1 /*
2 * PowerPC version
3 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
4 *
5 * Derived from "arch/i386/kernel/signal.c"
6 * Copyright (C) 1991, 1992 Linus Torvalds
7 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 */
14
15 #include <linux/sched.h>
16 #include <linux/mm.h>
17 #include <linux/smp.h>
18 #include <linux/kernel.h>
19 #include <linux/signal.h>
20 #include <linux/errno.h>
21 #include <linux/wait.h>
22 #include <linux/unistd.h>
23 #include <linux/stddef.h>
24 #include <linux/elf.h>
25 #include <linux/ptrace.h>
26 #include <linux/ratelimit.h>
27
28 #include <asm/sigcontext.h>
29 #include <asm/ucontext.h>
30 #include <asm/uaccess.h>
31 #include <asm/pgtable.h>
32 #include <asm/unistd.h>
33 #include <asm/cacheflush.h>
34 #include <asm/syscalls.h>
35 #include <asm/vdso.h>
36 #include <asm/switch_to.h>
37
38 #include "signal.h"
39
40 #define DEBUG_SIG 0
41
42 #define GP_REGS_SIZE min(sizeof(elf_gregset_t), sizeof(struct pt_regs))
43 #define FP_REGS_SIZE sizeof(elf_fpregset_t)
44
45 #define TRAMP_TRACEBACK 3
46 #define TRAMP_SIZE 6
47
48 /*
49 * When we have signals to deliver, we set up on the user stack,
50 * going down from the original stack pointer:
51 * 1) a rt_sigframe struct which contains the ucontext
52 * 2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller
53 * frame for the signal handler.
54 */
55
56 struct rt_sigframe {
57 /* sys_rt_sigreturn requires the ucontext be the first field */
58 struct ucontext uc;
59 unsigned long _unused[2];
60 unsigned int tramp[TRAMP_SIZE];
61 struct siginfo __user *pinfo;
62 void __user *puc;
63 struct siginfo info;
64 /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */
65 char abigap[288];
66 } __attribute__ ((aligned (16)));
67
68 static const char fmt32[] = KERN_INFO \
69 "%s[%d]: bad frame in %s: %08lx nip %08lx lr %08lx\n";
70 static const char fmt64[] = KERN_INFO \
71 "%s[%d]: bad frame in %s: %016lx nip %016lx lr %016lx\n";
72
73 /*
74 * Set up the sigcontext for the signal frame.
75 */
76
setup_sigcontext(struct sigcontext __user * sc,struct pt_regs * regs,int signr,sigset_t * set,unsigned long handler,int ctx_has_vsx_region)77 static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
78 int signr, sigset_t *set, unsigned long handler,
79 int ctx_has_vsx_region)
80 {
81 /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
82 * process never used altivec yet (MSR_VEC is zero in pt_regs of
83 * the context). This is very important because we must ensure we
84 * don't lose the VRSAVE content that may have been set prior to
85 * the process doing its first vector operation
86 * Userland shall check AT_HWCAP to know wether it can rely on the
87 * v_regs pointer or not
88 */
89 #ifdef CONFIG_ALTIVEC
90 elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful);
91 #endif
92 unsigned long msr = regs->msr;
93 long err = 0;
94
95 flush_fp_to_thread(current);
96
97 #ifdef CONFIG_ALTIVEC
98 err |= __put_user(v_regs, &sc->v_regs);
99
100 /* save altivec registers */
101 if (current->thread.used_vr) {
102 flush_altivec_to_thread(current);
103 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */
104 err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128));
105 /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg)
106 * contains valid data.
107 */
108 msr |= MSR_VEC;
109 }
110 /* We always copy to/from vrsave, it's 0 if we don't have or don't
111 * use altivec.
112 */
113 err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
114 #else /* CONFIG_ALTIVEC */
115 err |= __put_user(0, &sc->v_regs);
116 #endif /* CONFIG_ALTIVEC */
117 flush_fp_to_thread(current);
118 /* copy fpr regs and fpscr */
119 err |= copy_fpr_to_user(&sc->fp_regs, current);
120 #ifdef CONFIG_VSX
121 /*
122 * Copy VSX low doubleword to local buffer for formatting,
123 * then out to userspace. Update v_regs to point after the
124 * VMX data.
