Date: Tue, 9 Feb 2021 08:36:58 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: d4cd9db346bc - stable/12 - x86 vdso gettc: eliminate duplicated code in ifunc selectors. Message-ID: <202102090836.1198awAV014004@gitrepo.freebsd.org>
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The branch stable/12 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=d4cd9db346bc6382b90d585d1aa6b86eda66b7a3 commit d4cd9db346bc6382b90d585d1aa6b86eda66b7a3 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2021-01-06 15:00:48 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2021-02-09 08:36:20 +0000 x86 vdso gettc: eliminate duplicated code in ifunc selectors. Tested by: pho (cherry picked from commit 5bf4bafd13a4044b7c3d2e8246684a597c6f2134) --- lib/libc/x86/sys/__vdso_gettc.c | 87 ++++++++++++++++++++++++++++++----------- 1 file changed, 65 insertions(+), 22 deletions(-) diff --git a/lib/libc/x86/sys/__vdso_gettc.c b/lib/libc/x86/sys/__vdso_gettc.c index f9365eb33cf2..c3ace1685561 100644 --- a/lib/libc/x86/sys/__vdso_gettc.c +++ b/lib/libc/x86/sys/__vdso_gettc.c @@ -83,20 +83,6 @@ rdtsc_low_mb_none(const struct vdso_timehands *th) return (rdtsc_low(th)); } -DEFINE_UIFUNC(static, u_int, __vdso_gettc_rdtsc_low, - (const struct vdso_timehands *th), static) -{ - u_int p[4]; - /* Not a typo, string matches our do_cpuid() registers use. */ - static const char intel_id[] = "GenuntelineI"; - - if ((cpu_feature & CPUID_SSE2) == 0) - return (rdtsc_low_mb_none); - do_cpuid(0, p); - return (memcmp(p + 1, intel_id, sizeof(intel_id) - 1) == 0 ? - rdtsc_low_mb_lfence : rdtsc_low_mb_mfence); -} - static u_int rdtsc32_mb_lfence(void) { @@ -117,17 +103,74 @@ rdtsc32_mb_none(void) return (rdtsc32()); } -DEFINE_UIFUNC(static, u_int, __vdso_gettc_rdtsc32, (void), static) +struct tsc_selector_tag { + u_int (*ts_rdtsc32)(void); + u_int (*ts_rdtsc_low)(const struct vdso_timehands *); +}; + +static const struct tsc_selector_tag tsc_selector[] = { + [0] = { /* Intel or AMD Zen+, LFENCE */ + .ts_rdtsc32 = rdtsc32_mb_lfence, + .ts_rdtsc_low = rdtsc_low_mb_lfence, + }, + [1] = { /* AMD, MFENCE */ + .ts_rdtsc32 = rdtsc32_mb_mfence, + .ts_rdtsc_low = rdtsc_low_mb_mfence, + }, + [2] = { /* No SSE2 */ + .ts_rdtsc32 = rdtsc32_mb_none, + .ts_rdtsc_low = rdtsc_low_mb_none, + }, +}; + +static int +tsc_selector_idx(u_int cpu_feature) { - u_int p[4]; - /* Not a typo, string matches our do_cpuid() registers use. */ - static const char intel_id[] = "GenuntelineI"; + u_int amd_feature, cpu_exthigh, cpu_id, p[4], v[3]; + static const char amd_id[] = "AuthenticAMD"; + static const char hygon_id[] = "HygonGenuine"; + bool amd_cpu; + + if (cpu_feature == 0) + return (2); /* should not happen due to RDTSC */ - if ((cpu_feature & CPUID_SSE2) == 0) - return (rdtsc32_mb_none); do_cpuid(0, p); - return (memcmp(p + 1, intel_id, sizeof(intel_id) - 1) == 0 ? - rdtsc32_mb_lfence : rdtsc32_mb_mfence); + v[0] = p[1]; + v[1] = p[3]; + v[2] = p[2]; + amd_cpu = memcmp(v, amd_id, sizeof(amd_id) - 1) == 0 || + memcmp(v, hygon_id, sizeof(hygon_id) - 1) == 0; + + do_cpuid(1, p); + cpu_id = p[0]; + + if (cpu_feature != 0) { + do_cpuid(0x80000000, p); + cpu_exthigh = p[0]; + } else { + cpu_exthigh = 0; + } + if (cpu_exthigh >= 0x80000001) { + do_cpuid(0x80000001, p); + amd_feature = p[3]; + } else { + amd_feature = 0; + } + + if ((cpu_feature & CPUID_SSE2) == 0) + return (2); + return (amd_cpu ? 1 : 0); +} + +DEFINE_UIFUNC(static, u_int, __vdso_gettc_rdtsc_low, + (const struct vdso_timehands *th), static) +{ + return (tsc_selector[tsc_selector_idx(cpu_feature)].ts_rdtsc_low); +} + +DEFINE_UIFUNC(static, u_int, __vdso_gettc_rdtsc32, (void), static) +{ + return (tsc_selector[tsc_selector_idx(cpu_feature)].ts_rdtsc32); } #define HPET_DEV_MAP_MAX 10
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