swh:1:snp:173f8deb0c56c557784b4fd217e7608ac6197844
Tip revision: 2c85ebc57b3e1817b6ce1a6b703928e113a90442 authored by Linus Torvalds on 13 December 2020, 22:41:30 UTC
Linux 5.10
Linux 5.10
Tip revision: 2c85ebc
signal.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
* Chen Liqin <liqin.chen@sunplusct.com>
* Lennox Wu <lennox.wu@sunplusct.com>
* Copyright (C) 2012 Regents of the University of California
*/
#include <linux/signal.h>
#include <linux/uaccess.h>
#include <linux/syscalls.h>
#include <linux/tracehook.h>
#include <linux/linkage.h>
#include <asm/ucontext.h>
#include <asm/vdso.h>
#include <asm/switch_to.h>
#include <asm/csr.h>
extern u32 __user_rt_sigreturn[2];
#define DEBUG_SIG 0
struct rt_sigframe {
struct siginfo info;
struct ucontext uc;
#ifndef CONFIG_MMU
u32 sigreturn_code[2];
#endif
};
#ifdef CONFIG_FPU
static long restore_fp_state(struct pt_regs *regs,
union __riscv_fp_state __user *sc_fpregs)
{
long err;
struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
size_t i;
err = __copy_from_user(¤t->thread.fstate, state, sizeof(*state));
if (unlikely(err))
return err;
fstate_restore(current, regs);
/* We support no other extension state at this time. */
for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
u32 value;
err = __get_user(value, &sc_fpregs->q.reserved[i]);
if (unlikely(err))
break;
if (value != 0)
return -EINVAL;
}
return err;
}
static long save_fp_state(struct pt_regs *regs,
union __riscv_fp_state __user *sc_fpregs)
{
long err;
struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
size_t i;
fstate_save(current, regs);
err = __copy_to_user(state, ¤t->thread.fstate, sizeof(*state));
if (unlikely(err))
return err;
/* We support no other extension state at this time. */
for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
err = __put_user(0, &sc_fpregs->q.reserved[i]);
if (unlikely(err))
break;
}
return err;
}
#else
#define save_fp_state(task, regs) (0)
#define restore_fp_state(task, regs) (0)
#endif
static long restore_sigcontext(struct pt_regs *regs,
struct sigcontext __user *sc)
{
long err;
/* sc_regs is structured the same as the start of pt_regs */
err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
/* Restore the floating-point state. */
if (has_fpu)
err |= restore_fp_state(regs, &sc->sc_fpregs);
return err;
}
SYSCALL_DEFINE0(rt_sigreturn)
{
struct pt_regs *regs = current_pt_regs();
struct rt_sigframe __user *frame;
struct task_struct *task;
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->sp;
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:
task = current;
if (show_unhandled_signals) {
pr_info_ratelimited(
"%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
task->comm, task_pid_nr(task), __func__,
frame, (void *)regs->epc, (void *)regs->sp);
}
force_sig(SIGSEGV);
return 0;
}
static long setup_sigcontext(struct rt_sigframe __user *frame,
struct pt_regs *regs)
{
struct sigcontext __user *sc = &frame->uc.uc_mcontext;
long err;
/* sc_regs is structured the same as the start of pt_regs */
err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
/* Save the floating-point state. */
if (has_fpu)
err |= save_fp_state(regs, &sc->sc_fpregs);
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->sp;
/*
* 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 &= ~0xfUL;
return (void __user *)sp;
}
static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
long 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->sp);
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. */
#ifdef CONFIG_MMU
regs->ra = (unsigned long)VDSO_SYMBOL(
current->mm->context.vdso, rt_sigreturn);
#else
/*
* For the nommu case we don't have a VDSO. Instead we push two
* instructions to call the rt_sigreturn syscall onto the user stack.
*/
if (copy_to_user(&frame->sigreturn_code, __user_rt_sigreturn,
sizeof(frame->sigreturn_code)))
return -EFAULT;
regs->ra = (unsigned long)&frame->sigreturn_code;
#endif /* CONFIG_MMU */
/*
* 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->epc = (unsigned long)ksig->ka.sa.sa_handler;
regs->sp = (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 */
#if DEBUG_SIG
pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n",
current->comm, task_pid_nr(current), ksig->sig,
(void *)regs->epc, (void *)regs->ra, frame);
#endif
return 0;
}
static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
sigset_t *oldset = sigmask_to_save();
int ret;
/* Are we from a system call? */
if (regs->cause == EXC_SYSCALL) {
/* Avoid additional syscall restarting via ret_from_exception */
regs->cause = -1UL;
/* 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->epc -= 0x4;
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 (regs->cause == EXC_SYSCALL) {
/* Avoid additional syscall restarting via ret_from_exception */
regs->cause = -1UL;
/* Restart the system call - no handlers present */
switch (regs->a0) {
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
regs->a0 = regs->orig_a0;
regs->epc -= 0x4;
break;
case -ERESTART_RESTARTBLOCK:
regs->a0 = regs->orig_a0;
regs->a7 = __NR_restart_syscall;
regs->epc -= 0x4;
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 __visible void do_notify_resume(struct pt_regs *regs,
unsigned long thread_info_flags)
{
/* Handle pending signal delivery */
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(regs);
if (thread_info_flags & _TIF_NOTIFY_RESUME)
tracehook_notify_resume(regs);
}