From 7383ee05314be58f8f9f018ee0ac53bef3808aea Mon Sep 17 00:00:00 2001 From: Guo Ren Date: Tue, 5 Apr 2022 15:13:12 +0800 Subject: [PATCH] riscv: compat: signal: Add rt_frame implementation Implement compat_setup_rt_frame for sigcontext save & restore. The main process is the same with signal, but the rv32 pt_regs' size is different from rv64's, so we needs convert them. Signed-off-by: Guo Ren Signed-off-by: Guo Ren Reviewed-by: Palmer Dabbelt Tested-by: Heiko Stuebner Link: https://lore.kernel.org/r/20220405071314.3225832-19-guoren@kernel.org Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/signal32.h | 18 +++ arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/compat_signal.c | 243 ++++++++++++++++++++++++++++++++++++++ arch/riscv/kernel/signal.c | 7 +- 4 files changed, 268 insertions(+), 1 deletion(-) create mode 100644 arch/riscv/include/asm/signal32.h create mode 100644 arch/riscv/kernel/compat_signal.c diff --git a/arch/riscv/include/asm/signal32.h b/arch/riscv/include/asm/signal32.h new file mode 100644 index 0000000..96dc569 --- /dev/null +++ b/arch/riscv/include/asm/signal32.h @@ -0,0 +1,18 @@ +/* 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 diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index fec77d1..bf25162 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -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/ diff --git a/arch/riscv/kernel/compat_signal.c b/arch/riscv/kernel/compat_signal.c new file mode 100644 index 0000000..6ec4e34 --- /dev/null +++ b/arch/riscv/kernel/compat_signal.c @@ -0,0 +1,243 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#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; +} diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c index 9f4e59f..38b05ca 100644 --- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -6,6 +6,7 @@ * Copyright (C) 2012 Regents of the University of California */ +#include #include #include #include @@ -14,6 +15,7 @@ #include #include +#include #include #include @@ -261,7 +263,10 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) rseq_signal_deliver(ksig, regs); /* Set up the stack frame */ - ret = setup_rt_frame(ksig, oldset, regs); + 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); } -- 2.7.4