linux.git/arch/mips/vdso, branch v4.19.259

MIPS: vdso: Invalid GIC access through VDSO

2021-07-20T14:16:15+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

2021-05-07T08:49:25+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: Sudip Mukherjee 
Signed-off-by: Greg Kroah-Hartman

MIPS: VDSO: Use CLANG_FLAGS instead of filtering out '--target='

2021-03-07T11:18:54+00:00

commit 76d7fff22be3e4185ee5f9da2eecbd8188e76b2c upstream.

Commit ee67855ecd9d ("MIPS: vdso: Allow clang's --target flag in VDSO
cflags") allowed the '--target=' flag from the main Makefile to filter
through to the vDSO. However, it did not bring any of the other clang
specific flags for controlling the integrated assembler and the GNU
tools locations (--prefix=, --gcc-toolchain=, and -no-integrated-as).
Without these, we will get a warning (visible with tinyconfig):

arch/mips/vdso/elf.S:14:1: warning: DWARF2 only supports one section per
compilation unit
.pushsection .note.Linux, "a",@note ; .balign 4 ; .long 2f - 1f ; .long
4484f - 3f ; .long 0 ; 1:.asciz "Linux" ; 2:.balign 4 ; 3:
^
arch/mips/vdso/elf.S:34:2: warning: DWARF2 only supports one section per
compilation unit
 .section .mips_abiflags, "a"
 ^

All of these flags are bundled up under CLANG_FLAGS in the main Makefile
and exported so that they can be added to Makefiles that set their own
CFLAGS. Use this value instead of filtering out '--target=' so there is
no warning and all of the tools are properly used.

Cc: stable@vger.kernel.org
Fixes: ee67855ecd9d ("MIPS: vdso: Allow clang's --target flag in VDSO cflags")
Link: https://github.com/ClangBuiltLinux/linux/issues/1256
Reported-by: Anders Roxell 
Signed-off-by: Nathan Chancellor 
Tested-by: Anders Roxell 
Signed-off-by: Thomas Bogendoerfer 
[nc: Fix conflict due to lack of 99570c3da96a and 076f421da5d4 in 4.19]
Signed-off-by: Nathan Chancellor 
Signed-off-by: Greg Kroah-Hartman

mips/vdso: Fix resource leaks in genvdso.c

2020-09-03T09:24:21+00:00

[ Upstream commit a859647b4e6bfeb192284d27d24b6a0c914cae1d ]

Close "fd" before the return of map_vdso() and close "out_file"
in main().

Signed-off-by: Peng Fan 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Sasha Levin

MIPS: Disable Loongson MMI instructions for kernel build

2019-10-17T20:45:31+00:00

commit 2f2b4fd674cadd8c6b40eb629e140a14db4068fd upstream.

GCC 9.x automatically enables support for Loongson MMI instructions when
using some -march= flags, and then errors out when -msoft-float is
specified with:

  cc1: error: ‘-mloongson-mmi’ must be used with ‘-mhard-float’

The kernel shouldn't be using these MMI instructions anyway, just as it
doesn't use floating point instructions. Explicitly disable them in
order to fix the build with GCC 9.x.

Signed-off-by: Paul Burton 
Fixes: 3702bba5eb4f ("MIPS: Loongson: Add GCC 4.4 support for Loongson2E")
Fixes: 6f7a251a259e ("MIPS: Loongson: Add basic Loongson 2F support")
Fixes: 5188129b8c9f ("MIPS: Loongson-3: Improve -march option and move it to Platform")
Cc: Huacai Chen 
Cc: Jiaxun Yang 
Cc: stable@vger.kernel.org # v2.6.32+
Cc: linux-mips@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

MIPS: VDSO: Include $(ccflags-vdso) in o32,n32 .lds builds

2019-02-15T07:10:12+00:00

commit 67fc5dc8a541e8f458d7f08bf88ff55933bf9f9d upstream.

When generating vdso-o32.lds & vdso-n32.lds for use with programs
running as compat ABIs under 64b kernels, we previously haven't included
the compiler flags that are supposedly common to all ABIs - ie. those in
the ccflags-vdso variable.

This is problematic in cases where we need to provide the -m%-float flag
in order to ensure that we don't attempt to use a floating point ABI
that's incompatible with the target CPU & ABI. For example a toolchain
using current gcc trunk configured --with-fp-32=xx fails to build a
64r6el_defconfig kernel with the following error:

  cc1: error: '-march=mips1' requires '-mfp32'
  make[2]: *** [arch/mips/vdso/Makefile:135: arch/mips/vdso/vdso-o32.lds] Error 1

Include $(ccflags-vdso) for the compat VDSO .lds builds, just as it is
included for the native VDSO .lds & when compiling objects for the
compat VDSOs. This ensures we consistently provide the -msoft-float flag
amongst others, avoiding the problem by ensuring we're agnostic to the
toolchain defaults.