125 */
126 if (current->thread.used_vsr && ctx_has_vsx_region) {
127 __giveup_vsx(current);
128 v_regs += ELF_NVRREG;
129 err |= copy_vsx_to_user(v_regs, current);
130 /* set MSR_VSX in the MSR value in the frame to
131 * indicate that sc->vs_reg) contains valid data.
132 */
133 msr |= MSR_VSX;
134 }
135 #endif /* CONFIG_VSX */
136 err |= __put_user(&sc->gp_regs, &sc->regs);
137 WARN_ON(!FULL_REGS(regs));
138 err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE);
139 err |= __put_user(msr, &sc->gp_regs[PT_MSR]);
140 err |= __put_user(signr, &sc->signal);
141 err |= __put_user(handler, &sc->handler);
142 if (set != NULL)
143 err |= __put_user(set->sig[0], &sc->oldmask);
144
145 return err;
146 }
147
148 /*
149 * Restore the sigcontext from the signal frame.
150 */
151
restore_sigcontext(struct pt_regs * regs,sigset_t * set,int sig,struct sigcontext __user * sc)152 static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
153 struct sigcontext __user *sc)
154 {
155 #ifdef CONFIG_ALTIVEC
156 elf_vrreg_t __user *v_regs;
157 #endif
158 unsigned long err = 0;
159 unsigned long save_r13 = 0;
160 unsigned long msr;
161 #ifdef CONFIG_VSX
162 int i;
163 #endif
164
165 /* If this is not a signal return, we preserve the TLS in r13 */
166 if (!sig)
167 save_r13 = regs->gpr[13];
168
169 /* copy the GPRs */
170 err |= __copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr));
171 err |= __get_user(regs->nip, &sc->gp_regs[PT_NIP]);
172 /* get MSR separately, transfer the LE bit if doing signal return */
173 err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
174 if (sig)
175 regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);
176 err |= __get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3]);
177 err |= __get_user(regs->ctr, &sc->gp_regs[PT_CTR]);
178 err |= __get_user(regs->link, &sc->gp_regs[PT_LNK]);
179 err |= __get_user(regs->xer, &sc->gp_regs[PT_XER]);
180 err |= __get_user(regs->ccr, &sc->gp_regs[PT_CCR]);
181 /* skip SOFTE */
182 regs->trap = 0;
183 err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
184 err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
185 err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);
186
187 if (!sig)
188 regs->gpr[13] = save_r13;
189 if (set != NULL)
190 err |= __get_user(set->sig[0], &sc->oldmask);
191
192 /*
193 * Do this before updating the thread state in
194 * current->thread.fpr/vr. That way, if we get preempted
195 * and another task grabs the FPU/Altivec, it won't be
196 * tempted to save the current CPU state into the thread_struct
197 * and corrupt what we are writing there.
198 */
199 discard_lazy_cpu_state();
200
201 /*
202 * Force reload of FP/VEC.
203 * This has to be done before copying stuff into current->thread.fpr/vr
204 * for the reasons explained in the previous comment.
205 */
206 regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX);
207
208 #ifdef CONFIG_ALTIVEC
209 err |= __get_user(v_regs, &sc->v_regs);
210 if (err)
211 return err;
212 if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
213 return -EFAULT;
214 /* Copy 33 vec registers (vr0..31 and vscr) from the stack */
215 if (v_regs != 0 && (msr & MSR_VEC) != 0)
216 err |= __copy_from_user(current->thread.vr, v_regs,
217 33 * sizeof(vector128));
218 else if (current->thread.used_vr)
219 memset(current->thread.vr, 0, 33 * sizeof(vector128));
220 /* Always get VRSAVE back */
221 if (v_regs != 0)
222 err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
223 else
224 current->thread.vrsave = 0;
225 #endif /* CONFIG_ALTIVEC */
226 /* restore floating point */
227 err |= copy_fpr_from_user(current, &sc->fp_regs);
228 #ifdef CONFIG_VSX
229 /*
230 * Get additional VSX data. Update v_regs to point after the
231 * VMX data. Copy VSX low doubleword from userspace to local
232 * buffer for formatting, then into the taskstruct.
