Marco Elver [off-list ref] writes:

On Mon, 27 Feb 2023 at 23:16, Andrew Morton [off-list ref] wrote:

quoted

On Mon, 27 Feb 2023 10:47:27 +0100 Marco Elver [off-list ref] wrote:

quoted

With appropriate compiler support [1], KASAN builds use __asan prefixed
meminstrinsics, and KASAN no longer overrides memcpy/memset/memmove.

If compiler support is detected (CC_HAS_KASAN_MEMINTRINSIC_PREFIX),
define memintrinsics normally (do not prefix '__').

On powerpc, KASAN is the only user of __mem functions, which are used to
define instrumented memintrinsics. Alias the normal versions for KASAN
to use in its implementation.

Link: https://lore.kernel.org/all/20230224085942.1791837-1-elver@google.com/ (local) [1]
Link: https://lore.kernel.org/oe-kbuild-all/202302271348.U5lvmo0S-lkp@intel.com/ (local)
Reported-by: kernel test robot <redacted>
Signed-off-by: Marco Elver <elver@google.com>

Seems this is a fix against "kasan: treat meminstrinsic as builtins in
uninstrumented files", so I'll plan to fold this patch into that patch.

Yes, that looks right.

If a powerpc maintainer could take a quick look as well would be good.

The patch looks OK to me. It builds for various configs and I did a few
test boots with KASAN enabled, everything seems normal.

Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

The maze of memcpy/memmove/memset definitions and redefinitions isn't
the simplest - I hope in a few years we can delete all the old code
(before CC_HAS_KASAN_MEMINTRINSIC_PREFIX), and let the compilers just
"do the right thing".

Yeah that would be nice.

cheers