1 files changed, 416 insertions, 0 deletions
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
new file mode 100644
index 000000000..e18c48cb6
--- /dev/null
+++ b/arch/arm64/kernel/signal.c
@@ -0,0 +1,416 @@
+/*
+ * Based on arch/arm/kernel/signal.c
+ *
+ * Copyright (C) 1995-2009 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/compat.h>
+#include <linux/errno.h>
+#include <linux/signal.h>
+#include <linux/personality.h>
+#include <linux/freezer.h>
+#include <linux/uaccess.h>
+#include <linux/tracehook.h>
+#include <linux/ratelimit.h>
+
+#include <asm/debug-monitors.h>
+#include <asm/elf.h>
+#include <asm/cacheflush.h>
+#include <asm/ucontext.h>
+#include <asm/unistd.h>
+#include <asm/fpsimd.h>
+#include <asm/signal32.h>
+#include <asm/vdso.h>
+
+/*
+ * Do a signal return; undo the signal stack. These are aligned to 128-bit.
+ */
+struct rt_sigframe {
+	struct siginfo info;
+	struct ucontext uc;
+	u64 fp;
+	u64 lr;
+};
+
+static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
+{
+	struct fpsimd_state *fpsimd = &current->thread.fpsimd_state;
+	int err;
+
+	/* dump the hardware registers to the fpsimd_state structure */
+	fpsimd_preserve_current_state();
+
+	/* copy the FP and status/control registers */
+	err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
+	__put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
+	__put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
+
+	/* copy the magic/size information */
+	__put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
+	__put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
+
+	return err ? -EFAULT : 0;
+}
+
+static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
+{
+	struct fpsimd_state fpsimd;
+	__u32 magic, size;
+	int err = 0;
+
+	/* check the magic/size information */
+	__get_user_error(magic, &ctx->head.magic, err);
+	__get_user_error(size, &ctx->head.size, err);
+	if (err)
+		return -EFAULT;
+	if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
+		return -EINVAL;
+
+	/* copy the FP and status/control registers */
+	err = __copy_from_user(fpsimd.vregs, ctx->vregs,
+			       sizeof(fpsimd.vregs));
+	__get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
+	__get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
+
+	/* load the hardware registers from the fpsimd_state structure */
+	if (!err)
+		fpsimd_update_current_state(&fpsimd);
+
+	return err ? -EFAULT : 0;
+}
+
+static int restore_sigframe(struct pt_regs *regs,
+			    struct rt_sigframe __user *sf)
+{
+	sigset_t set;
+	int i, err;
+	void *aux = sf->uc.uc_mcontext.__reserved;
+
+	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
+	if (err == 0)
+		set_current_blocked(&set);
+
+	for (i = 0; i < 31; i++)
+		__get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
+				 err);
+	__get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
+	__get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
+	__get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
+
+	/*
+	 * Avoid sys_rt_sigreturn() restarting.
+	 */
+	regs->syscallno = ~0UL;
+
+	err |= !valid_user_regs(&regs->user_regs);
+
+	if (err == 0) {
+		struct fpsimd_context *fpsimd_ctx =
+			container_of(aux, struct fpsimd_context, head);
+		err |= restore_fpsimd_context(fpsimd_ctx);
+	}
+
+	return err;
+}
+
+asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->restart_block.fn = do_no_restart_syscall;
+
+	/*
+	 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
+	 * be word aligned here.
+	 */
+	if (regs->sp & 15)
+		goto badframe;
+
+	frame = (struct rt_sigframe __user *)regs->sp;
+
+	if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
+		goto badframe;
+
+	if (restore_sigframe(regs, frame))
+		goto badframe;
+
+	if (restore_altstack(&frame->uc.uc_stack))
+		goto badframe;
+
+	return regs->regs[0];
+
+badframe:
+	if (show_unhandled_signals)
+		pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
+				    current->comm, task_pid_nr(current), __func__,
+				    regs->pc, regs->sp);
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+static int setup_sigframe(struct rt_sigframe __user *sf,
+			  struct pt_regs *regs, sigset_t *set)
+{
+	int i, err = 0;
+	void *aux = sf->uc.uc_mcontext.__reserved;
+	struct _aarch64_ctx *end;
+
+	/* set up the stack frame for unwinding */
+	__put_user_error(regs->regs[29], &sf->fp, err);
+	__put_user_error(regs->regs[30], &sf->lr, err);
+
+	for (i = 0; i < 31; i++)
+		__put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
+				 err);
+	__put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
+	__put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
+	__put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
+
+	__put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
+
+	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
+
+	if (err == 0) {
+		struct fpsimd_context *fpsimd_ctx =
+			container_of(aux, struct fpsimd_context, head);
+		err |= preserve_fpsimd_context(fpsimd_ctx);
+		aux += sizeof(*fpsimd_ctx);
+	}
+
+	/* fault information, if valid */
+	if (current->thread.fault_code) {
+		struct esr_context *esr_ctx =
+			container_of(aux, struct esr_context, head);
+		__put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
+		__put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
+		__put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
+		aux += sizeof(*esr_ctx);
+	}
+
+	/* set the "end" magic */
+	end = aux;
+	__put_user_error(0, &end->magic, err);
+	__put_user_error(0, &end->size, err);
+
+	return err;
+}
+
+static struct rt_sigframe __user *get_sigframe(struct ksignal *ksig,
+					       struct pt_regs *regs)
+{
+	unsigned long sp, sp_top;
+	struct rt_sigframe __user *frame;
+
+	sp = sp_top = sigsp(regs->sp, ksig);
+
+	sp = (sp - sizeof(struct rt_sigframe)) & ~15;
+	frame = (struct rt_sigframe __user *)sp;
+
+	/*
+	 * Check that we can actually write to the signal frame.
