Commit Graph

33 Commits

Author SHA1 Message Date
Adrian Hunter
d2e58ab5cd vdso: Add vdso_data:: Max_cycles
Add vdso_data::max_cycles in preparation to use it to detect potential
multiplication overflow.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240325064023.2997-7-adrian.hunter@intel.com
2024-04-08 15:03:07 +02:00
Adrian Hunter
1beb35ec61 vdso, math64: Provide mul_u64_u32_add_u64_shr()
Provide mul_u64_u32_add_u64_shr() which is a calculation that will be used
by timekeeping and VDSO.

Place #include <vdso/math64.h> after #include <asm/div64.h> to allow
architecture-specific overrides, at least for the kernel.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240325064023.2997-6-adrian.hunter@intel.com
2024-04-08 15:03:07 +02:00
Arnd Bergmann
cffaefd15a vdso: Use CONFIG_PAGE_SHIFT in vdso/datapage.h
Both the vdso rework and the CONFIG_PAGE_SHIFT changes were merged during
the v6.9 merge window, so it is now possible to use CONFIG_PAGE_SHIFT
instead of including asm/page.h in the vdso.

This avoids the workaround for arm64 - commit 8b3843ae36 ("vdso/datapage:
Quick fix - use asm/page-def.h for ARM64") and addresses a build warning
for powerpc64:

In file included from <built-in>:4:
In file included from /home/arnd/arm-soc/arm-soc/lib/vdso/gettimeofday.c:5:
In file included from ../include/vdso/datapage.h:25:
arch/powerpc/include/asm/page.h:230:9: error: result of comparison of constant 13835058055282163712 with expression of type 'unsigned long' is always true [-Werror,-Wtautological-constant-out-of-range-compare]
  230 |         return __pa(kaddr) >> PAGE_SHIFT;
      |                ^~~~~~~~~~~
arch/powerpc/include/asm/page.h:217:37: note: expanded from macro '__pa'
  217 |         VIRTUAL_WARN_ON((unsigned long)(x) < PAGE_OFFSET);              \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
arch/powerpc/include/asm/page.h:202:73: note: expanded from macro 'VIRTUAL_WARN_ON'
  202 | #define VIRTUAL_WARN_ON(x)      WARN_ON(IS_ENABLED(CONFIG_DEBUG_VIRTUAL) && (x))
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
arch/powerpc/include/asm/bug.h:88:25: note: expanded from macro 'WARN_ON'
   88 |         int __ret_warn_on = !!(x);                              \
      |                                ^

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Link: https://lore.kernel.org/r/20240320180228.136371-1-arnd@kernel.org
2024-04-03 21:50:04 +02:00
Anna-Maria Behnsen
8b3843ae36 vdso/datapage: Quick fix - use asm/page-def.h for ARM64
The vdso rework for the generic union vdso_data_store broke compat VDSO on
arm64:

In file included from arch/arm64/include/asm/lse.h:5,
		 from arch/arm64/include/asm/cmpxchg.h:14,
		 from arch/arm64/include/asm/atomic.h:16,
		 from include/linux/atomic.h:7,
		 from include/asm-generic/bitops/atomic.h:5,
		 from arch/arm64/include/asm/bitops.h:25,
		 from include/linux/bitops.h:68,
		 from arch/arm64/include/asm/memory.h:209,
		 from arch/arm64/include/asm/page.h:46,
		 from include/vdso/datapage.h:22,
		 from lib/vdso/gettimeofday.c:5,
		 from <command-line>:
arch/arm64/include/asm/atomic_ll_sc.h:298:9: error: unknown type name 'u128'
  298 |         u128 full;
      |         ^~~~
arch/arm64/include/asm/atomic_ll_sc.h:305:24: error: unknown type name 'u128'
  305 | static __always_inline u128
	 \
      |

The reason is the include of asm/page.h which in turn includes headers
which are outside the scope of compat VDSO. The only reason for the
asm/page.h include is the required definition of PAGE_SIZE. But as arm64
defines PAGE_SIZE in asm/page-def.h without extra header includes, this
could be used instead.

