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[23.128.96.18]) by mx.google.com with ESMTP id m24si11635172pls.262.2021.09.26.23.54.43; Sun, 26 Sep 2021 23:54:55 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233101AbhI0Gyb (ORCPT + 99 others); Mon, 27 Sep 2021 02:54:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:43022 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233075AbhI0Gy2 (ORCPT ); Mon, 27 Sep 2021 02:54:28 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1EB0261041; Mon, 27 Sep 2021 06:52:46 +0000 (UTC) From: Huacai Chen To: Arnd Bergmann , Andy Lutomirski , Thomas Gleixner , Peter Zijlstra , Andrew Morton , David Airlie , Jonathan Corbet , Linus Torvalds Cc: linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Xuefeng Li , Yanteng Si , Huacai Chen , Jiaxun Yang , Huacai Chen , Eric Biederman , Al Viro Subject: [PATCH V4 14/22] LoongArch: Add signal handling support Date: Mon, 27 Sep 2021 14:42:51 +0800 Message-Id: <20210927064300.624279-15-chenhuacai@loongson.cn> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210927064300.624279-1-chenhuacai@loongson.cn> References: <20210927064300.624279-1-chenhuacai@loongson.cn> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch adds signal handling support for LoongArch. Cc: Eric Biederman Cc: Al Viro Signed-off-by: Huacai Chen --- arch/loongarch/include/uapi/asm/sigcontext.h | 30 ++ arch/loongarch/include/uapi/asm/ucontext.h | 35 ++ arch/loongarch/kernel/signal.c | 454 +++++++++++++++++++ 3 files changed, 519 insertions(+) create mode 100644 arch/loongarch/include/uapi/asm/sigcontext.h create mode 100644 arch/loongarch/include/uapi/asm/ucontext.h create mode 100644 arch/loongarch/kernel/signal.c diff --git a/arch/loongarch/include/uapi/asm/sigcontext.h b/arch/loongarch/include/uapi/asm/sigcontext.h new file mode 100644 index 000000000000..5d55f61c40af --- /dev/null +++ b/arch/loongarch/include/uapi/asm/sigcontext.h @@ -0,0 +1,30 @@ +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */ +/* + * Author: Hanlu Li + * Huacai Chen + * + * Copyright (C) 2020-2021 Loongson Technology Corporation Limited + */ +#ifndef _UAPI_ASM_SIGCONTEXT_H +#define _UAPI_ASM_SIGCONTEXT_H + +#include +#include +#include + +/* FP context was used */ +#define USED_FP (1 << 0) + +struct sigcontext { + __u64 sc_pc; + __u64 sc_regs[32]; + __u32 sc_flags; + __u32 sc_fcsr; + __u32 sc_vcsr; + __u64 sc_fcc; + __u64 sc_scr[4]; + union fpureg sc_fpregs[32] FPU_ALIGN; + __u8 sc_reserved[4096] __attribute__((__aligned__(16))); +}; + +#endif /* _UAPI_ASM_SIGCONTEXT_H */ diff --git a/arch/loongarch/include/uapi/asm/ucontext.h b/arch/loongarch/include/uapi/asm/ucontext.h new file mode 100644 index 000000000000..12577e22b1c7 --- /dev/null +++ b/arch/loongarch/include/uapi/asm/ucontext.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef __LOONGARCH_UAPI_ASM_UCONTEXT_H +#define __LOONGARCH_UAPI_ASM_UCONTEXT_H + +/** + * struct ucontext - user context structure + * @uc_flags: + * @uc_link: + * @uc_stack: + * @uc_mcontext: holds basic processor state + * @uc_sigmask: + * @uc_extcontext: holds extended processor state + */ +struct ucontext { + unsigned long uc_flags; + struct ucontext *uc_link; + 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 sigcontext uc_mcontext; +}; + +#endif /* __LOONGARCH_UAPI_ASM_UCONTEXT_H */ diff --git a/arch/loongarch/kernel/signal.c b/arch/loongarch/kernel/signal.c new file mode 100644 index 000000000000..2ff3a83c603f --- /dev/null +++ b/arch/loongarch/kernel/signal.c @@ -0,0 +1,454 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Author: Hanlu Li + * Huacai Chen + * Copyright (C) 2020-2021 Loongson Technology Corporation Limited + * + * Derived from MIPS: + * Copyright (C) 1991, 1992 Linus Torvalds + * Copyright (C) 1994 - 2000 Ralf Baechle + * Copyright (C) 1999, 2000 Silicon Graphics, Inc. + * Copyright (C) 2014, Imagination Technologies Ltd. