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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2010-01-29 07:25:12 -0500
committerIngo Molnar <mingo@elte.hu>2010-02-04 03:59:50 -0500
commitfce877e3a429940a986e085a41e8b57f2d922e36 (patch)
tree5bdf6beeda1cfe774dc2a633454bd4d1546e1c08
parent8c48e444191de0ff84e85d41180d7bc3e74f14ef (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.c10
-rw-r--r--include/linux/bitops.h33
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 {
93 struct perf_event *event_list[X86_PMC_IDX_MAX]; /* in enabled order */ 93 struct perf_event *event_list[X86_PMC_IDX_MAX]; /* in enabled order */
94}; 94};
95 95
96#define EVENT_CONSTRAINT(c, n, m) { \ 96#define __EVENT_CONSTRAINT(c, n, m, w) {\
97 { .idxmsk64[0] = (n) }, \ 97 { .idxmsk64[0] = (n) }, \
98 .code = (c), \ 98 .code = (c), \
99 .cmask = (m), \ 99 .cmask = (m), \
100 .weight = HWEIGHT64((u64)(n)), \ 100 .weight = (w), \
101} 101}
102 102
103#define EVENT_CONSTRAINT(c, n, m) \
104 __EVENT_CONSTRAINT(c, n, m, HWEIGHT(n))
105
103#define INTEL_EVENT_CONSTRAINT(c, n) \ 106#define INTEL_EVENT_CONSTRAINT(c, n) \
104 EVENT_CONSTRAINT(c, n, INTEL_ARCH_EVTSEL_MASK) 107 EVENT_CONSTRAINT(c, n, INTEL_ARCH_EVTSEL_MASK)
105 108
@@ -2622,7 +2625,8 @@ void __init init_hw_perf_events(void)
2622 register_die_notifier(&perf_event_nmi_notifier); 2625 register_die_notifier(&perf_event_nmi_notifier);
2623 2626
2624 unconstrained = (struct event_constraint) 2627 unconstrained = (struct event_constraint)
2625 EVENT_CONSTRAINT(0, (1ULL << x86_pmu.num_events) - 1, 0); 2628 __EVENT_CONSTRAINT(0, (1ULL << x86_pmu.num_events) - 1,
2629 0, x86_pmu.num_events);
2626 2630
2627 pr_info("... version: %d\n", x86_pmu.version); 2631 pr_info("... version: %d\n", x86_pmu.version);
2628 pr_info("... bit width: %d\n", x86_pmu.event_bits); 2632 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)
45 return sizeof(w) == 4 ? hweight32(w) : hweight64(w); 45 return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
46} 46}
47 47
48#define HWEIGHT8(w) \ 48/*
49 ( (!!((w) & (1ULL << 0))) + \ 49 * Clearly slow versions of the hweightN() functions, their benefit is
50 (!!((w) & (1ULL << 1))) + \ 50 * of course compile time evaluation of constant arguments.
51 (!!((w) & (1ULL << 2))) + \ 51 */
52 (!!((w) & (1ULL << 3))) + \ 52#define HWEIGHT8(w) \
53 (!!((w) & (1ULL << 4))) + \ 53 ( BUILD_BUG_ON_ZERO(!__builtin_constant_p(w)) + \
54 (!!((w) & (1ULL << 5))) + \ 54 (!!((w) & (1ULL << 0))) + \
55 (!!((w) & (1ULL << 6))) + \ 55 (!!((w) & (1ULL << 1))) + \
56 (!!((w) & (1ULL << 2))) + \
57 (!!((w) & (1ULL << 3))) + \
58 (!!((w) & (1ULL << 4))) + \
59 (!!((w) & (1ULL << 5))) + \
60 (!!((w) & (1ULL << 6))) + \
56 (!!((w) & (1ULL << 7))) ) 61 (!!((w) & (1ULL << 7))) )
57 62
58#define HWEIGHT16(w) (HWEIGHT8(w) + HWEIGHT8(w >> 8)) 63#define HWEIGHT16(w) (HWEIGHT8(w) + HWEIGHT8((w) >> 8))
59#define HWEIGHT32(w) (HWEIGHT16(w) + HWEIGHT16(w >> 16)) 64#define HWEIGHT32(w) (HWEIGHT16(w) + HWEIGHT16((w) >> 16))
60#define HWEIGHT64(w) (HWEIGHT32(w) + HWEIGHT32(w >> 32)) 65#define HWEIGHT64(w) (HWEIGHT32(w) + HWEIGHT32((w) >> 32))
66
67/*
68 * Type invariant version that simply casts things to the
69 * largest type.
70 */
71#define HWEIGHT(w) HWEIGHT64((u64)(w))
61 72
62/** 73/**
63 * rol32 - rotate a 32-bit value left 74 * rol32 - rotate a 32-bit value left