On Thu, Aug 14, 2025 at 11:49:54AM +0100, James Clark wrote:
Fix holes and convert the long list of bools to single bits to save some space because there's one of these for each ETM.
Signed-off-by: James Clark james.clark@linaro.org
drivers/hwtracing/coresight/coresight-etm4x.h | 39 ++++++++++++++------------- 1 file changed, 20 insertions(+), 19 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h index a355a1e9606d..1c67b263b01b 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.h +++ b/drivers/hwtracing/coresight/coresight-etm4x.h @@ -1020,29 +1020,30 @@ struct etmv4_drvdata { u8 ns_ex_level; u8 q_support; u8 os_lock_model;
- bool sticky_enable;
- bool boot_enable;
- bool os_unlock;
- bool instrp0;
- bool q_filt;
- bool trcbb;
- bool trccond;
- bool retstack;
- bool trccci;
- bool trc_error;
- bool syncpr;
- bool stallctl;
- bool sysstall;
- bool nooverflow;
- bool atbtrig;
- bool lpoverride;
- bool sticky_enable : 1;
- bool boot_enable : 1;
- bool os_unlock : 1;
- bool instrp0 : 1;
- bool q_filt : 1;
- bool trcbb : 1;
- bool trccond : 1;
- bool retstack : 1;
- bool trccci : 1;
- bool trc_error : 1;
- bool syncpr : 1;
- bool stallctl : 1;
- bool sysstall : 1;
- bool nooverflow : 1;
- bool atbtrig : 1;
- bool lpoverride : 1;
- bool state_needs_restore : 1;
- bool skip_power_up : 1;
- bool paused : 1;
I used pahole to check the structure layout. It is good to see that bool fields are packed into single cache line (and we don't expect these fields to modified frequently so no concern for false sharing).
/* XXX 1 byte hole, try to pack */
u16 ccitmin; /* 120 2 */ u8 s_ex_level; /* 122 1 */ u8 ns_ex_level; /* 123 1 */ u8 q_support; /* 124 1 */ u8 os_lock_model; /* 125 1 */ bool sticky_enable:1; /* 126: 0 1 */ bool boot_enable:1; /* 126: 1 1 */ bool os_unlock:1; /* 126: 2 1 */ bool instrp0:1; /* 126: 3 1 */ bool q_filt:1; /* 126: 4 1 */ bool trcbb:1; /* 126: 5 1 */ bool trccond:1; /* 126: 6 1 */ bool retstack:1; /* 126: 7 1 */ bool trccci:1; /* 127: 0 1 */ bool trc_error:1; /* 127: 1 1 */ bool syncpr:1; /* 127: 2 1 */ bool stallctl:1; /* 127: 3 1 */ bool sysstall:1; /* 127: 4 1 */ bool nooverflow:1; /* 127: 5 1 */ bool atbtrig:1; /* 127: 6 1 */ bool lpoverride:1; /* 127: 7 1 */ /* --- cacheline 2 boundary (128 bytes) --- */ bool state_needs_restore:1; /* 128: 0 1 */ bool skip_power_up:1; /* 128: 1 1 */ bool paused:1; /* 128: 2 1 */
Reviewed-by: Leo Yan leo.yan@arm.com
u64 trfcr; struct etmv4_config config; u64 save_trfcr; struct etmv4_save_state *save_state;
- bool state_needs_restore;
- bool skip_power_up;
- bool paused;
- DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
};
-- 2.34.1