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 { 79 /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the 80 * process never used altivec yet (MSR_VEC is zero in pt_regs of 81 * the context). This is very important because we must ensure we 82 * don't lose the VRSAVE content that may have been set prior to 83 * the process doing its first vector operation 84 * Userland shall check AT_HWCAP to know wether it can rely on the 85 * v_regs pointer or not 86 */ 87 #ifdef CONFIG_ALTIVEC 88 elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful); 89 #endif 90 long err = 0; 91 92 flush_fp_to_thread(current); 93 94 #ifdef CONFIG_ALTIVEC 95 err |= __put_user(v_regs, &sc->v_regs); 96 97 /* save altivec registers */ 98 if (current->thread.used_vr) { 99 flush_altivec_to_thread(current); 100 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */ 101 err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128)); 102 /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg) 103 * contains valid data. 104 */ 105 regs->msr |= MSR_VEC; 106 } 107 /* We always copy to/from vrsave, it's 0 if we don't have or don't 108 * use altivec. 109 */ 110 err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]); 111 #else /* CONFIG_ALTIVEC */ 112 err |= __put_user(0, &sc->v_regs); 113 #endif /* CONFIG_ALTIVEC */ 114 err |= __put_user(&sc->gp_regs, &sc->regs); 115 WARN_ON(!FULL_REGS(regs)); 116 err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE); 117 err |= __copy_to_user(&sc->fp_regs, ¤t->thread.fpr, FP_REGS_SIZE); 118 err |= __put_user(signr, &sc->signal); 119 err |= __put_user(handler, &sc->handler); 120 if (set != NULL) 121 err |= __put_user(set->sig[0], &sc->oldmask); 122 123 return err; 124 } 125 126 /* 127 * Restore the sigcontext from the signal frame. 128 */ 129 130 static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig, 131 struct sigcontext __user *sc) 132 { 133 #ifdef CONFIG_ALTIVEC 134 elf_vrreg_t __user *v_regs; 135 #endif 136 unsigned long err = 0; 137 unsigned long save_r13 = 0; 138 elf_greg_t *gregs = (elf_greg_t *)regs; 139 unsigned long msr; 140 int i; 141 142 /* If this is not a signal return, we preserve the TLS in r13 */ 143 if (!sig) 144 save_r13 = regs->gpr[13]; 145 146 /* copy everything before MSR */ 147 err |= __copy_from_user(regs, &sc->gp_regs, 148 PT_MSR*sizeof(unsigned long)); 149 150 /* get MSR separately, transfer the LE bit if doing signal return */ 151 err |= __get_user(msr, &sc->gp_regs[PT_MSR]); 152 if (sig) 153 regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE); 154 155 /* skip SOFTE */ 156 for (i = PT_MSR+1; i <= PT_RESULT; i++) { 157 if (i == PT_SOFTE) 158 continue; 159 err |= __get_user(gregs[i], &sc->gp_regs[i]); 160 } 161 162 if (!sig) 163 regs->gpr[13] = save_r13; 164 if (set != NULL) 165 err |= __get_user(set->sig[0], &sc->oldmask); 166 167 /* 168 * Do this before updating the thread state in 169 * current->thread.fpr/vr. That way, if we get preempted 170 * and another task grabs the FPU/Altivec, it won't be 171 * tempted to save the current CPU state into the thread_struct 172 * and corrupt what we are writing there. 173 */ 174 discard_lazy_cpu_state(); 175 176 /* 177 * Force reload of FP/VEC. 178 * This has to be done before copying stuff into current->thread.fpr/vr 179 * for the reasons explained in the previous comment. 