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// 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 *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);
}
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