From: Dmitry Safonov <dima@arista.com>
To: dima@arista.com
Cc: 0x7f454c46@gmail.com, adrian@lisas.de, arnd@arndb.de,
avagin@gmail.com, avagin@openvz.org,
christian.brauner@ubuntu.com,
containers@lists.linux-foundation.org, criu@openvz.org,
ebiederm@xmission.com, gorcunov@openvz.org, hpa@zytor.com,
jannh@google.com, jdike@addtoit.com, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, luto@kernel.org, mingo@redhat.com,
oleg@redhat.com, shuah@kernel.org, tglx@linutronix.de,
vincenzo.frascino@arm.com, x86@kernel.org, xemul@virtuozzo.com
Subject: [PATCHv6 25/37] x86/vdso: Switch image on setns()/clone()
Date: Wed, 7 Aug 2019 01:27:28 +0100 [thread overview]
Message-ID: <20190807002728.19743-1-dima@arista.com> (raw)
In-Reply-To: <20190729215758.28405-26-dima@arista.com>
As it has been discussed on timens RFC, adding a new conditional branch
`if (inside_time_ns)` on VDSO for all processes is undesirable.
It will add a penalty for everybody as branch predictor may mispredict
the jump. Also there are instruction cache lines wasted on cmp/jmp.
Those effects of introducing time namespace are very much unwanted
having in mind how much work have been spent on micro-optimisation
vdso code.
Addressing those problems, there are two versions of VDSO's .so:
for host tasks (without any penalty) and for processes inside of time
namespace with clk_to_ns() that subtracts offsets from host's time.
Whenever a user does setns() or unshare(CLONE_TIMENS) followed
by clone(), change VDSO image in mm and zap VVAR/VDSO page tables.
They will be re-faulted with corresponding image and VVAR offsets.
Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
v5..v6 Change:
Rebased over current_is_single_threaded() change in the first patch.
arch/x86/entry/vdso/vma.c | 23 +++++++++++++++++++++++
arch/x86/include/asm/vdso.h | 1 +
kernel/time_namespace.c | 11 +++++++++++
3 files changed, 35 insertions(+)
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 8a8211fd4cfc..91cf5a5c8c9e 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -25,6 +25,7 @@
#include <asm/cpufeature.h>
#include <clocksource/hyperv_timer.h>
#include <asm/page.h>
+#include <asm/tlb.h>
#if defined(CONFIG_X86_64)
unsigned int __read_mostly vdso64_enabled = 1;
@@ -266,6 +267,28 @@ static const struct vm_special_mapping vvar_mapping = {
.mremap = vvar_mremap,
};
+#ifdef CONFIG_TIME_NS
+int vdso_join_timens(struct task_struct *task)
+{
+ struct mm_struct *mm = task->mm;
+ struct vm_area_struct *vma;
+
+ if (down_write_killable(&mm->mmap_sem))
+ return -EINTR;
+
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ unsigned long size = vma->vm_end - vma->vm_start;
+
+ if (vma_is_special_mapping(vma, &vvar_mapping) ||
+ vma_is_special_mapping(vma, &vdso_mapping))
+ zap_page_range(vma, vma->vm_start, size);
+ }
+
+ up_write(&mm->mmap_sem);
+ return 0;
+}
+#endif
+
/*
* Add vdso and vvar mappings to current process.
* @image - blob to map
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 03f468c63a24..ccf89dedd04f 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -45,6 +45,7 @@ extern struct vdso_image vdso_image_32;
extern void __init init_vdso_image(struct vdso_image *image);
extern int map_vdso_once(const struct vdso_image *image, unsigned long addr);
+extern int vdso_join_timens(struct task_struct *task);
#endif /* __ASSEMBLER__ */
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
index cdfa1b75bd0d..2e7e0af44f04 100644
--- a/kernel/time_namespace.c
+++ b/kernel/time_namespace.c
@@ -15,6 +15,7 @@
#include <linux/cred.h>
#include <linux/err.h>
#include <linux/mm.h>
+#include <asm/vdso.h>
ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
struct timens_offsets *ns_offsets)
@@ -199,6 +200,7 @@ static void timens_put(struct ns_common *ns)
static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
{
struct time_namespace *ns = to_time_ns(new);
+ int ret;
if (!current_is_single_threaded())
return -EUSERS;
@@ -207,6 +209,10 @@ static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
!ns_capable(current_user_ns(), CAP_SYS_ADMIN))
return -EPERM;
+ ret = vdso_join_timens(current);
+ if (ret)
+ return ret;
+
get_time_ns(ns);
get_time_ns(ns);
put_time_ns(nsproxy->time_ns);
@@ -221,10 +227,15 @@ int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
{
struct ns_common *nsc = &nsproxy->time_ns_for_children->ns;
struct time_namespace *ns = to_time_ns(nsc);
+ int ret;
if (nsproxy->time_ns == nsproxy->time_ns_for_children)
return 0;
+ ret = vdso_join_timens(tsk);
+ if (ret)
+ return ret;
+
get_time_ns(ns);
put_time_ns(nsproxy->time_ns);
nsproxy->time_ns = ns;
--
2.22.0
next prev parent reply other threads:[~2019-08-07 0:27 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-29 21:56 [PATCHv5 00/37] kernel: Introduce Time Namespace Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 01/37] ns: " Dmitry Safonov
2019-08-01 5:29 ` Andy Lutomirski
2019-08-01 23:46 ` Dmitry Safonov
2019-08-07 0:24 ` [PATCHv6 " Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 02/37] timens: Add timens_offsets Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 03/37] posix-clocks: Rename the clock_get() into clock_get_timespec() Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 04/37] posix-clocks: Rename *_clock_get() functions into *_clock_get_timespec() Dmitry Safonov
2019-08-07 6:01 ` Thomas Gleixner
