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