Add ucontext/sigcontext definition and 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 | 44 ++
arch/loongarch/include/uapi/asm/signal.h | 13 +
arch/loongarch/include/uapi/asm/ucontext.h | 35 ++
arch/loongarch/kernel/signal.c | 566 +++++++++++++++++++
4 files changed, 658 insertions(+)
create mode 100644 arch/loongarch/include/uapi/asm/sigcontext.h
create mode 100644 arch/loongarch/include/uapi/asm/signal.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..be3d3c6ac83e
--- /dev/null
+++ b/arch/loongarch/include/uapi/asm/sigcontext.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/*
+ * Author: Hanlu Li <lihanlu@xxxxxxxxxxx>
+ * Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ *
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef _UAPI_ASM_SIGCONTEXT_H
+#define _UAPI_ASM_SIGCONTEXT_H
+
+#include <linux/types.h>
+#include <linux/posix_types.h>
+
+/* FP context was used */
+#define SC_USED_FP (1 << 0)
+/* Address error was due to memory load */
+#define SC_ADDRERR_RD (1 << 30)
+/* Address error was due to memory store */
+#define SC_ADDRERR_WR (1 << 31)
+
+struct sigcontext {
+ __u64 sc_pc;
+ __u64 sc_regs[32];
+ __u32 sc_flags;
+ __u64 sc_extcontext[0] __attribute__((__aligned__(16)));
+};
+
+#define CONTEXT_INFO_ALIGN 16
+struct _ctxinfo {
+ __u32 magic;
+ __u32 size;
+ __u64 padding; /* padding to 16 bytes */
+};
+
+/* FPU context */
+#define FPU_CTX_MAGIC 0x46505501
+#define FPU_CTX_ALIGN 8
+struct fpu_context {
+ __u64 regs[32];
+ __u64 fcc;
+ __u32 fcsr;
+};
+
+#endif /* _UAPI_ASM_SIGCONTEXT_H */
diff --git a/arch/loongarch/include/uapi/asm/signal.h b/arch/loongarch/include/uapi/asm/signal.h
new file mode 100644
index 000000000000..992d965aa13f
--- /dev/null
+++ b/arch/loongarch/include/uapi/asm/signal.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef _UAPI_ASM_SIGNAL_H
+#define _UAPI_ASM_SIGNAL_H
+
+#define MINSIGSTKSZ 4096
+#define SIGSTKSZ 16384
+
+#include <asm-generic/signal.h>
+
+#endif
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..7ffc77d56988
--- /dev/null
+++ b/arch/loongarch/kernel/signal.c
@@ -0,0 +1,566 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Author: Hanlu Li <lihanlu@xxxxxxxxxxx>
+ * Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ * Copyright (C) 2020-2022 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 <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);
+
+struct rt_sigframe {
+ struct siginfo rs_info;
+ struct ucontext rs_uctx;
+};
+
+struct _ctx_layout {
+ struct _ctxinfo *addr;
+ unsigned int size;
+};
+
+struct extctx_layout {
+ unsigned long size;
+ unsigned int flags;
+ struct _ctx_layout fpu;
+ struct _ctx_layout end;
+};
+
+static void __user *get_ctx_through_ctxinfo(struct _ctxinfo *info)
+{
+ return (void __user *)((char *)info + sizeof(struct _ctxinfo));
+}
+
+/*
+ * 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_fpu_to_sigcontext(struct fpu_context __user *ctx)
+{
+ int i;
+ int err = 0;
+ uint64_t __user *regs = (uint64_t *)&ctx->regs;
+ uint64_t __user *fcc = &ctx->fcc;
+ uint32_t __user *fcsr = &ctx->fcsr;
+
+ for (i = 0; i < NUM_FPU_REGS; i++) {
+ err |=
+ __put_user(get_fpr64(¤t->thread.fpu.fpr[i], 0),
+ ®s[i]);
+ }
+ err |= __put_user(current->thread.fpu.fcc, fcc);
+ err |= __put_user(current->thread.fpu.fcsr, fcsr);
+
+ return err;
+}
+
+static int copy_fpu_from_sigcontext(struct fpu_context __user *ctx)
+{
+ int i;
+ int err = 0;
+ u64 fpr_val;
+ uint64_t __user *regs = (uint64_t *)&ctx->regs;
+ uint64_t __user *fcc = &ctx->fcc;
+ uint32_t __user *fcsr = &ctx->fcsr;
+
+ for (i = 0; i < NUM_FPU_REGS; i++) {
+ err |= __get_user(fpr_val, ®s[i]);
+ set_fpr64(¤t->thread.fpu.fpr[i], 0, fpr_val);
+ }
+ err |= __get_user(current->thread.fpu.fcc, fcc);
+ err |= __get_user(current->thread.fpu.fcsr, fcsr);
+
+ return err;
+}
+
+/*
+ * Wrappers for the assembly _{save,restore}_fp_context functions.