2019-07-29 21:56 ` [PATCHv5 05/37] alarmtimer: Rename gettime() callback to get_ktime() Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 06/37] alarmtimer: Provide get_timespec() callback Dmitry Safonov
2019-08-07 6:04 ` Thomas Gleixner
2019-08-08 6:18 ` Andrei Vagin
2019-07-29 21:56 ` [PATCHv5 07/37] posix-clocks: Introduce clock_get_ktime() callback Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 08/37] posix-timers: Use clock_get_ktime() in common_timer_get() Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 09/37] posix-clocks: Introduce CLOCK_MONOTONIC time namespace offsets Dmitry Safonov
2019-08-07 6:07 ` Thomas Gleixner
2019-07-29 21:56 ` [PATCHv5 10/37] posix-clocks: Introduce CLOCK_BOOTTIME time namespace offset Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 11/37] kernel: Add do_timens_ktime_to_host() helper Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 12/37] timerfd: Make timerfd_settime() time namespace aware Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 13/37] posix-timers: Make timer_settime() " Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 14/37] alarmtimer: Make nanosleep " Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 15/37] hrtimers: Prepare hrtimer_nanosleep() for time namespaces Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 16/37] posix-timers: Make clock_nanosleep() time namespace aware Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 17/37] fd/proc: Respect boottime inside time namespace for /proc/uptime Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 18/37] x86/vdso2c: Correct err messages on file opening Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 19/37] x86/vdso2c: Convert iterator to unsigned Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 20/37] x86/vdso/Makefile: Add vobjs32 Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 21/37] x86/vdso: Restrict splitting VVAR VMA Dmitry Safonov
2019-08-01 5:23 ` Andy Lutomirski
2019-07-29 21:57 ` [PATCHv5 22/37] x86/vdso: Rename vdso_image {.data=>.text} Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 23/37] x86/vdso: Add offsets page in vvar Dmitry Safonov
2019-08-01 5:22 ` Andy Lutomirski
2019-07-29 21:57 ` [PATCHv5 24/37] x86/vdso: Allocate timens vdso Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 25/37] x86/vdso: Switch image on setns()/clone() Dmitry Safonov
2019-08-01 5:34 ` Andy Lutomirski
2019-08-01 6:09 ` hpa
2019-08-01 21:39 ` Andy Lutomirski
2019-08-07 0:27 ` Dmitry Safonov [this message]
2019-07-29 21:57 ` [PATCHv5 26/37] vdso: Introduce vdso_static_branch_unlikely() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 27/37] x86/vdso2c: Process jump tables Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 28/37] x86/vdso: Enable static branches for the timens vdso Dmitry Safonov
2019-08-01 5:21 ` Andy Lutomirski
2019-08-01 6:48 ` Thomas Gleixner
2019-07-29 21:57 ` [PATCHv5 29/37] posix-clocks: Add align for timens_offsets Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 30/37] fs/proc: Introduce /proc/pid/timens_offsets Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 31/37] selftest/timens: Add Time Namespace test for supported clocks Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 32/37] selftest/timens: Add a test for timerfd Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 33/37] selftest/timens: Add a test for clock_nanosleep() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 34/37] selftest/timens: Add procfs selftest Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 35/37] selftest/timens: Add timer offsets test Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 36/37] selftests/timens: Add a simple perf test for clock_gettime() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 37/37] selftest/timens: Check that a right vdso is mapped after fork and exec Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 00/37] kernel: Introduce Time Namespace Dmitry Safonov
2019-07-29 22:07 ` Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 01/37] ns: " Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 02/37] timens: Add timens_offsets Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 03/37] posix-clocks: Rename the clock_get() into clock_get_timespec() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 04/37] posix-clocks: Rename *_clock_get() functions into *_clock_get_timespec() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 05/37] alarmtimer: Rename gettime() callback to get_ktime() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 06/37] alarmtimer: Provide get_timespec() callback Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 07/37] posix-clocks: Introduce clock_get_ktime() callback Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 08/37] posix-timers: Use clock_get_ktime() in common_timer_get() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 09/37] posix-clocks: Introduce CLOCK_MONOTONIC time namespace offsets Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 10/37] posix-clocks: Introduce CLOCK_BOOTTIME time namespace offset Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 11/37] kernel: Add do_timens_ktime_to_host() helper Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 12/37] timerfd: Make timerfd_settime() time namespace aware Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 13/37] posix-timers: Make timer_settime() " Dmitry Safonov
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