History log of /linux-6.15/include/vdso/datapage.h (Results 1 – 24 of 24)
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Revision tags: v6.15, v6.15-rc7, v6.15-rc6, v6.15-rc5, v6.15-rc4, v6.15-rc3, v6.15-rc2, v6.15-rc1, v6.14, v6.14-rc7, v6.14-rc6
# 886653e3 03-Mar-2025 Anna-Maria Behnsen <[email protected]>

vdso: Rework struct vdso_time_data and introduce struct vdso_clock

To support multiple PTP clocks, the VDSO data structure needs to be
reworked. All clock specific data will end up in struct vdso_cl

vdso: Rework struct vdso_time_data and introduce struct vdso_clock

To support multiple PTP clocks, the VDSO data structure needs to be
reworked. All clock specific data will end up in struct vdso_clock and in
struct vdso_time_data there will be an array of VDSO clocks.

Now that all preparatory changes are in place:

Split the clock related struct members into a separate struct
vdso_clock. Make sure all users are aware, that vdso_time_data is no longer
initialized as an array and vdso_clock is now the array inside
vdso_data. Remove the vdso_clock define, which mapped it to vdso_time_data
for the transition.

Signed-off-by: Anna-Maria Behnsen <[email protected]>
Signed-off-by: Nam Cao <[email protected]>
Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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# 97a5a90c 03-Mar-2025 Anna-Maria Behnsen <[email protected]>

vdso: Move architecture related data before basetime data

Architecture related vdso data is required in the fast path when reading
CLOCK_MONOTONIC or CLOCK_REALTIME. At the moment, this information

vdso: Move architecture related data before basetime data

Architecture related vdso data is required in the fast path when reading
CLOCK_MONOTONIC or CLOCK_REALTIME. At the moment, this information is
located at the end of the vdso_time_data structure, which is a suboptimal
cache layout.

Move the architecture specific VDSO data right before the basetime
information, which is always required. This change does not have an impact
on architectures with CONFIG_ARCH_HAS_VDSO_DATA=n. Architectures, which
have it enabled, gain a better cache layout.

Signed-off-by: Anna-Maria Behnsen <[email protected]>
Signed-off-by: Nam Cao <[email protected]>
Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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# a05f14de 03-Mar-2025 Anna-Maria Behnsen <[email protected]>

vdso/datapage: Define vdso_clock to prepare for multiple PTP clocks

Multiple PTP clocks, which are independent of timekeeping, are required for
systems, which utilize PTP for synchronizing e.g. auto

vdso/datapage: Define vdso_clock to prepare for multiple PTP clocks

Multiple PTP clocks, which are independent of timekeeping, are required for
systems, which utilize PTP for synchronizing e.g. automation systems
independent of clock TAI.

PTP clocks are slow to access, but applications require fast access to the
relevant time similar to the regular timekeeping relevant clocks.

To prepare for that the VDSO data representation must be reworked. For
transition to the new structure of the vdso, add a define which maps
vdso_clock to vdso_data. This will be removed when all users are updated
step by step.

No functional change.

Signed-off-by: Anna-Maria Behnsen <[email protected]>
Signed-off-by: Nam Cao <[email protected]>
Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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# fa8152ca 03-Mar-2025 Anna-Maria Behnsen <[email protected]>

vdso: Make vdso_time_data cacheline aligned

vdso_time_data is not cacheline aligned at the moment. When instantiating
an array, the start of the second array member is not cache line aligned.

This

vdso: Make vdso_time_data cacheline aligned

vdso_time_data is not cacheline aligned at the moment. When instantiating
an array, the start of the second array member is not cache line aligned.

This increases the number of the required cache lines which needs to be
read when handling e.g. CLOCK_MONOTONIC_RAW, because the data spawns an
extra cache line if the previous data does not end at a cache line
boundary.

Therefore make struct vdso_time_data cacheline aligned.

Signed-off-by: Anna-Maria Behnsen <[email protected]>
Signed-off-by: Nam Cao <[email protected]>
Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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Revision tags: v6.14-rc5, v6.14-rc4, v6.14-rc3, v6.14-rc2
# ac1a42f4 04-Feb-2025 Thomas Weißschuh <[email protected]>

vdso: Remove remnants of architecture-specific time storage

All users of the time releated parts of the vDSO are now using the generic
storage implementation. Remove the therefore unnecessary compat

vdso: Remove remnants of architecture-specific time storage

All users of the time releated parts of the vDSO are now using the generic
storage implementation. Remove the therefore unnecessary compatibility
accessor functions and symbols.

