This is a note to let you know that I've just added the patch titled
x86/percpu: Use __force to cast from __percpu address space
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-percpu-use-__force-to-cast-from-__percpu-address.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 630d104c20f3075b584bc06fbe66b71c0b94877e
Author: Uros Bizjak <ubizjak@xxxxxxxxx>
Date: Tue Apr 2 19:50:38 2024 +0200
x86/percpu: Use __force to cast from __percpu address space
[ Upstream commit a55c1fdad5f61b4bfe42319694b23671a758cb28 ]
Fix Sparse warning when casting from __percpu address space by using
__force in the cast. x86 named address spaces are not considered to
be subspaces of the generic (flat) address space, so explicit casts
are required to convert pointers between these address spaces and the
generic address space (the application should cast to uintptr_t and
apply the segment base offset). The cast to uintptr_t removes
__percpu address space tag and Sparse reports:
warning: cast removes address space '__percpu' of expression
Use __force to inform Sparse that the cast is intentional.
Fixes: 9a462b9eafa6 ("x86/percpu: Use compiler segment prefix qualifier")
Reported-by: Charlemagne Lasse <charlemagnelasse@xxxxxxxxx>
Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240402175058.52649-1-ubizjak@xxxxxxxxx
Closes: https://lore.kernel.org/lkml/CAFGhKbzev7W4aHwhFPWwMZQEHenVgZUj7=aunFieVqZg3mt14A@xxxxxxxxxxxxxx/
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index dbfde44d88a31..ce5111cec36e2 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -77,7 +77,7 @@
#define arch_raw_cpu_ptr(_ptr) \
({ \
unsigned long tcp_ptr__ = __raw_my_cpu_offset; \
- tcp_ptr__ += (unsigned long)(_ptr); \
+ tcp_ptr__ += (__force unsigned long)(_ptr); \
(typeof(*(_ptr)) __kernel __force *)tcp_ptr__; \
})
#else
