1 /* 2 * Signal support for Hexagon processor 3 * 4 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 and 8 * only version 2 as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write to the Free Software 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 18 * 02110-1301, USA. 19 */ 20 21 #include <linux/linkage.h> 22 #include <linux/syscalls.h> 23 #include <linux/tracehook.h> 24 #include <asm/registers.h> 25 #include <asm/thread_info.h> 26 #include <asm/unistd.h> 27 #include <asm/uaccess.h> 28 #include <asm/ucontext.h> 29 #include <asm/cacheflush.h> 30 #include <asm/signal.h> 31 #include <asm/vdso.h> 32 33 struct rt_sigframe { 34 unsigned long tramp[2]; 35 struct siginfo info; 36 struct ucontext uc; 37 }; 38 39 static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, 40 size_t frame_size) 41 { 42 unsigned long sp = regs->r29; 43 44 /* Switch to signal stack if appropriate */ 45 if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0)) 46 sp = current->sas_ss_sp + current->sas_ss_size; 47 48 return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1)); 49 } 50 51 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) 52 { 53 unsigned long tmp; 54 int err = 0; 55 56 err |= copy_to_user(&sc->sc_regs.r0, ®s->r00, 57 32*sizeof(unsigned long)); 58 59 err |= __put_user(regs->sa0, &sc->sc_regs.sa0); 60 err |= __put_user(regs->lc0, &sc->sc_regs.lc0); 61 err |= __put_user(regs->sa1, &sc->sc_regs.sa1); 62 err |= __put_user(regs->lc1, &sc->sc_regs.lc1); 63 err |= __put_user(regs->m0, &sc->sc_regs.m0); 64 err |= __put_user(regs->m1, &sc->sc_regs.m1); 65 err |= __put_user(regs->usr, &sc->sc_regs.usr); 66 err |= __put_user(regs->preds, &sc->sc_regs.p3_0); 67 err |= __put_user(regs->gp, &sc->sc_regs.gp); 68 err |= __put_user(regs->ugp, &sc->sc_regs.ugp); 69 70 tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc); 71 tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause); 72 tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva); 73 74 return err; 75 } 76 77 static int restore_sigcontext(struct pt_regs *regs, 78 struct sigcontext __user *sc) 79 { 80 unsigned long tmp; 81 int err = 0; 82 83 err |= copy_from_user(®s->r00, &sc->sc_regs.r0, 84 32 * sizeof(unsigned long)); 85 86 err |= __get_user(regs->sa0, &sc->sc_regs.sa0); 87 err |= __get_user(regs->lc0, &sc->sc_regs.lc0); 88 err |= __get_user(regs->sa1, &sc->sc_regs.sa1); 89 err |= __get_user(regs->lc1, &sc->sc_regs.lc1); 90 err |= __get_user(regs->m0, &sc->sc_regs.m0); 91 err |= __get_user(regs->m1, &sc->sc_regs.m1); 92 err |= __get_user(regs->usr, &sc->sc_regs.usr); 93 err |= __get_user(regs->preds, &sc->sc_regs.p3_0); 94 err |= __get_user(regs->gp, &sc->sc_regs.gp); 95 err |= __get_user(regs->ugp, &sc->sc_regs.ugp); 96 97 err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp); 98 99 return err; 100 } 101 102 /* 103 * Setup signal stack frame with siginfo structure 104 */ 105 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info, 106 sigset_t *set, struct pt_regs *regs) 107 { 108 int err = 0; 109 struct rt_sigframe __user *frame; 110 struct hexagon_vdso *vdso = current->mm->context.vdso; 111 112 frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe)); 113 114 if (!access_ok(VERIFY_WRITE, frame, sizeof(struct rt_sigframe))) 115 goto sigsegv; 116 117 if (copy_siginfo_to_user(&frame->info, info)) 118 goto sigsegv; 119 120 /* The on-stack signal trampoline is no longer executed; 121 * however, the libgcc signal frame unwinding code checks for 122 * the presence of these two numeric magic values. 123 */ 124 err |= __put_user(0x7800d166, &frame->tramp[0]); 125 err |= __put_user(0x5400c004, &frame->tramp[1]); 126 err |= setup_sigcontext(regs, &frame->uc.uc_mcontext); 127 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 128 if (err) 129 goto sigsegv; 130 131 /* Load r0/r1 pair with signumber/siginfo pointer... */ 132 regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32) 133 | (unsigned long long)signr; 134 regs->r02 = (unsigned long) &frame->uc; 135 regs->r31 = (unsigned long) vdso->rt_signal_trampoline; 136 pt_psp(regs) = (unsigned long) frame; 137 pt_set_elr(regs, (unsigned long)ka->sa.sa_handler); 138 139 return 0; 140 141 sigsegv: 142 force_sigsegv(signr, current); 143 return -EFAULT; 144 } 145 146 /* 147 * Setup invocation of signal handler 148 */ 149 static void handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka, 150 struct pt_regs *regs) 151 { 152 /* 153 * If we're handling a signal that aborted a system call, 154 * set up the error return value before adding the signal 155 * frame to the stack. 