Co-developed-by: Nam Cao <[email protected]>
Signed-off-by: Nam Cao <[email protected]>
Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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# 998a8a26 04-Feb-2025 Thomas Weißschuh <[email protected]>

vdso: Remove remnants of architecture-specific random state storage

All users of the random vDSO are using the generic storage
implementation. Remove the now unnecessary compatibility accessor
funct

vdso: Remove remnants of architecture-specific random state storage

All users of the random vDSO are using the generic storage
implementation. Remove the now unnecessary compatibility accessor
functions and symbols.

Co-developed-by: Nam Cao <[email protected]>
Signed-off-by: Nam Cao <[email protected]>
Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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# 365841e1 04-Feb-2025 Thomas Weißschuh <[email protected]>

vdso: Add generic architecture-specific data storage

Some architectures need to expose architecture-specific data to the vDSO.

Enable the generic vDSO storage mechanism to both store and map this
d

vdso: Add generic architecture-specific data storage

Some architectures need to expose architecture-specific data to the vDSO.

Enable the generic vDSO storage mechanism to both store and map this
data. Some architectures require more than a single page, like LoongArch,
so prepare for that usecase, too.

Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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# 51d6ca37 04-Feb-2025 Thomas Weißschuh <[email protected]>

vdso: Add generic random data storage

Extend the generic vDSO data storage with a page for the random state data.
The random state data is stored in a dedicated page, as the existing
storage page is

vdso: Add generic random data storage

Extend the generic vDSO data storage with a page for the random state data.
The random state data is stored in a dedicated page, as the existing
storage page is only meant for time-related, time-namespace-aware data.
This simplifies to access logic to not need to handle time namespaces
anymore and also frees up more space in the time-related page.

In case further generic vDSO data store is required it can be added to
the random state page.

Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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# df7fcbef 04-Feb-2025 Thomas Weißschuh <[email protected]>

vdso: Add generic time data storage

Historically each architecture defined their own way to store the vDSO
data page. Add a generic mechanism to provide storage for that page.

Furthermore this gene

vdso: Add generic time data storage

Historically each architecture defined their own way to store the vDSO
data page. Add a generic mechanism to provide storage for that page.

Furthermore this generic storage will be extended to also provide
uniform storage for *non*-time-related data, like the random state or
architecture-specific data. These will have their own pages and data
structures, so rename 'vdso_data' into 'vdso_time_data' to make that
split clear from the name.

Also introduce a new consistent naming scheme for the symbols related to
the vDSO, which makes it clear if the symbol is accessible from
userspace or kernel space and the type of data behind the symbol.

The generic fault handler contains an optimization to prefault the vvar
page when the timens page is accessed. This was lifted from s390 and x86.

Co-developed-by: Nam Cao <[email protected]>
Signed-off-by: Nam Cao <[email protected]>
Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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Revision tags: v6.14-rc1, v6.13, v6.13-rc7, v6.13-rc6, v6.13-rc5, v6.13-rc4, v6.13-rc3, v6.13-rc2, v6.13-rc1, v6.12, v6.12-rc7, v6.12-rc6, v6.12-rc5, v6.12-rc4, v6.12-rc3
# a812eee0 10-Oct-2024 Nam Cao <[email protected]>

vdso: Rename struct arch_vdso_data to arch_vdso_time_data

The struct arch_vdso_data is only about vdso time data. So rename it to
arch_vdso_time_data to make it obvious.
Non time-related data will b

vdso: Rename struct arch_vdso_data to arch_vdso_time_data

The struct arch_vdso_data is only about vdso time data. So rename it to
arch_vdso_time_data to make it obvious.
Non time-related data will be migrated out of these structs soon.

