1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * PowerPC version
4 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
5 *
6 * Derived from "arch/i386/kernel/signal.c"
7 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
9 */
10
11#include <linux/sched.h>
12#include <linux/mm.h>
13#include <linux/smp.h>
14#include <linux/kernel.h>
15#include <linux/signal.h>
16#include <linux/errno.h>
17#include <linux/wait.h>
18#include <linux/unistd.h>
19#include <linux/stddef.h>
20#include <linux/elf.h>
21#include <linux/ptrace.h>
22#include <linux/ratelimit.h>
23#include <linux/syscalls.h>
24#include <linux/pagemap.h>
25
26#include <asm/sigcontext.h>
27#include <asm/ucontext.h>
28#include <linux/uaccess.h>
29#include <asm/unistd.h>
30#include <asm/cacheflush.h>
31#include <asm/syscalls.h>
32#include <asm/vdso.h>
33#include <asm/switch_to.h>
34#include <asm/tm.h>
35#include <asm/asm-prototypes.h>
36
37#include "signal.h"
38
39
40#define GP_REGS_SIZE min(sizeof(elf_gregset_t), sizeof(struct pt_regs))
41#define FP_REGS_SIZE sizeof(elf_fpregset_t)
42
43#define TRAMP_TRACEBACK 4
44#define TRAMP_SIZE 7
45
46/*
47 * When we have signals to deliver, we set up on the user stack,
48 * going down from the original stack pointer:
49 * 1) a rt_sigframe struct which contains the ucontext
50 * 2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller
51 * frame for the signal handler.
52 */
53
54struct rt_sigframe {
55 /* sys_rt_sigreturn requires the ucontext be the first field */
56 struct ucontext uc;
57#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
58 struct ucontext uc_transact;
59#endif
60 unsigned long _unused[2];
61 unsigned int tramp[TRAMP_SIZE];
62 struct siginfo __user *pinfo;
63 void __user *puc;
64 struct siginfo info;
65 /* New 64 bit little-endian ABI allows redzone of 512 bytes below sp */
66 char abigap[USER_REDZONE_SIZE];
67} __attribute__ ((aligned (16)));
68
69unsigned long get_min_sigframe_size_64(void)
70{
71 return sizeof(struct rt_sigframe) + __SIGNAL_FRAMESIZE;
72}
73
74/*
75 * This computes a quad word aligned pointer inside the vmx_reserve array
76 * element. For historical reasons sigcontext might not be quad word aligned,
77 * but the location we write the VMX regs to must be. See the comment in
78 * sigcontext for more detail.
79 */
80#ifdef CONFIG_ALTIVEC
81static elf_vrreg_t __user *sigcontext_vmx_regs(struct sigcontext __user *sc)
82{
83 return (elf_vrreg_t __user *) (((unsigned long)sc->vmx_reserve + 15) & ~0xful);
84}
85#endif
86
87static void prepare_setup_sigcontext(struct task_struct *tsk)
88{
89#ifdef CONFIG_ALTIVEC
90 /* save altivec registers */
91 if (tsk->thread.used_vr)
92 flush_altivec_to_thread(tsk);
93 if (cpu_has_feature(CPU_FTR_ALTIVEC))
94 tsk->thread.vrsave = mfspr(SPRN_VRSAVE);
95#endif /* CONFIG_ALTIVEC */
96
97 flush_fp_to_thread(tsk);
98
99#ifdef CONFIG_VSX
100 if (tsk->thread.used_vsr)
101 flush_vsx_to_thread(tsk);
102#endif /* CONFIG_VSX */
103}
104
105/*
106 * Set up the sigcontext for the signal frame.
107 */
108
109#define unsafe_setup_sigcontext(sc, tsk, signr, set, handler, ctx_has_vsx_region, label)\
110do { \
111 if (__unsafe_setup_sigcontext(sc, tsk, signr, set, handler, ctx_has_vsx_region))\
112 goto label; \
113} while (0)
114static long notrace __unsafe_setup_sigcontext(struct sigcontext __user *sc,
115 struct task_struct *tsk, int signr, sigset_t *set,
116 unsigned long handler, int ctx_has_vsx_region)
117{
118 /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
119 * process never used altivec yet (MSR_VEC is zero in pt_regs of
120 * the context). This is very important because we must ensure we
121 * don't lose the VRSAVE content that may have been set prior to
122 * the process doing its first vector operation
123 * Userland shall check AT_HWCAP to know whether it can rely on the
124 * v_regs pointer or not
125 */
126#ifdef CONFIG_ALTIVEC
127 elf_vrreg_t __user *v_regs = sigcontext_vmx_regs(sc);
128#endif
129 struct pt_regs *regs = tsk->thread.regs;
130 unsigned long msr = regs->msr;
131 /* Force usr to always see softe as 1 (interrupts enabled) */
132 unsigned long softe = 0x1;
133
134 BUG_ON(tsk != current);
135
136#ifdef CONFIG_ALTIVEC
137 unsafe_put_user(v_regs, &sc->v_regs, efault_out);
138
139 /* save altivec registers */
140 if (tsk->thread.used_vr) {
141 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */
142 unsafe_copy_to_user(v_regs, &tsk->thread.vr_state,
143 33 * sizeof(vector128), efault_out);
144 /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg)
145 * contains valid data.