Caution: this is a quick fix only! The final fix is an upcoming cleanup of
Arnd which consolidates PAGE_SIZE definition. After the cleanup, the
include of asm/page.h to access PAGE_SIZE is no longer required.

Fixes: a0d2fcd62a ("vdso/ARM: Make union vdso_data_store available for all architectures")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240226175023.56679-1-anna-maria@linutronix.de
Link: https://lore.kernel.org/lkml/CA+G9fYtrXXm_KO9fNPz3XaRxHV7UD_yQp-TEuPQrNRHU+_0W_Q@mail.gmail.com/
2024-02-26 23:13:41 +01:00
Anna-Maria Behnsen
a0d2fcd62a vdso/ARM: Make union vdso_data_store available for all architectures
The vDSO data page "union vdso_data_store" is defined in an ARM specific
header file and also defined in several other places.

Move the definition from the ARM header file into the generic vdso datapage
header to make it also usable for others and to prevent code duplication.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240219153939.75719-5-anna-maria@linutronix.de
2024-02-20 20:56:00 +01:00
Anna-Maria Behnsen
eeb9f5c2dc vdso/helpers: Fix grammar in comments
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240219153939.75719-2-anna-maria@linutronix.de
2024-02-20 20:56:00 +01:00
Arnd Bergmann
42874e4eb3 arch: vdso: consolidate gettime prototypes
The VDSO functions are defined as globals in the kernel sources but intended
to be called from userspace, so there is no need to declare them in a kernel
side header.

Without a prototype, this now causes warnings such as

arch/mips/vdso/vgettimeofday.c:14:5: error: no previous prototype for '__vdso_clock_gettime' [-Werror=missing-prototypes]
arch/mips/vdso/vgettimeofday.c:28:5: error: no previous prototype for '__vdso_gettimeofday' [-Werror=missing-prototypes]
arch/mips/vdso/vgettimeofday.c:36:5: error: no previous prototype for '__vdso_clock_getres' [-Werror=missing-prototypes]
arch/mips/vdso/vgettimeofday.c:42:5: error: no previous prototype for '__vdso_clock_gettime64' [-Werror=missing-prototypes]
arch/sparc/vdso/vclock_gettime.c:254:1: error: no previous prototype for '__vdso_clock_gettime' [-Werror=missing-prototypes]
arch/sparc/vdso/vclock_gettime.c:282:1: error: no previous prototype for '__vdso_clock_gettime_stick' [-Werror=missing-prototypes]
arch/sparc/vdso/vclock_gettime.c:307:1: error: no previous prototype for '__vdso_gettimeofday' [-Werror=missing-prototypes]
arch/sparc/vdso/vclock_gettime.c:343:1: error: no previous prototype for '__vdso_gettimeofday_stick' [-Werror=missing-prototypes]

Most architectures have already added workarounds for these by adding
declarations somewhere, but since these are all compatible, we should
really just have one copy, with an #ifdef check for the 32-bit vs
64-bit variant and use that everywhere.

Unfortunately, the sparc an um versions are currently incompatible
since they never added support for __vdso_clock_gettime64() in 32-bit
userland. For the moment, I'm leaving this one out, as I can't
easily test it and it requires a larger rework.

Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2023-11-23 11:32:32 +01:00
Andy Shevchenko
cbdb1f163a vdso/bits.h: Add BIT_ULL() for the sake of consistency
The minimization done in 3945ff37d2 ("linux/bits.h: Extract common header
for vDSO") was required to isolate the VDSO build from the larger kernel
header impact.

The split added some inconsistency since BIT() and BIT_ULL() are now
defined in the different files which confuses unprepared reader.

Move BIT_ULL() to vdso/bits.h. No functional change.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20221128141003.77929-1-andriy.shevchenko@linux.intel.com
2023-01-31 14:42:10 +01:00
Andy Shevchenko
a460513ed4 time64.h: Consolidated PSEC_PER_SEC definition
We have currently three users of the PSEC_PER_SEC each of them defining it
individually. Instead, move it to time64.h to be available for everyone.

