riscv: compat: signal: Add rt_frame implementation (7383ee05) · Commits · git / linux-net

arch/riscv/include/asm/signal32.h

0 → 100644

+18 −0

Original line number	Diff line number	Diff line
		/* SPDX-License-Identifier: GPL-2.0-only */

		#ifndef __ASM_SIGNAL32_H
		#define __ASM_SIGNAL32_H

		#if IS_ENABLED(CONFIG_COMPAT)
		int compat_setup_rt_frame(struct ksignal ksig, sigset_t set,
		struct pt_regs *regs);
		#else
		static inline
		int compat_setup_rt_frame(struct ksignal ksig, sigset_t set,
		struct pt_regs *regs)
		{
		return -1;
		}
		#endif

		#endif

arch/riscv/kernel/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -70,4 +70,5 @@ obj-$(CONFIG_JUMP_LABEL) += jump_label.o

		obj-$(CONFIG_EFI) += efi.o
		obj-$(CONFIG_COMPAT) += compat_syscall_table.o
		obj-$(CONFIG_COMPAT) += compat_signal.o
		obj-$(CONFIG_COMPAT) += compat_vdso/

arch/riscv/kernel/compat_signal.c

0 → 100644

+243 −0

Original line number	Diff line number	Diff line
		// 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(&current->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, &current->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;
		}

arch/riscv/kernel/signal.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -6,6 +6,7 @@
		* Copyright (C) 2012 Regents of the University of California
		*/

		#include <linux/compat.h>
		#include <linux/signal.h>
		#include <linux/uaccess.h>
		#include <linux/syscalls.h>
		@@ -14,6 +15,7 @@

		#include <asm/ucontext.h>
		#include <asm/vdso.h>
		#include <asm/signal32.h>
		#include <asm/switch_to.h>
		#include <asm/csr.h>

		@@ -261,6 +263,9 @@ static void handle_signal(struct ksignal ksig, struct pt_regs regs)
		rseq_signal_deliver(ksig, regs);

		/* Set up the stack frame */
		if (is_compat_task())
		ret = compat_setup_rt_frame(ksig, oldset, regs);
		else
		ret = setup_rt_frame(ksig, oldset, regs);

		signal_setup_done(ret, ksig, 0);