146 */
147 msr |= MSR_VEC;
148 }
149 /* We always copy to/from vrsave, it's 0 if we don't have or don't
150 * use altivec.
151 */
152 unsafe_put_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33], efault_out);
153#else /* CONFIG_ALTIVEC */
154 unsafe_put_user(0, &sc->v_regs, efault_out);
155#endif /* CONFIG_ALTIVEC */
156 /* copy fpr regs and fpscr */
157 unsafe_copy_fpr_to_user(&sc->fp_regs, tsk, efault_out);
158
159 /*
160 * Clear the MSR VSX bit to indicate there is no valid state attached
161 * to this context, except in the specific case below where we set it.
162 */
163 msr &= ~MSR_VSX;
164#ifdef CONFIG_VSX
165 /*
166 * Copy VSX low doubleword to local buffer for formatting,
167 * then out to userspace. Update v_regs to point after the
168 * VMX data.
169 */
170 if (tsk->thread.used_vsr && ctx_has_vsx_region) {
171 v_regs += ELF_NVRREG;
172 unsafe_copy_vsx_to_user(v_regs, tsk, efault_out);
173 /* set MSR_VSX in the MSR value in the frame to
174 * indicate that sc->vs_reg) contains valid data.
175 */
176 msr |= MSR_VSX;
177 }
178#endif /* CONFIG_VSX */
179 unsafe_put_user(&sc->gp_regs, &sc->regs, efault_out);
180 unsafe_copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE, efault_out);
181 unsafe_put_user(msr, &sc->gp_regs[PT_MSR], efault_out);
182 unsafe_put_user(softe, &sc->gp_regs[PT_SOFTE], efault_out);
183 unsafe_put_user(signr, &sc->signal, efault_out);
184 unsafe_put_user(handler, &sc->handler, efault_out);
185 if (set != NULL)
186 unsafe_put_user(set->sig[0], &sc->oldmask, efault_out);
187
188 return 0;
189
190efault_out:
191 return -EFAULT;
192}
193
194#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
195/*
196 * As above, but Transactional Memory is in use, so deliver sigcontexts
197 * containing checkpointed and transactional register states.
198 *
199 * To do this, we treclaim (done before entering here) to gather both sets of
200 * registers and set up the 'normal' sigcontext registers with rolled-back
201 * register values such that a simple signal handler sees a correct
202 * checkpointed register state. If interested, a TM-aware sighandler can
203 * examine the transactional registers in the 2nd sigcontext to determine the
204 * real origin of the signal.
205 */
206static long setup_tm_sigcontexts(struct sigcontext __user *sc,
207 struct sigcontext __user *tm_sc,
208 struct task_struct *tsk,
209 int signr, sigset_t *set, unsigned long handler,
210 unsigned long msr)
211{
212 /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
213 * process never used altivec yet (MSR_VEC is zero in pt_regs of
214 * the context). This is very important because we must ensure we
215 * don't lose the VRSAVE content that may have been set prior to
216 * the process doing its first vector operation
217 * Userland shall check AT_HWCAP to know wether it can rely on the
218 * v_regs pointer or not.
219 */
220#ifdef CONFIG_ALTIVEC
221 elf_vrreg_t __user *v_regs = sigcontext_vmx_regs(sc);
222 elf_vrreg_t __user *tm_v_regs = sigcontext_vmx_regs(tm_sc);
223#endif
224 struct pt_regs *regs = tsk->thread.regs;
225 long err = 0;
226
227 BUG_ON(tsk != current);
228
229 BUG_ON(!MSR_TM_ACTIVE(msr));
230
231 WARN_ON(tm_suspend_disabled);
232
233 /* Restore checkpointed FP, VEC, and VSX bits from ckpt_regs as
234 * it contains the correct FP, VEC, VSX state after we treclaimed
235 * the transaction and giveup_all() was called on reclaiming.
236 */
237 msr |= tsk->thread.ckpt_regs.msr & (MSR_FP | MSR_VEC | MSR_VSX);
238
239#ifdef CONFIG_ALTIVEC
240 err |= __put_user(v_regs, &sc->v_regs);
241 err |= __put_user(tm_v_regs, &tm_sc->v_regs);
242
243 /* save altivec registers */
244 if (tsk->thread.used_vr) {
245 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */
246 err |= __copy_to_user(v_regs, &tsk->thread.ckvr_state,
247 33 * sizeof(vector128));
248 /* If VEC was enabled there are transactional VRs valid too,
249 * else they're a copy of the checkpointed VRs.
