linux-stable.git/arch/mips/include/asm/vdso, branch linux-5.4.y

MIPS: vdso: Invalid GIC access through VDSO

2021-07-20T14:10:53+00:00

[ Upstream commit 47ce8527fbba145a7723685bc9a27d9855e06491 ]

Accessing raw timers (currently only CLOCK_MONOTONIC_RAW) through VDSO
doesn't return the correct time when using the GIC as clock source.
The address of the GIC mapped page is in this case not calculated
correctly. The GIC mapped page is calculated from the VDSO data by
subtracting PAGE_SIZE:

  void *get_gic(const struct vdso_data *data) {
    return (void __iomem *)data - PAGE_SIZE;
  }

However, the data pointer is not page aligned for raw clock sources.
This is because the VDSO data for raw clock sources (CS_RAW = 1) is
stored after the VDSO data for coarse clock sources (CS_HRES_COARSE = 0).
Therefore, only the VDSO data for CS_HRES_COARSE is page aligned:

  +--------------------+
  |                    |
  | vd[CS_RAW]         | ---+
  | vd[CS_HRES_COARSE] |    |
  +--------------------+    | -PAGE_SIZE
  |                    |    |
  |  GIC mapped page   | <--+
  |                    |
  +--------------------+

When __arch_get_hw_counter() is called with &vd[CS_RAW], get_gic returns
the wrong address (somewhere inside the GIC mapped page). The GIC counter
values are not returned which results in an invalid time.

Fixes: a7f4df4e21dd ("MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()")
Signed-off-by: Martin Fäcknitz 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Sasha Levin

mips: Do not include hi and lo in clobber list for R6

2021-05-07T08:51:36+00:00

commit 1d7ba0165d8206ac073f7ac3b14fc0836b66eae7 upstream.

From [1]
"GCC 10 (PR 91233) won't silently allow registers that are not
architecturally available to be present in the clobber list anymore,
resulting in build failure for mips*r6 targets in form of:
...
.../sysdep.h:146:2: error: the register ‘lo’ cannot be clobbered in ‘asm’ for the current target
  146 |  __asm__ volatile (      \
      |  ^~~~~~~

This is because base R6 ISA doesn't define hi and lo registers w/o DSP
extension. This patch provides the alternative clobber list for r6 targets
that won't include those registers."

Since kernel 5.4 and mips support for generic vDSO [2], the kernel fail to
build for mips r6 cpus with gcc 10 for the same reason as glibc.

[1] https://sourceware.org/git/?p=glibc.git;a=commit;h=020b2a97bb15f807c0482f0faee2184ed05bcad8
[2] '24640f233b46 ("mips: Add support for generic vDSO")'

Signed-off-by: Romain Naour 
Signed-off-by: Sudip Mukherjee 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Greg Kroah-Hartman

mips: Fix gettimeofday() in the vdso library

2020-01-17T18:49:04+00:00

[ Upstream commit 7d2aa4bb90f5f6f1b8de8848c26042403f2d7bf9 ]

The libc provides a discovery mechanism for vDSO library and its
symbols. When a symbol is not exposed by the vDSOs the libc falls back
on the system calls.

With the introduction of the unified vDSO library on mips this behavior
is not honored anymore by the kernel in the case of gettimeofday().

The issue has been noticed and reported due to a dhclient failure on the
CI20 board:

root@letux:~# dhclient
../../../../lib/isc/unix/time.c:200: Operation not permitted
root@letux:~#

Restore the original behavior fixing gettimeofday() in the vDSO library.

Reported-by: H. Nikolaus Schaller 
Tested-by: H. Nikolaus Schaller  # CI20 with JZ4780
Signed-off-by: Vincenzo Frascino 
Signed-off-by: Paul Burton 
Cc: mips-creator-ci20-dev@googlegroups.com
Cc: letux-kernel@openphoenux.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Sasha Levin

timekeeping/vsyscall: Update VDSO data unconditionally

2019-11-04T22:02:53+00:00

The update of the VDSO data is depending on __arch_use_vsyscall() returning
True. This is a leftover from the attempt to map the features of various
architectures 1:1 into generic code.

The usage of __arch_use_vsyscall() in the actual vsyscall implementations
got dropped and replaced by the requirement for the architecture code to
return U64_MAX if the global clocksource is not usable in the VDSO.

But the __arch_use_vsyscall() check in the update code stayed which causes
the VDSO data to be stale or invalid when an architecture actually
implements that function and returns False when the current clocksource is
not usable in the VDSO.

