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From: Dmitry Safonov <dima@arista.com>
To: linux-kernel@vger.kernel.org
Cc: Dmitry Safonov <0x7f454c46@gmail.com>,
	Dmitry Safonov <dima@arista.com>, Adrian Reber <adrian@lisas.de>,
	Andrei Vagin <avagin@openvz.org>,
	Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Cyrill Gorcunov <gorcunov@openvz.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Jann Horn <jannh@google.com>, Jeff Dike <jdike@addtoit.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Pavel Emelyanov <xemul@virtuozzo.com>,
	Shuah Khan <shuah@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	containers@lists.linux-foundation.org, criu@openvz.org,
	linux-api@vger.kernel.org, x86@kernel.org
Subject: [PATCHv8 19/34] x86/vdso: Restrict splitting VVAR VMA
Date: Tue, 12 Nov 2019 01:27:08 +0000
Message-ID: <20191112012724.250792-20-dima@arista.com> (raw)
In-Reply-To: <20191112012724.250792-1-dima@arista.com>

Forbid splitting VVAR resulting in stricter ABI and reducing amount
of corner-cases to consider while working further on VDSO.

As offset from timens to VVAR page is computed compile-time,
the pages in VVAR should stay together and not being partically
mremap()'ed.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/entry/vdso/vma.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index f5937742b290..000db8282cc8 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -84,6 +84,18 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
 	return 0;
 }
 
+static int vvar_mremap(const struct vm_special_mapping *sm,
+		struct vm_area_struct *new_vma)
+{
+	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+	const struct vdso_image *image = new_vma->vm_mm->context.vdso_image;
+
+	if (new_size != -image->sym_vvar_start)
+		return -EINVAL;
+
+	return 0;
+}
+
 static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		      struct vm_area_struct *vma, struct vm_fault *vmf)
 {
@@ -136,6 +148,7 @@ static const struct vm_special_mapping vdso_mapping = {
 static const struct vm_special_mapping vvar_mapping = {
 	.name = "[vvar]",
 	.fault = vvar_fault,
+	.mremap = vvar_mremap,
 };
 