Signed-off-by: Nam Cao <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Heiko Carstens <[email protected]> # s390
Link: https://lore.kernel.org/all/[email protected]

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Revision tags: v6.12-rc2, v6.12-rc1, v6.11, v6.11-rc7, v6.11-rc6, v6.11-rc5, v6.11-rc4, v6.11-rc3, v6.11-rc2, v6.11-rc1, v6.10, v6.10-rc7, v6.10-rc6, v6.10-rc5, v6.10-rc4, v6.10-rc3, v6.10-rc2, v6.10-rc1, v6.9, v6.9-rc7, v6.9-rc6, v6.9-rc5, v6.9-rc4, v6.9-rc3, v6.9-rc2, v6.9-rc1, v6.8, v6.8-rc7, v6.8-rc6, v6.8-rc5, v6.8-rc4, v6.8-rc3, v6.8-rc2, v6.8-rc1, v6.7, v6.7-rc8, v6.7-rc7, v6.7-rc6, v6.7-rc5, v6.7-rc4, v6.7-rc3, v6.7-rc2, v6.7-rc1, v6.6, v6.6-rc7, v6.6-rc6, v6.6-rc5, v6.6-rc4, v6.6-rc3, v6.6-rc2, v6.6-rc1, v6.5, v6.5-rc7, v6.5-rc6, v6.5-rc5, v6.5-rc4, v6.5-rc3, v6.5-rc2, v6.5-rc1, v6.4, v6.4-rc7, v6.4-rc6, v6.4-rc5, v6.4-rc4, v6.4-rc3, v6.4-rc2, v6.4-rc1, v6.3, v6.3-rc7, v6.3-rc6, v6.3-rc5, v6.3-rc4, v6.3-rc3, v6.3-rc2, v6.3-rc1, v6.2, v6.2-rc8, v6.2-rc7, v6.2-rc6, v6.2-rc5, v6.2-rc4, v6.2-rc3, v6.2-rc2, v6.2-rc1, v6.1, v6.1-rc8, v6.1-rc7, v6.1-rc6
# 4ad10a5f 18-Nov-2022 Jason A. Donenfeld <[email protected]>

random: introduce generic vDSO getrandom() implementation

Provide a generic C vDSO getrandom() implementation, which operates on
an opaque state returned by vgetrandom_alloc() and produces random by

random: introduce generic vDSO getrandom() implementation

Provide a generic C vDSO getrandom() implementation, which operates on
an opaque state returned by vgetrandom_alloc() and produces random bytes
the same way as getrandom(). This has the following API signature:

ssize_t vgetrandom(void *buffer, size_t len, unsigned int flags,
void *opaque_state, size_t opaque_len);

The return value and the first three arguments are the same as ordinary
getrandom(), while the last two arguments are a pointer to the opaque
allocated state and its size. Were all five arguments passed to the
getrandom() syscall, nothing different would happen, and the functions
would have the exact same behavior.

The actual vDSO RNG algorithm implemented is the same one implemented by
drivers/char/random.c, using the same fast-erasure techniques as that.
Should the in-kernel implementation change, so too will the vDSO one.

It requires an implementation of ChaCha20 that does not use any stack,
in order to maintain forward secrecy if a multi-threaded program forks
(though this does not account for a similar issue with SA_SIGINFO
copying registers to the stack), so this is left as an
architecture-specific fill-in. Stack-less ChaCha20 is an easy algorithm
to implement on a variety of architectures, so this shouldn't be too
onerous.

Initially, the state is keyless, and so the first call makes a
getrandom() syscall to generate that key, and then uses it for
subsequent calls. By keeping track of a generation counter, it knows
when its key is invalidated and it should fetch a new one using the
syscall. Later, more than just a generation counter might be used.

Since MADV_WIPEONFORK is set on the opaque state, the key and related
state is wiped during a fork(), so secrets don't roll over into new
processes, and the same state doesn't accidentally generate the same
random stream. The generation counter, as well, is always >0, so that
the 0 counter is a useful indication of a fork() or otherwise
uninitialized state.

If the kernel RNG is not yet initialized, then the vDSO always calls the
syscall, because that behavior cannot be emulated in userspace, but
fortunately that state is short lived and only during early boot. If it
has been initialized, then there is no need to inspect the `flags`
argument, because the behavior does not change post-initialization
regardless of the `flags` value.

Since the opaque state passed to it is mutated, vDSO getrandom() is not
reentrant, when used with the same opaque state, which libc should be
mindful of.

The function works over an opaque per-thread state of a particular size,
which must be marked VM_WIPEONFORK, VM_DONTDUMP, VM_NORESERVE, and
VM_DROPPABLE for proper operation. Over time, the nuances of these
allocations may change or grow or even differ based on architectural
features.

