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2023-12-08 01573e231f18eb2d99162747186f59511f56b64d

 kernel/arch/x86/mm/pkeys.c
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@@ -1,15 +1,7 @@
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+// SPDX-License-Identifier: GPL-2.0-only
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 /*
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  * Intel Memory Protection Keys management
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  * Copyright (c) 2015, Intel Corporation.
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- *
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- * This program is free software; you can redistribute it and/or modify it
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- * under the terms and conditions of the GNU General Public License,
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- * version 2, as published by the Free Software Foundation.
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- *
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- * This program is distributed in the hope it will be useful, but WITHOUT
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- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
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- * more details.
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  */
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 #include <linux/debugfs.h>		/* debugfs_create_u32()		*/
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 #include <linux/mm_types.h>             /* mm_struct, vma, etc...       */
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@@ -18,6 +10,7 @@
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10
 
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 #include <asm/cpufeature.h>             /* boot_cpu_has, ...            */
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 #include <asm/mmu_context.h>            /* vma_pkey()                   */
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+#include <asm/fpu/internal.h>		/* init_fpstate			*/
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 int __execute_only_pkey(struct mm_struct *mm)
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 {
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@@ -39,17 +32,12 @@
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 	 * dance to set PKRU if we do not need to.  Check it
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 	 * first and assume that if the execute-only pkey is
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 	 * write-disabled that we do not have to set it
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-	 * ourselves.  We need preempt off so that nobody
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-	 * can make fpregs inactive.
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+	 * ourselves.
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 	 */
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-	preempt_disable();
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 	if (!need_to_set_mm_pkey &&
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-	    current->thread.fpu.initialized &&
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 	    !__pkru_allows_read(read_pkru(), execute_only_pkey)) {
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-		preempt_enable();
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 		return execute_only_pkey;
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 	}
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-	preempt_enable();
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 	/*
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 	 * Set up PKRU so that it denies access for everything
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@@ -75,7 +63,7 @@
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 static inline bool vma_is_pkey_exec_only(struct vm_area_struct *vma)
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 {
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 	/* Do this check first since the vm_flags should be hot */
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-	if ((vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)) != VM_EXEC)
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+	if ((vma->vm_flags & VM_ACCESS_FLAGS) != VM_EXEC)
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 		return false;
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 	if (vma_pkey(vma) != vma->vm_mm->context.execute_only_pkey)
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 		return false;
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@@ -147,13 +135,6 @@
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 {
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 	u32 init_pkru_value_snapshot = READ_ONCE(init_pkru_value);
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 	/*
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-	 * Any write to PKRU takes it out of the XSAVE 'init
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-	 * state' which increases context switch cost.  Avoid
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-	 * writing 0 when PKRU was already 0.
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-	 */
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-	if (!init_pkru_value_snapshot && !read_pkru())
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-		return;
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-	/*
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 	 * Override the PKRU state that came from 'init_fpstate'
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 	 * with the baseline from the process.
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 	 */
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@@ -173,6 +154,7 @@
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 static ssize_t init_pkru_write_file(struct file *file,
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 		 const char __user *user_buf, size_t count, loff_t *ppos)
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 {
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+	struct pkru_state *pk;
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 	char buf[32];
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 	ssize_t len;
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 	u32 new_init_pkru;
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@@ -195,6 +177,10 @@
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 		return -EINVAL;
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 	WRITE_ONCE(init_pkru_value, new_init_pkru);
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+	pk = get_xsave_addr(&init_fpstate.xsave, XFEATURE_PKRU);
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+	if (!pk)
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+		return -EINVAL;
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+	pk->pkru = new_init_pkru;
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 	return count;
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 }
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