1 /* 2 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd. 3 * Chen Liqin <liqin.chen@sunplusct.com> 4 * Lennox Wu <lennox.wu@sunplusct.com> 5 * Copyright (C) 2012 Regents of the University of California 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, see the file COPYING, or write 19 * to the Free Software Foundation, Inc., 20 */ 21 22 #include <linux/signal.h> 23 #include <linux/uaccess.h> 24 #include <linux/syscalls.h> 25 #include <linux/tracehook.h> 26 #include <linux/linkage.h> 27 28 #include <asm/ucontext.h> 29 #include <asm/vdso.h> 30 #include <asm/switch_to.h> 31 #include <asm/csr.h> 32 33 #define DEBUG_SIG 0 34 35 struct rt_sigframe { 36 struct siginfo info; 37 struct ucontext uc; 38 }; 39 40 #ifdef CONFIG_FPU 41 static long restore_fp_state(struct pt_regs *regs, 42 union __riscv_fp_state *sc_fpregs) 43 { 44 long err; 45 struct __riscv_d_ext_state __user *state = &sc_fpregs->d; 46 size_t i; 47 48 err = __copy_from_user(¤t->thread.fstate, state, sizeof(*state)); 49 if (unlikely(err)) 50 return err; 51 52 fstate_restore(current, regs); 53 54 /* We support no other extension state at this time. */ 55 for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) { 56 u32 value; 57 58 err = __get_user(value, &sc_fpregs->q.reserved[i]); 59 if (unlikely(err)) 60 break; 61 if (value != 0) 62 return -EINVAL; 63 } 64 65 return err; 66 } 67 68 static long save_fp_state(struct pt_regs *regs, 69 union __riscv_fp_state *sc_fpregs) 70 { 71 long err; 72 struct __riscv_d_ext_state __user *state = &sc_fpregs->d; 73 size_t i; 74 75 fstate_save(current, regs); 76 err = __copy_to_user(state, ¤t->thread.fstate, sizeof(*state)); 77 if (unlikely(err)) 78 return err; 79 80 /* We support no other extension state at this time. */ 81 for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) { 82 err = __put_user(0, &sc_fpregs->q.reserved[i]); 83 if (unlikely(err)) 84 break; 85 } 86 87 return err; 88 } 89 #else 90 #define save_fp_state(task, regs) (0) 91 #define restore_fp_state(task, regs) (0) 92 #endif 93 94 static long restore_sigcontext(struct pt_regs *regs, 95 struct sigcontext __user *sc) 96 { 97 long err; 98 /* sc_regs is structured the same as the start of pt_regs */ 99 err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs)); 100 /* Restore the floating-point state. */ 101 if (has_fpu) 102 err |= restore_fp_state(regs, &sc->sc_fpregs); 103 return err; 104 } 105 106 SYSCALL_DEFINE0(rt_sigreturn) 107 { 108 struct pt_regs *regs = current_pt_regs(); 109 struct rt_sigframe __user *frame; 110 struct task_struct *task; 111 sigset_t set; 112 113 /* Always make any pending restarted system calls return -EINTR */ 114 current->restart_block.fn = do_no_restart_syscall; 115 116 frame = (struct rt_sigframe __user *)regs->sp; 117 118 if (!access_ok(frame, sizeof(*frame))) 119 goto badframe; 120 121 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 122 goto badframe; 123 124 set_current_blocked(&set); 125 126 if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) 127 goto badframe; 128 129 if (restore_altstack(&frame->uc.uc_stack)) 130 goto badframe; 131 132 return regs->a0; 133 134 badframe: 135 task = current; 136 if (show_unhandled_signals) { 137 pr_info_ratelimited( 138 "%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n", 139 task->comm, task_pid_nr(task), __func__, 140 frame, (void *)regs->sepc, (void *)regs->sp); 141 } 142 force_sig(SIGSEGV, task); 143 return 0; 144 } 145 146 static long setup_sigcontext(struct rt_sigframe __user *frame, 147 struct pt_regs *regs) 148 { 149 struct sigcontext __user *sc = &frame->uc.uc_mcontext; 150 long err; 151 /* sc_regs is structured the same as the start of pt_regs */ 152 err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs)); 153 /* Save the floating-point state. */ 154 if (has_fpu) 155 err |= save_fp_state(regs, &sc->sc_fpregs); 156 return err; 157 } 158 159 static inline void __user *get_sigframe(struct ksignal *ksig, 160 struct pt_regs *regs, size_t framesize) 161 { 162 unsigned long sp; 163 /* Default to using normal stack */ 164 sp = regs->sp; 165 166 /* 167 * If we are on the alternate signal stack and would overflow it, don't. 168 * Return an always-bogus address instead so we will die with SIGSEGV. 