diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2018-09-17 16:29:13 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-09-27 20:39:38 +0200 |
| commit | 69c31e69df3d2efc4ad7f53d500fdd920d3865a4 (patch) | |
| tree | 0615952a93400f07f1529dcb3d063f5dc4177a11 /arch/x86/mm | |
| parent | 5c280cf6081ff99078e28b51172d78359f194fd9 (diff) | |
x86/mm/cpa: Avoid static protection checks on unmap
If the new pgprot has the PRESENT bit cleared, then conflicts vs. RW/NX are
completely irrelevant.
Before:
1G pages checked: 2
1G pages sameprot: 0
1G pages preserved: 0
2M pages checked: 540
2M pages sameprot: 466
2M pages preserved: 47
4K pages checked: 800770
4K pages set-checked: 7668
After:
1G pages checked: 2
1G pages sameprot: 0
1G pages preserved: 0
2M pages checked: 540
2M pages sameprot: 466
2M pages preserved: 47
4K pages checked: 800709
4K pages set-checked: 7668
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Bin Yang <bin.yang@intel.com>
Cc: Mark Gross <mark.gross@intel.com>
Link: https://lkml.kernel.org/r/20180917143546.245849757@linutronix.de
Diffstat (limited to 'arch/x86/mm')
| -rw-r--r-- | arch/x86/mm/pageattr.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index cdf52eb86f3a..8f9083eb21ac 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -526,6 +526,13 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long start, pgprotval_t forbidden, res; unsigned long end; + /* + * There is no point in checking RW/NX conflicts when the requested + * mapping is setting the page !PRESENT. + */ + if (!(pgprot_val(prot) & _PAGE_PRESENT)) + return prot; + /* Operate on the virtual address */ end = start + npg * PAGE_SIZE - 1; |