250 */
251 if (msr & MSR_VEC)
252 err |= __copy_to_user(tm_v_regs,
253 &tsk->thread.vr_state,
254 33 * sizeof(vector128));
255 else
256 err |= __copy_to_user(tm_v_regs,
257 &tsk->thread.ckvr_state,
258 33 * sizeof(vector128));
259
260 /* set MSR_VEC in the MSR value in the frame to indicate
261 * that sc->v_reg contains valid data.
262 */
263 msr |= MSR_VEC;
264 }
265 /* We always copy to/from vrsave, it's 0 if we don't have or don't
266 * use altivec.
267 */
268 if (cpu_has_feature(CPU_FTR_ALTIVEC))
269 tsk->thread.ckvrsave = mfspr(SPRN_VRSAVE);
270 err |= __put_user(tsk->thread.ckvrsave, (u32 __user *)&v_regs[33]);
271 if (msr & MSR_VEC)
272 err |= __put_user(tsk->thread.vrsave,
273 (u32 __user *)&tm_v_regs[33]);
274 else
275 err |= __put_user(tsk->thread.ckvrsave,
276 (u32 __user *)&tm_v_regs[33]);
277
278#else /* CONFIG_ALTIVEC */
279 err |= __put_user(0, &sc->v_regs);
280 err |= __put_user(0, &tm_sc->v_regs);
281#endif /* CONFIG_ALTIVEC */
282
283 /* copy fpr regs and fpscr */
284 err |= copy_ckfpr_to_user(&sc->fp_regs, tsk);
285 if (msr & MSR_FP)
286 err |= copy_fpr_to_user(&tm_sc->fp_regs, tsk);
287 else
288 err |= copy_ckfpr_to_user(&tm_sc->fp_regs, tsk);
289
290#ifdef CONFIG_VSX
291 /*
292 * Copy VSX low doubleword to local buffer for formatting,
293 * then out to userspace. Update v_regs to point after the
294 * VMX data.
295 */
296 if (tsk->thread.used_vsr) {
297 v_regs += ELF_NVRREG;
298 tm_v_regs += ELF_NVRREG;
299
300 err |= copy_ckvsx_to_user(v_regs, tsk);
301
302 if (msr & MSR_VSX)
303 err |= copy_vsx_to_user(tm_v_regs, tsk);
304 else
305 err |= copy_ckvsx_to_user(tm_v_regs, tsk);
306
307 /* set MSR_VSX in the MSR value in the frame to
308 * indicate that sc->vs_reg) contains valid data.
309 */
310 msr |= MSR_VSX;
311 }
312#endif /* CONFIG_VSX */
313
314 err |= __put_user(&sc->gp_regs, &sc->regs);
315 err |= __put_user(&tm_sc->gp_regs, &tm_sc->regs);
316 err |= __copy_to_user(&tm_sc->gp_regs, regs, GP_REGS_SIZE);
317 err |= __copy_to_user(&sc->gp_regs,
318 &tsk->thread.ckpt_regs, GP_REGS_SIZE);
319 err |= __put_user(msr, &tm_sc->gp_regs[PT_MSR]);
320 err |= __put_user(msr, &sc->gp_regs[PT_MSR]);
321 err |= __put_user(signr, &sc->signal);
322 err |= __put_user(handler, &sc->handler);
323 if (set != NULL)
324 err |= __put_user(set->sig[0], &sc->oldmask);
325
326 return err;
327}
328#endif
329
330/*
331 * Restore the sigcontext from the signal frame.
332 */
333#define unsafe_restore_sigcontext(tsk, set, sig, sc, label) do { \
334 if (__unsafe_restore_sigcontext(tsk, set, sig, sc)) \
335 goto label; \
336} while (0)
337static long notrace __unsafe_restore_sigcontext(struct task_struct *tsk, sigset_t *set,
338 int sig, struct sigcontext __user *sc)
339{
340#ifdef CONFIG_ALTIVEC
341 elf_vrreg_t __user *v_regs;
342#endif
343 unsigned long save_r13 = 0;
344 unsigned long msr;
345 struct pt_regs *regs = tsk->thread.regs;
346#ifdef CONFIG_VSX
347 int i;
348#endif
349
350 BUG_ON(tsk != current);
351
352 /* If this is not a signal return, we preserve the TLS in r13 */
353 if (!sig)
354 save_r13 = regs->gpr[13];
355
356 /* copy the GPRs */
357 unsafe_copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr), efault_out);
358 unsafe_get_user(regs->nip, &sc->gp_regs[PT_NIP], efault_out);
359 /* get MSR separately, transfer the LE bit if doing signal return */
360 unsafe_get_user(msr, &sc->gp_regs[PT_MSR], efault_out);
361 if (sig)
362 regs_set_return_msr(regs, (regs->msr & ~MSR_LE) | (msr & MSR_LE));
363 unsafe_get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3], efault_out);
364 unsafe_get_user(regs->ctr, &sc->gp_regs[PT_CTR], efault_out);
365 unsafe_get_user(regs->link, &sc->gp_regs[PT_LNK], efault_out);
366 unsafe_get_user(regs->xer, &sc->gp_regs[PT_XER], efault_out);
367 unsafe_get_user(regs->ccr, &sc->gp_regs[PT_CCR], efault_out);
368 /* Don't allow userspace to set SOFTE */
369 set_trap_norestart(regs);
370 unsafe_get_user(regs->dar, &sc->gp_regs[PT_DAR], efault_out);
371 unsafe_get_user(regs->dsisr, &sc->gp_regs[PT_DSISR], efault_out);
372 unsafe_get_user(regs->result, &sc->gp_regs[PT_RESULT], efault_out);
373
374 if (!sig)
375 regs->gpr[13] = save_r13;
376 if (set != NULL)
377 unsafe_get_user(set->sig[0], &sc->oldmask, efault_out);
378
379 /*
380 * Force reload of FP/VEC/VSX so userspace sees any changes.
