| // 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; |
| unsigned long sr = regs->sr; |
| |
| /* 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)); |
| |
| /* BIT(0) of regs->sr is Condition Code/Carry bit */ |
| regs->sr = (sr & ~1) | (regs->sr & 1); |
| |
| /* 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 __user *frame; |
| int err = 0; |
| struct csky_vdso *vdso = current->mm->context.vdso; |
| |
| 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->rt_signal_retcode); |
| |
| /* |
| * 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) |
| do_signal(regs); |
| |
| if (thread_info_flags & _TIF_NOTIFY_RESUME) { |
| tracehook_notify_resume(regs); |
| rseq_handle_notify_resume(NULL, regs); |
| } |
| } |