From: Martin Kepplinger martink@posteo.de
This patch has been added to the stable tree. If you have any objections, please let us know.
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[ Upstream commit 48e203e21b29cd4b2c58403fe8bca68e2e854895 ]
Months back, this was discussed, see https://lkml.org/lkml/2015/1/18/289 The result was the 64-bit version being "likely fine", "valuable" and "correct". The discussion fell asleep but since there are possible users, let's add it.
Signed-off-by: Martin Kepplinger martin.kepplinger@theobroma-systems.com Cc: Peter Zijlstra a.p.zijlstra@chello.nl Cc: Ingo Molnar mingo@redhat.com Cc: Arnaldo Carvalho de Melo acme@kernel.org Cc: Thomas Gleixner tglx@linutronix.de Cc: "H. Peter Anvin" hpa@zytor.com Cc: George Spelvin linux@horizon.com Cc: Rasmus Villemoes linux@rasmusvillemoes.dk Cc: Maxime Coquelin maxime.coquelin@st.com Cc: Denys Vlasenko dvlasenk@redhat.com Cc: Yury Norov yury.norov@gmail.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- include/linux/bitops.h | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 297f5bda4fdf..858020682ac8 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -171,6 +171,17 @@ static inline __s32 sign_extend32(__u32 value, int index) return (__s32)(value << shift) >> shift; }
+/** + * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit + * @value: value to sign extend + * @index: 0 based bit index (0<=index<64) to sign bit + */ +static inline __s64 sign_extend64(__u64 value, int index) +{ + __u8 shift = 63 - index; + return (__s64)(value << shift) >> shift; +} + static inline unsigned fls_long(unsigned long l) { if (sizeof(l) == 4)