This patch adds signal handling support for LoongArch.
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
---
arch/loongarch/include/uapi/asm/sigcontext.h | 30 ++
arch/loongarch/include/uapi/asm/ucontext.h | 35 ++
arch/loongarch/kernel/signal.c | 455 +++++++++++++++++++
3 files changed, 520 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 <lihanlu@xxxxxxxxxxx>
+ * Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ *
+ * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
+ */
+#ifndef _UAPI_ASM_SIGCONTEXT_H
+#define _UAPI_ASM_SIGCONTEXT_H
+
+#include <linux/types.h>
+#include <linux/posix_types.h>
+#include <asm/processor.h>
+
+/* 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..c71e0026fe2c
--- /dev/null
+++ b/arch/loongarch/kernel/signal.c
@@ -0,0 +1,455 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Author: Hanlu Li <lihanlu@xxxxxxxxxxx>
+ * Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ * 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 <linux/audit.h>
+#include <linux/cache.h>
+#include <linux/context_tracking.h>
+#include <linux/irqflags.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/personality.h>
+#include <linux/smp.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/ptrace.h>
+#include <linux/unistd.h>
+#include <linux/compiler.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
+#include <linux/tracehook.h>
+
+#include <asm/asm.h>
+#include <asm/cacheflush.h>
+#include <asm/cpu-features.h>
+#include <asm/fpu.h>
+#include <asm/ucontext.h>
+#include <asm/vdso.h>
+
+#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);
+
+ regs->regs[0] = 0; /* No syscall restarting */
+ 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