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +#ifdef DEBUG_SIG +# define DEBUGP(fmt, args...) printk("%s: " fmt, __func__, ##args) +#else +# define DEBUGP(fmt, args...) +#endif + +/* Make sure we will not lose FPU ownership */ +#define lock_fpu_owner() ({ preempt_disable(); pagefault_disable(); }) +#define unlock_fpu_owner() ({ pagefault_enable(); preempt_enable(); }) + +/* Assembly functions to move context to/from the FPU */ +extern asmlinkage int +_save_fp_context(void __user *fpregs, void __user *fcc, void __user *csr); +extern asmlinkage int +_restore_fp_context(void __user *fpregs, void __user *fcc, void __user *csr); + +static int (*save_fp_context)(struct sigcontext __user *sc); +static int (*restore_fp_context)(struct sigcontext __user *sc); + +struct rt_sigframe { + struct siginfo rs_info; + struct ucontext rs_uctx; +}; + +/* + * Thread saved context copy to/from a signal context presumed to be on the + * user stack, and therefore accessed with appropriate macros from uaccess.h. + */ +static int copy_fp_to_sigcontext(struct sigcontext __user *sc) +{ + int i; + int err = 0; + int inc = 1; + uint64_t __user *fcc = &sc->sc_fcc; + uint32_t __user *csr = &sc->sc_fcsr; + uint64_t __user *fpregs = (uint64_t *)&sc->sc_fpregs; + + for (i = 0; i < NUM_FPU_REGS; i += inc) { + err |= + __put_user(get_fpr64(¤t->thread.fpu.fpr[i], 0), + &fpregs[4*i]); + } + err |= __put_user(current->thread.fpu.fcsr, csr); + err |= __put_user(current->thread.fpu.fcc, fcc); + + return err; +} + +static int copy_fp_from_sigcontext(struct sigcontext __user *sc) +{ + int i; + int err = 0; + int inc = 1; + u64 fpr_val; + uint64_t __user *fcc = &sc->sc_fcc; + uint32_t __user *csr = &sc->sc_fcsr; + uint64_t __user *fpregs = (uint64_t *)&sc->sc_fpregs; + + for (i = 0; i < NUM_FPU_REGS; i += inc) { + err |= __get_user(fpr_val, &fpregs[4*i]); + set_fpr64(¤t->thread.fpu.fpr[i], 0, fpr_val); + } + err |= __get_user(current->thread.fpu.fcsr, csr); + err |= __get_user(current->thread.fpu.fcc, fcc); + + return err; +} + +/* + * Wrappers for the assembly _{save,restore}_fp_context functions. + */ +static int save_hw_fp_context(struct sigcontext __user *sc) +{ + uint64_t __user *fcc = &sc->sc_fcc; + uint32_t __user *fcsr = &sc->sc_fcsr; + uint64_t __user *fpregs = (uint64_t *)&sc->sc_fpregs; + + return _save_fp_context(fpregs, fcc, fcsr); +} + +static int restore_hw_fp_context(struct sigcontext __user *sc) +{ + uint64_t __user *fcc = &sc->sc_fcc; + uint32_t __user *csr = &sc->sc_fcsr; + uint64_t __user *fpregs = (uint64_t *)&sc->sc_fpregs; + + return _restore_fp_context(fpregs, fcc, csr); +} + +int fpcsr_pending(unsigned int __user *fpcsr) +{ + int err, sig = 0; + unsigned int csr, enabled; + + err = __get_user(csr, fpcsr); + enabled = ((csr & FPU_CSR_ALL_E) << 24); + /* + * If the signal handler set some FPU exceptions, clear it and + * send SIGFPE. + */ + if (csr & enabled) { + csr &= ~enabled; + err |= __put_user(csr, fpcsr); + sig = SIGFPE; + } + return err ?: sig; +} + +/* + * Helper routines + */ +static int protected_save_fp_context(struct sigcontext __user *sc) +{ + int err = 0; + unsigned int