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In <sys/platform/x86.h>, define CPU features as enum instead of using the C preprocessor magic to make it easier to wrap this functionality in other languages. Move the C preprocessor magic to internal header for better GCC codegen when more than one features are checked in a single expression as in x86-64 dl-hwcaps-subdirs.c. 1. Rename COMMON_CPUID_INDEX_XXX to CPUID_INDEX_XXX. 2. Move CPUID_INDEX_MAX to sysdeps/x86/include/cpu-features.h. 3. Remove struct cpu_features and __x86_get_cpu_features from <sys/platform/x86.h>. 4. Add __x86_get_cpuid_feature_leaf to <sys/platform/x86.h> and put it in libc. 5. Make __get_cpu_features() private to glibc. 6. Replace __x86_get_cpu_features(N) with __get_cpu_features(). 7. Add _dl_x86_get_cpu_features to GLIBC_PRIVATE. 8. Use a single enum index for each CPU feature detection. 9. Pass the CPUID feature leaf to __x86_get_cpuid_feature_leaf. 10. Return zero struct cpuid_feature for the older glibc binary with a smaller CPUID_INDEX_MAX [BZ #27104]. 11. Inside glibc, use the C preprocessor magic so that cpu_features data can be loaded just once leading to more compact code for glibc. 256 bits are used for each CPUID leaf. Some leaves only contain a few features. We can add exceptions to such leaves. But it will increase code sizes and it is harder to provide backward/forward compatibilities when new features are added to such leaves in the future. When new leaves are added, _rtld_global_ro offsets will change which leads to race condition during in-place updates. We may avoid in-place updates by 1. Rename the old glibc. 2. Install the new glibc. 3. Remove the old glibc. NB: A function, __x86_get_cpuid_feature_leaf , is used to avoid the copy relocation issue with IFUNC resolver as shown in IFUNC resolver tests. |
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| .. | ||
| 64 | ||
| x32 | ||
| ____longjmp_chk.S | ||
| __start_context.S | ||
| clone.S | ||
| compat-timer.h | ||
| configure | ||
| configure.ac | ||
| dl-cache.h | ||
| dl-procinfo.c | ||
| dl-procinfo.h | ||
| getcontext.S | ||
| Implies | ||
| kernel_stat.h | ||
| kernel-features.h | ||
| ldconfig.h | ||
| ldd-rewrite.sed | ||
| libmvec.abilist | ||
| makecontext.c | ||
| Makefile | ||
| register-dump.h | ||
| setcontext.S | ||
| sigaction.c | ||
| sigaltstack-offsets.sym | ||
| sigcontextinfo.h | ||
| swapcontext.S | ||
| syscall.S | ||
| syscalls.list | ||
| sysdep.h | ||
| sysdep.S | ||
| timer_create.c | ||
| timer_delete.c | ||
| timer_getoverr.c | ||
| timer_gettime.c | ||
| timer_settime.c | ||
| tst-glibc-hwcaps-2.c | ||
| ucontext_i.sym | ||
| Versions | ||
| vfork.S | ||
| x86-64-isa-level-VALUE.c | ||