381 * Clear these bits from the user process' MSR before copying into the
382 * thread struct. If we are rescheduled or preempted and another task
383 * uses FP/VEC/VSX, and this process has the MSR bits set, then the
384 * context switch code will save the current CPU state into the
385 * thread_struct - possibly overwriting the data we are updating here.
386 */
387 regs_set_return_msr(regs, regs->msr & ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX));
388
389#ifdef CONFIG_ALTIVEC
390 unsafe_get_user(v_regs, &sc->v_regs, efault_out);
391 if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128)))
392 return -EFAULT;
393 /* Copy 33 vec registers (vr0..31 and vscr) from the stack */
394 if (v_regs != NULL && (msr & MSR_VEC) != 0) {
395 unsafe_copy_from_user(&tsk->thread.vr_state, v_regs,
396 33 * sizeof(vector128), efault_out);
397 tsk->thread.used_vr = true;
398 } else if (tsk->thread.used_vr) {
399 memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128));
400 }
401 /* Always get VRSAVE back */
402 if (v_regs != NULL)
403 unsafe_get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33], efault_out);
404 else
405 tsk->thread.vrsave = 0;
406 if (cpu_has_feature(CPU_FTR_ALTIVEC))
407 mtspr(SPRN_VRSAVE, tsk->thread.vrsave);
408#endif /* CONFIG_ALTIVEC */
409 /* restore floating point */
410 unsafe_copy_fpr_from_user(tsk, &sc->fp_regs, efault_out);
411#ifdef CONFIG_VSX
412 /*
413 * Get additional VSX data. Update v_regs to point after the
414 * VMX data. Copy VSX low doubleword from userspace to local
415 * buffer for formatting, then into the taskstruct.
416 */
417 v_regs += ELF_NVRREG;
418 if ((msr & MSR_VSX) != 0) {
419 unsafe_copy_vsx_from_user(tsk, v_regs, efault_out);
420 tsk->thread.used_vsr = true;
421 } else {
422 for (i = 0; i < 32 ; i++)
423 tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
424 }
425#endif
426 return 0;
427
428efault_out:
429 return -EFAULT;
430}
431
432#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
433/*
434 * Restore the two sigcontexts from the frame of a transactional processes.
435 */
436
437static long restore_tm_sigcontexts(struct task_struct *tsk,
438 struct sigcontext __user *sc,
439 struct sigcontext __user *tm_sc)
440{
441#ifdef CONFIG_ALTIVEC
442 elf_vrreg_t __user *v_regs, *tm_v_regs;
443#endif
444 unsigned long err = 0;
445 unsigned long msr;
446 struct pt_regs *regs = tsk->thread.regs;
447#ifdef CONFIG_VSX
448 int i;
449#endif
450
451 BUG_ON(tsk != current);
452
453 if (tm_suspend_disabled)
454 return -EINVAL;
455
456 /* copy the GPRs */
457 err |= __copy_from_user(regs->gpr, tm_sc->gp_regs, sizeof(regs->gpr));
458 err |= __copy_from_user(&tsk->thread.ckpt_regs, sc->gp_regs,
459 sizeof(regs->gpr));
460
461 /*
462 * TFHAR is restored from the checkpointed 'wound-back' ucontext's NIP.
463 * TEXASR was set by the signal delivery reclaim, as was TFIAR.
464 * Users doing anything abhorrent like thread-switching w/ signals for
465 * TM-Suspended code will have to back TEXASR/TFIAR up themselves.
466 * For the case of getting a signal and simply returning from it,
467 * we don't need to re-copy them here.