156 */ 157 158 if (regs->syscall_nr >= 0) { 159 switch (regs->r00) { 160 case -ERESTART_RESTARTBLOCK: 161 case -ERESTARTNOHAND: 162 regs->r00 = -EINTR; 163 break; 164 case -ERESTARTSYS: 165 if (!(ka->sa.sa_flags & SA_RESTART)) { 166 regs->r00 = -EINTR; 167 break; 168 } 169 /* Fall through */ 170 case -ERESTARTNOINTR: 171 regs->r06 = regs->syscall_nr; 172 pt_set_elr(regs, pt_elr(regs) - 4); 173 regs->r00 = regs->restart_r0; 174 break; 175 default: 176 break; 177 } 178 } 179 180 /* 181 * Set up the stack frame; not doing the SA_SIGINFO thing. We 182 * only set up the rt_frame flavor. 183 */ 184 /* If there was an error on setup, no signal was delivered. */ 185 if (setup_rt_frame(sig, ka, info, sigmask_to_save(), regs) < 0) 186 return; 187 188 signal_delivered(sig, info, ka, regs, 189 test_thread_flag(TIF_SINGLESTEP)); 190 } 191 192 /* 193 * Called from return-from-event code. 194 */ 195 static void do_signal(struct pt_regs *regs) 196 { 197 struct k_sigaction sigact; 198 siginfo_t info; 199 int signo; 200 201 if (!user_mode(regs)) 202 return; 203 204 signo = get_signal_to_deliver(&info, &sigact, regs, NULL); 205 206 if (signo > 0) { 207 handle_signal(signo, &info, &sigact, regs); 208 return; 209 } 210 211 /* 212 * If we came from a system call, handle the restart. 213 */ 214 if (regs->syscall_nr >= 0) { 215 switch (regs->r00) { 216 case -ERESTARTNOHAND: 217 case -ERESTARTSYS: 218 case -ERESTARTNOINTR: 219 regs->r06 = regs->syscall_nr; 220 break; 221 case -ERESTART_RESTARTBLOCK: 222 regs->r06 = __NR_restart_syscall; 223 break; 224 default: 225 goto no_restart; 226 } 227 pt_set_elr(regs, pt_elr(regs) - 4); 228 regs->r00 = regs->restart_r0; 229 } 230 231 no_restart: 232 /* If there's no signal to deliver, put the saved sigmask back */ 233 restore_saved_sigmask(); 234 } 235 236 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 237 { 238 if (thread_info_flags & _TIF_SIGPENDING) 239 do_signal(regs); 240 241 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 242 clear_thread_flag(TIF_NOTIFY_RESUME); 243 tracehook_notify_resume(regs); 244 } 245 } 246 247 /* 248 * Architecture-specific wrappers for signal-related system calls 249 */ 250 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss) 251 { 252 struct pt_regs *regs = current_pt_regs(); 253 254 return do_sigaltstack(uss, uoss, regs->r29); 255 } 256 257 asmlinkage int sys_rt_sigreturn(void) 258 { 259 struct pt_regs *regs = current_pt_regs(); 260 struct rt_sigframe __user *frame; 261 sigset_t blocked; 262 263 /* Always make any pending restarted system calls return -EINTR */ 264 current_thread_info()->restart_block.fn = do_no_restart_syscall; 265 266 frame = (struct rt_sigframe __user *)pt_psp(regs); 267 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 268 goto badframe; 269 if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked))) 270 goto badframe; 271 272 set_current_blocked(&blocked); 273 274 if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) 275 goto badframe; 276 277 /* Restore the user's stack as well */ 278 pt_psp(regs) = regs->r29; 279 280 /* 281 * Leave a trace in the stack frame that this was a sigreturn. 282 * If the system call is to replay, we've already restored the 283 * number in the GPR slot and it will be regenerated on the 284 * new system call trap entry. Note that if restore_sigcontext() 285 * did something other than a bulk copy of the pt_regs struct, 286 * we could avoid this assignment by simply not overwriting 287 * regs->syscall_nr. 288 */ 289 regs->syscall_nr = __NR_rt_sigreturn; 290 291 /* 292 * If we were meticulous, we'd only call this if we knew that 293 * we were actually going to use an alternate stack, and we'd 294 * consider any error to be fatal. What we do here, in common 295 * with many other architectures, is call it blindly and only 296 * consider the -EFAULT return case to be proof of a problem. 297 */ 298 if (do_sigaltstack(&frame->uc.uc_stack, NULL, pt_psp(regs)) == -EFAULT) 299 goto badframe; 300 301 return 0; 302 303 badframe: 304 force_sig(SIGSEGV, current); 305 return 0; 306 } 307