Messages in this thread Patch in this message | | | Date | Sat, 12 Sep 2015 14:04:30 +0800 | From | Wang YanQing <> | Subject | [PATCH] ARM: mm: avoid unneeded page protection fault for memory range with (VM_PFNMAP|VM_PFNWRITE) |
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Add L_PTE_DIRTY to PTEs for memory range with (VM_PFNMAP|VM_PFNWRITE), then we could avoid unneeded page protection fault in write access first time due to L_PTE_RDONLY.
There are no valid struct pages behind VM_PFNMAP range, so it make no sense to set L_PTE_DIRTY in page fault handler.
Signed-off-by: Wang YanQing <udknight@gmail.com> --- arch/arm/include/asm/mman.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 arch/arm/include/asm/mman.h
diff --git a/arch/arm/include/asm/mman.h b/arch/arm/include/asm/mman.h new file mode 100644 index 0000000..f59bbf3 --- /dev/null +++ b/arch/arm/include/asm/mman.h @@ -0,0 +1,21 @@ +/* + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#ifndef __ASM_ARM_MMAN_H +#define __ASM_ARM_MMAN_H + +#include <uapi/asm/mman.h> + +static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags) +{ + if ((vm_flags & (VM_PFNMAP|VM_WRITE)) == (VM_PFNMAP|VM_WRITE)) + return __pgprot(L_PTE_DIRTY); + else + return __pgprot(0); +} +#define arch_vm_get_page_prot(vm_flags) arch_vm_get_page_prot(vm_flags) + +#endif /* __ASM_ARM_MMAN_H */ -- 1.8.5.6.2.g3d8a54e.dirty
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