468 */
469 err |= __get_user(regs->nip, &tm_sc->gp_regs[PT_NIP]);
470 err |= __get_user(tsk->thread.tm_tfhar, &sc->gp_regs[PT_NIP]);
471
472 /* get MSR separately, transfer the LE bit if doing signal return */
473 err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
474 /* Don't allow reserved mode. */
475 if (MSR_TM_RESV(msr))
476 return -EINVAL;
477
478 /* pull in MSR LE from user context */
479 regs_set_return_msr(regs, (regs->msr & ~MSR_LE) | (msr & MSR_LE));
480
481 /* The following non-GPR non-FPR non-VR state is also checkpointed: */
482 err |= __get_user(regs->ctr, &tm_sc->gp_regs[PT_CTR]);
483 err |= __get_user(regs->link, &tm_sc->gp_regs[PT_LNK]);
484 err |= __get_user(regs->xer, &tm_sc->gp_regs[PT_XER]);
485 err |= __get_user(regs->ccr, &tm_sc->gp_regs[PT_CCR]);
486 err |= __get_user(tsk->thread.ckpt_regs.ctr,
487 &sc->gp_regs[PT_CTR]);
488 err |= __get_user(tsk->thread.ckpt_regs.link,
489 &sc->gp_regs[PT_LNK]);
490 err |= __get_user(tsk->thread.ckpt_regs.xer,
491 &sc->gp_regs[PT_XER]);
492 err |= __get_user(tsk->thread.ckpt_regs.ccr,
493 &sc->gp_regs[PT_CCR]);
494 /* Don't allow userspace to set SOFTE */
495 set_trap_norestart(regs);
496 /* These regs are not checkpointed; they can go in 'regs'. */
497 err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
498 err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
499 err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);
500
501 /*
502 * Force reload of FP/VEC.
503 * This has to be done before copying stuff into tsk->thread.fpr/vr
504 * for the reasons explained in the previous comment.
505 */
506 regs_set_return_msr(regs, regs->msr & ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX));
507
508#ifdef CONFIG_ALTIVEC
509 err |= __get_user(v_regs, &sc->v_regs);
510 err |= __get_user(tm_v_regs, &tm_sc->v_regs);
511 if (err)
512 return err;
513 if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128)))
514 return -EFAULT;
515 if (tm_v_regs && !access_ok(tm_v_regs, 34 * sizeof(vector128)))
516 return -EFAULT;
517 /* Copy 33 vec registers (vr0..31 and vscr) from the stack */
518 if (v_regs != NULL && tm_v_regs != NULL && (msr & MSR_VEC) != 0) {
519 err |= __copy_from_user(&tsk->thread.ckvr_state, v_regs,
520 33 * sizeof(vector128));
521 err |= __copy_from_user(&tsk->thread.vr_state, tm_v_regs,
522 33 * sizeof(vector128));
523 current->thread.used_vr = true;
524 }
525 else if (tsk->thread.used_vr) {
526 memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128));
527 memset(&tsk->thread.ckvr_state, 0, 33 * sizeof(vector128));
528 }
529 /* Always get VRSAVE back */
530 if (v_regs != NULL && tm_v_regs != NULL) {
531 err |= __get_user(tsk->thread.ckvrsave,
532 (u32 __user *)&v_regs[33]);
533 err |= __get_user(tsk->thread.vrsave,
534 (u32 __user *)&tm_v_regs[33]);
535 }
536 else {
537 tsk->thread.vrsave = 0;
538 tsk->thread.ckvrsave = 0;
539 }
540 if (cpu_has_feature(CPU_FTR_ALTIVEC))
541 mtspr(SPRN_VRSAVE, tsk->thread.vrsave);
542#endif /* CONFIG_ALTIVEC */
543 /* restore floating point */
544 err |= copy_fpr_from_user(tsk, &tm_sc->fp_regs);
545 err |= copy_ckfpr_from_user(tsk, &sc->fp_regs);
546#ifdef CONFIG_VSX
547 /*
548 * Get additional VSX data. Update v_regs to point after the
549 * VMX data. Copy VSX low doubleword from userspace to local
550 * buffer for formatting, then into the taskstruct.
551 */
552 if (v_regs && ((msr & MSR_VSX) != 0)) {
553 v_regs += ELF_NVRREG;
554 tm_v_regs += ELF_NVRREG;
555 err |= copy_vsx_from_user(tsk, tm_v_regs);
556 err |= copy_ckvsx_from_user(tsk, v_regs);
557 tsk->thread.used_vsr = true;
558 } else {
559 for (i = 0; i < 32 ; i++) {
560 tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
561 tsk->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
562 }
563 }
564#endif
565 tm_enable();
566 /* Make sure the transaction is marked as failed */
567 tsk->thread.tm_texasr |= TEXASR_FS;
568
569 /*
570 * Disabling preemption, since it is unsafe to be preempted
571 * with MSR[TS] set without recheckpointing.
572 */
573 preempt_disable();
574
575 /* pull in MSR TS bits from user context */
576 regs_set_return_msr(regs, regs->msr | (msr & MSR_TS_MASK));
577
578 /*
579 * Ensure that TM is enabled in regs->msr before we leave the signal
580 * handler. It could be the case that (a) user disabled the TM bit
581 * through the manipulation of the MSR bits in uc_mcontext or (b) the
582 * TM bit was disabled because a sufficient number of context switches
583 * happened whilst in the signal handler and load_tm overflowed,
584 * disabling the TM bit. In either case we can end up with an illegal
585 * TM state leading to a TM Bad Thing when we return to userspace.
