| Message ID | 20230103210648.2569652-1-hjl.tools@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] x86: Check minimum/maximum of non_temporal_threshold [BZ #29953] | expand |
On Tue, Jan 3, 2023 at 1:06 PM H.J. Lu <hjl.tools@gmail.com> wrote: > > The minimum non_temporal_threshold is 0x4040. non_temporal_threshold may > be set to less than the minimum value when the shared cache size isn't > available (e.g., in an emulator) or by the tunable. Add checks for > minimum and maximum of non_temporal_threshold. > > This fixes BZ #29953. > --- > sysdeps/x86/dl-cacheinfo.h | 25 ++++++++++++++++--------- > 1 file changed, 16 insertions(+), 9 deletions(-) > > diff --git a/sysdeps/x86/dl-cacheinfo.h b/sysdeps/x86/dl-cacheinfo.h > index e9f3382108..637b5a022d 100644 > --- a/sysdeps/x86/dl-cacheinfo.h > +++ b/sysdeps/x86/dl-cacheinfo.h > @@ -861,6 +861,18 @@ dl_init_cacheinfo (struct cpu_features *cpu_features) > share of the cache, it has a substantial risk of negatively > impacting the performance of other threads running on the chip. */ > unsigned long int non_temporal_threshold = shared * 3 / 4; > + /* SIZE_MAX >> 4 because memmove-vec-unaligned-erms right-shifts the value of > + 'x86_non_temporal_threshold' by `LOG_4X_MEMCPY_THRESH` (4) and it is best > + if that operation cannot overflow. Minimum of 0x4040 (16448) because the > + L(large_memset_4x) loops need 64-byte to cache align and enough space for > + at least 1 iteration of 4x PAGE_SIZE unrolled loop. Both values are > + reflected in the manual. */ > + unsigned long int maximum_non_temporal_threshold = SIZE_MAX >> 4; > + unsigned long int minimum_non_temporal_threshold = 0x4040; > + if (non_temporal_threshold < minimum_non_temporal_threshold) > + non_temporal_threshold = minimum_non_temporal_threshold; > + else if (non_temporal_threshold > maximum_non_temporal_threshold) > + non_temporal_threshold = maximum_non_temporal_threshold; > > #if HAVE_TUNABLES > /* NB: The REP MOVSB threshold must be greater than VEC_SIZE * 8. */ > @@ -915,8 +927,8 @@ dl_init_cacheinfo (struct cpu_features *cpu_features) > shared = tunable_size; > > tunable_size = TUNABLE_GET (x86_non_temporal_threshold, long int, NULL); > - /* NB: Ignore the default value 0. */ > - if (tunable_size != 0) > + if (tunable_size > minimum_non_temporal_threshold > + && tunable_size <= maximum_non_temporal_threshold) > non_temporal_threshold = tunable_size; > > tunable_size = TUNABLE_GET (x86_rep_movsb_threshold, long int, NULL); > @@ -931,14 +943,9 @@ dl_init_cacheinfo (struct cpu_features *cpu_features) > > TUNABLE_SET_WITH_BOUNDS (x86_data_cache_size, data, 0, SIZE_MAX); > TUNABLE_SET_WITH_BOUNDS (x86_shared_cache_size, shared, 0, SIZE_MAX); > - /* SIZE_MAX >> 4 because memmove-vec-unaligned-erms right-shifts the value of > - 'x86_non_temporal_threshold' by `LOG_4X_MEMCPY_THRESH` (4) and it is best > - if that operation cannot overflow. Minimum of 0x4040 (16448) because the > - L(large_memset_4x) loops need 64-byte to cache align and enough space for > - at least 1 iteration of 4x PAGE_SIZE unrolled loop. Both values are > - reflected in the manual. */ > TUNABLE_SET_WITH_BOUNDS (x86_non_temporal_threshold, non_temporal_threshold, > - 0x4040, SIZE_MAX >> 4); > + minimum_non_temporal_threshold, > + maximum_non_temporal_threshold); > TUNABLE_SET_WITH_BOUNDS (x86_rep_movsb_threshold, rep_movsb_threshold, > minimum_rep_movsb_threshold, SIZE_MAX); > TUNABLE_SET_WITH_BOUNDS (x86_rep_stosb_threshold, rep_stosb_threshold, 1, > -- > 2.39.0 > LGTM.