233 */
234 v_regs += ELF_NVRREG;
235 if ((msr & MSR_VSX) != 0)
236 err |= copy_vsx_from_user(current, v_regs);
237 else
238 for (i = 0; i < 32 ; i++)
239 current->thread.fpr[i][TS_VSRLOWOFFSET] = 0;
240 #endif
241 return err;
242 }
243
244 /*
245 * Setup the trampoline code on the stack
246 */
setup_trampoline(unsigned int syscall,unsigned int __user * tramp)247 static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
248 {
249 int i;
250 long err = 0;
251
252 /* addi r1, r1, __SIGNAL_FRAMESIZE # Pop the dummy stackframe */
253 err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]);
254 /* li r0, __NR_[rt_]sigreturn| */
255 err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]);
256 /* sc */
257 err |= __put_user(0x44000002UL, &tramp[2]);
258
259 /* Minimal traceback info */
260 for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
261 err |= __put_user(0, &tramp[i]);
262
263 if (!err)
264 flush_icache_range((unsigned long) &tramp[0],
265 (unsigned long) &tramp[TRAMP_SIZE]);
266
267 return err;
268 }
269
270 /*
271 * Userspace code may pass a ucontext which doesn't include VSX added
272 * at the end. We need to check for this case.
273 */
274 #define UCONTEXTSIZEWITHOUTVSX \
275 (sizeof(struct ucontext) - 32*sizeof(long))
276
277 /*
278 * Handle {get,set,swap}_context operations
279 */
sys_swapcontext(struct ucontext __user * old_ctx,struct ucontext __user * new_ctx,long ctx_size,long r6,long r7,long r8,struct pt_regs * regs)280 int sys_swapcontext(struct ucontext __user *old_ctx,
281 struct ucontext __user *new_ctx,
282 long ctx_size, long r6, long r7, long r8, struct pt_regs *regs)
283 {
284 unsigned char tmp;
285 sigset_t set;
286 unsigned long new_msr = 0;
287 int ctx_has_vsx_region = 0;
288
289 if (new_ctx &&
290 get_user(new_msr, &new_ctx->uc_mcontext.gp_regs[PT_MSR]))
291 return -EFAULT;
292 /*
293 * Check that the context is not smaller than the original
294 * size (with VMX but without VSX)
295 */
296 if (ctx_size < UCONTEXTSIZEWITHOUTVSX)
297 return -EINVAL;
298 /*
299 * If the new context state sets the MSR VSX bits but
300 * it doesn't provide VSX state.
301 */
302 if ((ctx_size < sizeof(struct ucontext)) &&
303 (new_msr & MSR_VSX))
304 return -EINVAL;
305 /* Does the context have enough room to store VSX data? */
306 if (ctx_size >= sizeof(struct ucontext))
307 ctx_has_vsx_region = 1;
308
309 if (old_ctx != NULL) {
310 if (!access_ok(VERIFY_WRITE, old_ctx, ctx_size)
311 || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0,
312 ctx_has_vsx_region)
313 || __copy_to_user(&old_ctx->uc_sigmask,
314 ¤t->blocked, sizeof(sigset_t)))
315 return -EFAULT;
316 }
317 if (new_ctx == NULL)
318 return 0;
319 if (!access_ok(VERIFY_READ, new_ctx, ctx_size)
320 || __get_user(tmp, (u8 __user *) new_ctx)
321 || __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1))
322 return -EFAULT;
323
324 /*
325 * If we get a fault copying the context into the kernel's
326 * image of the user's registers, we can't just return -EFAULT
327 * because the user's registers will be corrupted. For instance
328 * the NIP value may have been updated but not some of the
329 * other registers. Given that we have done the access_ok
330 * and successfully read the first and last bytes of the region
331 * above, this should only happen in an out-of-memory situation
332 * or if another thread unmaps the region containing the context.
333 * We kill the task with a SIGSEGV in this situation.
334 */
335
336 if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set)))
337 do_exit(SIGSEGV);
338 restore_sigmask(&set);
339 if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext))
340 do_exit(SIGSEGV);
341
342 /* This returns like rt_sigreturn */
343 set_thread_flag(TIF_RESTOREALL);
344 return 0;
345 }
346
347
348 /*
349 * Do a signal return; undo the signal stack.