Signed-off-by: Paul Burton 
Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
Cc: linux-mips@vger.kernel.org
Cc: Kevin Hilman 
Cc: Guenter Roeck 
Cc: Maciej W . Rozycki 
Cc: stable@vger.kernel.org # v4.4+
Signed-off-by: Greg Kroah-Hartman

MIPS: VDSO: Use same -m%-float cflag as the kernel proper

2019-02-15T07:10:11+00:00

commit 0648e50e548d881d025b9419a1a168753c8e2bf7 upstream.

The MIPS VDSO build currently doesn't provide the -msoft-float flag to
the compiler as the kernel proper does. This results in an attempt to
use the compiler's default floating point configuration, which can be
problematic in cases where this is incompatible with the target CPU's
-march= flag. For example decstation_defconfig fails to build using
toolchains in which gcc was configured --with-fp-32=xx with the
following error:

    LDS     arch/mips/vdso/vdso.lds
  cc1: error: '-march=r3000' requires '-mfp32'
  make[2]: *** [scripts/Makefile.build:379: arch/mips/vdso/vdso.lds] Error 1

The kernel proper avoids this error because we build with the
-msoft-float compiler flag, rather than using the compiler's default.
Pass this flag through to the VDSO build so that it too becomes agnostic
to the toolchain's floating point configuration.

Note that this is filtered out from KBUILD_CFLAGS rather than simply
always using -msoft-float such that if we switch the kernel to use
-mno-float in the future the VDSO will automatically inherit the change.

The VDSO doesn't actually include any floating point code, and its
.MIPS.abiflags section is already manually generated to specify that
it's compatible with any floating point ABI. As such this change should
have no effect on the resulting VDSO, apart from fixing the build
failure for affected toolchains.

Signed-off-by: Paul Burton 
Reported-by: Kevin Hilman 
Reported-by: Guenter Roeck 
Tested-by: Kevin Hilman 
References: https://lore.kernel.org/linux-mips/1477843551-21813-1-git-send-email-linux@roeck-us.net/
References: https://kernelci.org/build/id/5c4e4ae059b5142a249ad004/logs/
Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
Cc: Maciej W. Rozycki 
Cc: linux-mips@vger.kernel.org
Cc: stable@vger.kernel.org # v4.4+
Signed-off-by: Greg Kroah-Hartman

MIPS: VDSO: Force link endianness

2018-08-07T23:16:13+00:00

When building the VDSO with clang it appears to invoke ld without
specifying endianness, even though clang itself was provided with a -EB
or -EL flag. This results in the build failing due to a mismatch between
the objects that are the input to ld, and the output it is attempting to
create:

  VDSO    arch/mips/vdso/vdso.so.dbg.raw
  mips-linux-ld: arch/mips/vdso/elf.o: compiled for a big endian system
    and target is little endian
  mips-linux-ld: arch/mips/vdso/elf.o: endianness incompatible with that
    of the selected emulation
  mips-linux-ld: failed to merge target specific data of file
    arch/mips/vdso/elf.o
  ...

Work around this problem by explicitly specifying the link endianness
using -Wl,-EB or -Wl,-EL when -EB or -EL are part of KBUILD_CFLAGS. This
resolves the build failure when using clang, and doesn't have any
negative effect on gcc.

Signed-off-by: Paul Burton

MIPS: vdso: Allow clang's --target flag in VDSO cflags

2018-08-06T22:53:33+00:00

The MIPS VDSO code filters out a subset of known-good flags from
KBUILD_CFLAGS to use when building VDSO libraries. When we build using
clang we need to allow the --target flag through, otherwise we'll
generally attempt to build the VDSO for the architecture of the build
machine rather than for MIPS.

Signed-off-by: Paul Burton 
Patchwork: https://patchwork.linux-mips.org/patch/20154/
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org

MIPS: genvdso: Remove GOT checks

2018-08-06T22:28:46+00:00

Our genvdso tool performs some rather paranoid checking that the VDSO
library isn't attempting to make use of a GOT by constraining the number
of entries that the GOT is allowed to contain to the minimum 2 entries
that are always generated by binutils.

Unfortunately lld prior to revision 334390 generates a third entry,
which is unused & thus harmless but falls foul of genvdso's checks &
causes the build to fail.

Since we already check that the VDSO contains no relocations it seems
reasonable to presume that it also doesn't contain use of a GOT, which
would involve relocations. Thus rather than attempting to work around
this issue by allowing 3 GOT entries when using lld, simply remove the
GOT checks which seem overly paranoid.

Signed-off-by: Paul Burton 
Patchwork: https://patchwork.linux-mips.org/patch/20152/
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org