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- // SPDX-License-Identifier: GPL-2.0
- #include <linux/signal.h>
- #include <linux/uaccess.h>
- #include <linux/syscalls.h>
- #include <linux/resume_user_mode.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;
- 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)
- resume_user_mode_work(regs);
- }
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