+ */
+static int save_hw_fpu_context(struct fpu_context __user *ctx)
+{
+ uint64_t __user *regs = (uint64_t *)&ctx->regs;
+ uint64_t __user *fcc = &ctx->fcc;
+ uint32_t __user *fcsr = &ctx->fcsr;
+
+ return _save_fp_context(regs, fcc, fcsr);
+}
+
+static int restore_hw_fpu_context(struct fpu_context __user *ctx)
+{
+ uint64_t __user *regs = (uint64_t *)&ctx->regs;
+ uint64_t __user *fcc = &ctx->fcc;
+ uint32_t __user *fcsr = &ctx->fcsr;
+
+ return _restore_fp_context(regs, fcc, fcsr);
+}
+
+static int fcsr_pending(unsigned int __user *fcsr)
+{
+ int err, sig = 0;
+ unsigned int csr, enabled;
+
+ err = __get_user(csr, fcsr);
+ 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, fcsr);
+ sig = SIGFPE;
+ }
+ return err ?: sig;
+}
+
+/*
+ * Helper routines
+ */
+static int protected_save_fpu_context(struct extctx_layout *extctx)
+{
+ int err = 0;
+ struct _ctxinfo __user *info = extctx->fpu.addr;
+ struct fpu_context __user *fpu_ctx = (struct fpu_context *)get_ctx_through_ctxinfo(info);
+ uint64_t __user *regs = (uint64_t *)&fpu_ctx->regs;
+ uint64_t __user *fcc = &fpu_ctx->fcc;
+ uint32_t __user *fcsr = &fpu_ctx->fcsr;
+
+ while (1) {
+ lock_fpu_owner();
+ if (is_fpu_owner())
+ err = save_hw_fpu_context(fpu_ctx);
+ else
+ err = copy_fpu_to_sigcontext(fpu_ctx);
+ unlock_fpu_owner();
+
+ err |= __put_user(FPU_CTX_MAGIC, &info->magic);
+ err |= __put_user(extctx->fpu.size, &info->size);
+
+ if (likely(!err))
+ break;
+ /* Touch the FPU context and try again */
+ err = __put_user(0, ®s[0]) |
+ __put_user(0, ®s[31]) |
+ __put_user(0, fcc) |
+ __put_user(0, fcsr);
+ if (err)
+ return err; /* really bad sigcontext */
+ }
+
+ return err;
+}
+
+static int protected_restore_fpu_context(struct extctx_layout *extctx)
+{
+ int err = 0, sig = 0, tmp __maybe_unused;
+ struct _ctxinfo __user *info = extctx->fpu.addr;
+ struct fpu_context __user *fpu_ctx = (struct fpu_context *)get_ctx_through_ctxinfo(info);
+ uint64_t __user *regs = (uint64_t *)&fpu_ctx->regs;
+ uint64_t __user *fcc = &fpu_ctx->fcc;
+ uint32_t __user *fcsr = &fpu_ctx->fcsr;
+
+ err = sig = fcsr_pending(fcsr);
+ if (err < 0)
+ return err;
+
+ while (1) {
+ lock_fpu_owner();
+ if (is_fpu_owner())
+ err = restore_hw_fpu_context(fpu_ctx);
+ else
+ err = copy_fpu_from_sigcontext(fpu_ctx);
+ unlock_fpu_owner();
+
+ if (likely(!err))
+ break;
+ /* Touch the FPU context and try again */
+ err = __get_user(tmp, ®s[0]) |
+ __get_user(tmp, ®s[31]) |
+ __get_user(tmp, fcc) |
+ __get_user(tmp, fcsr);
+ if (err)
+ break; /* really bad sigcontext */
+ }
+
+ return err ?: sig;
+}
+
+static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
+ struct extctx_layout *extctx)
+{
+ int i, err = 0;
+ struct _ctxinfo __user *info;
+
+ err |= __put_user(regs->csr_era, &sc->sc_pc);
+ err |= __put_user(extctx->flags, &sc->sc_flags);
+
+ err |= __put_user(0, &sc->sc_regs[0]);
+ for (i = 1; i < 32; i++)
+ err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
+
+ if (extctx->fpu.addr)
+ err |= protected_save_fpu_context(extctx);
+
+ /* Set the "end" magic */
+ info = (struct _ctxinfo *)extctx->end.addr;
+ err |= __put_user(0, &info->magic);
+ err |= __put_user(0, &info->size);
+
+ return err;
+}
+
+static int parse_extcontext(struct sigcontext __user *sc, struct extctx_layout *extctx)
+{
+ int err = 0;
+ unsigned int magic, size;
+ struct _ctxinfo __user *info = (struct _ctxinfo __user *)&sc->sc_extcontext;
+
+ while(1) {
+ err |= __get_user(magic, &info->magic);
+ err |= __get_user(size, &info->size);
+ if (err)
+ return err;
+
+ switch (magic) {
+ case 0: /* END */
+ goto done;
+
+ case FPU_CTX_MAGIC:
+ if (size < (sizeof(struct _ctxinfo) +
+ sizeof(struct fpu_context)))
+ goto invalid;
+ extctx->fpu.addr = info;
+ break;
+
+ default:
+ goto invalid;
+ }
+
+ info = (struct _ctxinfo *)((char *)info + size);
+ }
+
+done:
+ return 0;
+
+invalid:
+ return -EINVAL;
+}
+
+static int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
+{
+ int i, err = 0;
+ struct extctx_layout extctx;
+
+ memset(&extctx, 0, sizeof(struct extctx_layout));
+
+ err = __get_user(extctx.flags, &sc->sc_flags);
+ if (err)
+ goto bad;
+
+ err = parse_extcontext(sc, &extctx);
+ if (err)
+ goto bad;
+
+ conditional_used_math(extctx.flags & SC_USED_FP);
+
+ /*
+ * The signal handler may have used FPU; give it up if the program
+ * doesn't want it following sigreturn.
