1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Signal support for Hexagon processor 4 * 5 * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved. 6 */ 7 8 #include <linux/linkage.h> 9 #include <linux/syscalls.h> 10 #include <linux/sched/task_stack.h> 11 12 #include <asm/registers.h> 13 #include <asm/thread_info.h> 14 #include <asm/unistd.h> 15 #include <linux/uaccess.h> 16 #include <asm/ucontext.h> 17 #include <asm/cacheflush.h> 18 #include <asm/signal.h> 19 #include <asm/vdso.h> 20 21 struct rt_sigframe { 22 unsigned long tramp[2]; 23 struct siginfo info; 24 struct ucontext uc; 25 }; 26 27 static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, 28 size_t frame_size) 29 { 30 unsigned long sp = sigsp(regs->r29, ksig); 31 32 return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1)); 33 } 34 35 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) 36 { 37 scoped_user_write_access(sc, Efault) { 38 unsafe_copy_to_user(&sc->sc_regs.r0, ®s->r00, 39 32*sizeof(unsigned long), Efault); 40 41 unsafe_put_user(regs->sa0, &sc->sc_regs.sa0, Efault); 42 unsafe_put_user(regs->lc0, &sc->sc_regs.lc0, Efault); 43 unsafe_put_user(regs->sa1, &sc->sc_regs.sa1, Efault); 44 unsafe_put_user(regs->lc1, &sc->sc_regs.lc1, Efault); 45 unsafe_put_user(regs->m0, &sc->sc_regs.m0, Efault); 46 unsafe_put_user(regs->m1, &sc->sc_regs.m1, Efault); 47 unsafe_put_user(regs->usr, &sc->sc_regs.usr, Efault); 48 unsafe_put_user(regs->preds, &sc->sc_regs.p3_0, Efault); 49 unsafe_put_user(regs->gp, &sc->sc_regs.gp, Efault); 50 unsafe_put_user(regs->ugp, &sc->sc_regs.ugp, Efault); 51 #if CONFIG_HEXAGON_ARCH_VERSION >= 4 52 unsafe_put_user(regs->cs0, &sc->sc_regs.cs0, Efault); 53 unsafe_put_user(regs->cs1, &sc->sc_regs.cs1, Efault); 54 #endif 55 unsafe_put_user(pt_elr(regs), &sc->sc_regs.pc, Efault); 56 unsafe_put_user(pt_cause(regs), &sc->sc_regs.cause, Efault); 57 unsafe_put_user(pt_badva(regs), &sc->sc_regs.badva, Efault); 58 } 59 return 0; 60 61 Efault: 62 return -EFAULT; 63 } 64 65 static int restore_sigcontext(struct pt_regs *regs, 66 struct sigcontext __user *sc) 67 { 68 unsigned long tmp; 69 70 scoped_user_read_access(sc, Efault) { 71 unsafe_copy_from_user(®s->r00, &sc->sc_regs.r0, 72 32 * sizeof(unsigned long), Efault); 73 74 unsafe_get_user(regs->sa0, &sc->sc_regs.sa0, Efault); 75 unsafe_get_user(regs->lc0, &sc->sc_regs.lc0, Efault); 76 unsafe_get_user(regs->sa1, &sc->sc_regs.sa1, Efault); 77 unsafe_get_user(regs->lc1, &sc->sc_regs.lc1, Efault); 78 unsafe_get_user(regs->m0, &sc->sc_regs.m0, Efault); 79 unsafe_get_user(regs->m1, &sc->sc_regs.m1, Efault); 80 unsafe_get_user(regs->usr, &sc->sc_regs.usr, Efault); 81 unsafe_get_user(regs->preds, &sc->sc_regs.p3_0, Efault); 82 unsafe_get_user(regs->gp, &sc->sc_regs.gp, Efault); 83 unsafe_get_user(regs->ugp, &sc->sc_regs.ugp, Efault); 84 #if CONFIG_HEXAGON_ARCH_VERSION >= 4 85 unsafe_get_user(regs->cs0, &sc->sc_regs.cs0, Efault); 86 unsafe_get_user(regs->cs1, &sc->sc_regs.cs1, Efault); 87 #endif 88 unsafe_get_user(tmp, &sc->sc_regs.pc, Efault); 89 } 90 pt_set_elr(regs, tmp); 91 return 0; 92 93 Efault: 94 return -EFAULT; 95 } 96 97 /* 98 * Setup signal stack frame with siginfo structure 99 */ 100 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, 101 struct pt_regs *regs) 102 { 103 int err = 0; 104 struct rt_sigframe __user *frame; 105 struct hexagon_vdso *vdso = current->mm->context.vdso; 106 107 frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe)); 108 109 if (!access_ok(frame, sizeof(struct rt_sigframe))) 110 return -EFAULT; 111 112 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 113 return -EFAULT; 114 115 /* The on-stack signal trampoline is no longer executed; 116 * however, the libgcc signal frame unwinding code checks for 117 * the presence of these two numeric magic values. 