linux.git/lib/vdso, branch arm64-uaccess

vdso: Fix powerpc build U64_MAX undeclared error

2024-04-09T10:35:19+00:00

U64_MAX is not in include/vdso/limits.h, although that isn't noticed on x86
because x86 includes include/linux/limits.h indirectly. However powerpc is
more selective, resulting in the following build error:

  In file included from :
  lib/vdso/gettimeofday.c: In function 'vdso_calc_ns':
  lib/vdso/gettimeofday.c:11:33: error: 'U64_MAX' undeclared
     11 | # define VDSO_DELTA_MASK(vd)    U64_MAX
        |                                 ^~~~~~~

Use ULLONG_MAX instead which will work just as well and is in
include/vdso/limits.h.

Fixes: c8e3a8b6f2e6 ("vdso: Consolidate vdso_calc_delta()")
Reported-by: Stephen Rothwell 
Signed-off-by: Adrian Hunter 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20240409062639.3393-1-adrian.hunter@intel.com
Closes: https://lore.kernel.org/all/20240409124905.6816db37@canb.auug.org.au/

vdso: Make delta calculation overflow safe

2024-04-08T13:03:07+00:00

Kernel timekeeping is designed to keep the change in cycles (since the last
timer interrupt) below max_cycles, which prevents multiplication overflow
when converting cycles to nanoseconds. However, if timer interrupts stop,
the calculation will eventually overflow.

Add protection against that, enabled by config option
CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT. Check against max_cycles, falling
back to a slower higher precision calculation.

Suggested-by: Thomas Gleixner 
Signed-off-by: Adrian Hunter 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20240325064023.2997-8-adrian.hunter@intel.com

vdso: Add CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT

2024-04-08T13:03:06+00:00

Add CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT in preparation to add
multiplication overflow protection to the VDSO time getter functions.

Suggested-by: Thomas Gleixner 
Signed-off-by: Adrian Hunter 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20240325064023.2997-4-adrian.hunter@intel.com

vdso: Consolidate nanoseconds calculation

2024-04-08T13:03:06+00:00

Consolidate nanoseconds calculation to simplify and reduce code
duplication.

Suggested-by: Thomas Gleixner 
Signed-off-by: Adrian Hunter 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20240325064023.2997-3-adrian.hunter@intel.com

vdso: Consolidate vdso_calc_delta()

2024-04-08T13:03:06+00:00

Consolidate vdso_calc_delta(), in preparation for further simplification.

Suggested-by: Thomas Gleixner 
Signed-off-by: Adrian Hunter 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20240325064023.2997-2-adrian.hunter@intel.com

vdso: Improve cmd_vdso_check to check all dynamic relocations

2023-03-21T20:15:34+00:00

The actual intention is that no dynamic relocation exists in the VDSO. For
this the VDSO build validates that the resulting .so file does not have any
relocations which are specified via $(ARCH_REL_TYPE_ABS) per architecture,
which is fragile as e.g. ARM64 lacks an entry for R_AARCH64_RELATIVE. Aside
of that ARCH_REL_TYPE_ABS is a misnomer as it checks for relative
relocations too.

However, some GNU ld ports produce unneeded R_*_NONE relocation entries. If
a port fails to determine the exact .rel[a].dyn size, the trailing zeros
become R_*_NONE relocations. E.g. ld's powerpc port recently fixed
https://sourceware.org/bugzilla/show_bug.cgi?id=29540). R_*_NONE are
generally a no-op in the dynamic loaders. So just ignore them.

Remove the ARCH_REL_TYPE_ABS defines and just validate that the resulting
.so file does not contain any R_* relocation entries except R_*_NONE.

Signed-off-by: Fangrui Song 
Signed-off-by: Thomas Gleixner 
Tested-by: Vincenzo Frascino  # for aarch64
Reviewed-by: Christophe Leroy 
Reviewed-by: Vincenzo Frascino  # for vDSO, aarch64
Acked-by: Michael Ellerman  (powerpc)
Link: https://lore.kernel.org/r/20230310190750.3323802-1-maskray@google.com

lib/vdso: use "grep -E" instead of "egrep"

2022-11-23T18:50:15+00:00

The latest version of grep claims the egrep is now obsolete so the build
now contains warnings that look like:
	egrep: warning: egrep is obsolescent; using grep -E
fix this up by moving the vdso Makefile to use "grep -E" instead.

Cc: Andy Lutomirski 
Cc: Thomas Gleixner 
Reviewed-by: Vincenzo Frascino 
Link: https://lore.kernel.org/r/20220920170633.3133829-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman

lib/vdso: Add vdso_data pointer as input to __arch_get_timens_vdso_data()

2021-04-14T13:04:44+00:00

For the same reason as commit e876f0b69dc9 ("lib/vdso: Allow
architectures to provide the vdso data pointer"), powerpc wants to
avoid calculation of relative position to code.

As the timens_vdso_data is next page to vdso_data, provide
vdso_data pointer to __arch_get_timens_vdso_data() in order
to ease the calculation on powerpc in following patches.

Signed-off-by: Christophe Leroy 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Vincenzo Frascino 
Acked-by: Andrei Vagin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/539c4204b1baa77c55f758904a1ea239abbc7a5c.1617209142.git.christophe.leroy@csgroup.eu

lib/vdso: Mark do_hres_timens() and do_coarse_timens() __always_inline()

2021-04-14T13:04:44+00:00

In the same spirit as commit c966533f8c6c ("lib/vdso: Mark do_hres()
and do_coarse() as __always_inline"), mark do_hres_timens() and
do_coarse_timens() __always_inline.

The measurement below in on a non timens process, ie on the fastest path.

On powerpc32, without the patch:

clock-gettime-monotonic-raw:    vdso: 1155 nsec/call
clock-gettime-monotonic-coarse:    vdso: 813 nsec/call
clock-gettime-monotonic:    vdso: 1076 nsec/call

With the patch:

clock-gettime-monotonic-raw:    vdso: 1100 nsec/call
clock-gettime-monotonic-coarse:    vdso: 667 nsec/call
clock-gettime-monotonic:    vdso: 1025 nsec/call

Signed-off-by: Christophe Leroy 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Vincenzo Frascino 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/90dcf45ebadfd5a07f24241551c62f619d1cb930.1617209142.git.christophe.leroy@csgroup.eu

vdso/treewide: Add vdso_data pointer argument to __arch_get_hw_counter()

2020-08-06T08:57:30+00:00

MIPS already uses and S390 will need the vdso data pointer in
__arch_get_hw_counter().

This works nicely as long as the architecture does not support time
namespaces in the VDSO. With time namespaces enabled the regular
accessor to the vdso data pointer __arch_get_vdso_data() will return the
namespace specific VDSO data page for tasks which are part of a
non-root time namespace. This would cause the architectures which need
the vdso data pointer in __arch_get_hw_counter() to access the wrong
vdso data page.

Add a vdso_data pointer argument to __arch_get_hw_counter() and hand it in
from the call sites in the core code. For architectures which do not need
the data pointer in their counter accessor function the compiler will just
optimize it out.

Fix up all existing architecture implementations and make MIPS utilize the
pointer instead of invoking the accessor function.

No functional change and no change in the resulting object code (except
MIPS).

Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/draft-87wo2ekuzn.fsf@nanos.tec.linutronix.de