diff options
| author | Peter Zijlstra | 2010-01-29 13:25:12 +0100 |
|---|---|---|
| committer | Ingo Molnar | 2010-02-04 09:59:50 +0100 |
| commit | fce877e3a429940a986e085a41e8b57f2d922e36 (patch) | |
| tree | 5bdf6beeda1cfe774dc2a633454bd4d1546e1c08 | |
| parent | 8c48e444191de0ff84e85d41180d7bc3e74f14ef (diff) | |
bitops: Ensure the compile time HWEIGHT is only used for such
Avoid accidental misuse by failing to compile things
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 10 | ||||
| -rw-r--r-- | include/linux/bitops.h | 33 |
2 files changed, 29 insertions, 14 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 5b91992b6b25..96cfc1a4fe9f 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -93,13 +93,16 @@ struct cpu_hw_events { struct perf_event *event_list[X86_PMC_IDX_MAX]; /* in enabled order */ }; -#define EVENT_CONSTRAINT(c, n, m) { \ +#define __EVENT_CONSTRAINT(c, n, m, w) {\ { .idxmsk64[0] = (n) }, \ .code = (c), \ .cmask = (m), \ - .weight = HWEIGHT64((u64)(n)), \ + .weight = (w), \ } +#define EVENT_CONSTRAINT(c, n, m) \ + __EVENT_CONSTRAINT(c, n, m, HWEIGHT(n)) + #define INTEL_EVENT_CONSTRAINT(c, n) \ EVENT_CONSTRAINT(c, n, INTEL_ARCH_EVTSEL_MASK) @@ -2622,7 +2625,8 @@ void __init init_hw_perf_events(void) register_die_notifier(&perf_event_nmi_notifier); unconstrained = (struct event_constraint) - EVENT_CONSTRAINT(0, (1ULL << x86_pmu.num_events) - 1, 0); + __EVENT_CONSTRAINT(0, (1ULL << x86_pmu.num_events) - 1, + 0, x86_pmu.num_events); pr_info("... version: %d\n", x86_pmu.version); pr_info("... bit width: %d\n", x86_pmu.event_bits); diff --git a/include/linux/bitops.h b/include/linux/bitops.h index ba0fd1eb4af7..25b8b2f33ae9 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -45,19 +45,30 @@ static inline unsigned long hweight_long(unsigned long w) return sizeof(w) == 4 ? hweight32(w) : hweight64(w); } -#define HWEIGHT8(w) \ - ( (!!((w) & (1ULL << 0))) + \ - (!!((w) & (1ULL << 1))) + \ - (!!((w) & (1ULL << 2))) + \ - (!!((w) & (1ULL << 3))) + \ - (!!((w) & (1ULL << 4))) + \ - (!!((w) & (1ULL << 5))) + \ - (!!((w) & (1ULL << 6))) + \ +/* + * Clearly slow versions of the hweightN() functions, their benefit is + * of course compile time evaluation of constant arguments. + */ +#define HWEIGHT8(w) \ + ( BUILD_BUG_ON_ZERO(!__builtin_constant_p(w)) + \ + (!!((w) & (1ULL << 0))) + \ + (!!((w) & (1ULL << 1))) + \ + (!!((w) & (1ULL << 2))) + \ + (!!((w) & (1ULL << 3))) + \ + (!!((w) & (1ULL << 4))) + \ + (!!((w) & (1ULL << 5))) + \ + (!!((w) & (1ULL << 6))) + \ (!!((w) & (1ULL << 7))) ) -#define HWEIGHT16(w) (HWEIGHT8(w) + HWEIGHT8(w >> 8)) -#define HWEIGHT32(w) (HWEIGHT16(w) + HWEIGHT16(w >> 16)) -#define HWEIGHT64(w) (HWEIGHT32(w) + HWEIGHT32(w >> 32)) +#define HWEIGHT16(w) (HWEIGHT8(w) + HWEIGHT8((w) >> 8)) +#define HWEIGHT32(w) (HWEIGHT16(w) + HWEIGHT16((w) >> 16)) +#define HWEIGHT64(w) (HWEIGHT32(w) + HWEIGHT32((w) >> 32)) + +/* + * Type invariant version that simply casts things to the + * largest type. + */ +#define HWEIGHT(w) HWEIGHT64((u64)(w)) /** * rol32 - rotate a 32-bit value left |