1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * OpenRISC signal.c 4 * 5 * Linux architectural port borrowing liberally from similar works of 6 * others. All original copyrights apply as per the original source 7 * declaration. 8 * 9 * Modifications for the OpenRISC architecture: 10 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> 11 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> 12 */ 13 14 #include <linux/sched.h> 15 #include <linux/mm.h> 16 #include <linux/smp.h> 17 #include <linux/kernel.h> 18 #include <linux/signal.h> 19 #include <linux/errno.h> 20 #include <linux/wait.h> 21 #include <linux/ptrace.h> 22 #include <linux/unistd.h> 23 #include <linux/stddef.h> 24 #include <linux/resume_user_mode.h> 25 26 #include <asm/fpu.h> 27 #include <asm/processor.h> 28 #include <asm/syscall.h> 29 #include <asm/ucontext.h> 30 #include <linux/uaccess.h> 31 32 struct rt_sigframe { 33 struct siginfo info; 34 struct ucontext uc; 35 unsigned char retcode[16]; /* trampoline code */ 36 }; 37 38 asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs); 39 40 asmlinkage int do_work_pending(struct pt_regs *regs, unsigned int thread_flags, 41 int syscall); 42 43 #ifdef CONFIG_FPU 44 static long restore_fp_state(struct sigcontext __user *sc) 45 { 46 long err; 47 48 err = __copy_from_user(¤t->thread.fpcsr, &sc->fpcsr, sizeof(unsigned long)); 49 if (unlikely(err)) 50 return err; 51 52 /* Restore the FPU state */ 53 restore_fpu(current); 54 55 return 0; 56 } 57 58 static long save_fp_state(struct sigcontext __user *sc) 59 { 60 long err; 61 62 /* Sync the user FPU state so we can copy to sigcontext */ 63 save_fpu(current); 64 65 err = __copy_to_user(&sc->fpcsr, ¤t->thread.fpcsr, sizeof(unsigned long)); 66 67 return err; 68 } 69 #else 70 #define save_fp_state(sc) (0) 71 #define restore_fp_state(sc) (0) 72 #endif 73 74 static int restore_sigcontext(struct pt_regs *regs, 75 struct sigcontext __user *sc) 76 { 77 int err = 0; 78 79 /* Always make any pending restarted system calls return -EINTR */ 80 current->restart_block.fn = do_no_restart_syscall; 81 82 /* 83 * Restore the regs from &sc->regs. 84 * (sc is already checked since the sigframe was 85 * checked in sys_sigreturn previously) 86 */ 87 err |= __copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long)); 88 err |= __copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long)); 89 err |= __copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long)); 90 err |= restore_fp_state(sc); 91 92 /* make sure the SM-bit is cleared so user-mode cannot fool us */ 93 regs->sr &= ~SPR_SR_SM; 94 95 regs->orig_gpr11 = -1; /* Avoid syscall restart checks */ 96 97 /* TODO: the other ports use regs->orig_XX to disable syscall checks 98 * after this completes, but we don't use that mechanism. maybe we can 99 * use it now ? 100 */ 101 102 return err; 103 } 104 105 asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs) 106 { 107 struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->sp; 108 sigset_t set; 109 110 /* 111 * Since we stacked the signal on a dword boundary, 112 * then frame should be dword aligned here. If it's 113 * not, then the user is trying to mess with us. 114 */ 115 if (((unsigned long)frame) & 3) 116 goto badframe; 117 118 if (!access_ok(frame, sizeof(*frame))) 119 goto badframe; 120 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 121 goto badframe; 122 123 set_current_blocked(&set); 124 125 if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) 126 goto badframe; 127 128 if (restore_altstack(&frame->uc.uc_stack)) 129 goto badframe; 130 131 return regs->gpr[11]; 132 133 badframe: 134 force_sig(SIGSEGV); 135 return 0; 136 } 137 138 /* 139 * Set up a signal frame. 140 */ 141 142 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) 143 { 144 int err = 0; 145 146 /* copy the regs */ 147 /* There should be no need to save callee-saved registers here... 148 * ...but we save them anyway. Revisit this 149 */ 150 err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long)); 151 err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long)); 152 err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long)); 153 err |= save_fp_state(sc); 154 155 return err; 156 } 157 158 static inline unsigned long align_sigframe(unsigned long sp) 159 { 160 return sp & ~3UL; 161 } 162 163 /* 164 * Work out where the signal frame should go. It's either on the user stack 165 * or the alternate stack. 166 */ 167 168 static inline void __user *get_sigframe(struct ksignal *ksig, 169 struct pt_regs *regs, size_t frame_size) 170 { 171 unsigned long sp = regs->sp; 172 173 /* redzone */ 174 sp -= STACK_FRAME_OVERHEAD; 175 sp = sigsp(sp, ksig); 176 sp = align_sigframe(sp - frame_size); 177 178 return (void __user *)sp; 179 } 180 181 /* grab and setup a signal frame. 182 * 183 * basically we stack a lot of state info, and arrange for the 184 * user-mode program to return to the kernel using either a 185 * trampoline which performs the syscall sigreturn, or a provided 186 * user-mode trampoline. 