used; + uint32_t __user *fcc = &sc->sc_fcsr; + uint32_t __user *fcsr = &sc->sc_fcsr; + uint32_t __user *vcsr = &sc->sc_vcsr; + uint32_t __user *flags = &sc->sc_flags; + uint64_t __user *fpregs = (uint64_t *)&sc->sc_fpregs; + + used = used_math() ? USED_FP : 0; + if (!used) + goto fp_done; + + while (1) { + lock_fpu_owner(); + if (is_fpu_owner()) + err = save_fp_context(sc); + else + err |= copy_fp_to_sigcontext(sc); + unlock_fpu_owner(); + if (likely(!err)) + break; + /* touch the sigcontext and try again */ + err = __put_user(0, &fpregs[0]) | + __put_user(0, &fpregs[32*4 - 1]) | + __put_user(0, fcc) | + __put_user(0, fcsr) | + __put_user(0, vcsr); + if (err) + return err; /* really bad sigcontext */ + } + +fp_done: + return __put_user(used, flags); +} + +static int protected_restore_fp_context(struct sigcontext __user *sc) +{ + unsigned int used; + int err = 0, sig = 0, tmp __maybe_unused; + uint32_t __user *fcc = &sc->sc_fcsr; + uint32_t __user *fcsr = &sc->sc_fcsr; + uint32_t __user *vcsr = &sc->sc_vcsr; + uint32_t __user *flags = &sc->sc_flags; + uint64_t __user *fpregs = (uint64_t *)&sc->sc_fpregs; + + err = __get_user(used, flags); + conditional_used_math(used & USED_FP); + + /* + * The signal handler may have used FPU; give it up if the program + * doesn't want it following sigreturn. + */ + if (err || !(used & USED_FP)) + lose_fpu(0); + + if (err) + return err; + + if (!(used & USED_FP)) + goto fp_done; + + err = sig = fpcsr_pending(fcsr); + if (err < 0) + return err; + + while (1) { + lock_fpu_owner(); + if (is_fpu_owner()) + err = restore_fp_context(sc); + else + err |= copy_fp_from_sigcontext(sc); + unlock_fpu_owner(); + if (likely(!err)) + break; + /* touch the sigcontext and try again */ + err = __get_user(tmp, &fpregs[0]) | + __get_user(tmp, &fpregs[32*4 - 1]) | + __get_user(tmp, fcc) | + __get_user(tmp, fcsr) | + __get_user(tmp, vcsr); + if (err) + break; /* really bad sigcontext */ + } + +fp_done: + return err ?: sig; +} + +static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) +{ + int i, err = 0; + + err |= __put_user(regs->csr_epc, &sc->sc_pc); + + err |= __put_user(0, &sc->sc_regs[0]); + for (i = 1; i < 32; i++) + err |= __put_user(regs->regs[i], &sc->sc_regs[i]); + + /* + * Save FPU state to signal context. Signal handler + * will "inherit" current FPU state. + */ + err |= protected_save_fp_context(sc); + + return err; +} + +static int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) +{ + int i, err = 0; + + /* Always make any pending restarted system calls return -EINTR */ + current->restart_block.fn = do_no_restart_syscall; + + err |= __get_user(regs->csr_epc, &sc->sc_pc); + + for (i = 1; i < 32; i++) + err |= __get_user(regs->regs[i], &sc->sc_regs[i]); + + return err ?: protected_restore_fp_context(sc); +} + +void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, + size_t frame_size) +{ + unsigned long sp; + + /* Default to using normal stack */ + sp = regs->regs[3]; + sp -= 32; /* Reserve 32-bytes. */ + + sp = sigsp(sp, ksig); + + return (void __user *)((sp - frame_size) & ALMASK); +} + +/* + * Atomically swap in the new signal mask, and wait for a signal. + */ + +asmlinkage long sys_rt_sigreturn(void) +{ + int sig; + sigset_t set; + struct pt_regs *regs; + struct rt_sigframe __user *frame; + + regs = current_pt_regs(); + frame = (struct rt_sigframe __user *)regs->regs[3]; + if (!access_ok(frame, sizeof(*frame))) + goto badframe; + if (__copy_from_user(&set, &frame->rs_uctx.uc_sigmask, sizeof(set))) + goto