350 */
351
sys_rt_sigreturn(unsigned long r3,unsigned long r4,unsigned long r5,unsigned long r6,unsigned long r7,unsigned long r8,struct pt_regs * regs)352 int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
353 unsigned long r6, unsigned long r7, unsigned long r8,
354 struct pt_regs *regs)
355 {
356 struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
357 sigset_t set;
358
359 /* Always make any pending restarted system calls return -EINTR */
360 current_thread_info()->restart_block.fn = do_no_restart_syscall;
361
362 if (!access_ok(VERIFY_READ, uc, sizeof(*uc)))
363 goto badframe;
364
365 if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
366 goto badframe;
367 restore_sigmask(&set);
368 if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext))
369 goto badframe;
370
371 /* do_sigaltstack expects a __user pointer and won't modify
372 * what's in there anyway
373 */
374 do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]);
375
376 set_thread_flag(TIF_RESTOREALL);
377 return 0;
378
379 badframe:
380 #if DEBUG_SIG
381 printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n",
382 regs, uc, &uc->uc_mcontext);
383 #endif
384 if (show_unhandled_signals)
385 printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
386 current->comm, current->pid, "rt_sigreturn",
387 (long)uc, regs->nip, regs->link);
388
389 force_sig(SIGSEGV, current);
390 return 0;
391 }
392
handle_rt_signal64(int signr,struct k_sigaction * ka,siginfo_t * info,sigset_t * set,struct pt_regs * regs)393 int handle_rt_signal64(int signr, struct k_sigaction *ka, siginfo_t *info,
394 sigset_t *set, struct pt_regs *regs)
395 {
396 /* Handler is *really* a pointer to the function descriptor for
397 * the signal routine. The first entry in the function
398 * descriptor is the entry address of signal and the second
399 * entry is the TOC value we need to use.
400 */
401 func_descr_t __user *funct_desc_ptr;
402 struct rt_sigframe __user *frame;
403 unsigned long newsp = 0;
404 long err = 0;
405
406 frame = get_sigframe(ka, regs, sizeof(*frame), 0);
407 if (unlikely(frame == NULL))
408 goto badframe;
409
410 err |= __put_user(&frame->info, &frame->pinfo);
411 err |= __put_user(&frame->uc, &frame->puc);
412 err |= copy_siginfo_to_user(&frame->info, info);
413 if (err)
414 goto badframe;
415
416 /* Create the ucontext. */
417 err |= __put_user(0, &frame->uc.uc_flags);
418 err |= __put_user(0, &frame->uc.uc_link);
419 err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
420 err |= __put_user(sas_ss_flags(regs->gpr[1]),
421 &frame->uc.uc_stack.ss_flags);
422 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
423 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL,
424 (unsigned long)ka->sa.sa_handler, 1);
425 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
426 if (err)
427 goto badframe;
428
429 /* Make sure signal handler doesn't get spurious FP exceptions */
430 current->thread.fpscr.val = 0;
431
432 /* Set up to return from userspace. */
433 if (vdso64_rt_sigtramp && current->mm->context.vdso_base) {
434 regs->link = current->mm->context.vdso_base + vdso64_rt_sigtramp;
435 } else {
436 err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
437 if (err)
438 goto badframe;
439 regs->link = (unsigned long) &frame->tramp[0];
440 }
441 funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler;
442
443 /* Allocate a dummy caller frame for the signal handler. */
444 newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE;
445 err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
446
447 /* Set up "regs" so we "return" to the signal handler. */
448 err |= get_user(regs->nip, &funct_desc_ptr->entry);
449 /* enter the signal handler in big-endian mode */
450 regs->msr &= ~MSR_LE;
451 regs->gpr[1] = newsp;
452 err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
453 regs->gpr[3] = signr;
454 regs->result = 0;
455 if (ka->sa.sa_flags & SA_SIGINFO) {
456 err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo);
457 err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc);
458 regs->gpr[6] = (unsigned long) frame;
459 } else {
460 regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext;
461 }
462 if (err)
463 goto badframe;
464
465 return 1;
466
467 badframe:
468 #if DEBUG_SIG
469 printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n",
470 regs, frame, newsp);
471 #endif
472 if (show_unhandled_signals)
473 printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
474 current->comm, current->pid, "setup_rt_frame",
475 (long)frame, regs->nip, regs->link);
476
477 force_sigsegv(signr, current);
478 return 0;
479 }
480