From: Vincenzo Frascino vincenzo.frascino@arm.com On Thursday, May 30, 2019 7:16 AM
The x86 vDSO library requires some adaptations to take advantage of the newly introduced generic vDSO library.
Introduce the following changes:
- Modification of vdso.c to be compliant with the common vdso datapage
- Use of lib/vdso for gettimeofday
Cc: Thomas Gleixner tglx@linutronix.de Signed-off-by: Vincenzo Frascino vincenzo.frascino@arm.com
diff --git a/arch/x86/include/asm/mshyperv-tsc.h b/arch/x86/include/asm/mshyperv-tsc.h new file mode 100644 index 000000000000..99c98ccea0bf --- /dev/null +++ b/arch/x86/include/asm/mshyperv-tsc.h @@ -0,0 +1,76 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_MSHYPER_TSCPAGE_H +#define _ASM_X86_MSHYPER_TSCPAGE_H
+#include <asm/hyperv-tlfs.h>
+#ifdef CONFIG_HYPERV_TSCPAGE +struct ms_hyperv_tsc_page *hv_get_tsc_page(void); +static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
u64 *cur_tsc)+{
- u64 scale, offset;
- u32 sequence;
- /*
* The protocol for reading Hyper-V TSC page is specified in Hypervisor* Top-Level Functional Specification ver. 3.0 and above. To get the* reference time we must do the following:* - READ ReferenceTscSequence* A special '0' value indicates the time source is unreliable and we* need to use something else. The currently published specification* versions (up to 4.0b) contain a mistake and wrongly claim '-1'* instead of '0' as the special value, see commit c35b82ef0294.* - ReferenceTime =* ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset* - READ ReferenceTscSequence again. In case its value has changed* since our first reading we need to discard ReferenceTime and repeat* the whole sequence as the hypervisor was updating the page in* between.*/- do {
sequence = READ_ONCE(tsc_pg->tsc_sequence);if (!sequence)return U64_MAX;/** Make sure we read sequence before we read other values from* TSC page.*/smp_rmb();scale = READ_ONCE(tsc_pg->tsc_scale);offset = READ_ONCE(tsc_pg->tsc_offset);*cur_tsc = rdtsc_ordered();/** Make sure we read sequence after we read all other values* from TSC page.*/smp_rmb();- } while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
- return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
+}
+static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg) +{
- u64 cur_tsc;
- return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
+}
+#else +static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void) +{
- return NULL;
+}
+static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
u64 *cur_tsc)+{
- BUG();
- return U64_MAX;
+} +#endif +#endif diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h index cc60e617931c..db095a992f3e 100644 --- a/arch/x86/include/asm/mshyperv.h +++ b/arch/x86/include/asm/mshyperv.h @@ -7,6 +7,7 @@ #include <linux/nmi.h> #include <asm/io.h> #include <asm/hyperv-tlfs.h> +#include <asm/mshyperv-tsc.h> #include <asm/nospec-branch.h>
#define VP_INVAL U32_MAX @@ -387,73 +388,4 @@ static inline int hyperv_flush_guest_mapping_range(u64 as, } #endif /* CONFIG_HYPERV */
-#ifdef CONFIG_HYPERV_TSCPAGE -struct ms_hyperv_tsc_page *hv_get_tsc_page(void); -static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
u64 *cur_tsc)-{
- u64 scale, offset;
- u32 sequence;
- /*
* The protocol for reading Hyper-V TSC page is specified in Hypervisor* Top-Level Functional Specification ver. 3.0 and above. To get the* reference time we must do the following:* - READ ReferenceTscSequence* A special '0' value indicates the time source is unreliable and we* need to use something else. The currently published specification* versions (up to 4.0b) contain a mistake and wrongly claim '-1'* instead of '0' as the special value, see commit c35b82ef0294.* - ReferenceTime =* ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset* - READ ReferenceTscSequence again. In case its value has changed* since our first reading we need to discard ReferenceTime and repeat* the whole sequence as the hypervisor was updating the page in* between.*/- do {
sequence = READ_ONCE(tsc_pg->tsc_sequence);if (!sequence)return U64_MAX;/** Make sure we read sequence before we read other values from* TSC page.*/smp_rmb();scale = READ_ONCE(tsc_pg->tsc_scale);offset = READ_ONCE(tsc_pg->tsc_offset);*cur_tsc = rdtsc_ordered();/** Make sure we read sequence after we read all other values* from TSC page.*/smp_rmb();- } while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
- return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
-}
-static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg) -{
- u64 cur_tsc;
- return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
-}
-#else -static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void) -{
- return NULL;
-}
-static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
u64 *cur_tsc)-{
- BUG();
- return U64_MAX;
-} -#endif #endif
Vincenzo -- these changes for Hyper-V are a subset of a larger patch set I have that moves all of the Hyper-V clock/timer code into a separate clocksource driver in drivers/clocksource, with an include file in includes/clocksource. That new include file should be able to work instead of your new mshyperv-tsc.h. It also has the benefit of being ISA neutral, so it will work with my in-progress patch set to support Linux on Hyper-V on ARM64. See https://lkml.org/lkml/2019/5/27/231 for the new clocksource driver patch set.
Michael