commit a55c1fdad5f61b4bfe42319694b23671a758cb28 upstream.
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.
The patch deviates from upstream commit due to the unification of arch_raw_cpu_ptr() defines in the commit:
4e5b0e8003df ("x86/percpu: Unify arch_raw_cpu_ptr() defines").
Fixes: 9a462b9eafa6 ("x86/percpu: Use compiler segment prefix qualifier") Reported-by: Charlemagne Lasse charlemagnelasse@gmail.com Closes: https://lore.kernel.org/lkml/CAFGhKbzev7W4aHwhFPWwMZQEHenVgZUj7=aunFieVqZg3m... Cc: stable@vger.kernel.org # v6.8 Link: https://lore.kernel.org/r/20240402175058.52649-1-ubizjak@gmail.com Signed-off-by: Uros Bizjak ubizjak@gmail.com --- arch/x86/include/asm/percpu.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h index 44958ebaf626..66ed36b8cdb4 100644 --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -70,7 +70,7 @@ unsigned long tcp_ptr__; \ tcp_ptr__ = __raw_cpu_read(, this_cpu_off); \ \ - tcp_ptr__ += (unsigned long)(ptr); \ + tcp_ptr__ += (__force unsigned long)(ptr); \ (typeof(*(ptr)) __kernel __force *)tcp_ptr__; \ }) #else /* CONFIG_USE_X86_SEG_SUPPORT */ @@ -85,7 +85,7 @@ : "=r" (tcp_ptr__) \ : "m" (__my_cpu_var(this_cpu_off))); \ \ - tcp_ptr__ += (unsigned long)(ptr); \ + tcp_ptr__ += (__force unsigned long)(ptr); \ (typeof(*(ptr)) __kernel __force *)tcp_ptr__; \ }) #endif /* CONFIG_USE_X86_SEG_SUPPORT */ @@ -102,8 +102,8 @@ #endif /* CONFIG_SMP */
#define __my_cpu_type(var) typeof(var) __percpu_seg_override -#define __my_cpu_ptr(ptr) (__my_cpu_type(*ptr) *)(uintptr_t)(ptr) -#define __my_cpu_var(var) (*__my_cpu_ptr(&var)) +#define __my_cpu_ptr(ptr) (__my_cpu_type(*(ptr))*)(__force uintptr_t)(ptr) +#define __my_cpu_var(var) (*__my_cpu_ptr(&(var))) #define __percpu_arg(x) __percpu_prefix "%" #x #define __force_percpu_arg(x) __force_percpu_prefix "%" #x