586 *
587 * CAUTION:
588 * After regs->MSR[TS] being updated, make sure that get_user(),
589 * put_user() or similar functions are *not* called. These
590 * functions can generate page faults which will cause the process
591 * to be de-scheduled with MSR[TS] set but without calling
592 * tm_recheckpoint(). This can cause a bug.
593 */
594 regs_set_return_msr(regs, regs->msr | MSR_TM);
595
596 /* This loads the checkpointed FP/VEC state, if used */
597 tm_recheckpoint(&tsk->thread);
598
599 msr_check_and_set(msr & (MSR_FP | MSR_VEC));
600 if (msr & MSR_FP) {
601 load_fp_state(&tsk->thread.fp_state);
602 regs_set_return_msr(regs, regs->msr | (MSR_FP | tsk->thread.fpexc_mode));
603 }
604 if (msr & MSR_VEC) {
605 load_vr_state(&tsk->thread.vr_state);
606 regs_set_return_msr(regs, regs->msr | MSR_VEC);
607 }
608
609 preempt_enable();
610
611 return err;
612}
613#else /* !CONFIG_PPC_TRANSACTIONAL_MEM */
614static long restore_tm_sigcontexts(struct task_struct *tsk, struct sigcontext __user *sc,
615 struct sigcontext __user *tm_sc)
616{
617 return -EINVAL;
618}
619#endif
620
621/*
622 * Setup the trampoline code on the stack
623 */
624static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
625{
626 int i;
627 long err = 0;
628
629 /* Call the handler and pop the dummy stackframe*/
630 err |= __put_user(PPC_RAW_BCTRL(), &tramp[0]);
631 err |= __put_user(PPC_RAW_ADDI(_R1, _R1, __SIGNAL_FRAMESIZE), &tramp[1]);
632
633 err |= __put_user(PPC_RAW_LI(_R0, syscall), &tramp[2]);
634 err |= __put_user(PPC_RAW_SC(), &tramp[3]);
635
636 /* Minimal traceback info */
637 for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
638 err |= __put_user(0, &tramp[i]);
639
640 if (!err)
641 flush_icache_range(start: (unsigned long) &tramp[0],
642 end: (unsigned long) &tramp[TRAMP_SIZE]);
643
644 return err;
645}
646
647/*
648 * Userspace code may pass a ucontext which doesn't include VSX added
649 * at the end. We need to check for this case.
650 */
651#define UCONTEXTSIZEWITHOUTVSX \
652 (sizeof(struct ucontext) - 32*sizeof(long))
653
654/*
655 * Handle {get,set,swap}_context operations
656 */
657SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
658 struct ucontext __user *, new_ctx, long, ctx_size)
659{
660 sigset_t set;
661 unsigned long new_msr = 0;
662 int ctx_has_vsx_region = 0;
663
664 if (new_ctx &&
665 get_user(new_msr, &new_ctx->uc_mcontext.gp_regs[PT_MSR]))
666 return -EFAULT;
667 /*
668 * Check that the context is not smaller than the original
669 * size (with VMX but without VSX)
670 */
671 if (ctx_size < UCONTEXTSIZEWITHOUTVSX)
672 return -EINVAL;
673 /*
674 * If the new context state sets the MSR VSX bits but
675 * it doesn't provide VSX state.
676 */
677 if ((ctx_size < sizeof(struct ucontext)) &&
678 (new_msr & MSR_VSX))
679 return -EINVAL;
680 /* Does the context have enough room to store VSX data? */
681 if (ctx_size >= sizeof(struct ucontext))
682 ctx_has_vsx_region = 1;
683
684 if (old_ctx != NULL) {
685 prepare_setup_sigcontext(current);
686 if (!user_write_access_begin(old_ctx, ctx_size))
687 return -EFAULT;
688
689 unsafe_setup_sigcontext(&old_ctx->uc_mcontext, current, 0, NULL,
690 0, ctx_has_vsx_region, efault_out);
691 unsafe_copy_to_user(&old_ctx->uc_sigmask, &current->blocked,
692 sizeof(sigset_t), efault_out);
693
694 user_write_access_end();
695 }
696 if (new_ctx == NULL)
697 return 0;
698 if (!access_ok(new_ctx, ctx_size) ||
699 fault_in_readable(uaddr: (char __user *)new_ctx, size: ctx_size))
700 return -EFAULT;
701
702 /*
703 * If we get a fault copying the context into the kernel's
704 * image of the user's registers, we can't just return -EFAULT
705 * because the user's registers will be corrupted. For instance
706 * the NIP value may have been updated but not some of the
707 * other registers. Given that we have done the access_ok
708 * and successfully read the first and last bytes of the region
709 * above, this should only happen in an out-of-memory situation
710 * or if another thread unmaps the region containing the context.
