TIF_RESTOREALL)
271 ret = _TIF_RESTOREALL;
272 else
273 regs->gpr[3] = r3;
274 clear_bits(_TIF_PERSYSCALL_MASK, ¤t_thread_info()->flags);
275 } else {
276 regs->gpr[3] = r3;
277 }
278
279 if (unlikely(ti_flags & _TIF_SYSCALL_DOTRACE)) {
280 do_syscall_trace_leave(regs);
281 ret |= _TIF_RESTOREALL;
282 }
283
284 local_irq_disable();
285
286 again:
287 ti_flags = READ_ONCE(current_thread_info()->flags);
288 while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) {
289 local_irq_enable();
290 if (ti_flags & _TIF_NEED_RESCHED) {
291 schedule();
292 } else {
293 /*
294 * SIGPENDING must restore signal handler function
295 * argument GPRs, and some non-volatiles (e.g., r1).
296 * Restore all for now. This could be made lighter.
297 */
298 if (ti_flags & _TIF_SIGPENDING)
299 ret |= _TIF_RESTOREALL;
300 do_notify_resume(regs, ti_flags);
301 }
302 local_irq_disable();
303 ti_flags = READ_ONCE(current_thread_info()->flags);
304 }
305
306 if (IS_ENABLED(CONFIG_PPC_BOOK3S) && IS_ENABLED(CONFIG_PPC_FPU)) {
307 if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) &&
308 unlikely((ti_flags & _TIF_RESTORE_TM))) {
309 restore_tm_state(regs);
310 } else {
311 unsigned long mathflags = MSR_FP;
312
313 if (cpu_has_feature(CPU_FTR_VSX))
314 mathflags |= MSR_VEC | MSR_VSX;
315 else if (cpu_has_feature(CPU_FTR_ALTIVEC))
316 mathflags |= MSR_VEC;
317
318 /*
319 * If userspace MSR has all available FP bits set,
320 * then they are live and no need to restore. If not,
321 * it means the regs were given up and restore_math
322 * may decide to restore them (to avoid taking an FP
323 * fault).
324 */
325 if ((regs->msr & mathflags) != mathflags)
326 restore_math(regs);
327 }
328 }
329
330 user_enter_irqoff();
331
332 /* scv need not set RI=0 because SRRs are not used */
333 if (unlikely(!__prep_irq_for_enabled_exit(is_not_scv))) {
334 user_exit_irqoff();
335 local_irq_enable();
336 local_irq_disable();
337 goto again;
338 }
339
340 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
341 local_paca->tm_scratch = regs->msr;
342 #endif
343
344 booke_load_dbcr0();
345
346 account_cpu_user_exit();
347
348 /* Restore user access locks last */
349 kuap_user_restore(regs);
350 kuep_unlock();
351
352 return ret;
353 }
354
interrupt_exit_user_prepare(struct pt_regs * regs,unsigned long msr)355 notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned long msr)
356 {
357 unsigned long ti_flags;
358 unsigned long flags;
359 unsigned long ret = 0;
360
361 if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x))
362 BUG_ON(!(regs->msr & MSR_RI));
363 BUG_ON(!(regs->msr & MSR_PR));
364 BUG_ON(arch_irq_disabled_regs(regs));
365 CT_WARN_ON(ct_state() == CONTEXT_USER);
366
367 /*
368 * We don't need to restore AMR on the way back to userspace for KUAP.
369 * AMR can only have been unlocked if we interrupted the kernel.
370 */
371 kuap_assert_locked();
372
373 local_irq_save(flags);
374
375 again:
376 ti_flags = READ_ONCE(current_thread_info()->flags);
377 while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) {
378 local_irq_enable(); /* returning to user: may enable */
379 if (ti_flags & _TIF_NEED_RESCHED) {
380 schedule();
381 } else {
382 if (ti_flags & _TIF_SIGPENDING)
383 ret |= _TIF_RESTOREALL;
384 do_notify_resume(regs, ti_flags);
385 }
386 local_irq_disable();
387 ti_flags = READ_ONCE(current_thread_info()->flags);
388 }
389
390 if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && IS_ENABLED(CONFIG_PPC_FPU)) {
391 if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) &&
392 unlikely((ti_flags & _TIF_RESTORE_TM))) {
393 restore_tm_state(regs);
394 } else {
395 unsigned long mathflags = MSR_FP;
396
397 if (cpu_has_feature(CPU_FTR_VSX))
398 mathflags |= MSR_VEC | MSR_VSX;
399 else if (cpu_has_feature(CPU_FTR_ALTIVEC))
400 mathflags |= MSR_VEC;
401
402 /* See above restore_math comment */
403 if ((regs->msr & mathflags) != mathflags)
404 restore_math(regs);
405 }
406 }
407
408 user_enter_irqoff();
409
410 if (unlikely(!__prep_irq_for_enabled_exit(true))) {
411 user_exit_irqoff();
412 local_irq_enable();
413 local_irq_disable();
414 goto again;
415 }
416
417 booke_load_dbcr0();
418
419 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
420 local_paca->tm_scratch = regs->msr;
421 #endif
422
423 account_cpu_user_exit();
424
425 /* Restore user access locks last */
426 kuap_user_restore(regs);
427 kuep_unlock();
428
429 return ret;
430 }
431
432 void preempt_schedule_irq(void);
433
interrupt_exit_kernel_prepare(struct pt_regs * regs,unsigned long msr)434 notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsigned long msr)
435 {
436 unsigned long flags;
437 unsigned long ret = 0;
438 unsigned long kuap;
439
440 if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x) &&
441 unlikely(!(regs->msr & MSR_RI)))
442 unrecoverable_exception(regs);
443 BUG_ON(regs->msr & MSR_PR);
444 /*
445 * CT_WARN_ON comes here via program_check_exception,
446 * so avoid recursion.
447 */
448 if (TRAP(regs) != INTERRUPT_PROGRAM)
449 CT_WARN_ON(ct_state() == CONTEXT_USER);
450
451 kuap = kuap_get_and_assert_locked();
452
453 if (unlikely(current_thread_info()->flags & _TIF_EMULATE_STACK_STORE)) {
454 clear_bits(_TIF_EMULATE_STACK_STORE, ¤t_thread_info()->flags);
455 ret = 1;
456 }
457
458 local_irq_save(flags);
459
460 if (!arch_irq_disabled_regs(regs)) {
461 /* Returning to a kernel context with local irqs enabled. */
462 WARN_ON_ONCE(!(regs->msr & MSR_EE));
463 again:
464 if (IS_ENABLED(CONFIG_PREEMPT)) {
465 /* Return to preemptible kernel context */
466 if (unlikely(current_thread_info()->flags & _TIF_NEED_RESCHED)) {
467 if (preempt_count() == 0)
468 preempt_schedule_irq();
469 }
470 }
471
472 if (unlikely(!prep_irq_for_enabled_exit(true, !irqs_disabled_flags(flags))))
473 goto again;
474 } else {
475 /* Returning to a kernel context with local irqs disabled. */
476 __hard_EE_RI_disable();
477 #ifdef CONFIG_PPC64
478 if (regs->msr & MSR_EE)
479 local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
480 #endif
481 }
482
483
484 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
485 local_paca->tm_scratch = regs->msr;
486 #endif
487
488 /*
489 * 64s does not want to mfspr(SPRN_AMR) here, because this comes after
490 * mtmsr, which would cause Read-After-Write stalls. Hence, take the
491 * AMR value from the check above.
492 */
493 kuap_kernel_restore(regs, kuap);
494
495 return ret;
496 }
497