 /*
-- 
2.24.0

  parent reply index

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-12  1:26 [PATCHv8 00/34] kernel: Introduce Time Namespace Dmitry Safonov
2019-11-12  1:26 ` [PATCHv8 01/34] lib/vdso: Add unlikely() hint into vdso_read_begin() Dmitry Safonov
2019-11-12  1:26 ` [PATCHv8 02/34] lib/vdso: make do_hres and do_coarse as __always_inline Dmitry Safonov
     [not found]   ` <20191112012724.250792-3-dima-nzgTgzXrdUbQT0dZR+AlfA@public.gmane.org>
2020-01-10  9:45     ` Vincenzo Frascino
2020-01-10 11:42       ` Thomas Gleixner
     [not found]         ` <878smfa66i.fsf-ecDvlHI5BZPZikZi3RtOZ1XZhhPuCNm+@public.gmane.org>
2020-01-10 11:47           ` Vincenzo Frascino
2020-01-10 12:02             ` Thomas Gleixner
     [not found]               ` <875zhja59q.fsf-ecDvlHI5BZPZikZi3RtOZ1XZhhPuCNm+@public.gmane.org>
2020-01-10 12:18                 ` Vincenzo Frascino
2020-01-13  5:27               ` Andrei Vagin
2019-11-12  1:26 ` [PATCHv8 03/34] ns: Introduce Time Namespace Dmitry Safonov
     [not found]   ` <20191112012724.250792-4-dima-nzgTgzXrdUbQT0dZR+AlfA@public.gmane.org>
2020-01-27 14:12     ` Dmitry Vyukov
     [not found]       ` <CACT4Y+b70bRRS2XD3yxhBoy4E-LFy_K3wMrjeuPmiEvaPe_c2Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-01-27 14:19         ` Dmitry Safonov
2020-02-17 14:20   ` Time Namespaces: CLONE_NEWTIME and clone3()? Michael Kerrisk
2020-02-17 14:59     ` Christian Brauner
2020-02-17 21:47       ` Michael Kerrisk (man-pages)
2020-02-17 23:03         ` Christian Brauner
2020-02-17 23:29           ` Thomas Gleixner
2020-02-18  2:37             ` Eric W. Biederman
2020-02-18 17:11           ` Adrian Reber
2020-02-18 17:26             ` Christian Brauner
2019-11-12  1:26 ` [PATCHv8 04/34] time: Add timens_offsets to be used for tasks in timens Dmitry Safonov
2019-11-12  1:26 ` [PATCHv8 05/34] posix-clocks: Rename the clock_get() callback to clock_get_timespec() Dmitry Safonov
2019-11-12  1:26 ` [PATCHv8 06/34] posix-clocks: Rename .clock_get_timespec() callbacks accordingly Dmitry Safonov
2019-11-12  1:26 ` [PATCHv8 07/34] alarmtimer: Rename gettime() callback to get_ktime() Dmitry Safonov
2019-11-12  1:26 ` [PATCHv8 08/34] alarmtimer: Provide get_timespec() callback Dmitry Safonov
2019-11-12  1:26 ` [PATCHv8 09/34] posix-clocks: Introduce clock_get_ktime() callback Dmitry Safonov
2019-11-12  1:26 ` [PATCHv8 10/34] posix-timers: Use clock_get_ktime() in common_timer_get() Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 11/34] posix-clocks: Wire up clock_gettime() with timens offsets Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 12/34] kernel: Add do_timens_ktime_to_host() helper Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 13/34] timerfd: Make timerfd_settime() time namespace aware Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 14/34] posix-timers: Make timer_settime() " Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 15/34] alarmtimer: Make nanosleep " Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 16/34] hrtimers: Prepare hrtimer_nanosleep() for time namespaces Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 17/34] posix-timers: Make clock_nanosleep() time namespace aware Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 18/34] fs/proc: Respect boottime inside time namespace for /proc/uptime Dmitry Safonov
2019-11-12  1:27 ` Dmitry Safonov [this message]
2019-11-12  1:27 ` [PATCHv8 20/34] lib/vdso: Prepare for time namespace support Dmitry Safonov
     [not found]   ` <20191112012724.250792-21-dima-nzgTgzXrdUbQT0dZR+AlfA@public.gmane.org>
2020-01-12 10:32     ` Thomas Gleixner
2019-11-12  1:27 ` [PATCHv8 21/34] x86/vdso: Provide vdso_data offset on vvar_page Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 22/34] x86/vdso: Add timens page Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 23/34] time: Allocate per-timens vvar page Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 24/34] x86/vdso: Handle faults on timens page Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 25/34] x86/vdso: On timens page fault prefault also VVAR page Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 26/34] x86/vdso: Zap vvar pages on switch a time namspace Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 27/34] fs/proc: Introduce /proc/pid/timens_offsets Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 28/34] selftests/timens: Add Time Namespace test for supported clocks Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 29/34] selftests/timens: Add a test for timerfd Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 30/34] selftests/timens: Add a test for clock_nanosleep() Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 31/34] selftests/timens: Add procfs selftest Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 32/34] selftests/timens: Add timer offsets test Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 33/34] selftests/timens: Add a simple perf test for clock_gettime() Dmitry Safonov
2019-11-12  1:27 ` [PATCHv8 34/34] selftests/timens: Check for right timens offsets after fork and exec Dmitry Safonov
2019-11-21 18:05 ` [PATCHv8 00/34] kernel: Introduce Time Namespace Andrei Vagin
2019-12-11 20:38   ` Dmitry Safonov
2020-01-09 21:09     ` Thomas Gleixner
2020-01-10  9:52       ` Vincenzo Frascino

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