add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/arch/arm64/kernel/signal.c
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..
@@ -1,20 +1,9 @@
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+// SPDX-License-Identifier: GPL-2.0-only
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 /*
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  * Based on arch/arm/kernel/signal.c
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  *
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  * Copyright (C) 1995-2009 Russell King
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  * Copyright (C) 2012 ARM Ltd.
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- *
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- * This program is free software; you can redistribute it and/or modify
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- * it under the terms of the GNU General Public License version 2 as
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- * published by the Free Software Foundation.
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- *
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- * This program is distributed in the hope that it will be useful,
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- * but WITHOUT ANY WARRANTY; without even the implied warranty of
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- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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- * GNU General Public License for more details.
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- *
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- * You should have received a copy of the GNU General Public License
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- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
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  */
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8
 
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 #include <linux/cache.h>
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..
@@ -40,6 +29,7 @@
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 #include <asm/unistd.h>
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 #include <asm/fpsimd.h>
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 #include <asm/ptrace.h>
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+#include <asm/syscall.h>
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 #include <asm/signal32.h>
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 #include <asm/traps.h>
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 #include <asm/vdso.h>
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..
@@ -255,7 +245,8 @@
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 	if (vq) {
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 		/*
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 		 * This assumes that the SVE state has already been saved to
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-		 * the task struct by calling preserve_fpsimd_context().
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+		 * the task struct by calling the function
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+		 * fpsimd_signal_preserve_current_state().
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 		 */
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 		err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
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 				      current->thread.sve_state,
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@@ -296,11 +287,6 @@
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 	 */
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 	fpsimd_flush_task_state(current);
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-	barrier();
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-	/* From now, fpsimd_thread_switch() won't clear TIF_FOREIGN_FPSTATE */
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-
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-	set_thread_flag(TIF_FOREIGN_FPSTATE);
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-	barrier();
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 	/* From now, fpsimd_thread_switch() won't touch thread.sve_state */
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 	sve_alloc(current);
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@@ -387,6 +373,8 @@
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 			goto done;
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 		case FPSIMD_MAGIC:
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+			if (!system_supports_fpsimd())
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+				goto invalid;
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 			if (user->fpsimd)
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 				goto invalid;
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..
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@@ -470,7 +458,7 @@
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 			offset = 0;
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 			limit = extra_size;
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-			if (!access_ok(VERIFY_READ, base, limit))
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+			if (!access_ok(base, limit))
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 				goto invalid;
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 			continue;
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@@ -522,7 +510,7 @@
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 	if (err == 0)
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 		err = parse_user_sigframe(&user, sf);
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-	if (err == 0) {
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+	if (err == 0 && system_supports_fpsimd()) {
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 		if (!user.fpsimd)
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 			return -EINVAL;
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@@ -556,7 +544,7 @@
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 	frame = (struct rt_sigframe __user *)regs->sp;
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-	if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
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+	if (!access_ok(frame, sizeof (*frame)))
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 		goto badframe;
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 	if (restore_sigframe(regs, frame))
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@@ -584,10 +572,12 @@
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 {
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 	int err;
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-	err = sigframe_alloc(user, &user->fpsimd_offset,
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-			     sizeof(struct fpsimd_context));
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-	if (err)
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-		return err;
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+	if (system_supports_fpsimd()) {
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+		err = sigframe_alloc(user, &user->fpsimd_offset,
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+				     sizeof(struct fpsimd_context));
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+		if (err)
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+			return err;
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+	}
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 	/* fault information, if valid */
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 	if (add_all || current->thread.fault_code) {
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@@ -639,7 +629,7 @@
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629
 
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 	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
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-	if (err == 0) {
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+	if (err == 0 && system_supports_fpsimd()) {
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 		struct fpsimd_context __user *fpsimd_ctx =
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 			apply_user_offset(user, user->fpsimd_offset);
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 		err |= preserve_fpsimd_context(fpsimd_ctx);
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@@ -730,7 +720,7 @@
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 	/*
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 	 * Check that we can actually write to the signal frame.
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 	 */
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-	if (!access_ok(VERIFY_WRITE, user->sigframe, sp_top - sp))
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+	if (!access_ok(user->sigframe, sp_top - sp))
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 		return -EFAULT;
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 	return 0;
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@@ -745,6 +735,25 @@
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 	regs->sp = (unsigned long)user->sigframe;
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 	regs->regs[29] = (unsigned long)&user->next_frame->fp;
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 	regs->pc = (unsigned long)ka->sa.sa_handler;
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+
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+	/*
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+	 * Signal delivery is a (wacky) indirect function call in
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+	 * userspace, so simulate the same setting of BTYPE as a BLR
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+	 * <register containing the signal handler entry point>.
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+	 * Signal delivery to a location in a PROT_BTI guarded page
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+	 * that is not a function entry point will now trigger a
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+	 * SIGILL in userspace.
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+	 *
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+	 * If the signal handler entry point is not in a PROT_BTI
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+	 * guarded page, this is harmless.
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+	 */
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+	if (system_supports_bti()) {
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+		regs->pstate &= ~PSR_BTYPE_MASK;
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+		regs->pstate |= PSR_BTYPE_C;
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+	}
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+
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+	/* TCO (Tag Check Override) always cleared for signal handlers */
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+	regs->pstate &= ~PSR_TCO_BIT;
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 	if (ka->sa.sa_flags & SA_RESTORER)
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 		sigtramp = ka->sa.sa_restorer;
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@@ -884,7 +893,7 @@
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 		     retval == -ERESTART_RESTARTBLOCK ||
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 		     (retval == -ERESTARTSYS &&
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 		      !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
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-			regs->regs[0] = -EINTR;
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+			syscall_set_return_value(current, regs, -EINTR, 0);
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 			regs->pc = continue_addr;
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 		}
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@@ -908,18 +917,11 @@
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 asmlinkage void do_notify_resume(struct pt_regs *regs,
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 				 unsigned long thread_flags)
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 {
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-	/*
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-	 * The assembly code enters us with IRQs off, but it hasn't
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-	 * informed the tracing code of that for efficiency reasons.
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-	 * Update the trace code with the current status.
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-	 */
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-	trace_hardirqs_off();
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-
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 	do {
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 		/* Check valid user FS if needed */
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 		addr_limit_user_check();
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-		if (thread_flags & _TIF_NEED_RESCHED_MASK) {
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+		if (thread_flags & _TIF_NEED_RESCHED) {
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 			/* Unmask Debug and SError for the next task */
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 			local_daif_restore(DAIF_PROCCTX_NOIRQ);
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..
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@@ -930,11 +932,16 @@
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 			if (thread_flags & _TIF_UPROBE)
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 				uprobe_notify_resume(regs);
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-			if (thread_flags & _TIF_SIGPENDING)
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+			if (thread_flags & _TIF_MTE_ASYNC_FAULT) {
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+				clear_thread_flag(TIF_MTE_ASYNC_FAULT);
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+				send_sig_fault(SIGSEGV, SEGV_MTEAERR,
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+					       (void __user *)NULL, current);
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+			}
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+
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+			if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
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 				do_signal(regs);
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 			if (thread_flags & _TIF_NOTIFY_RESUME) {
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-				clear_thread_flag(TIF_NOTIFY_RESUME);
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 				tracehook_notify_resume(regs);
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 				rseq_handle_notify_resume(NULL, regs);
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 			}