187 */ 188 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, 189 struct pt_regs *regs) 190 { 191 struct rt_sigframe __user *frame; 192 unsigned long return_ip; 193 int err = 0; 194 195 frame = get_sigframe(ksig, regs, sizeof(*frame)); 196 197 if (!access_ok(frame, sizeof(*frame))) 198 return -EFAULT; 199 200 /* Create siginfo. */ 201 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 202 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 203 204 /* Create the ucontext. */ 205 err |= __put_user(0, &frame->uc.uc_flags); 206 err |= __put_user(NULL, &frame->uc.uc_link); 207 err |= __save_altstack(&frame->uc.uc_stack, regs->sp); 208 err |= setup_sigcontext(regs, &frame->uc.uc_mcontext); 209 210 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 211 212 if (err) 213 return -EFAULT; 214 215 /* trampoline - the desired return ip is the retcode itself */ 216 return_ip = (unsigned long)&frame->retcode; 217 /* This is: 218 l.ori r11,r0,__NR_sigreturn 219 l.sys 1 220 */ 221 err |= __put_user(0xa960, (short __user *)(frame->retcode + 0)); 222 err |= __put_user(__NR_rt_sigreturn, (short __user *)(frame->retcode + 2)); 223 err |= __put_user(0x20000001, (unsigned long __user *)(frame->retcode + 4)); 224 err |= __put_user(0x15000000, (unsigned long __user *)(frame->retcode + 8)); 225 226 if (err) 227 return -EFAULT; 228 229 /* Set up registers for signal handler */ 230 regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */ 231 regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */ 232 regs->gpr[3] = (unsigned long)ksig->sig; /* arg 1: signo */ 233 regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */ 234 regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */ 235 236 /* actually move the usp to reflect the stacked frame */ 237 regs->sp = (unsigned long)frame; 238 239 return 0; 240 } 241 242 static inline void 243 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 244 { 245 int ret; 246 247 ret = setup_rt_frame(ksig, sigmask_to_save(), regs); 248 249 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP)); 250 } 251 252 /* 253 * Note that 'init' is a special process: it doesn't get signals it doesn't 254 * want to handle. Thus you cannot kill init even with a SIGKILL even by 255 * mistake. 256 * 257 * Also note that the regs structure given here as an argument, is the latest 258 * pushed pt_regs. It may or may not be the same as the first pushed registers 259 * when the initial usermode->kernelmode transition took place. Therefore 260 * we can use user_mode(regs) to see if we came directly from kernel or user 261 * mode below. 262 */ 263 264 static int do_signal(struct pt_regs *regs, int syscall) 265 { 266 struct ksignal ksig; 267 unsigned long continue_addr = 0; 268 unsigned long restart_addr = 0; 269 unsigned long retval = 0; 270 int restart = 0; 271 272 if (syscall) { 273 continue_addr = regs->pc; 274 restart_addr = continue_addr - 4; 275 retval = regs->gpr[11]; 276 277 /* 278 * Setup syscall restart here so that a debugger will 279 * see the already changed PC. 280 */ 281 switch (retval) { 282 case -ERESTART_RESTARTBLOCK: 283 restart = -2; 284 fallthrough; 285 case -ERESTARTNOHAND: 286 case -ERESTARTSYS: 287 case -ERESTARTNOINTR: 288 restart++; 289 regs->gpr[11] = regs->orig_gpr11; 290 regs->pc = restart_addr; 291 break; 292 } 293 } 294 295 /* 296 * Get the signal to deliver. During the call to get_signal the 297 * debugger may change all our registers so we may need to revert 298 * the decision to restart the syscall; specifically, if the PC is 299 * changed, don't restart the syscall. 300 */ 301 if (get_signal(&ksig)) { 302 if (unlikely(restart) && regs->pc == restart_addr) { 303 if (retval == -ERESTARTNOHAND || 304 retval == -ERESTART_RESTARTBLOCK 305 || (retval == -ERESTARTSYS 306 && !(ksig.ka.sa.sa_flags & SA_RESTART))) { 307 /* No automatic restart */ 308 regs->gpr[11] = -EINTR; 309 regs->pc = continue_addr; 310 } 311 } 312 handle_signal(&ksig, regs); 313 } else { 314 /* no handler */ 315 restore_saved_sigmask(); 316 /* 317 * Restore pt_regs PC as syscall restart will be handled by 318 * kernel without return to userspace 319 */ 320 if (unlikely(restart) && regs->pc == restart_addr) { 321 regs->pc = continue_addr; 322 return restart; 323 } 324 } 325 326 return 0; 327 } 328 329 asmlinkage int 330 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) 331 { 332 do { 333 if (likely(thread_flags & _TIF_NEED_RESCHED)) { 334 schedule(); 335 } else { 336 if (unlikely(!user_mode(regs))) 337 return 0; 338 local_irq_enable(); 339 if (thread_flags & (_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)) { 340 int restart = do_signal(regs, syscall); 341 if (unlikely(restart)) { 342 /* 343 * Restart without handlers. 344 * Deal with it without leaving 345 * the kernel space. 346 */ 347 return restart; 348 } 349 syscall = 0; 350 } else { 351 resume_user_mode_work(regs); 352 } 353 } 354 local_irq_disable(); 355 thread_flags = read_thread_flags(); 356 } while (thread_flags & _TIF_WORK_MASK); 357 return 0; 358 } 359