badframe; + + set_current_blocked(&set); + + sig = restore_sigcontext(regs, &frame->rs_uctx.uc_mcontext); + if (sig < 0) + goto badframe; + else if (sig) + force_sig(sig); + + if (restore_altstack(&frame->rs_uctx.uc_stack)) + goto badframe; + + return regs->regs[4]; + +badframe: + force_sig(SIGSEGV); + return 0; +} + +static int setup_rt_frame(void *sig_return, struct ksignal *ksig, + struct pt_regs *regs, sigset_t *set) +{ + int err = 0; + struct rt_sigframe __user *frame; + + frame = get_sigframe(ksig, regs, sizeof(*frame)); + if (!access_ok(frame, sizeof(*frame))) + return -EFAULT; + + /* Create siginfo. */ + err |= copy_siginfo_to_user(&frame->rs_info, &ksig->info); + + /* Create the ucontext. */ + err |= __put_user(0, &frame->rs_uctx.uc_flags); + err |= __put_user(NULL, &frame->rs_uctx.uc_link); + err |= __save_altstack(&frame->rs_uctx.uc_stack, regs->regs[3]); + err |= setup_sigcontext(regs, &frame->rs_uctx.uc_mcontext); + err |= __copy_to_user(&frame->rs_uctx.uc_sigmask, set, sizeof(*set)); + + if (err) + return -EFAULT; + + /* + * Arguments to signal handler: + * + * a0 = signal number + * a1 = 0 (should be cause) + * a2 = pointer to ucontext + * + * $25 and c0_epc point to the signal handler, $29 points to + * the struct rt_sigframe. + */ + regs->regs[4] = ksig->sig; + regs->regs[5] = (unsigned long) &frame->rs_info; + regs->regs[6] = (unsigned long) &frame->rs_uctx; + regs->regs[3] = (unsigned long) frame; + regs->regs[1] = (unsigned long) sig_return; + regs->csr_epc = (unsigned long) ksig->ka.sa.sa_handler; + + DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n", + current->comm, current->pid, + frame, regs->csr_epc, regs->regs[1]); + + return 0; +} + +static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) +{ + int ret; + sigset_t *oldset = sigmask_to_save(); + void *vdso = current->mm->context.vdso; + + /* Are we from a system call? */ + if (regs->regs[0]) { + switch (regs->regs[4]) { + case -ERESTART_RESTARTBLOCK: + case -ERESTARTNOHAND: + regs->regs[4] = -EINTR; + break; + case -ERESTARTSYS: + if (!(ksig->ka.sa.sa_flags & SA_RESTART)) { + regs->regs[4] = -EINTR; + break; + } + fallthrough; + case -ERESTARTNOINTR: + regs->regs[4] = regs->orig_a0; + regs->csr_epc -= 4; + } + + regs->regs[0] = 0; /* Don't deal with this again. */ + } + + rseq_signal_deliver(ksig, regs); + + ret = setup_rt_frame(vdso + current->thread.vdso->offset_sigreturn, ksig, regs, oldset); + + signal_setup_done(ret, ksig, 0); +} + +void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal) +{ + struct ksignal ksig; + + if (has_signal && get_signal(&ksig)) { + /* Whee! Actually deliver the signal. */ + handle_signal(&ksig, regs); + return; + } + + /* Are we from a system call? */ + if (regs->regs[0]) { + switch (regs->regs[4]) { + case -ERESTARTNOHAND: + case -ERESTARTSYS: + case -ERESTARTNOINTR: + regs->regs[4] = regs->orig_a0; + regs->csr_epc -= 4; + break; + + case -ERESTART_RESTARTBLOCK: + regs->regs[4] = regs->orig_a0; + regs->regs[11] = __NR_restart_syscall; + regs->csr_epc -= 4; + break; + } + regs->regs[0] = 0; /* Don't deal with this again. */ + } + + /* + * If there's no signal to deliver, we just put the saved sigmask + * back + */ + restore_saved_sigmask(); +} + +static int signal_setup(void) +{ + if (cpu_has_fpu) { + save_fp_context = save_hw_fp_context; + restore_fp_context = restore_hw_fp_context; + } else { + save_fp_context = copy_fp_to_sigcontext; + restore_fp_context = copy_fp_from_sigcontext; + } + + return 0; +} + +arch_initcall(signal_setup); -- 2.27.0