+ */
+ if (!(extctx.flags & SC_USED_FP))
+ lose_fpu(0);
+
+ /* Always make any pending restarted system calls return -EINTR */
+ current->restart_block.fn = do_no_restart_syscall;
+
+ err |= __get_user(regs->csr_era, &sc->sc_pc);
+ for (i = 1; i < 32; i++)
+ err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
+
+ if (extctx.fpu.addr)
+ err |= protected_restore_fpu_context(&extctx);
+
+bad:
+ return err;
+}
+
+static unsigned int handle_flags(void)
+{
+ unsigned int flags = 0;
+
+ flags = used_math() ? SC_USED_FP : 0;
+
+ switch (current->thread.error_code) {
+ case 1:
+ flags |= SC_ADDRERR_RD;
+ break;
+ case 2:
+ flags |= SC_ADDRERR_WR;
+ break;
+ }
+
+ return flags;
+}
+
+static unsigned long extframe_alloc(struct extctx_layout *extctx,
+ struct _ctx_layout *layout,
+ size_t size, unsigned int align, unsigned long base)
+{
+ unsigned long new_base = base - size;
+
+ new_base = round_down(new_base, (align < 16 ? 16 : align));
+ new_base -= sizeof(struct _ctxinfo);
+
+ layout->addr = (void *)new_base;
+ layout->size = (unsigned int)(base - new_base);
+ extctx->size += layout->size;
+
+ return new_base;
+}
+
+static unsigned long setup_extcontext(struct extctx_layout *extctx, unsigned long sp)
+{
+ unsigned long new_sp = sp;
+
+ memset(extctx, 0, sizeof(struct extctx_layout));
+
+ extctx->flags = handle_flags();
+
+ /* Grow down, alloc "end" context info first. */
+ new_sp -= sizeof(struct _ctxinfo);
+ extctx->end.addr = (void *)new_sp;
+ extctx->end.size = (unsigned int)sizeof(struct _ctxinfo);
+ extctx->size += extctx->end.size;
+
+ if (extctx->flags & SC_USED_FP) {
+ if (cpu_has_fpu)
+ new_sp = extframe_alloc(extctx, &extctx->fpu,
+ sizeof(struct fpu_context), FPU_CTX_ALIGN, new_sp);
+ }
+
+ return new_sp;
+}
+
+void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
+ struct extctx_layout *extctx)
+{
+ unsigned long sp;
+
+ /* Default to using normal stack */
+ sp = regs->regs[3];
+
+ /*
+ * 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 - sizeof(struct rt_sigframe))))
+ return (void __user __force *)(-1UL);
+
+ sp = sigsp(sp, ksig);
+ sp = round_down(sp, 16);
+ sp = setup_extcontext(extctx, sp);
+ sp -= sizeof(struct rt_sigframe);
+
+ if (!IS_ALIGNED(sp, 16))
+ BUG();
+
+ return (void __user *)sp;
+}
+
+/*
+ * 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 extctx_layout extctx;
+ struct rt_sigframe __user *frame;
+
+ frame = get_sigframe(ksig, regs, &extctx);
+ if (!access_ok(frame, sizeof(*frame) + extctx.size))
+ 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, &extctx);
+ err |= __copy_to_user(&frame->rs_uctx.uc_sigmask, set, sizeof(*set));
+
+ if (err)
+ return -EFAULT;
+
+ /*
+ * Arguments to signal handler:
+ *
+ * a0 = signal number
+ * a1 = pointer to siginfo
+ * a2 = pointer to ucontext
+ *
+ * c0_era point to the signal handler, $r3 (sp) 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_era = (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_era, 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_era -= 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_era -= 4;
+ break;
+
+ case -ERESTART_RESTARTBLOCK:
+ regs->regs[4] = regs->orig_a0;
+ regs->regs[11] = __NR_restart_syscall;
+ regs->csr_era -= 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();
+}
--
2.27.0
