diff options
| author | H. Peter Anvin <hpa@zytor.com> | 2009-11-13 15:28:16 -0800 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2009-11-16 13:44:59 -0800 |
| commit | 4763ed4d45522b876c97e1f7f4b659d211f75571 (patch) | |
| tree | ae053500de9f1c374e4b7f34d8f21d45a5b961d2 /arch/x86/mm | |
| parent | 583140afb989f24d115e80be5c91e503b58ccfc0 (diff) | |
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 <hpa@zytor.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Chris Wright <chrisw@sous-sol.org>
LKML-Reference: <1258154897-6770-5-git-send-email-hpa@zytor.com>
Acked-by: Kees Cook <kees.cook@canonical.com>
Diffstat (limited to 'arch/x86/mm')
| -rw-r--r-- | arch/x86/mm/init.c | 4 | ||||
| -rw-r--r-- | arch/x86/mm/setup_nx.c | 43 |
2 files changed, 8 insertions, 39 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 73ffd5536f6..27ec2c23fd4 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 513d8ed5d2e..355818b087b 100644 --- a/arch/x86/mm/setup_nx.c +++ b/arch/x86/mm/setup_nx.c @@ -3,10 +3,8 @@ #include <linux/init.h> #include <asm/pgtable.h> +#include <asm/proto.h> -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 - |