There is a new user coming with the same constant in use. It will also
make its life easier.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-04-06 16:32:17 -07:00
Sven Schnelle
d60d7de3e1 lib/vdso: Allow to add architecture-specific vdso data
The initial assumption that all VDSO related data can be completely generic
does not hold. S390 needs architecture specific storage to access the clock
steering information.

Add struct arch_vdso_data to the vdso data struct. For architectures which
do not need extra data this defaults to an empty struct. Architectures
which require it, enable CONFIG_ARCH_HAS_VDSO_DATA and provide their
specific struct in asm/vdso/data.h.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200804150124.41692-2-svens@linux.ibm.com
2020-08-06 10:57:30 +02:00
Thomas Gleixner
19d0070a27 timekeeping/vsyscall: Provide vdso_update_begin/end()
Architectures can have the requirement to add additional architecture
specific data to the VDSO data page which needs to be updated independent
of the timekeeper updates.

To protect these updates vs. concurrent readers and a conflicting update
through timekeeping, provide helper functions to make such updates safe.

vdso_update_begin() takes the timekeeper_lock to protect against a
potential update from timekeeper code and increments the VDSO sequence
count to signal data inconsistency to concurrent readers. vdso_update_end()
makes the sequence count even again to signal data consistency and drops
the timekeeper lock.

[ Sven: Add interrupt disable handling to the functions ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200804150124.41692-3-svens@linux.ibm.com
2020-08-06 10:57:30 +02:00
Andrei Vagin
3503d56cc7 arm64/vdso: Add time namespace page
Allocate the time namespace page among VVAR pages.  Provide
__arch_get_timens_vdso_data() helper for VDSO code to get the
code-relative position of VVARs on that special page.

If a task belongs to a time namespace then the VVAR page which contains
the system wide VDSO data is replaced with a namespace specific page
which has the same layout as the VVAR page. That page has vdso_data->seq
set to 1 to enforce the slow path and vdso_data->clock_mode set to
VCLOCK_TIMENS to enforce the time namespace handling path.

The extra check in the case that vdso_data->seq is odd, e.g. a concurrent
update of the VDSO data is in progress, is not really affecting regular
tasks which are not part of a time namespace as the task is spin waiting
for the update to finish and vdso_data->seq to become even again.

If a time namespace task hits that code path, it invokes the corresponding
time getter function which retrieves the real VVAR page, reads host time
and then adds the offset for the requested clock which is stored in the
special VVAR page.

The time-namespace page isn't allocated on !CONFIG_TIME_NAMESPACE, but
vma is the same size, which simplifies criu/vdso migration between
different kernel configs.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Dmitry Safonov <dima@arista.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20200624083321.144975-4-avagin@gmail.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-07-24 13:15:20 +01:00
Christian Brauner
ac84bac406 vdso/datapage: Use correct clock mode name in comment
While the explanation for time namespace <-> vdso interactions is very
helpful it uses the wrong name in the comment when describing the clock
mode making grepping a bit annoying.

This seems like an accidental oversight when moving from VCLOCK_TIMENS
to VDSO_CLOCKMODE_TIMENS. It seems that
660fd04f93 ("lib/vdso: Prepare for time namespace support") misspelled
VCLOCK_TIMENS as VLOCK_TIMENS which explains why it got missed when
VCLOCK_TIMENS became VDSO_CLOCKMODE_TIMENS in
2d6b01bd88 ("lib/vdso: Move VCLOCK_TIMENS to vdso_clock_modes").

Update the comment to use VDSO_CLOCKMODE_TIMENS.

Fixes: 660fd04f93 ("lib/vdso: Prepare for time namespace support")
Fixes: 2d6b01bd88 ("lib/vdso: Move VCLOCK_TIMENS to vdso_clock_modes")
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andrei Vagin <avagin@gmail.com>
Acked-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lkml.kernel.org/r/20200420100615.1549804-1-christian.brauner@ubuntu.com
2020-04-20 19:19:52 +02:00
Vincenzo Frascino
ca214e2c17 vdso: Fix clocksource.h macro detection
CONFIG_GENERIC_GETTIMEOFDAY is a sufficient condition to verify if an
architecture implements asm/vdso/clocksource.h or not. The current
implementation wrongly assumes that the same is true for the config
option CONFIG_ARCH_CLOCKSOURCE_DATA.

