Re: [PATCH 00/13] kmsan: Enable on powerpc

[Christophe Leroy]

Le 14/12/2023 à 06:55, Nicholas Miehlbradt a écrit :
> This series provides the minimal support for Kernal Memory Sanitizer on
> powerpc pseries le guests. Kernal Memory Sanitizer is a tool which detects
> uses of uninitialized memory. Currently KMSAN is clang only.
> 
> The clang support for powerpc has not yet been merged, the pull request can
> be found here [1].

As clang doesn't support it yet, it is probably prematurate to merge 
that in the kernel.

I have open https://github.com/linuxppc/issues/issues/475 to follow through

In the meantime I flag this series as "change requested" for a revisit 
it when time comes

Christophe

> 
> In addition to this series, there are a number of changes required in
> generic kmsan code. These changes are already on mailing lists as part of
> the series implementing KMSAN for s390 [2]. This series is intended to be
> rebased on top of the s390 series.
> 
> In addition, I found a bug in the rtc driver used on powerpc. I have sent
> a fix to this in a seperate series [3].
> 
> With this series and the two series mentioned above, I can successfully
> boot pseries le defconfig without KMSAN warnings. I have not tested other
> powerpc platforms.
> 
> [1] https://github.com/llvm/llvm-project/pull/73611
> [2] https://lore.kernel.org/linux-mm/20231121220155.1217090-1-iii@xxxxxxxxxxxxx/
> [3] https://lore.kernel.org/linux-rtc/20231129073647.2624497-1-nicholas@xxxxxxxxxxxxx/
> 
> Nicholas Miehlbradt (13):
>    kmsan: Export kmsan_handle_dma
>    hvc: Fix use of uninitialized array in udbg_hvc_putc
>    powerpc: Disable KMSAN santitization for prom_init, vdso and purgatory
>    powerpc: Disable CONFIG_DCACHE_WORD_ACCESS when KMSAN is enabled
>    powerpc: Unpoison buffers populated by hcalls
>    powerpc/pseries/nvram: Unpoison buffer populated by rtas_call
>    powerpc/kprobes: Unpoison instruction in kprobe struct
>    powerpc: Unpoison pt_regs
>    powerpc: Disable KMSAN checks on functions which walk the stack
>    powerpc: Define KMSAN metadata address ranges for vmalloc and ioremap
>    powerpc: Implement architecture specific KMSAN interface
>    powerpc/string: Add KMSAN support
>    powerpc: Enable KMSAN on powerpc
> 
>   arch/powerpc/Kconfig                          |  3 +-
>   arch/powerpc/include/asm/book3s/64/pgtable.h  | 42 +++++++++++++++
>   arch/powerpc/include/asm/interrupt.h          |  2 +
>   arch/powerpc/include/asm/kmsan.h              | 51 +++++++++++++++++++
>   arch/powerpc/include/asm/string.h             | 18 ++++++-
>   arch/powerpc/kernel/Makefile                  |  2 +
>   arch/powerpc/kernel/irq_64.c                  |  2 +
>   arch/powerpc/kernel/kprobes.c                 |  2 +
>   arch/powerpc/kernel/module.c                  |  2 +-
>   arch/powerpc/kernel/process.c                 |  6 +--
>   arch/powerpc/kernel/stacktrace.c              | 10 ++--
>   arch/powerpc/kernel/vdso/Makefile             |  1 +
>   arch/powerpc/lib/Makefile                     |  2 +
>   arch/powerpc/lib/mem_64.S                     |  5 +-
>   arch/powerpc/lib/memcpy_64.S                  |  2 +
>   arch/powerpc/perf/callchain.c                 |  2 +-
>   arch/powerpc/platforms/pseries/hvconsole.c    |  2 +
>   arch/powerpc/platforms/pseries/nvram.c        |  4 ++
>   arch/powerpc/purgatory/Makefile               |  1 +
>   arch/powerpc/sysdev/xive/spapr.c              |  3 ++
>   drivers/tty/hvc/hvc_vio.c                     |  2 +-
>   mm/kmsan/hooks.c                              |  1 +
>   .../selftests/powerpc/copyloops/asm/kmsan.h   |  0
>   .../powerpc/copyloops/linux/export.h          |  1 +
>   24 files changed, 152 insertions(+), 14 deletions(-)
>   create mode 100644 arch/powerpc/include/asm/kmsan.h
>   create mode 100644 tools/testing/selftests/powerpc/copyloops/asm/kmsan.h
>