From 4763ed4d45522b876c97e1f7f4b659d211f75571 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Fri, 13 Nov 2009 15:28:16 -0800 Subject: x86, mm: Clean up and simplify NX enablement The 32- and 64-bit code used very different mechanisms for enabling NX, but even the 32-bit code was enabling NX in head_32.S if it is available. Furthermore, we had a bewildering collection of tests for the available of NX. This patch: a) merges the 32-bit set_nx() and the 64-bit check_efer() function into a single x86_configure_nx() function. EFER control is left to the head code. b) eliminates the nx_enabled variable entirely. Things that need to test for NX enablement can verify __supported_pte_mask directly, and cpu_has_nx gives the supported status of NX. Signed-off-by: H. Peter Anvin Cc: Tejun Heo Cc: Brian Gerst Cc: Yinghai Lu Cc: Pekka Enberg Cc: Vegard Nossum Cc: Jeremy Fitzhardinge Cc: Chris Wright LKML-Reference: <1258154897-6770-5-git-send-email-hpa@zytor.com> Acked-by: Kees Cook --- arch/x86/mm/init.c | 4 ++-- arch/x86/mm/setup_nx.c | 43 ++++++------------------------------------- 2 files changed, 8 insertions(+), 39 deletions(-) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 73ffd55..27ec2c2 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -146,8 +146,8 @@ unsigned long __init_refok init_memory_mapping(unsigned long start, use_gbpages = direct_gbpages; #endif - set_nx(); - if (nx_enabled) + /* XXX: replace this with Kees' improved messages */ + if (__supported_pte_mask & _PAGE_NX) printk(KERN_INFO "NX (Execute Disable) protection: active\n"); /* Enable PSE if available */ diff --git a/arch/x86/mm/setup_nx.c b/arch/x86/mm/setup_nx.c index 513d8ed..355818b 100644 --- a/arch/x86/mm/setup_nx.c +++ b/arch/x86/mm/setup_nx.c @@ -3,10 +3,8 @@ #include #include +#include -int nx_enabled; - -#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE) static int disable_nx __cpuinitdata; /* @@ -22,48 +20,19 @@ static int __init noexec_setup(char *str) if (!str) return -EINVAL; if (!strncmp(str, "on", 2)) { - __supported_pte_mask |= _PAGE_NX; disable_nx = 0; } else if (!strncmp(str, "off", 3)) { disable_nx = 1; - __supported_pte_mask &= ~_PAGE_NX; } + x86_configure_nx(); return 0; } early_param("noexec", noexec_setup); -#endif - -#ifdef CONFIG_X86_PAE -void __init set_nx(void) -{ - unsigned int v[4], l, h; - - if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) { - cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]); - - if ((v[3] & (1 << 20)) && !disable_nx) { - rdmsr(MSR_EFER, l, h); - l |= EFER_NX; - wrmsr(MSR_EFER, l, h); - nx_enabled = 1; - __supported_pte_mask |= _PAGE_NX; - } - } -} -#else -void set_nx(void) -{ -} -#endif -#ifdef CONFIG_X86_64 -void __cpuinit check_efer(void) +void __cpuinit x86_configure_nx(void) { - unsigned long efer; - - rdmsrl(MSR_EFER, efer); - if (!(efer & EFER_NX) || disable_nx) + if (cpu_has_nx && !disable_nx) + __supported_pte_mask |= _PAGE_NX; + else __supported_pte_mask &= ~_PAGE_NX; } -#endif - -- cgit v1.1