To prepare for supporting boot-time page size selection, refactor code to remove assumptions about PAGE_SIZE being compile-time constant. Code intended to be equivalent when compile-time page size is active. Refactor a BUILD_BUG_ON() so that we test against the limit; _format is invariant to page size so testing it is no bigger than the minimum supported size is sufficient. Wrap global variables that are initialized with PAGE_SIZE derived values using DEFINE_GLOBAL_PAGE_SIZE_VAR() so their initialization can be deferred for boot-time page size builds. Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> --- ***NOTE*** Any confused maintainers may want to read the cover note here for context: https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@xxxxxxx/ include/linux/perf_event.h | 2 +- kernel/events/core.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 1a8942277ddad..b7972155f93eb 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1872,7 +1872,7 @@ _name##_show(struct device *dev, \ struct device_attribute *attr, \ char *page) \ { \ - BUILD_BUG_ON(sizeof(_format) >= PAGE_SIZE); \ + BUILD_BUG_ON(sizeof(_format) >= PAGE_SIZE_MIN); \ return sprintf(page, _format "\n"); \ } \ diff --git a/kernel/events/core.c b/kernel/events/core.c index 8a6c6bbcd658a..81149663ab7d8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -419,7 +419,7 @@ static struct kmem_cache *perf_event_cache; int sysctl_perf_event_paranoid __read_mostly = 2; /* Minimum for 512 kiB + 1 user control page */ -int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */ +__DEFINE_GLOBAL_PAGE_SIZE_VAR(int, sysctl_perf_event_mlock, __read_mostly, 512 + (PAGE_SIZE / 1024)); /* 'free' kiB per user */ /* * max perf event sample rate -- 2.43.0