+	 */
+	if (!access_ok(VERIFY_WRITE, frame, sp_top - sp))
+		frame = NULL;
+
+	return frame;
+}
+
+static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
+			 void __user *frame, int usig)
+{
+	__sigrestore_t sigtramp;
+
+	regs->regs[0] = usig;
+	regs->sp = (unsigned long)frame;
+	regs->regs[29] = regs->sp + offsetof(struct rt_sigframe, fp);
+	regs->pc = (unsigned long)ka->sa.sa_handler;
+
+	if (ka->sa.sa_flags & SA_RESTORER)
+		sigtramp = ka->sa.sa_restorer;
+	else
+		sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
+
+	regs->regs[30] = (unsigned long)sigtramp;
+}
+
+static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
+			  struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame;
+	int err = 0;
+
+	frame = get_sigframe(ksig, regs);
+	if (!frame)
+		return 1;
+
+	__put_user_error(0, &frame->uc.uc_flags, err);
+	__put_user_error(NULL, &frame->uc.uc_link, err);
+
+	err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
+	err |= setup_sigframe(frame, regs, set);
+	if (err == 0) {
+		setup_return(regs, &ksig->ka, frame, usig);
+		if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+			err |= copy_siginfo_to_user(&frame->info, &ksig->info);
+			regs->regs[1] = (unsigned long)&frame->info;
+			regs->regs[2] = (unsigned long)&frame->uc;
+		}
+	}
+
+	return err;
+}
+
+static void setup_restart_syscall(struct pt_regs *regs)
+{
+	if (is_compat_task())
+		compat_setup_restart_syscall(regs);
+	else
+		regs->regs[8] = __NR_restart_syscall;
+}
+
+/*
+ * OK, we're invoking a handler
+ */
+static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
+{
+	struct task_struct *tsk = current;
+	sigset_t *oldset = sigmask_to_save();
+	int usig = ksig->sig;
+	int ret;
+
+	/*
+	 * Set up the stack frame
+	 */
+	if (is_compat_task()) {
+		if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+			ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
+		else
+			ret = compat_setup_frame(usig, ksig, oldset, regs);
+	} else {
+		ret = setup_rt_frame(usig, ksig, oldset, regs);
+	}
+
+	/*
+	 * Check that the resulting registers are actually sane.
+	 */
+	ret |= !valid_user_regs(&regs->user_regs);
+
+	/*
+	 * Fast forward the stepping logic so we step into the signal
+	 * handler.
+	 */
+	if (!ret)
+		user_fastforward_single_step(tsk);
+
+	signal_setup_done(ret, ksig, 0);
+}
+
+/*
+ * Note that 'init' is a special process: it doesn't get signals it doesn't
+ * want to handle. Thus you cannot kill init even with a SIGKILL even by
+ * mistake.
+ *
+ * Note that we go through the signals twice: once to check the signals that
+ * the kernel can handle, and then we build all the user-level signal handling
+ * stack-frames in one go after that.
+ */
+static void do_signal(struct pt_regs *regs)
+{
+	unsigned long continue_addr = 0, restart_addr = 0;
+	int retval = 0;
+	int syscall = (int)regs->syscallno;
+	struct ksignal ksig;
+
+	/*
+	 * If we were from a system call, check for system call restarting...
+	 */
+	if (syscall >= 0) {
+		continue_addr = regs->pc;
+		restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
+		retval = regs->regs[0];
+
+		/*
+		 * Avoid additional syscall restarting via ret_to_user.
+		 */
+		regs->syscallno = ~0UL;
+
+		/*
+		 * Prepare for system call restart. We do this here so that a
+		 * debugger will see the already changed PC.
+		 */
+		switch (retval) {
+		case -ERESTARTNOHAND:
+		case -ERESTARTSYS:
+		case -ERESTARTNOINTR:
+		case -ERESTART_RESTARTBLOCK:
+			regs->regs[0] = regs->orig_x0;
+			regs->pc = restart_addr;
+			break;
+		}
+	}
+
+	/*
+	 * Get the signal to deliver. When running under ptrace, at this point
+	 * the debugger may change all of our registers.
+	 */
+	if (get_signal(&ksig)) {
+		/*
+		 * Depending on the signal settings, we may need to revert the
+		 * decision to restart the system call, but skip this if a
+		 * debugger has chosen to restart at a different PC.
+		 */
+		if (regs->pc == restart_addr &&
+		    (retval == -ERESTARTNOHAND ||
+		     retval == -ERESTART_RESTARTBLOCK ||
+		     (retval == -ERESTARTSYS &&
+		      !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
+			regs->regs[0] = -EINTR;
+			regs->pc = continue_addr;
+		}
+
+		handle_signal(&ksig, regs);
+		return;
+	}
+
+	/*
+	 * Handle restarting a different system call. As above, if a debugger
+	 * has chosen to restart at a different PC, ignore the restart.
+	 */
+	if (syscall >= 0 && regs->pc == restart_addr) {
+		if (retval == -ERESTART_RESTARTBLOCK)
+			setup_restart_syscall(regs);
+		user_rewind_single_step(current);
+	}
+
+	restore_saved_sigmask();
+}
+
+asmlinkage void do_notify_resume(struct pt_regs *regs,
+				 unsigned int thread_flags)
+{
+	if (thread_flags & _TIF_SIGPENDING)
+		do_signal(regs);
+
+	if (thread_flags & _TIF_NOTIFY_RESUME) {
+		clear_thread_flag(TIF_NOTIFY_RESUME);
+		tracehook_notify_resume(regs);
+	}
+
+	if (thread_flags & _TIF_FOREIGN_FPSTATE)
+		fpsimd_restore_current_state();
+
+}