180 */ 181 regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC); 182 183 err |= __copy_from_user(¤t->thread.fpr, &sc->fp_regs, FP_REGS_SIZE); 184 185 #ifdef CONFIG_ALTIVEC 186 err |= __get_user(v_regs, &sc->v_regs); 187 if (err) 188 return err; 189 if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128))) 190 return -EFAULT; 191 /* Copy 33 vec registers (vr0..31 and vscr) from the stack */ 192 if (v_regs != 0 && (msr & MSR_VEC) != 0) 193 err |= __copy_from_user(current->thread.vr, v_regs, 194 33 * sizeof(vector128)); 195 else if (current->thread.used_vr) 196 memset(current->thread.vr, 0, 33 * sizeof(vector128)); 197 /* Always get VRSAVE back */ 198 if (v_regs != 0) 199 err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]); 200 else 201 current->thread.vrsave = 0; 202 #endif /* CONFIG_ALTIVEC */ 203 204 return err; 205 } 206 207 /* 208 * Setup the trampoline code on the stack 209 */ 210 static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp) 211 { 212 int i; 213 long err = 0; 214 215 /* addi r1, r1, __SIGNAL_FRAMESIZE # Pop the dummy stackframe */ 216 err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]); 217 /* li r0, __NR_[rt_]sigreturn| */ 218 err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]); 219 /* sc */ 220 err |= __put_user(0x44000002UL, &tramp[2]); 221 222 /* Minimal traceback info */ 223 for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++) 224 err |= __put_user(0, &tramp[i]); 225 226 if (!err) 227 flush_icache_range((unsigned long) &tramp[0], 228 (unsigned long) &tramp[TRAMP_SIZE]); 229 230 return err; 231 } 232 233 /* 234 * Handle {get,set,swap}_context operations 235 */ 236 int sys_swapcontext(struct ucontext __user *old_ctx, 237 struct ucontext __user *new_ctx, 238 long ctx_size, long r6, long r7, long r8, struct pt_regs *regs) 239 { 240 unsigned char tmp; 241 sigset_t set; 242 243 /* Context size is for future use. Right now, we only make sure 244 * we are passed something we understand 245 */ 246 if (ctx_size < sizeof(struct ucontext)) 247 return -EINVAL; 248 249 if (old_ctx != NULL) { 250 if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx)) 251 || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0) 252 || __copy_to_user(&old_ctx->uc_sigmask, 253 ¤t->blocked, sizeof(sigset_t))) 254 return -EFAULT; 255 } 256 if (new_ctx == NULL) 257 return 0; 258 if (!access_ok(VERIFY_READ, new_ctx, sizeof(*new_ctx)) 259 || __get_user(tmp, (u8 __user *) new_ctx) 260 || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 1)) 261 return -EFAULT; 262 263 /* 264 * If we get a fault copying the context into the kernel's 265 * image of the user's registers, we can't just return -EFAULT 266 * because the user's registers will be corrupted. For instance 267 * the NIP value may have been updated but not some of the 268 * other registers. Given that we have done the access_ok 269 * and successfully read the first and last bytes of the region 270 * above, this should only happen in an out-of-memory situation 271 * or if another thread unmaps the region containing the context. 272 * We kill the task with a SIGSEGV in this situation. 273 */ 274 275 if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set))) 276 do_exit(SIGSEGV); 277 restore_sigmask(&set); 278 if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext)) 279 do_exit(SIGSEGV); 280 281 /* This returns like rt_sigreturn */ 282 set_thread_flag(TIF_RESTOREALL); 283 return 0; 284 } 285 286 287 /* 288 * Do a signal return; undo the signal stack. 289 */ 290 291 int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5, 292 unsigned long r6, unsigned long r7, unsigned long r8, 293 struct pt_regs *regs) 294 { 295 struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1]; 296 sigset_t set; 297 298 /* Always make any pending restarted system calls return -EINTR */ 299 current_thread_info()->restart_block.fn = do_no_restart_syscall; 300 301 if (!access_ok(VERIFY_READ, uc, sizeof(*uc))) 302 goto badframe; 303 304 if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set))) 305 goto badframe; 306 restore_sigmask(&set); 307 if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext)) 