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mirror of https://sourceware.org/git/glibc.git synced 2025-10-12 19:04:54 +03:00

tunables: Simplify TUNABLE_SET interface

The TUNABLE_SET interface took a primitive C type argument, which
resulted in inconsistent type conversions internally due to incorrect
dereferencing of types, especialy on 32-bit architectures.  This
change simplifies the TUNABLE setting logic along with the interfaces.

Now all numeric tunable values are stored as signed numbers in
tunable_num_t, which is intmax_t.  All calls to set tunables cast the
input value to its primitive type and then to tunable_num_t for
storage.  This relies on gcc-specific (although I suspect other
compilers woul also do the same) unsigned to signed integer conversion
semantics, i.e. the bit pattern is conserved.  The reverse conversion
is guaranteed by the standard.
This commit is contained in:
Siddhesh Poyarekar
2021-02-05 13:18:58 +05:30
parent e604a5e4bb
commit 61117bfa1b
6 changed files with 76 additions and 128 deletions

View File

@@ -104,7 +104,7 @@ init_cpu_features (struct cpu_features *cpu_features)
cpu_features->mte_state = (GLRO (dl_hwcap2) & HWCAP2_MTE) ? mte_state : 0;
/* If we lack the MTE feature, disable the tunable, since it will
otherwise cause instructions that won't run on this CPU to be used. */
TUNABLE_SET (glibc, mem, tagging, unsigned, cpu_features->mte_state);
TUNABLE_SET (glibc, mem, tagging, cpu_features->mte_state);
# endif
if (cpu_features->mte_state & 2)

View File

@@ -929,17 +929,14 @@ dl_init_cacheinfo (struct cpu_features *cpu_features)
rep_stosb_threshold = TUNABLE_GET (x86_rep_stosb_threshold,
long int, NULL);
TUNABLE_SET_WITH_BOUNDS (x86_data_cache_size, long int, data,
TUNABLE_SET_WITH_BOUNDS (x86_data_cache_size, data, 0, (long int) -1);
TUNABLE_SET_WITH_BOUNDS (x86_shared_cache_size, shared, 0, (long int) -1);
TUNABLE_SET_WITH_BOUNDS (x86_non_temporal_threshold, non_temporal_threshold,
0, (long int) -1);
TUNABLE_SET_WITH_BOUNDS (x86_shared_cache_size, long int, shared,
0, (long int) -1);
TUNABLE_SET_WITH_BOUNDS (x86_non_temporal_threshold, long int,
non_temporal_threshold, 0, (long int) -1);
TUNABLE_SET_WITH_BOUNDS (x86_rep_movsb_threshold, long int,
rep_movsb_threshold,
TUNABLE_SET_WITH_BOUNDS (x86_rep_movsb_threshold, rep_movsb_threshold,
minimum_rep_movsb_threshold, (long int) -1);
TUNABLE_SET_WITH_BOUNDS (x86_rep_stosb_threshold, long int,
rep_stosb_threshold, 1, (long int) -1);
TUNABLE_SET_WITH_BOUNDS (x86_rep_stosb_threshold, rep_stosb_threshold, 1,
(long int) -1);
#endif
cpu_features->data_cache_size = data;