Date: Sun, 10 Jan 2021 02:43:14 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: de898cb96042 - main - x86 vdso gettc: reorganize ifunctions. Message-ID: <202101100243.10A2hEum058108@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=de898cb96042a026ef703d81aea6cdf1ffce8f32 commit de898cb96042a026ef703d81aea6cdf1ffce8f32 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2021-01-05 21:14:11 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2021-01-10 02:42:34 +0000 x86 vdso gettc: reorganize ifunctions. Instead of providing ifuncs for each kind of fence, define ifuncs that combine fence and invocation of RDTSC. This refactoring makes introduction of RDTSCP use possible. Reviewed by: gallatin, markj MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D27986 --- lib/libc/x86/sys/__vdso_gettc.c | 68 ++++++++++++++++++++++++++++------------- 1 file changed, 47 insertions(+), 21 deletions(-) diff --git a/lib/libc/x86/sys/__vdso_gettc.c b/lib/libc/x86/sys/__vdso_gettc.c index 7a958ca256da..b08b11e9c714 100644 --- a/lib/libc/x86/sys/__vdso_gettc.c +++ b/lib/libc/x86/sys/__vdso_gettc.c @@ -53,57 +53,83 @@ __FBSDID("$FreeBSD$"); #include <x86/ifunc.h> #include "libc_private.h" -static void -rdtsc_mb_lfence(void) +static inline u_int +rdtsc_low(const struct vdso_timehands *th) { + u_int rv; - lfence(); + __asm __volatile("rdtsc; shrd %%cl, %%edx, %0" + : "=a" (rv) : "c" (th->th_x86_shift) : "edx"); + return (rv); } -static void -rdtsc_mb_mfence(void) +static u_int +rdtsc_low_mb_lfence(const struct vdso_timehands *th) { + lfence(); + return (rdtsc_low(th)); +} +static u_int +rdtsc_low_mb_mfence(const struct vdso_timehands *th) +{ mfence(); + return (rdtsc_low(th)); } -static void -rdtsc_mb_none(void) +static u_int +rdtsc_low_mb_none(const struct vdso_timehands *th) { + return (rdtsc_low(th)); } -DEFINE_UIFUNC(static, void, rdtsc_mb, (void)) +DEFINE_UIFUNC(static, u_int, __vdso_gettc_rdtsc_low, + (const struct vdso_timehands *th)) { 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_mb_none); + return (rdtsc_low_mb_none); do_cpuid(0, p); return (memcmp(p + 1, intel_id, sizeof(intel_id) - 1) == 0 ? - rdtsc_mb_lfence : rdtsc_mb_mfence); + rdtsc_low_mb_lfence : rdtsc_low_mb_mfence); } static u_int -__vdso_gettc_rdtsc_low(const struct vdso_timehands *th) +rdtsc32_mb_lfence(void) { - u_int rv; - - rdtsc_mb(); - __asm __volatile("rdtsc; shrd %%cl, %%edx, %0" - : "=a" (rv) : "c" (th->th_x86_shift) : "edx"); - return (rv); + lfence(); + return (rdtsc32()); } static u_int -__vdso_rdtsc32(void) +rdtsc32_mb_mfence(void) { + mfence(); + return (rdtsc32()); +} - rdtsc_mb(); +static u_int +rdtsc32_mb_none(void) +{ return (rdtsc32()); } +DEFINE_UIFUNC(static, u_int, __vdso_gettc_rdtsc32, (void)) +{ + 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 (rdtsc32_mb_none); + do_cpuid(0, p); + return (memcmp(p + 1, intel_id, sizeof(intel_id) - 1) == 0 ? + rdtsc32_mb_lfence : rdtsc32_mb_mfence); +} + #define HPET_DEV_MAP_MAX 10 static volatile char *hpet_dev_map[HPET_DEV_MAP_MAX]; @@ -199,7 +225,7 @@ __vdso_hyperv_tsc(struct hyperv_reftsc *tsc_ref, u_int *tc) scale = tsc_ref->tsc_scale; ofs = tsc_ref->tsc_ofs; - rdtsc_mb(); + mfence(); /* XXXKIB */ tsc = rdtsc(); /* ret = ((tsc * scale) >> 64) + ofs */ @@ -231,7 +257,7 @@ __vdso_gettc(const struct vdso_timehands *th, u_int *tc) switch (th->th_algo) { case VDSO_TH_ALGO_X86_TSC: *tc = th->th_x86_shift > 0 ? __vdso_gettc_rdtsc_low(th) : - __vdso_rdtsc32(); + __vdso_gettc_rdtsc32(); return (0); case VDSO_TH_ALGO_X86_HPET: idx = th->th_x86_hpet_idx;
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