// SPDX-License-Identifier: GPL-2.0
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#include <linux/spinlock.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/pgtable.h>
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#include <asm/proto.h>
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#include <asm/cpufeature.h>
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static int disable_nx;
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/*
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* noexec = on|off
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*
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* Control non-executable mappings for processes.
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*
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* on Enable
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* off Disable
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*/
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static int __init noexec_setup(char *str)
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{
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if (!str)
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return -EINVAL;
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if (!strncmp(str, "on", 2)) {
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disable_nx = 0;
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} else if (!strncmp(str, "off", 3)) {
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disable_nx = 1;
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}
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x86_configure_nx();
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return 0;
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}
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early_param("noexec", noexec_setup);
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void x86_configure_nx(void)
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{
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if (boot_cpu_has(X86_FEATURE_NX) && !disable_nx)
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__supported_pte_mask |= _PAGE_NX;
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else
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__supported_pte_mask &= ~_PAGE_NX;
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}
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void __init x86_report_nx(void)
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{
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if (!boot_cpu_has(X86_FEATURE_NX)) {
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printk(KERN_NOTICE "Notice: NX (Execute Disable) protection "
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"missing in CPU!\n");
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} else {
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#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
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if (disable_nx) {
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printk(KERN_INFO "NX (Execute Disable) protection: "
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"disabled by kernel command line option\n");
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} else {
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printk(KERN_INFO "NX (Execute Disable) protection: "
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"active\n");
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}
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#else
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/* 32bit non-PAE kernel, NX cannot be used */
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printk(KERN_NOTICE "Notice: NX (Execute Disable) protection "
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"cannot be enabled: non-PAE kernel!\n");
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#endif
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}
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}
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