linux-kernel - [tip: timers/core] x86/vdso: On timens page fault prefault also VVAR page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 14 Jan 2020 13:02:15 -0000
From:   "tip-bot2 for Dmitry Safonov" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Andrei Vagin <avagin@...il.com>,
        Dmitry Safonov <dima@...sta.com>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: timers/core] x86/vdso: On timens page fault prefault also VVAR page

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     e6b28ec65b6d433624a2c290073bc356c4fce914
Gitweb:        https://git.kernel.org/tip/e6b28ec65b6d433624a2c290073bc356c4fce914
Author:        Dmitry Safonov <dima@...sta.com>
AuthorDate:    Tue, 12 Nov 2019 01:27:14 
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Tue, 14 Jan 2020 12:20:59 +01:00

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

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@...utronix.de>
Co-developed-by: Andrei Vagin <avagin@...il.com>
Signed-off-by: Andrei Vagin <avagin@...il.com>
Signed-off-by: Dmitry Safonov <dima@...sta.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-26-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 e5f3361..d2fd8a5 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -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) {