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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 | // SPDX-License-Identifier: GPL-2.0 #include <linux/signal.h> #include <linux/uaccess.h> #include <linux/syscalls.h> #include <linux/tracehook.h> #include <asm/traps.h> #include <asm/ucontext.h> #include <asm/vdso.h> #include <abi/regdef.h> #ifdef CONFIG_CPU_HAS_FPU #include <abi/fpu.h> static int restore_fpu_state(struct sigcontext __user *sc) { int err = 0; struct user_fp user_fp; err = __copy_from_user(&user_fp, &sc->sc_user_fp, sizeof(user_fp)); restore_from_user_fp(&user_fp); return err; } static int save_fpu_state(struct sigcontext __user *sc) { struct user_fp user_fp; save_to_user_fp(&user_fp); return __copy_to_user(&sc->sc_user_fp, &user_fp, sizeof(user_fp)); } #else #define restore_fpu_state(sigcontext) (0) #define save_fpu_state(sigcontext) (0) #endif struct rt_sigframe { /* * pad[3] is compatible with the same struct defined in * gcc/libgcc/config/csky/linux-unwind.h */ int pad[3]; struct siginfo info; struct ucontext uc; }; static long restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) { int err = 0; /* sc_pt_regs is structured the same as the start of pt_regs */ err |= __copy_from_user(regs, &sc->sc_pt_regs, sizeof(struct pt_regs)); /* Restore the floating-point state. */ err |= restore_fpu_state(sc); return err; } SYSCALL_DEFINE0(rt_sigreturn) { struct pt_regs *regs = current_pt_regs(); struct rt_sigframe __user *frame; sigset_t set; /* Always make any pending restarted system calls return -EINTR */ current->restart_block.fn = do_no_restart_syscall; frame = (struct rt_sigframe __user *)regs->usp; if (!access_ok(frame, sizeof(*frame))) goto badframe; if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) goto badframe; set_current_blocked(&set); if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) goto badframe; if (restore_altstack(&frame->uc.uc_stack)) goto badframe; return regs->a0; badframe: force_sig(SIGSEGV); return 0; } static int setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs) { struct sigcontext __user *sc = &frame->uc.uc_mcontext; int err = 0; err |= __copy_to_user(&sc->sc_pt_regs, regs, sizeof(struct pt_regs)); err |= save_fpu_state(sc); return err; } static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t framesize) { unsigned long sp; /* Default to using normal stack */ sp = regs->usp; /* * If we are on the alternate signal stack and would overflow it, don't. * Return an always-bogus address instead so we will die with SIGSEGV. */ if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize))) return (void __user __force *)(-1UL); /* This is the X/Open sanctioned signal stack switching. */ sp = sigsp(sp, ksig) - framesize; /* Align the stack frame. */ sp &= -8UL; return (void __user *)sp; } static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct rt_sigframe *frame; int err = 0; frame = get_sigframe(ksig, regs, sizeof(*frame)); if (!access_ok(frame, sizeof(*frame))) return -EFAULT; err |= copy_siginfo_to_user(&frame->info, &ksig->info); /* Create the ucontext. */ err |= __put_user(0, &frame->uc.uc_flags); err |= __put_user(NULL, &frame->uc.uc_link); err |= __save_altstack(&frame->uc.uc_stack, regs->usp); err |= setup_sigcontext(frame, regs); err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); if (err) return -EFAULT; /* Set up to return from userspace. */ regs->lr = (unsigned long)VDSO_SYMBOL( current->mm->context.vdso, rt_sigreturn); /* * Set up registers for signal handler. * Registers that we don't modify keep the value they had from * user-space at the time we took the signal. * We always pass siginfo and mcontext, regardless of SA_SIGINFO, * since some things rely on this (e.g. glibc's debug/segfault.c). */ regs->pc = (unsigned long)ksig->ka.sa.sa_handler; regs->usp = (unsigned long)frame; regs->a0 = ksig->sig; /* a0: signal number */ regs->a1 = (unsigned long)(&(frame->info)); /* a1: siginfo pointer */ regs->a2 = (unsigned long)(&(frame->uc)); /* a2: ucontext pointer */ return 0; } static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) { sigset_t *oldset = sigmask_to_save(); int ret; rseq_signal_deliver(ksig, regs); /* Are we from a system call? */ if (in_syscall(regs)) { /* Avoid additional syscall restarting via ret_from_exception */ forget_syscall(regs); /* If so, check system call restarting.. */ switch (regs->a0) { case -ERESTART_RESTARTBLOCK: case -ERESTARTNOHAND: regs->a0 = -EINTR; break; case -ERESTARTSYS: if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { regs->a0 = -EINTR; break; } fallthrough; case -ERESTARTNOINTR: regs->a0 = regs->orig_a0; regs->pc -= TRAP0_SIZE; break; } } /* Set up the stack frame */ ret = setup_rt_frame(ksig, oldset, regs); signal_setup_done(ret, ksig, 0); } static void do_signal(struct pt_regs *regs) { struct ksignal ksig; if (get_signal(&ksig)) { /* Actually deliver the signal */ handle_signal(&ksig, regs); return; } /* Did we come from a system call? */ if (in_syscall(regs)) { /* Avoid additional syscall restarting via ret_from_exception */ forget_syscall(regs); /* Restart the system call - no handlers present */ switch (regs->a0) { case -ERESTARTNOHAND: case -ERESTARTSYS: case -ERESTARTNOINTR: regs->a0 = regs->orig_a0; regs->pc -= TRAP0_SIZE; break; case -ERESTART_RESTARTBLOCK: regs->a0 = regs->orig_a0; regs_syscallid(regs) = __NR_restart_syscall; regs->pc -= TRAP0_SIZE; break; } } /* * If there is no signal to deliver, we just put the saved * sigmask back. */ restore_saved_sigmask(); } /* * notification of userspace execution resumption * - triggered by the _TIF_WORK_MASK flags */ asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) { if (thread_info_flags & _TIF_UPROBE) uprobe_notify_resume(regs); /* Handle pending signal delivery */ if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) do_signal(regs); if (thread_info_flags & _TIF_NOTIFY_RESUME) { tracehook_notify_resume(regs); rseq_handle_notify_resume(NULL, regs); } } |