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x86/vdso: On timens page fault prefault also VVAR page

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As timens page has offsets to data on VVAR page VVAR is going
to be accessed shortly. Set it up with timens in one page fault
as optimization.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-26-dima@arista.com
This commit is contained in:
Dmitry Safonov 2019-11-12 01:27:14 +00:00 committed by Thomas Gleixner
parent af34ebeb86
commit e6b28ec65b
1 changed files with 16 additions and 1 deletions
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17
arch/x86/entry/vdso/vma.c
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@ -170,8 +170,23 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
* offset.
* See also the comment near timens_setup_vdso_data().
*/
if (timens_page)
if (timens_page) {
unsigned long addr;
vm_fault_t err;
/*
* Optimization: inside time namespace pre-fault
* VVAR page too. As on timens page there are only
* offsets for clocks on VVAR, it'll be faulted
* shortly by VDSO code.
*/
addr = vmf->address + (image->sym_timens_page - sym_offset);
err = vmf_insert_pfn(vma, addr, pfn);
if (unlikely(err & VM_FAULT_ERROR))
return err;
pfn = page_to_pfn(timens_page);
}
return vmf_insert_pfn(vma, vmf->address, pfn);
} else if (sym_offset == image->sym_pvclock_page) {