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| author | Yury Norov <yury.norov@gmail.com> | 2023-02-27 11:24:36 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-07-19 16:21:58 +0200 |
| commit | 29ddfd5460638469a03f033f24e64fd0e164cc0c (patch) | |
| tree | ac2d0f29590b0308f972772dc488b12944033ae5 /lib | |
| parent | d986fb02a1eae6263a9b646ee538905b3dde5493 (diff) | |
| download | linux-29ddfd5460638469a03f033f24e64fd0e164cc0c.tar.gz | |
lib/bitmap: drop optimization of bitmap_{from,to}_arr64
[ Upstream commit c1d2ba10f594046831d14b03f194e8d05e78abad ]
bitmap_{from,to}_arr64() optimization is overly optimistic on 32-bit LE
architectures when it's wired to bitmap_copy_clear_tail().
bitmap_copy_clear_tail() takes care of unused bits in the bitmap up to
the next word boundary. But on 32-bit machines when copying bits from
bitmap to array of 64-bit words, it's expected that the unused part of
a recipient array must be cleared up to 64-bit boundary, so the last 4
bytes may stay untouched when nbits % 64 <= 32.
While the copying part of the optimization works correct, that clear-tail
trick makes corresponding tests reasonably fail:
test_bitmap: bitmap_to_arr64(nbits == 1): tail is not safely cleared: 0xa5a5a5a500000001 (must be 0x0000000000000001)
Fix it by removing bitmap_{from,to}_arr64() optimization for 32-bit LE
arches.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/lkml/20230225184702.GA3587246@roeck-us.net/
Fixes: 0a97953fd221 ("lib: add bitmap_{from,to}_arr64")
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/bitmap.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/bitmap.c b/lib/bitmap.c index 1c81413c51f8..ddb31015e38a 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -1495,7 +1495,7 @@ void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits) EXPORT_SYMBOL(bitmap_to_arr32); #endif -#if (BITS_PER_LONG == 32) && defined(__BIG_ENDIAN) +#if BITS_PER_LONG == 32 /** * bitmap_from_arr64 - copy the contents of u64 array of bits to bitmap * @bitmap: array of unsigned longs, the destination bitmap |