2020-06-08 17:49:17

by Alexander Gordeev

Subject: [PATCH v2] lib: fix bitmap_parse() on 64-bit big endian archs

Commit 2d6261583be0 ("lib: rework bitmap_parse()") does not
take into account order of halfwords on 64-bit big endian
architectures. As result (at least) Receive Packet Steering,
IRQ affinity masks and runtime kernel test "test_bitmap" get
broken on s390.

Fixes: 2d6261583be0 ("lib: rework bitmap_parse()")
Cc: [email protected]
Cc: Andrew Morton <[email protected]>
Cc: Yury Norov <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Amritha Nambiar <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Miklos Szeredi <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Steffen Klassert <[email protected]>
Cc: "Tobin C . Harding" <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Signed-off-by: Alexander Gordeev <[email protected]>
---
lib/bitmap.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 89260aa342d6..80d26b183248 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -739,6 +739,7 @@ int bitmap_parse(const char *start, unsigned int buflen,
const char *end = strnchrnul(start, buflen, '\n') - 1;
int chunks = BITS_TO_U32(nmaskbits);
u32 *bitmap = (u32 *)maskp;
+ int chunk = 0;
int unset_bit;

while (1) {
@@ -749,9 +750,14 @@ int bitmap_parse(const char *start, unsigned int buflen,
if (!chunks--)
return -EOVERFLOW;

- end = bitmap_get_x32_reverse(start, end, bitmap++);
+#if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN)
+ end = bitmap_get_x32_reverse(start, end, &bitmap[chunk ^ 1]);
+#else
+ end = bitmap_get_x32_reverse(start, end, &bitmap[chunk]);
+#endif
if (IS_ERR(end))
return PTR_ERR(end);
+ chunk++;
}

unset_bit = (BITS_TO_U32(nmaskbits) - chunks) * 32;
--
2.23.0

2020-06-09 10:50:37

by Andy Shevchenko

Subject: Re: [PATCH v2] lib: fix bitmap_parse() on 64-bit big endian archs

On Mon, Jun 8, 2020 at 8:47 PM Alexander Gordeev <[email protected]> wrote:
>
> Commit 2d6261583be0 ("lib: rework bitmap_parse()") does not
> take into account order of halfwords on 64-bit big endian
> architectures. As result (at least) Receive Packet Steering,
> IRQ affinity masks and runtime kernel test "test_bitmap" get
> broken on s390.

LGTM (I would replace while loop, but it's style preference and one
can consider worse than infinite loop)

Reviewed-by: Andy Shevchenko <[email protected]>

>
> Fixes: 2d6261583be0 ("lib: rework bitmap_parse()")
> Cc: [email protected]
> Cc: Andrew Morton <[email protected]>
> Cc: Yury Norov <[email protected]>
> Cc: Andy Shevchenko <[email protected]>
> Cc: Amritha Nambiar <[email protected]>
> Cc: Arnaldo Carvalho de Melo <[email protected]>
> Cc: Chris Wilson <[email protected]>
> Cc: Kees Cook <[email protected]>
> Cc: Matthew Wilcox <[email protected]>
> Cc: Miklos Szeredi <[email protected]>
> Cc: Rasmus Villemoes <[email protected]>
> Cc: Steffen Klassert <[email protected]>
> Cc: "Tobin C . Harding" <[email protected]>
> Cc: Vineet Gupta <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Willem de Bruijn <[email protected]>
> Signed-off-by: Alexander Gordeev <[email protected]>
> ---
> lib/bitmap.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index 89260aa342d6..80d26b183248 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -739,6 +739,7 @@ int bitmap_parse(const char *start, unsigned int buflen,
> const char *end = strnchrnul(start, buflen, '\n') - 1;
> int chunks = BITS_TO_U32(nmaskbits);
> u32 *bitmap = (u32 *)maskp;
> + int chunk = 0;
> int unset_bit;
>
> while (1) {
> @@ -749,9 +750,14 @@ int bitmap_parse(const char *start, unsigned int buflen,
> if (!chunks--)
> return -EOVERFLOW;
>
> - end = bitmap_get_x32_reverse(start, end, bitmap++);
> +#if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN)
> + end = bitmap_get_x32_reverse(start, end, &bitmap[chunk ^ 1]);
> +#else
> + end = bitmap_get_x32_reverse(start, end, &bitmap[chunk]);
> +#endif
> if (IS_ERR(end))
> return PTR_ERR(end);
> + chunk++;
> }
>
> unset_bit = (BITS_TO_U32(nmaskbits) - chunks) * 32;
> --
> 2.23.0
>


--
With Best Regards,
Andy Shevchenko