308 goto badframe; 309 310 /* do_sigaltstack expects a __user pointer and won't modify 311 * what's in there anyway 312 */ 313 do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]); 314 315 set_thread_flag(TIF_RESTOREALL); 316 return 0; 317 318 badframe: 319 #if DEBUG_SIG 320 printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n", 321 regs, uc, &uc->uc_mcontext); 322 #endif 323 if (show_unhandled_signals && printk_ratelimit()) 324 printk(regs->msr & MSR_SF ? fmt64 : fmt32, 325 current->comm, current->pid, "rt_sigreturn", 326 (long)uc, regs->nip, regs->link); 327 328 force_sig(SIGSEGV, current); 329 return 0; 330 } 331 332 int handle_rt_signal64(int signr, struct k_sigaction *ka, siginfo_t *info, 333 sigset_t *set, struct pt_regs *regs) 334 { 335 /* Handler is *really* a pointer to the function descriptor for 336 * the signal routine. The first entry in the function 337 * descriptor is the entry address of signal and the second 338 * entry is the TOC value we need to use. 339 */ 340 func_descr_t __user *funct_desc_ptr; 341 struct rt_sigframe __user *frame; 342 unsigned long newsp = 0; 343 long err = 0; 344 345 frame = get_sigframe(ka, regs, sizeof(*frame)); 346 if (unlikely(frame == NULL)) 347 goto badframe; 348 349 err |= __put_user(&frame->info, &frame->pinfo); 350 err |= __put_user(&frame->uc, &frame->puc); 351 err |= copy_siginfo_to_user(&frame->info, info); 352 if (err) 353 goto badframe; 354 355 /* Create the ucontext. */ 356 err |= __put_user(0, &frame->uc.uc_flags); 357 err |= __put_user(0, &frame->uc.uc_link); 358 err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 359 err |= __put_user(sas_ss_flags(regs->gpr[1]), 360 &frame->uc.uc_stack.ss_flags); 361 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 362 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL, 363 (unsigned long)ka->sa.sa_handler); 364 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 365 if (err) 366 goto badframe; 367 368 /* Make sure signal handler doesn't get spurious FP exceptions */ 369 current->thread.fpscr.val = 0; 370 371 /* Set up to return from userspace. */ 372 if (vdso64_rt_sigtramp && current->mm->context.vdso_base) { 373 regs->link = current->mm->context.vdso_base + vdso64_rt_sigtramp; 374 } else { 375 err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]); 376 if (err) 377 goto badframe; 378 regs->link = (unsigned long) &frame->tramp[0]; 379 } 380 funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler; 381 382 /* Allocate a dummy caller frame for the signal handler. */ 383 newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE; 384 err |= put_user(regs->gpr[1], (unsigned long __user *)newsp); 385 386 /* Set up "regs" so we "return" to the signal handler. */ 387 err |= get_user(regs->nip, &funct_desc_ptr->entry); 388 /* enter the signal handler in big-endian mode */ 389 regs->msr &= ~MSR_LE; 390 regs->gpr[1] = newsp; 391 err |= get_user(regs->gpr[2], &funct_desc_ptr->toc); 392 regs->gpr[3] = signr; 393 regs->result = 0; 394 if (ka->sa.sa_flags & SA_SIGINFO) { 395 err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo); 396 err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc); 397 regs->gpr[6] = (unsigned long) frame; 398 } else { 399 regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext; 400 } 401 if (err) 402 goto badframe; 403 404 return 1; 405 406 badframe: 407 #if DEBUG_SIG 408 printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n", 409 regs, frame, newsp); 410 #endif 411 if (show_unhandled_signals && printk_ratelimit()) 412 printk(regs->msr & MSR_SF ? fmt64 : fmt32, 413 current->comm, current->pid, "setup_rt_frame", 414 (long)frame, regs->nip, regs->link); 415 416 force_sigsegv(signr, current); 417 return 0; 418 } 419