From ff6d62e9edb5dce537a6dd4a237d6053f331f09c Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 25 Dec 2020 07:30:46 -0800 Subject: : Remove the C preprocessor magic In , 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 . 4. Add __x86_get_cpuid_feature_leaf to 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. --- sysdeps/unix/sysv/linux/i386/ld.abilist | 1 - sysdeps/unix/sysv/linux/i386/libc.abilist | 1 + sysdeps/unix/sysv/linux/x86_64/64/ld.abilist | 1 - sysdeps/unix/sysv/linux/x86_64/64/libc.abilist | 1 + sysdeps/unix/sysv/linux/x86_64/tst-glibc-hwcaps-2.c | 3 +-- sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist | 1 - sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist | 1 + 7 files changed, 4 insertions(+), 5 deletions(-) (limited to 'sysdeps/unix') diff --git a/sysdeps/unix/sysv/linux/i386/ld.abilist b/sysdeps/unix/sysv/linux/i386/ld.abilist index 04655651b0..0478e22071 100644 --- a/sysdeps/unix/sysv/linux/i386/ld.abilist +++ b/sysdeps/unix/sysv/linux/i386/ld.abilist @@ -3,4 +3,3 @@ GLIBC_2.1 __libc_stack_end D 0x4 GLIBC_2.1 _dl_mcount F GLIBC_2.3 ___tls_get_addr F GLIBC_2.3 __tls_get_addr F -GLIBC_2.33 __x86_get_cpu_features F diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist index 4f0d3c1eb5..ddc5837059 100644 --- a/sysdeps/unix/sysv/linux/i386/libc.abilist +++ b/sysdeps/unix/sysv/linux/i386/libc.abilist @@ -2229,6 +2229,7 @@ GLIBC_2.32 sigabbrev_np F GLIBC_2.32 sigdescr_np F GLIBC_2.32 strerrordesc_np F GLIBC_2.32 strerrorname_np F +GLIBC_2.33 __x86_get_cpuid_feature_leaf F GLIBC_2.33 fstat F GLIBC_2.33 fstat64 F GLIBC_2.33 fstatat F diff --git a/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist b/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist index e632c6198e..d3cdf7611e 100644 --- a/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist +++ b/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist @@ -2,4 +2,3 @@ GLIBC_2.2.5 __libc_stack_end D 0x8 GLIBC_2.2.5 _dl_mcount F GLIBC_2.2.5 _r_debug D 0x28 GLIBC_2.3 __tls_get_addr F -GLIBC_2.33 __x86_get_cpu_features F diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist index 4fff61818b..2744bba4af 100644 --- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist +++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist @@ -2076,6 +2076,7 @@ GLIBC_2.32 sigabbrev_np F GLIBC_2.32 sigdescr_np F GLIBC_2.32 strerrordesc_np F GLIBC_2.32 strerrorname_np F +GLIBC_2.33 __x86_get_cpuid_feature_leaf F GLIBC_2.33 fstat F GLIBC_2.33 fstat64 F GLIBC_2.33 fstatat F diff --git a/sysdeps/unix/sysv/linux/x86_64/tst-glibc-hwcaps-2.c b/sysdeps/unix/sysv/linux/x86_64/tst-glibc-hwcaps-2.c index fe91bfd224..2d8f7ec462 100644 --- a/sysdeps/unix/sysv/linux/x86_64/tst-glibc-hwcaps-2.c +++ b/sysdeps/unix/sysv/linux/x86_64/tst-glibc-hwcaps-2.c @@ -29,8 +29,7 @@ extern int dso_isa_level (void); static int do_test (void) { - const struct cpu_features *cpu_features - = __x86_get_cpu_features (COMMON_CPUID_INDEX_MAX); + const struct cpu_features *cpu_features = __get_cpu_features (); unsigned int isa_level = get_isa_level (cpu_features); bool has_isa_baseline = ((isa_level & GNU_PROPERTY_X86_ISA_1_BASELINE) == GNU_PROPERTY_X86_ISA_1_BASELINE); diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist index 9d9d0befde..c70bccf782 100644 --- a/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist +++ b/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist @@ -2,4 +2,3 @@ GLIBC_2.16 __libc_stack_end D 0x4 GLIBC_2.16 __tls_get_addr F GLIBC_2.16 _dl_mcount F GLIBC_2.16 _r_debug D 0x14 -GLIBC_2.33 __x86_get_cpu_features F diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist index 102ed47a9c..ce2f4fb72b 100644 --- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist +++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist @@ -2173,6 +2173,7 @@ GLIBC_2.32 sigabbrev_np F GLIBC_2.32 sigdescr_np F GLIBC_2.32 strerrordesc_np F GLIBC_2.32 strerrorname_np F +GLIBC_2.33 __x86_get_cpuid_feature_leaf F GLIBC_2.33 fstat F GLIBC_2.33 fstat64 F GLIBC_2.33 fstatat F -- cgit v1.2.3