// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/compat.h>
#include <linux/signal.h>
#include <linux/uaccess.h>
#include <linux/syscalls.h>
#include <linux/linkage.h>
#include <asm/csr.h>
#include <asm/signal32.h>
#include <asm/switch_to.h>
#include <asm/ucontext.h>
#include <asm/vdso.h>
#define COMPAT_DEBUG_SIG 0
struct compat_sigcontext {
struct compat_user_regs_struct sc_regs;
union __riscv_fp_state sc_fpregs;
};
struct compat_ucontext {
compat_ulong_t uc_flags;
struct compat_ucontext *uc_link;
compat_stack_t uc_stack;
sigset_t uc_sigmask;
/* There's some padding here to allow sigset_t to be expanded in the
* future. Though this is unlikely, other architectures put uc_sigmask
* at the end of this structure and explicitly state it can be
* expanded, so we didn't want to box ourselves in here. */
__u8 __unused[1024 / 8 - sizeof(sigset_t)];
/* We can't put uc_sigmask at the end of this structure because we need
* to be able to expand sigcontext in the future. For example, the
* vector ISA extension will almost certainly add ISA state. We want
* to ensure all user-visible ISA state can be saved and restored via a
* ucontext, so we're putting this at the end in order to allow for
* infinite extensibility. Since we know this will be extended and we
* assume sigset_t won't be extended an extreme amount, we're
* prioritizing this. */
struct compat_sigcontext uc_mcontext;
};
struct compat_rt_sigframe {
struct compat_siginfo info;
struct compat_ucontext uc;
};
#ifdef CONFIG_FPU
static long compat_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 compat_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 compat_save_fp_state(task, regs) (0)
#define compat_restore_fp_state(task, regs) (0)
#endif
static long compat_restore_sigcontext(struct pt_regs *regs,
struct compat_sigcontext __user *sc)
{
long err;
struct compat_user_regs_struct cregs;
/* sc_regs is structured the same as the start of pt_regs */
err = __copy_from_user(&cregs, &sc->sc_regs, sizeof(sc->sc_regs));
cregs_to_regs(&cregs, regs);
/* Restore the floating-point state. */
if (has_fpu())
err |= compat_restore_fp_state(regs, &sc->sc_fpregs);
return err;
}
COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
{
struct pt_regs *regs = current_pt_regs();
struct compat_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 compat_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 (compat_restore_sigcontext(regs, &frame->uc.uc_mcontext))
goto badframe;
if (compat_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 compat_setup_sigcontext(struct compat_rt_sigframe __user *frame,
struct pt_regs *regs)
{
struct compat_sigcontext __user *sc = &frame->uc.uc_mcontext;
struct compat_user_regs_struct cregs;
long err;
regs_to_cregs(&cregs, regs);
/* sc_regs is structured the same as the start of pt_regs */
err = __copy_to_user(&sc->sc_regs, &cregs, sizeof(sc->sc_regs));
/* Save the floating-point state. */
if (has_fpu())
err |= compat_save_fp_state(regs, &sc->sc_fpregs);
return err;
}
static inline void __user *compat_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;
}
int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set,
struct pt_regs *regs)
{
struct compat_rt_sigframe __user *frame;
long err = 0;
frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
if (!access_ok(frame, sizeof(*frame)))
return -EFAULT;
err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(NULL, &frame->uc.uc_link);
err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
err |= compat_setup_sigcontext(frame, regs);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
return -EFAULT;
regs->ra = (unsigned long)COMPAT_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->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 COMPAT_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;
}
