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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2017-07-17 01:59:51 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-07-21 10:05:18 +0200 |
| commit | 44b04912fa72489d403738f39e1c782614b7ae7c (patch) | |
| tree | 460fe18da21058de8080c90500fdc688d59902d8 /arch/x86/include/asm/processor.h | |
| parent | e8f01a8dad7cdf9ddaa792451733a45ab5d385af (diff) | |
| download | lwn-44b04912fa72489d403738f39e1c782614b7ae7c.tar.gz lwn-44b04912fa72489d403738f39e1c782614b7ae7c.zip | |
x86/mpx: Do not allow MPX if we have mappings above 47-bit
MPX (without MAWA extension) cannot handle addresses above 47 bits, so we
need to make sure that MPX cannot be enabled if we already have a VMA above
the boundary and forbid creating such VMAs once MPX is enabled.
The patch implements mpx_unmapped_area_check() which is called from all
variants of get_unmapped_area() to check if the requested address fits
mpx.
On enabling MPX, we check if we already have any vma above 47-bit
boundary and forbit the enabling if we do.
As long as DEFAULT_MAP_WINDOW is equal to TASK_SIZE_MAX, the change is
nop. It will change when we allow userspace to have mappings above
47-bits.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170716225954.74185-6-kirill.shutemov@linux.intel.com
[ Readability edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/processor.h')
| -rw-r--r-- | arch/x86/include/asm/processor.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 973709d2938f..c8d59fcc5665 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -809,6 +809,7 @@ static inline void spin_lock_prefetch(const void *x) #define IA32_PAGE_OFFSET PAGE_OFFSET #define TASK_SIZE PAGE_OFFSET #define TASK_SIZE_MAX TASK_SIZE +#define DEFAULT_MAP_WINDOW TASK_SIZE #define STACK_TOP TASK_SIZE #define STACK_TOP_MAX STACK_TOP @@ -850,6 +851,8 @@ static inline void spin_lock_prefetch(const void *x) */ #define TASK_SIZE_MAX ((1UL << 47) - PAGE_SIZE) +#define DEFAULT_MAP_WINDOW TASK_SIZE_MAX + /* This decides where the kernel will search for a free chunk of vm * space during mmap's. */ |