xref: /openbmc/linux/arch/powerpc/kernel/signal_64.c (revision e4787e71)
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 
54 struct 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 
get_min_sigframe_size_64(void)69 unsigned 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
sigcontext_vmx_regs(struct sigcontext __user * sc)81 static 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 
prepare_setup_sigcontext(struct task_struct * tsk)87 static 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)\
110 do {											\
111 	if (__unsafe_setup_sigcontext(sc, tsk, signr, set, handler, ctx_has_vsx_region))\
112 		goto label;								\
113 } while (0)
__unsafe_setup_sigcontext(struct sigcontext __user * sc,struct task_struct * tsk,int signr,sigset_t * set,unsigned long handler,int ctx_has_vsx_region)114 static 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 
190 efault_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  */
setup_tm_sigcontexts(struct sigcontext __user * sc,struct sigcontext __user * tm_sc,struct task_struct * tsk,int signr,sigset_t * set,unsigned long handler,unsigned long msr)206 static 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)
__unsafe_restore_sigcontext(struct task_struct * tsk,sigset_t * set,int sig,struct sigcontext __user * sc)337 static 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 
428 efault_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 
restore_tm_sigcontexts(struct task_struct * tsk,struct sigcontext __user * sc,struct sigcontext __user * tm_sc)437 static 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 */
restore_tm_sigcontexts(struct task_struct * tsk,struct sigcontext __user * sc,struct sigcontext __user * tm_sc)614 static 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  */
setup_trampoline(unsigned int syscall,unsigned int __user * tramp)624 static 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((unsigned long) &tramp[0],
642 			   (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  */
SYSCALL_DEFINE3(swapcontext,struct ucontext __user *,old_ctx,struct ucontext __user *,new_ctx,long,ctx_size)657 SYSCALL_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((char __user *)new_ctx, 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(&set, &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, 0, &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 
734 efault_out:
735 	user_write_access_end();
736 	return -EFAULT;
737 }
738 
739 
740 /*
741  * Do a signal return; undo the signal stack.
742  */
743 
SYSCALL_DEFINE0(rt_sigreturn)744 SYSCALL_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(&set, &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, &uc->uc_mcontext,
815 					   &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 
848 badframe_block:
849 	user_read_access_end();
850 badframe:
851 	signal_fault(current, regs, "rt_sigreturn", uc);
852 
853 	force_sig(SIGSEGV);
854 	return 0;
855 }
856 
handle_rt_signal64(struct ksignal * ksig,sigset_t * set,struct task_struct * tsk)857 int 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, sizeof(*frame), 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(&frame->info, &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, &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 
971 badframe_block:
972 	user_write_access_end();
973 badframe:
974 	signal_fault(current, regs, "handle_rt_signal64", frame);
975 
976 	return 1;
977 }
978