| From | Dmitry Safonov <> | Subject | [PATCHv8 25/34] x86/vdso: On timens page fault prefault also VVAR page | Date | Tue, 12 Nov 2019 01:27:14 +0000 |
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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> --- arch/x86/entry/vdso/vma.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index f6e13ab29d94..d6cb8a16f368 100644 --- a/arch/x86/entry/vdso/vma.c +++ b/arch/x86/entry/vdso/vma.c @@ -169,8 +169,23 @@ 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) { -- 2.24.0
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