From: Dmitry Safonov <dima@arista.com>
To: linux-kernel@vger.kernel.org
Cc: Dmitry Safonov <0x7f454c46@gmail.com>,
Andrei Vagin <avagin@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: [PATCHv5 28/37] x86/vdso: Enable static branches for the timens vdso
Date: Mon, 29 Jul 2019 22:57:10 +0100 [thread overview]
Message-ID: <20190729215758.28405-29-dima@arista.com> (raw)
In-Reply-To: <20190729215758.28405-1-dima@arista.com>
From: Andrei Vagin <avagin@gmail.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.
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.
The timens code in vdso looks like this:
if (timens_static_branch_unlikely()) {
clk_to_ns(clk, ts);
}
This static branch is disabled by default. And the code generated consist
of a single atomic 'no-op' instruction, in the straight-line code path.
Enable static branches in the timens vdso: the 'no-op' instruction
gets replaced with a 'jump' instruction to the out-of-line true branch.
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
arch/x86/entry/vdso/vma.c | 30 ++++++++++++++++++++++++------
arch/x86/kernel/jump_label.c | 14 ++++++++++++++
include/linux/jump_label.h | 8 ++++++++
init/Kconfig | 1 +
4 files changed, 47 insertions(+), 6 deletions(-)
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 91cf5a5c8c9e..1a3eb4656eb6 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -15,6 +15,7 @@
#include <linux/cpu.h>
#include <linux/ptrace.h>
#include <linux/time_namespace.h>
+#include <linux/jump_label.h>
#include <asm/pvclock.h>
#include <asm/vgtod.h>
#include <asm/proto.h>
@@ -31,20 +32,37 @@
unsigned int __read_mostly vdso64_enabled = 1;
#endif
-void __init init_vdso_image(struct vdso_image *image)
+#ifdef CONFIG_TIME_NS
+static __init void init_timens(struct vdso_image *image)
{
- BUG_ON(image->size % PAGE_SIZE != 0);
+ struct vdso_jump_entry *entries;
+ unsigned long entries_nr;
+
+ if (WARN_ON(image->jump_table == -1UL))
+ return;
- apply_alternatives((struct alt_instr *)(image->text + image->alt),
- (struct alt_instr *)(image->text + image->alt +
- image->alt_len));
-#ifdef CONFIG_TIME_NS
image->text_timens = vmalloc_32(image->size);
if (WARN_ON(image->text_timens == NULL))
return;
memcpy(image->text_timens, image->text, image->size);
+
+ entries = image->text_timens + image->jump_table;
+ entries_nr = image->jump_table_len / sizeof(struct vdso_jump_entry);
+ apply_vdso_jump_labels(entries, entries_nr);
+}
+#else
+static inline void init_timens(struct vdso_image *image) {}
#endif
+
+void __init init_vdso_image(struct vdso_image *image)
+{
+ BUG_ON(image->size % PAGE_SIZE != 0);
+
+ apply_alternatives((struct alt_instr *)(image->text + image->alt),
+ (struct alt_instr *)(image->text + image->alt +
+ image->alt_len));
+ init_timens(image);
}
struct linux_binprm;
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index 044053235302..7820ac61b688 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -24,6 +24,20 @@ union jump_code_union {
} __attribute__((packed));
};
+__init void apply_vdso_jump_labels(struct vdso_jump_entry *ent, unsigned long nr)
+{
+ while (nr--) {
+ void *code_addr = (void *)ent + ent->code;
+ union jump_code_union jmp;
+
+ jmp.jump = 0xe9; /* JMP rel32 */
+ jmp.offset = ent->target - ent->code - JUMP_LABEL_NOP_SIZE;
+ memcpy(code_addr, &jmp, JUMP_LABEL_NOP_SIZE);
+
+ ent++;
+ }
+}
+
static void bug_at(unsigned char *ip, int line)
{
/*
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 3526c0aee954..bb9d828ee49a 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -125,6 +125,11 @@ struct jump_entry {
long key; // key may be far away from the core kernel under KASLR
};
+struct vdso_jump_entry {
+ u16 code;
+ u16 target;
+};
+
static inline unsigned long jump_entry_code(const struct jump_entry *entry)
{
return (unsigned long)&entry->code + entry->code;
@@ -229,6 +234,9 @@ extern void static_key_enable(struct static_key *key);
extern void static_key_disable(struct static_key *key);
extern void static_key_enable_cpuslocked(struct static_key *key);
extern void static_key_disable_cpuslocked(struct static_key *key);
+extern void apply_vdso_jump_labels(struct vdso_jump_entry *ent,
+ unsigned long nr);
+
/*
* We should be using ATOMIC_INIT() for initializing .enabled, but
diff --git a/init/Kconfig b/init/Kconfig
index 9e40c07da4e1..be8bd41774f6 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1072,6 +1072,7 @@ config UTS_NS
config TIME_NS
bool "TIME namespace"
depends on ARCH_HAS_VDSO_TIME_NS
+ depends on JUMP_LABEL
default y
help
In this namespace boottime and monotonic clocks can be set.
--
2.22.0
next prev parent reply other threads:[~2019-07-29 21:58 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 ` [PATCHv6 " Dmitry Safonov
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 ` Dmitry Safonov [this message]
2019-08-01 5:21 ` [PATCHv5 28/37] x86/vdso: Enable static branches for the timens vdso 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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