The opaque state passed to vDSO getrandom() must be allocated using the
mmap_flags and mmap_prot parameters provided by the vgetrandom_opaque_params
struct, which also contains the size of each state. That struct can be
obtained with a call to vgetrandom(NULL, 0, 0, &params, ~0UL). Then,
libc can call mmap(2) and slice up the returned array into a state per
each thread, while ensuring that no single state straddles a page
boundary. Libc is expected to allocate a chunk of these on first use,
and then dole them out to threads as they're created, allocating more
when needed.

vDSO getrandom() provides the ability for userspace to generate random
bytes quickly and safely, and is intended to be integrated into libc's
thread management. As an illustrative example, the introduced code in
the vdso_test_getrandom self test later in this series might be used to
do the same outside of libc. In a libc the various pthread-isms are
expected to be elided into libc internals.

Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>

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# d00106bb 01-Jul-2024 Anna-Maria Behnsen <[email protected]>

vdso: Add comment about reason for vdso struct ordering

struct vdso_data is optimized for fast access to the often required struct
members. The optimization is not documented in the struct descripti

vdso: Add comment about reason for vdso struct ordering

struct vdso_data is optimized for fast access to the often required struct
members. The optimization is not documented in the struct description but
it should be kept in mind, when working with the vdso_data struct.

Add a comment to the struct description.

Signed-off-by: Anna-Maria Behnsen <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Vincenzo Frascino <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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# d2e58ab5 25-Mar-2024 Adrian Hunter <[email protected]>

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 <[email protected]>
Signed-off-by: Ad

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 <[email protected]>
Signed-off-by: Adrian Hunter <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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# cffaefd1 20-Mar-2024 Arnd Bergmann <[email protected]>

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

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 8b3843ae3634 ("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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Acked-by: Michael Ellerman <[email protected]> (powerpc)
Link: https://lore.kernel.org/r/[email protected]

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# 8b3843ae 26-Feb-2024 Anna-Maria Behnsen <[email protected]>

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,
fr

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: a0d2fcd62ac2 ("vdso/ARM: Make union vdso_data_store available for all architectures")
Reported-by: Linux Kernel Functional Testing <[email protected]>
Signed-off-by: Anna-Maria Behnsen <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Link: https://lore.kernel.org/lkml/CA+G9fYtrXXm_KO9fNPz3XaRxHV7UD_yQp-TEuPQrNRHU+_0W_Q@mail.gmail.com/

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# a0d2fcd6 19-Feb-2024 Anna-Maria Behnsen <[email protected]>

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.

M

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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Vincenzo Frascino <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...


Revision tags: v6.1-rc5, v6.1-rc4, v6.1-rc3, v6.1-rc2, v6.1-rc1, v6.0, v6.0-rc7, v6.0-rc6, v6.0-rc5, v6.0-rc4, v6.0-rc3, v6.0-rc2, v6.0-rc1, v5.19, v5.19-rc8, v5.19-rc7, v5.19-rc6, v5.19-rc5, v5.19-rc4, v5.19-rc3, v5.19-rc2, v5.19-rc1, v5.18, v5.18-rc7, v5.18-rc6, v5.18-rc5, v5.18-rc4, v5.18-rc3, v5.18-rc2, v5.18-rc1, v5.17, v5.17-rc8, v5.17-rc7, v5.17-rc6, v5.17-rc5, v5.17-rc4, v5.17-rc3, v5.17-rc2, v5.17-rc1, v5.16, v5.16-rc8, v5.16-rc7, v5.16-rc6, v5.16-rc5, v5.16-rc4, v5.16-rc3, v5.16-rc2, v5.16-rc1, v5.15, v5.15-rc7, v5.15-rc6, v5.15-rc5, v5.15-rc4, v5.15-rc3, v5.15-rc2, v5.15-rc1, v5.14, v5.14-rc7, v5.14-rc6, v5.14-rc5, v5.14-rc4, v5.14-rc3, v5.14-rc2, v5.14-rc1, v5.13, v5.13-rc7, v5.13-rc6, v5.13-rc5, v5.13-rc4, v5.13-rc3, v5.13-rc2, v5.13-rc1, v5.12, v5.12-rc8, v5.12-rc7, v5.12-rc6, v5.12-rc5, v5.12-rc4, v5.12-rc3, v5.12-rc2, v5.12-rc1, v5.12-rc1-dontuse, v5.11, v5.11-rc7, v5.11-rc6, v5.11-rc5, v5.11-rc4, v5.11-rc3, v5.11-rc2, v5.11-rc1, v5.10, v5.10-rc7, v5.10-rc6, v5.10-rc5, v5.10-rc4, v5.10-rc3, v5.10-rc2, v5.10-rc1, v5.9, v5.9-rc8, v5.9-rc7, v5.9-rc6, v5.9-rc5, v5.9-rc4, v5.9-rc3, v5.9-rc2, v5.9-rc1
# d60d7de3 04-Aug-2020 Sven Schnelle <[email protected]>

