Commit ccb88db8dac8 ("bpf: Don't hand out a linked element as extra element") made alloc_htab_elem() take the per-cpu spare element with try_cmpxchg_local(), the first caller of cmpxchg_local() outside of architecture code. It doesn't build on arc, hexagon and openrisc: include/linux/atomic/atomic-arch-fallback.h:384:27: error: implicit declaration of function 'arch_cmpxchg_local'; did you mean 'raw_cmpxchg_local'? [-Werror=implicit-function-declaration] raw_cmpxchg_local() maps to arch_cmpxchg_local() unconditionally, but these three architectures don't define it, and unlike nios2 and microblaze they don't get it from asm-generic/cmpxchg.h either. cmpxchg_local() only has to be atomic with respect to the local CPU, so an architecture's own arch_cmpxchg() can serve for the sizes it supports. arc uses its relaxed LLOCK/SCOND variant when ARC_HAS_LLSC is set and its atomic_ops_lock() variant otherwise, and openrisc uses its LL/SC arch_cmpxchg(), the way arm64, riscv and s390 alias theirs. The hexagon arch_cmpxchg() only handles 32-bit words, so hexagon uses the generic version that disables interrupts, like sh, sparc32 and xtensa do. Linux has no NMIs on hexagon, so that is sufficient there. Fixes: ccb88db8dac8 ("bpf: Don't hand out a linked element as extra element") Reported-by: kernelci.org bot Closes: https://d.kernelci.org/i/maestro:78b65519ee4561df1fbf1e72f1dec9da7e5b153e Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202610181750.BoqAddaF-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202610182048.aEaiBP8W-lkp@intel.com/ Signed-off-by: Sasha Levin --- The only user is in bpf-next, so it is probably easiest to take this through bpf-next with acks from the arc, hexagon and openrisc maintainers. A similar change was posted in 2023 for objpool and stalled once objpool stopped using try_cmpxchg_local(): https://lore.kernel.org/all/20231121142347.241356-1-wuqiang.matt@bytedance.com/ Build tested on arc with and without LLSC (including both KernelCI configs), hexagon (clang) and openrisc. arch/arc/include/asm/cmpxchg.h | 4 ++++ arch/hexagon/include/asm/cmpxchg.h | 6 ++++++ arch/openrisc/include/asm/cmpxchg.h | 2 ++ 3 files changed, 12 insertions(+) diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h index 66b3743c94008..93f7153eb267a 100644 --- a/arch/arc/include/asm/cmpxchg.h +++ b/arch/arc/include/asm/cmpxchg.h @@ -59,6 +59,8 @@ _prev_; \ }) +#define arch_cmpxchg_local arch_cmpxchg_relaxed + #else #define arch_cmpxchg(ptr, old, new) \ @@ -80,6 +82,8 @@ _prev_; \ }) +#define arch_cmpxchg_local arch_cmpxchg + #endif /* diff --git a/arch/hexagon/include/asm/cmpxchg.h b/arch/hexagon/include/asm/cmpxchg.h index 9c58fb81f7fd6..e6114e713db9f 100644 --- a/arch/hexagon/include/asm/cmpxchg.h +++ b/arch/hexagon/include/asm/cmpxchg.h @@ -8,6 +8,8 @@ #ifndef _ASM_CMPXCHG_H #define _ASM_CMPXCHG_H +#include + /* * __arch_xchg - atomically exchange a register and a memory location * @x: value to swap @@ -72,4 +74,8 @@ __arch_xchg(unsigned long x, volatile void *ptr, int size) __oldval; \ }) +#define arch_cmpxchg_local(ptr, o, n) \ + ((__typeof__(*(ptr)))__generic_cmpxchg_local((ptr), \ + (unsigned long)(o), (unsigned long)(n), sizeof(*(ptr)))) + #endif /* _ASM_CMPXCHG_H */ diff --git a/arch/openrisc/include/asm/cmpxchg.h b/arch/openrisc/include/asm/cmpxchg.h index 8ee151c072e41..fcf1bc8db8fe9 100644 --- a/arch/openrisc/include/asm/cmpxchg.h +++ b/arch/openrisc/include/asm/cmpxchg.h @@ -140,6 +140,8 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, sizeof(*(ptr))); \ }) +#define arch_cmpxchg_local arch_cmpxchg + /* * This function doesn't exist, so you'll get a linker error if * something tries to do an invalidly-sized xchg(). base-commit: a6303535c2ad9d49598d52556183911f02287791 -- 2.53.0