169 */ 170 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize))) 171 return (void __user __force *)(-1UL); 172 173 /* This is the X/Open sanctioned signal stack switching. */ 174 sp = sigsp(sp, ksig) - framesize; 175 176 /* Align the stack frame. */ 177 sp &= ~0xfUL; 178 179 return (void __user *)sp; 180 } 181 182 183 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, 184 struct pt_regs *regs) 185 { 186 struct rt_sigframe __user *frame; 187 long err = 0; 188 189 frame = get_sigframe(ksig, regs, sizeof(*frame)); 190 if (!access_ok(frame, sizeof(*frame))) 191 return -EFAULT; 192 193 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 194 195 /* Create the ucontext. */ 196 err |= __put_user(0, &frame->uc.uc_flags); 197 err |= __put_user(NULL, &frame->uc.uc_link); 198 err |= __save_altstack(&frame->uc.uc_stack, regs->sp); 199 err |= setup_sigcontext(frame, regs); 200 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 201 if (err) 202 return -EFAULT; 203 204 /* Set up to return from userspace. */ 205 regs->ra = (unsigned long)VDSO_SYMBOL( 206 current->mm->context.vdso, rt_sigreturn); 207 208 /* 209 * Set up registers for signal handler. 210 * Registers that we don't modify keep the value they had from 211 * user-space at the time we took the signal. 212 * We always pass siginfo and mcontext, regardless of SA_SIGINFO, 213 * since some things rely on this (e.g. glibc's debug/segfault.c). 214 */ 215 regs->sepc = (unsigned long)ksig->ka.sa.sa_handler; 216 regs->sp = (unsigned long)frame; 217 regs->a0 = ksig->sig; /* a0: signal number */ 218 regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */ 219 regs->a2 = (unsigned long)(&frame->uc); /* a2: ucontext pointer */ 220 221 #if DEBUG_SIG 222 pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n", 223 current->comm, task_pid_nr(current), ksig->sig, 224 (void *)regs->sepc, (void *)regs->ra, frame); 225 #endif 226 227 return 0; 228 } 229 230 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) 231 { 232 sigset_t *oldset = sigmask_to_save(); 233 int ret; 234 235 /* Are we from a system call? */ 236 if (regs->scause == EXC_SYSCALL) { 237 /* Avoid additional syscall restarting via ret_from_exception */ 238 regs->scause = -1UL; 239 240 /* If so, check system call restarting.. */ 241 switch (regs->a0) { 242 case -ERESTART_RESTARTBLOCK: 243 case -ERESTARTNOHAND: 244 regs->a0 = -EINTR; 245 break; 246 247 case -ERESTARTSYS: 248 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { 249 regs->a0 = -EINTR; 250 break; 251 } 252 /* fallthrough */ 253 case -ERESTARTNOINTR: 254 regs->a0 = regs->orig_a0; 255 regs->sepc -= 0x4; 256 break; 257 } 258 } 259 260 /* Set up the stack frame */ 261 ret = setup_rt_frame(ksig, oldset, regs); 262 263 signal_setup_done(ret, ksig, 0); 264 } 265 266 static void do_signal(struct pt_regs *regs) 267 { 268 struct ksignal ksig; 269 270 if (get_signal(&ksig)) { 271 /* Actually deliver the signal */ 272 handle_signal(&ksig, regs); 273 return; 274 } 275 276 /* Did we come from a system call? */ 277 if (regs->scause == EXC_SYSCALL) { 278 /* Avoid additional syscall restarting via ret_from_exception */ 279 regs->scause = -1UL; 280 281 /* Restart the system call - no handlers present */ 282 switch (regs->a0) { 283 case -ERESTARTNOHAND: 284 case -ERESTARTSYS: 285 case -ERESTARTNOINTR: 286 regs->a0 = regs->orig_a0; 287 regs->sepc -= 0x4; 288 break; 289 case -ERESTART_RESTARTBLOCK: 290 regs->a0 = regs->orig_a0; 291 regs->a7 = __NR_restart_syscall; 292 regs->sepc -= 0x4; 293 break; 294 } 295 } 296 297 /* 298 * If there is no signal to deliver, we just put the saved 299 * sigmask back. 300 */ 301 restore_saved_sigmask(); 302 } 303 304 /* 305 * notification of userspace execution resumption 306 * - triggered by the _TIF_WORK_MASK flags 307 */ 308 asmlinkage void do_notify_resume(struct pt_regs *regs, 309 unsigned long thread_info_flags) 310 { 311 /* Handle pending signal delivery */ 312 if (thread_info_flags & _TIF_SIGPENDING) 313 do_signal(regs); 314 315 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 316 clear_thread_flag(TIF_NOTIFY_RESUME); 317 tracehook_notify_resume(regs); 318 } 319 } 320