This results in a series of build errors on ia64/sparc/sparc64 like this:

  In file included from ./include/linux/clocksource.h:31,
                   from ./include/linux/clockchips.h:14,
                   from ./include/linux/tick.h:8,
                   from fs/proc/stat.c:15:
  ./include/vdso/clocksource.h:9:10: fatal error: asm/vdso/clocksource.h:
  No such file or directory
      9 | #include <asm/vdso/clocksource.h>
        |          ^~~~~~~~~~~~~~~~~~~~~~~~

Fix the issue removing the unneeded config condition.

Fixes: 14ee2ac618 ("linux/clocksource.h: Extract common header for vDSO")
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200323133920.46546-1-vincenzo.frascino@arm.com
2020-03-23 18:51:08 +01:00
Vincenzo Frascino
8c59ab839f lib/vdso: Enable common headers
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Refactor the unified vdso code to use the common headers.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-26-vincenzo.frascino@arm.com
2020-03-21 15:24:03 +01:00
Vincenzo Frascino
d8bb6993d8 common: Introduce processor.h
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Introduce processor.h to contain all the processor specific functions
that are suitable for vDSO inclusion.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-16-vincenzo.frascino@arm.com
2020-03-21 15:23:59 +01:00
Vincenzo Frascino
cc56f32f00 linux/ktime.h: Extract common header for vDSO
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split ktime.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-15-vincenzo.frascino@arm.com
2020-03-21 15:23:59 +01:00
Vincenzo Frascino
97b01d2eab linux/jiffies.h: Extract common header for vDSO
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split jiffies.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-14-vincenzo.frascino@arm.com
2020-03-21 15:23:58 +01:00
Vincenzo Frascino
b72a9c5e02 linux/time64.h: Extract common header for vDSO
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split time64.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-13-vincenzo.frascino@arm.com
2020-03-21 15:23:58 +01:00
Vincenzo Frascino
9a41623169 linux/time32.h: Extract common header for vDSO
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split time32.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-12-vincenzo.frascino@arm.com
2020-03-21 15:23:57 +01:00
Vincenzo Frascino
639fff1cce linux/time.h: Extract common header for vDSO
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split time.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-11-vincenzo.frascino@arm.com
2020-03-21 15:23:57 +01:00
Vincenzo Frascino
b874b8358c linux/math64.h: Extract common header for vDSO
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split math64.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-10-vincenzo.frascino@arm.com
2020-03-21 15:23:56 +01:00
Vincenzo Frascino
14ee2ac618 linux/clocksource.h: Extract common header for vDSO
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split clocksource.h into linux and common headers to make the latter
suitable for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-9-vincenzo.frascino@arm.com
2020-03-21 15:23:56 +01:00
Vincenzo Frascino
3e0e9f8c6e linux/limits.h: Extract common header for vDSO
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split limits.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-4-vincenzo.frascino@arm.com
2020-03-21 15:23:54 +01:00
Vincenzo Frascino
3945ff37d2 linux/bits.h: Extract common header for vDSO
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split bits.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-3-vincenzo.frascino@arm.com
2020-03-21 15:23:53 +01:00
Vincenzo Frascino
8165b57bca linux/const.h: Extract common header for vDSO
The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split const.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-2-vincenzo.frascino@arm.com
2020-03-21 15:23:53 +01:00
Thomas Gleixner
2d6b01bd88 lib/vdso: Move VCLOCK_TIMENS to vdso_clock_modes
Move the time namespace indicator clock mode to the other ones for
consistency sake.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lkml.kernel.org/r/20200207124403.656097274@linutronix.de
2020-02-17 20:12:17 +01:00
Thomas Gleixner
660fd04f93 lib/vdso: Prepare for time namespace support
To support time namespaces in the vdso with a minimal impact on regular non
time namespace affected tasks, the namespace handling needs to be hidden in
a slow path.

The most obvious place is vdso_seq_begin(). If a task belongs to a time
namespace then the VVAR page which contains the system wide vdso data is
replaced with a namespace specific page which has the same layout as the
VVAR page. That page has vdso_data->seq set to 1 to enforce the slow path
and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce the time
namespace handling path.

