diff options
Diffstat (limited to 'include/linux/context_tracking_state.h')
| -rw-r--r-- | include/linux/context_tracking_state.h | 44 |
1 files changed, 37 insertions, 7 deletions
diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h index 7b8433d5a8ef..0b81248aa03e 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -18,12 +18,6 @@ enum ctx_state { CT_STATE_MAX = 4, }; -/* Odd value for watching, else even. */ -#define CT_RCU_WATCHING CT_STATE_MAX - -#define CT_STATE_MASK (CT_STATE_MAX - 1) -#define CT_RCU_WATCHING_MASK (~CT_STATE_MASK) - struct context_tracking { #ifdef CONFIG_CONTEXT_TRACKING_USER /* @@ -44,9 +38,45 @@ struct context_tracking { #endif }; +/* + * We cram two different things within the same atomic variable: + * + * CT_RCU_WATCHING_START CT_STATE_START + * | | + * v v + * MSB [ RCU watching counter ][ context_state ] LSB + * ^ ^ + * | | + * CT_RCU_WATCHING_END CT_STATE_END + * + * Bits are used from the LSB upwards, so unused bits (if any) will always be in + * upper bits of the variable. + */ #ifdef CONFIG_CONTEXT_TRACKING +#define CT_SIZE (sizeof(((struct context_tracking *)0)->state) * BITS_PER_BYTE) + +#define CT_STATE_WIDTH bits_per(CT_STATE_MAX - 1) +#define CT_STATE_START 0 +#define CT_STATE_END (CT_STATE_START + CT_STATE_WIDTH - 1) + +#define CT_RCU_WATCHING_MAX_WIDTH (CT_SIZE - CT_STATE_WIDTH) +#define CT_RCU_WATCHING_WIDTH (IS_ENABLED(CONFIG_RCU_DYNTICKS_TORTURE) ? 2 : CT_RCU_WATCHING_MAX_WIDTH) +#define CT_RCU_WATCHING_START (CT_STATE_END + 1) +#define CT_RCU_WATCHING_END (CT_RCU_WATCHING_START + CT_RCU_WATCHING_WIDTH - 1) +#define CT_RCU_WATCHING BIT(CT_RCU_WATCHING_START) + +#define CT_STATE_MASK GENMASK(CT_STATE_END, CT_STATE_START) +#define CT_RCU_WATCHING_MASK GENMASK(CT_RCU_WATCHING_END, CT_RCU_WATCHING_START) + +#define CT_UNUSED_WIDTH (CT_RCU_WATCHING_MAX_WIDTH - CT_RCU_WATCHING_WIDTH) + +static_assert(CT_STATE_WIDTH + + CT_RCU_WATCHING_WIDTH + + CT_UNUSED_WIDTH == + CT_SIZE); + DECLARE_PER_CPU(struct context_tracking, context_tracking); -#endif +#endif /* CONFIG_CONTEXT_TRACKING */ #ifdef CONFIG_CONTEXT_TRACKING_USER static __always_inline int __ct_state(void) |