118 */ 119 scoped_user_write_access(frame, Efault) { 120 unsafe_put_user(0x7800d166, &frame->tramp[0], Efault); 121 unsafe_put_user(0x5400c004, &frame->tramp[1], Efault); 122 } 123 err |= setup_sigcontext(regs, &frame->uc.uc_mcontext); 124 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 125 err |= __save_altstack(&frame->uc.uc_stack, user_stack_pointer(regs)); 126 if (err) 127 return -EFAULT; 128 129 /* Load r0/r1 pair with signumber/siginfo pointer... */ 130 regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32) 131 | (unsigned long long)ksig->sig; 132 regs->r02 = (unsigned long) &frame->uc; 133 regs->r31 = (unsigned long) vdso->rt_signal_trampoline; 134 pt_psp(regs) = (unsigned long) frame; 135 pt_set_elr(regs, (unsigned long)ksig->ka.sa.sa_handler); 136 137 return 0; 138 139 Efault: 140 return -EFAULT; 141 } 142 143 /* 144 * Setup invocation of signal handler 145 */ 146 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) 147 { 148 int ret; 149 150 /* 151 * If we're handling a signal that aborted a system call, 152 * set up the error return value before adding the signal 153 * frame to the stack. 154 */ 155 156 if (regs->syscall_nr >= 0) { 157 switch (regs->r00) { 158 case -ERESTART_RESTARTBLOCK: 159 case -ERESTARTNOHAND: 160 regs->r00 = -EINTR; 161 break; 162 case -ERESTARTSYS: 163 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { 164 regs->r00 = -EINTR; 165 break; 166 } 167 fallthrough; 168 case -ERESTARTNOINTR: 169 regs->r06 = regs->syscall_nr; 170 pt_set_elr(regs, pt_elr(regs) - 4); 171 regs->r00 = regs->restart_r0; 172 break; 173 default: 174 break; 175 } 176 } 177 178 /* 179 * Set up the stack frame; not doing the SA_SIGINFO thing. We 180 * only set up the rt_frame flavor. 181 */ 182 /* If there was an error on setup, no signal was delivered. */ 183 ret = setup_rt_frame(ksig, sigmask_to_save(), regs); 184 185 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP)); 186 } 187 188 /* 189 * Called from return-from-event code. 190 */ 191 void do_signal(struct pt_regs *regs) 192 { 193 struct ksignal ksig; 194 195 if (!user_mode(regs)) 196 return; 197 198 if (get_signal(&ksig)) { 199 handle_signal(&ksig, regs); 200 return; 201 } 202 203 /* 204 * No (more) signals; if we came from a system call, handle the restart. 205 */ 206 207 if (regs->syscall_nr >= 0) { 208 switch (regs->r00) { 209 case -ERESTARTNOHAND: 210 case -ERESTARTSYS: 211 case -ERESTARTNOINTR: 212 regs->r06 = regs->syscall_nr; 213 break; 214 case -ERESTART_RESTARTBLOCK: 215 regs->r06 = __NR_restart_syscall; 216 break; 217 default: 218 goto no_restart; 219 } 220 pt_set_elr(regs, pt_elr(regs) - 4); 221 regs->r00 = regs->restart_r0; 222 } 223 224 no_restart: 225 /* If there's no signal to deliver, put the saved sigmask back */ 226 restore_saved_sigmask(); 227 } 228 229 /* 230 * Architecture-specific wrappers for signal-related system calls 231 */ 232 233 SYSCALL_DEFINE0(rt_sigreturn) 234 { 235 struct pt_regs *regs = current_pt_regs(); 236 struct rt_sigframe __user *frame; 237 sigset_t blocked; 238 239 /* Always make any pending restarted system calls return -EINTR */ 240 current->restart_block.fn = do_no_restart_syscall; 241 242 frame = (struct rt_sigframe __user *)pt_psp(regs); 243 if (!access_ok(frame, sizeof(*frame))) 244 goto badframe; 245 if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked))) 246 goto badframe; 247 248 set_current_blocked(&blocked); 249 250 if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) 251 goto badframe; 252 253 /* Restore the user's stack as well */ 254 pt_psp(regs) = regs->r29; 255 256 regs->syscall_nr = -1; 257 258 if (restore_altstack(&frame->uc.uc_stack)) 259 goto badframe; 260 261 return regs->r00; 262 263 badframe: 264 force_sig(SIGSEGV); 265 return 0; 266 } 267