The extra check in the case that vdso_data->seq is odd, e.g. a concurrent
update of the vdso data is in progress, is not really affecting regular
tasks which are not part of a time namespace as the task is spin waiting
for the update to finish and vdso_data->seq to become even again.

If a time namespace task hits that code path, it invokes the corresponding
time getter function which retrieves the real VVAR page, reads host time
and then adds the offset for the requested clock which is stored in the
special VVAR page.

If VDSO time namespace support is disabled the whole magic is compiled out.

Initial testing shows that the disabled case is almost identical to the
host case which does not take the slow timens path. With the special timens
page installed the performance hit is constant time and in the range of
5-7%.

For the vdso functions which are not using the sequence count an
unconditional check for vdso_data->clock_mode is added which switches to
the real vdso when the clock_mode is VCLOCK_TIMENS.

[avagin: Make do_hres_timens() work with raw clocks too: choose vdso_data
 pointer by CS_RAW offset.]

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-21-dima@arista.com
2020-01-14 12:20:57 +01:00
Andrei Vagin
0898a16a36 lib/vdso: Add unlikely() hint into vdso_read_begin()
Place the branch with no concurrent write before the contended case.

Performance numbers for Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
(more clock_gettime() cycles - the better):
        | before    | after
-----------------------------------
        | 150252214 | 153242367
        | 150301112 | 153324800
        | 150392773 | 153125401
        | 150373957 | 153399355
        | 150303157 | 153489417
        | 150365237 | 153494270
-----------------------------------
avg     | 150331408 | 153345935
diff %  | 2	    | 0
-----------------------------------
stdev % | 0.3	    | 0.1

Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20191112012724.250792-2-dima@arista.com
2020-01-14 12:20:47 +01:00
Catalin Marinas
ed75e8f60b vdso: Remove superfluous #ifdef __KERNEL__ in vdso/datapage.h
With the move to UAPI headers, such #ifdefs are no longer necessary.

Fixes: 361f8aee9b ("vdso: Define standardized vdso_datapage")
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Huw Davies <huw@codeweavers.com>
Cc: Shijith Thotton <sthotton@marvell.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Link: https://lkml.kernel.org/r/20190624135624.GB29120@arrakis.emea.arm.com
2019-06-26 07:28:09 +02:00
Vincenzo Frascino
44f57d788e timekeeping: Provide a generic update_vsyscall() implementation
The new generic VDSO library allows to unify the update_vsyscall[_tz]()
implementations.

Provide a generic implementation based on the x86 code and the bindings
which need to be implemented in architecture specific code.

[ tglx: Moved it into kernel/time where it belongs. Removed the pointless
  	line breaks in the stub functions. Massaged changelog ]

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Shijith Thotton <sthotton@marvell.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Huw Davies <huw@codeweavers.com>
Link: https://lkml.kernel.org/r/20190621095252.32307-4-vincenzo.frascino@arm.com
2019-06-22 21:21:06 +02:00
Vincenzo Frascino
00b26474c2 lib/vdso: Provide generic VDSO implementation
In the last few years the kernel gained quite some architecture specific
vdso implementations which contain very similar code.

Introduce a generic VDSO implementation of gettimeofday() which will be
shareable between architectures once they are converted over.

The implementation is based on the current x86 VDSO code.

[ tglx: Massaged changelog and made the kernel doc tabular ]

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Shijith Thotton <sthotton@marvell.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Huw Davies <huw@codeweavers.com>
Link: https://lkml.kernel.org/r/20190621095252.32307-3-vincenzo.frascino@arm.com
2019-06-22 21:21:05 +02:00
Vincenzo Frascino
361f8aee9b vdso: Define standardized vdso_datapage
Define a common formet for the vdso datapage as a preparation for sharing
the VDSO implementation as a generic library.

The datastructures are based on the current x86 layout.

[ tglx: Massaged changelog ]

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Shijith Thotton <sthotton@marvell.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Huw Davies <huw@codeweavers.com>
Link: https://lkml.kernel.org/r/20190621095252.32307-2-vincenzo.frascino@arm.com
2019-06-22 21:21:05 +02:00