711 * We kill the task with a SIGSEGV in this situation.
712 */
713
714 if (__get_user_sigset(dst: &set, src: &new_ctx->uc_sigmask)) {
715 force_exit_sig(SIGSEGV);
716 return -EFAULT;
717 }
718 set_current_blocked(&set);
719
720 if (!user_read_access_begin(new_ctx, ctx_size))
721 return -EFAULT;
722 if (__unsafe_restore_sigcontext(current, NULL, sig: 0, sc: &new_ctx->uc_mcontext)) {
723 user_read_access_end();
724 force_exit_sig(SIGSEGV);
725 return -EFAULT;
726 }
727 user_read_access_end();
728
729 /* This returns like rt_sigreturn */
730 set_thread_flag(TIF_RESTOREALL);
731
732 return 0;
733
734efault_out:
735 user_write_access_end();
736 return -EFAULT;
737}
738
739
740/*
741 * Do a signal return; undo the signal stack.
742 */
743
744SYSCALL_DEFINE0(rt_sigreturn)
745{
746 struct pt_regs *regs = current_pt_regs();
747 struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
748 sigset_t set;
749 unsigned long msr;
750
751 /* Always make any pending restarted system calls return -EINTR */
752 current->restart_block.fn = do_no_restart_syscall;
753
754 if (!access_ok(uc, sizeof(*uc)))
755 goto badframe;
756
757 if (__get_user_sigset(dst: &set, src: &uc->uc_sigmask))
758 goto badframe;
759 set_current_blocked(&set);
760
761 if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM)) {
762 /*
763 * If there is a transactional state then throw it away.
764 * The purpose of a sigreturn is to destroy all traces of the
765 * signal frame, this includes any transactional state created
766 * within in. We only check for suspended as we can never be
767 * active in the kernel, we are active, there is nothing better to
768 * do than go ahead and Bad Thing later.
769 * The cause is not important as there will never be a
770 * recheckpoint so it's not user visible.
771 */
772 if (MSR_TM_SUSPENDED(mfmsr()))
773 tm_reclaim_current(0);
774
775 /*
776 * Disable MSR[TS] bit also, so, if there is an exception in the
777 * code below (as a page fault in copy_ckvsx_to_user()), it does
778 * not recheckpoint this task if there was a context switch inside
779 * the exception.
780 *
781 * A major page fault can indirectly call schedule(). A reschedule
782 * process in the middle of an exception can have a side effect
783 * (Changing the CPU MSR[TS] state), since schedule() is called
784 * with the CPU MSR[TS] disable and returns with MSR[TS]=Suspended
785 * (switch_to() calls tm_recheckpoint() for the 'new' process). In
786 * this case, the process continues to be the same in the CPU, but
787 * the CPU state just changed.
788 *
789 * This can cause a TM Bad Thing, since the MSR in the stack will
790 * have the MSR[TS]=0, and this is what will be used to RFID.
791 *
792 * Clearing MSR[TS] state here will avoid a recheckpoint if there
793 * is any process reschedule in kernel space. The MSR[TS] state
794 * does not need to be saved also, since it will be replaced with
795 * the MSR[TS] that came from user context later, at
796 * restore_tm_sigcontexts.
797 */
798 regs_set_return_msr(regs, regs->msr & ~MSR_TS_MASK);
799
800 if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
801 goto badframe;
802 }
803
804 if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && MSR_TM_ACTIVE(msr)) {
805 /* We recheckpoint on return. */
806 struct ucontext __user *uc_transact;
807
808 /* Trying to start TM on non TM system */
809 if (!cpu_has_feature(CPU_FTR_TM))
810 goto badframe;
811
812 if (__get_user(uc_transact, &uc->uc_link))
813 goto badframe;
814 if (restore_tm_sigcontexts(current, sc: &uc->uc_mcontext,
815 tm_sc: &uc_transact->uc_mcontext))
816 goto badframe;
817 } else {
818 /*
819 * Fall through, for non-TM restore
820 *
821 * Unset MSR[TS] on the thread regs since MSR from user
822 * context does not have MSR active, and recheckpoint was
823 * not called since restore_tm_sigcontexts() was not called
824 * also.
825 *
826 * If not unsetting it, the code can RFID to userspace with
827 * MSR[TS] set, but without CPU in the proper state,
828 * causing a TM bad thing.