As a consequence the VDSO implementations of clock_getres(), time(),
clock_gettime(CLOCK_.*_COARSE) operate on invalid data and return bogus
information.

Remove the __arch_use_vsyscall() check from the VDSO update function and
update the VDSO data unconditionally.

[ tglx: Massaged changelog and removed the now useless implementations in
  	asm-generic/ARM64/MIPS ]

Fixes: 44f57d788e7deecb50 ("timekeeping: Provide a generic update_vsyscall() implementation")
Signed-off-by: Huacai Chen 
Signed-off-by: Thomas Gleixner 
Cc: Andy Lutomirski 
Cc: Vincenzo Frascino 
Cc: Arnd Bergmann 
Cc: Paul Burton 
Cc: linux-mips@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1571887709-11447-1-git-send-email-chenhc@lemote.com

mips: vdso: Fix __arch_get_hw_counter()

2019-10-18T21:29:16+00:00

On some MIPS variants (e.g. MIPS r1), vDSO clock_mode is set to
VDSO_CLOCK_NONE.

When VDSO_CLOCK_NONE is set the expected kernel behavior is to fallback
on syscalls. To do that the generic vDSO library expects UULONG_MAX as
return value of __arch_get_hw_counter().

Fix __arch_get_hw_counter() on MIPS defining a __VDSO_USE_SYSCALL case
that addressed the described scenario.

Reported-by: Maxime Bizon 
Signed-off-by: Vincenzo Frascino 
Tested-by: Maxime Bizon 
Signed-off-by: Paul Burton 
Cc: linux-mips@vger.kernel.org

mips: compat: vdso: Use legacy syscalls as fallback

2019-09-03T14:35:23+00:00

The generic VDSO implementation uses the Y2038 safe clock_gettime64() and
clock_getres_time64() syscalls as fallback for 32bit VDSO. This breaks
seccomp setups because these syscalls might be not (yet) allowed.

Implement the 32bit variants which use the legacy syscalls and select the
variant in the core library.

The 64bit time variants are not removed because they are required for the
time64 based vdso accessors.

Cc: Paul Burton 
Fixes: 00b26474c2f1 ("lib/vdso: Provide generic VDSO implementation")
Signed-off-by: Vincenzo Frascino 
Signed-off-by: Paul Burton 
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: catalin.marinas@arm.com
Cc: will@kernel.org
Cc: tglx@linutronix.de
Cc: salyzyn@android.com
Cc: 0x7f454c46@gmail.com
Cc: luto@kernel.org

mips: fix vdso32 build, again

2019-08-06T21:32:15+00:00

The generic vdso support adds the same #if hack in two places,
asm/vdso/vdso.h and config-n32-o32-env.c, but only the second
is actually used. The result lacks the BUILD_VDSO32_64 macro,
and that triggers a build error:

./include/linux/page-flags-layout.h:95:2: error: #error "Not enough bits in page flags"

Move the macro into the other place, and remove the duplicated
bits.

Reported-by: Guenter Roeck 
Fixes: ee38d94a0ad8 ("page flags: prioritize kasan bits over last-cpuid")
Fixes: 24640f233b46 ("mips: Add support for generic vDSO")
Signed-off-by: Arnd Bergmann 
Signed-off-by: Paul Burton 
Cc: Andrew Morton 
Cc: Andrey Konovalov 
Cc: Andrey Ryabinin 
Cc: Dmitry Vyukov 
Cc: Will Deacon 
Cc: Christoph Lameter 
Cc: Mark Rutland 
Cc: Ralf Baechle 
Cc: Vincenzo Frascino 
Cc: James Hogan 
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

mips: Add clock_getres entry point

2019-07-26T04:45:35+00:00

The generic vDSO library provides an implementation of clock_getres()
that can be leveraged by each architecture.

Add clock_getres() entry point on mips.

Cc: Ralf Baechle 
Cc: Paul Burton 
Signed-off-by: Vincenzo Frascino 
Signed-off-by: Paul Burton

mips: Add support for generic vDSO

2019-07-26T04:45:05+00:00

The mips vDSO library requires some adaptations to take advantage of the
newly introduced generic vDSO library.

Introduce the following changes:
 - Modification of vdso.c to be compliant with the common vdso datapage
 - Use of lib/vdso for gettimeofday

Cc: Ralf Baechle 
Cc: Paul Burton 
Signed-off-by: Vincenzo Frascino 
[paul.burton@mips.com: Prepend $(src) to config-n32-o32-env.c path.]
Signed-off-by: Paul Burton