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 t

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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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Revision tags: v5.8, v5.8-rc7, v5.8-rc6, v5.8-rc5, v5.8-rc4, v5.8-rc3
# 3503d56c 24-Jun-2020 Andrei Vagin <[email protected]>

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

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 <[email protected]>
Reviewed-by: Vincenzo Frascino <[email protected]>
Reviewed-by: Dmitry Safonov <[email protected]>
Cc: Mark Rutland <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

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Revision tags: v5.8-rc2, v5.8-rc1, v5.7, v5.7-rc7, v5.7-rc6, v5.7-rc5, v5.7-rc4, v5.7-rc3
# ac84bac4 20-Apr-2020 Christian Brauner <[email protected]>

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
m

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
660fd04f9317 ("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
2d6b01bd88cc ("lib/vdso: Move VCLOCK_TIMENS to vdso_clock_modes").

Update the comment to use VDSO_CLOCKMODE_TIMENS.

Fixes: 660fd04f9317 ("lib/vdso: Prepare for time namespace support")
Fixes: 2d6b01bd88cc ("lib/vdso: Move VCLOCK_TIMENS to vdso_clock_modes")
Signed-off-by: Christian Brauner <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Andrei Vagin <[email protected]>
Acked-by: Vincenzo Frascino <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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Revision tags: v5.7-rc2, v5.7-rc1, v5.6, v5.6-rc7
# 8c59ab83 20-Mar-2020 Vincenzo Frascino <[email protected]>

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 ne

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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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Revision tags: v5.6-rc6, v5.6-rc5, v5.6-rc4, v5.6-rc3, v5.6-rc2, v5.6-rc1
# 2d6b01bd 07-Feb-2020 Thomas Gleixner <[email protected]>

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 <[email protected]>
Reviewed-by

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 <[email protected]>
Reviewed-by: Vincenzo Frascino <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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Revision tags: v5.5, v5.5-rc7, v5.5-rc6, v5.5-rc5, v5.5-rc4, v5.5-rc3, v5.5-rc2, v5.5-rc1, v5.4, v5.4-rc8
# 660fd04f 12-Nov-2019 Thomas Gleixner <[email protected]>

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

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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Andrei Vagin <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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Revision tags: v5.4-rc7, v5.4-rc6, v5.4-rc5, v5.4-rc4, v5.4-rc3, v5.4-rc2, v5.4-rc1, v5.3, v5.3-rc8, v5.3-rc7, v5.3-rc6, v5.3-rc5, v5.3-rc4, v5.3-rc3, v5.3-rc2, v5.3-rc1, v5.2, v5.2-rc7
# ed75e8f6 24-Jun-2019 Catalin Marinas <[email protected]>

vdso: Remove superfluous #ifdef __KERNEL__ in vdso/datapage.h

With the move to UAPI headers, such #ifdefs are no longer necessary.

Fixes: 361f8aee9b09 ("vdso: Define standardized vdso_datapage")
Si

vdso: Remove superfluous #ifdef __KERNEL__ in vdso/datapage.h

With the move to UAPI headers, such #ifdefs are no longer necessary.

Fixes: 361f8aee9b09 ("vdso: Define standardized vdso_datapage")
Signed-off-by: Catalin Marinas <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Vincenzo Frascino <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Will Deacon <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Russell King <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Mark Salyzyn <[email protected]>
Cc: Peter Collingbourne <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Dmitry Safonov <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Huw Davies <[email protected]>
Cc: Shijith Thotton <[email protected]>
Cc: Andre Przywara <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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Revision tags: v5.2-rc6
# 361f8aee 21-Jun-2019 Vincenzo Frascino <[email protected]>

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 c

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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Shijith Thotton <[email protected]>
Tested-by: Andre Przywara <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Russell King <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Mark Salyzyn <[email protected]>
Cc: Peter Collingbourne <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Dmitry Safonov <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Huw Davies <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

show more ...