829 */
830 regs_set_return_msr(current->thread.regs,
831 current->thread.regs->msr & ~MSR_TS_MASK);
832 if (!user_read_access_begin(&uc->uc_mcontext, sizeof(uc->uc_mcontext)))
833 goto badframe;
834
835 unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext,
836 badframe_block);
837
838 user_read_access_end();
839 }
840
841 if (restore_altstack(&uc->uc_stack))
842 goto badframe;
843
844 set_thread_flag(TIF_RESTOREALL);
845
846 return 0;
847
848badframe_block:
849 user_read_access_end();
850badframe:
851 signal_fault(current, regs, where: "rt_sigreturn", ptr: uc);
852
853 force_sig(SIGSEGV);
854 return 0;
855}
856
857int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
858 struct task_struct *tsk)
859{
860 struct rt_sigframe __user *frame;
861 unsigned long newsp = 0;
862 long err = 0;
863 struct pt_regs *regs = tsk->thread.regs;
864 /* Save the thread's msr before get_tm_stackpointer() changes it */
865 unsigned long msr = regs->msr;
866
867 frame = get_sigframe(ksig, tsk, frame_size: sizeof(*frame), is_32: 0);
868
869 /*
870 * This only applies when calling unsafe_setup_sigcontext() and must be
871 * called before opening the uaccess window.
872 */
873 if (!MSR_TM_ACTIVE(msr))
874 prepare_setup_sigcontext(tsk);
875
876 if (!user_write_access_begin(frame, sizeof(*frame)))
877 goto badframe;
878
879 unsafe_put_user(&frame->info, &frame->pinfo, badframe_block);
880 unsafe_put_user(&frame->uc, &frame->puc, badframe_block);
881
882 /* Create the ucontext. */
883 unsafe_put_user(0, &frame->uc.uc_flags, badframe_block);
884 unsafe_save_altstack(&frame->uc.uc_stack, regs->gpr[1], badframe_block);
885
886 if (MSR_TM_ACTIVE(msr)) {
887#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
888 /* The ucontext_t passed to userland points to the second
889 * ucontext_t (for transactional state) with its uc_link ptr.
890 */
891 unsafe_put_user(&frame->uc_transact, &frame->uc.uc_link, badframe_block);
892
893 user_write_access_end();
894
895 err |= setup_tm_sigcontexts(&frame->uc.uc_mcontext,
896 &frame->uc_transact.uc_mcontext,
897 tsk, ksig->sig, NULL,
898 (unsigned long)ksig->ka.sa.sa_handler,
899 msr);
900
901 if (!user_write_access_begin(&frame->uc.uc_sigmask,
902 sizeof(frame->uc.uc_sigmask)))
903 goto badframe;
904
905#endif
906 } else {
907 unsafe_put_user(0, &frame->uc.uc_link, badframe_block);
908 unsafe_setup_sigcontext(&frame->uc.uc_mcontext, tsk, ksig->sig,
909 NULL, (unsigned long)ksig->ka.sa.sa_handler,
910 1, badframe_block);
911 }
912
913 unsafe_copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set), badframe_block);
914 user_write_access_end();
915
916 /* Save the siginfo outside of the unsafe block. */
917 if (copy_siginfo_to_user(to: &frame->info, from: &ksig->info))
918 goto badframe;
919
920 /* Make sure signal handler doesn't get spurious FP exceptions */
921 tsk->thread.fp_state.fpscr = 0;
922
923 /* Set up to return from userspace. */
924 if (tsk->mm->context.vdso) {
925 regs_set_return_ip(regs, VDSO64_SYMBOL(tsk->mm->context.vdso, sigtramp_rt64));
926 } else {
927 err |= setup_trampoline(__NR_rt_sigreturn, tramp: &frame->tramp[0]);
928 if (err)
929 goto badframe;
930 regs_set_return_ip(regs, (unsigned long) &frame->tramp[0]);
931 }
932
933 /* Allocate a dummy caller frame for the signal handler. */
934 newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE;
935 err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
936
937 /* Set up "regs" so we "return" to the signal handler. */
938 if (is_elf2_task()) {
939 regs->ctr = (unsigned long) ksig->ka.sa.sa_handler;
940 regs->gpr[12] = regs->ctr;
941 } else {
942 /* Handler is *really* a pointer to the function descriptor for
943 * the signal routine. The first entry in the function
944 * descriptor is the entry address of signal and the second
945 * entry is the TOC value we need to use.
946 */
947 struct func_desc __user *ptr =
948 (struct func_desc __user *)ksig->ka.sa.sa_handler;
949
950 err |= get_user(regs->ctr, &ptr->addr);
951 err |= get_user(regs->gpr[2], &ptr->toc);
952 }
953
954 /* enter the signal handler in native-endian mode */
955 regs_set_return_msr(regs, (regs->msr & ~MSR_LE) | (MSR_KERNEL & MSR_LE));
956 regs->gpr[1] = newsp;
957 regs->gpr[3] = ksig->sig;
958 regs->result = 0;
959 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
960 regs->gpr[4] = (unsigned long)&frame->info;
961 regs->gpr[5] = (unsigned long)&frame->uc;
962 regs->gpr[6] = (unsigned long) frame;
963 } else {
964 regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext;
965 }
966 if (err)
967 goto badframe;
968
969 return 0;
970
971badframe_block:
972 user_write_access_end();
973badframe:
974 signal_fault(current, regs, where: "handle_rt_signal64", ptr: frame);
975
976 return 1;
977}
978

source code of linux/arch/powerpc/kernel/signal_64.c