diff --git a/sysdeps/x86/dl-cacheinfo.h b/sysdeps/x86/dl-cacheinfo.h index e9f3382108..637b5a022d 100644 --- a/sysdeps/x86/dl-cacheinfo.h +++ b/sysdeps/x86/dl-cacheinfo.h @@ -861,6 +861,18 @@ dl_init_cacheinfo (struct cpu_features *cpu_features) share of the cache, it has a substantial risk of negatively impacting the performance of other threads running on the chip. */ unsigned long int non_temporal_threshold = shared * 3 / 4; + /* SIZE_MAX >> 4 because memmove-vec-unaligned-erms right-shifts the value of + 'x86_non_temporal_threshold' by `LOG_4X_MEMCPY_THRESH` (4) and it is best + if that operation cannot overflow. Minimum of 0x4040 (16448) because the + L(large_memset_4x) loops need 64-byte to cache align and enough space for + at least 1 iteration of 4x PAGE_SIZE unrolled loop. Both values are + reflected in the manual. */ + unsigned long int maximum_non_temporal_threshold = SIZE_MAX >> 4; + unsigned long int minimum_non_temporal_threshold = 0x4040; + if (non_temporal_threshold < minimum_non_temporal_threshold) + non_temporal_threshold = minimum_non_temporal_threshold; + else if (non_temporal_threshold > maximum_non_temporal_threshold) + non_temporal_threshold = maximum_non_temporal_threshold; #if HAVE_TUNABLES /* NB: The REP MOVSB threshold must be greater than VEC_SIZE * 8. */ @@ -915,8 +927,8 @@ dl_init_cacheinfo (struct cpu_features *cpu_features) shared = tunable_size; tunable_size = TUNABLE_GET (x86_non_temporal_threshold, long int, NULL); - /* NB: Ignore the default value 0. */ - if (tunable_size != 0) + if (tunable_size > minimum_non_temporal_threshold + && tunable_size <= maximum_non_temporal_threshold) non_temporal_threshold = tunable_size; tunable_size = TUNABLE_GET (x86_rep_movsb_threshold, long int, NULL); @@ -931,14 +943,9 @@ dl_init_cacheinfo (struct cpu_features *cpu_features) TUNABLE_SET_WITH_BOUNDS (x86_data_cache_size, data, 0, SIZE_MAX); TUNABLE_SET_WITH_BOUNDS (x86_shared_cache_size, shared, 0, SIZE_MAX); - /* SIZE_MAX >> 4 because memmove-vec-unaligned-erms right-shifts the value of - 'x86_non_temporal_threshold' by `LOG_4X_MEMCPY_THRESH` (4) and it is best - if that operation cannot overflow. Minimum of 0x4040 (16448) because the - L(large_memset_4x) loops need 64-byte to cache align and enough space for - at least 1 iteration of 4x PAGE_SIZE unrolled loop. Both values are - reflected in the manual. */ TUNABLE_SET_WITH_BOUNDS (x86_non_temporal_threshold, non_temporal_threshold, - 0x4040, SIZE_MAX >> 4); + minimum_non_temporal_threshold, + maximum_non_temporal_threshold); TUNABLE_SET_WITH_BOUNDS (x86_rep_movsb_threshold, rep_movsb_threshold, minimum_rep_movsb_threshold, SIZE_MAX); TUNABLE_SET_WITH_BOUNDS (x86_rep_stosb_threshold, rep_stosb_threshold, 1,