From: Boqun Feng <boqun.feng@gmail.com>
To: linux-hyperv@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Cc: Michael Kelley <mikelley@microsoft.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Sasha Levin <sashal@kernel.org>,
xen-devel@lists.xenproject.org,
Stefano Stabellini <sstabellini@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>
Subject: [RFC 1/6] arm64: hyperv: Allow hv_get_raw_timer() definition to be overridden
Date: Mon, 16 Dec 2019 08:19:17 +0800 [thread overview]
Message-ID: <20191216001922.23008-2-boqun.feng@gmail.com> (raw)
In-Reply-To: <20191216001922.23008-1-boqun.feng@gmail.com>
In order to support vDSO, hv_read_tsc_page() should be able to be called
from userspace if tsc page mapped. As a result, hv_get_raw_timer(),
called by hv_read_tsc_page() requires to be called by both kernel and
vDSO. Currently, it's defined as arch_timer_read_counter(), which is a
function pointer initialized (using a kernel address) by the arch timer
driver, therefore not usable in vDSO.
Fix this by allowing a previous definition to override the default one,
so that in vDSO code, we can define it as a function callable in
userspace.
Signed-off-by: Boqun Feng (Microsoft) <boqun.feng@gmail.com>
---
arch/arm64/include/asm/mshyperv.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index a8468a611912..9cc4aeddf2d0 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -97,8 +97,15 @@ extern void hv_get_vpreg_128(u32 reg, struct hv_get_vp_register_output *result);
#define hv_disable_stimer0_percpu_irq(irq) disable_percpu_irq(irq)
#endif
-/* ARM64 specific code to read the hardware clock */
+/*
+ * ARM64 specific code to read the hardware clock.
+ *
+ * This could be used in both kernel space and userspace (vDSO), so make it
+ * possible for a previous definition to override the default one.
+ */
+#ifndef hv_get_raw_timer
#define hv_get_raw_timer() arch_timer_read_counter()
+#endif
#include <asm-generic/mshyperv.h>
--
2.24.0
next prev parent reply other threads:[~2019-12-16 0:19 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-16 0:19 [RFC 0/6] vDSO support for Hyper-V guest on ARM64 Boqun Feng
2019-12-16 0:19 ` Boqun Feng [this message]
2019-12-16 0:19 ` [RFC 2/6] arm64: vdso: Add support for multiple vDSO data pages Boqun Feng
2019-12-16 0:19 ` [RFC 3/6] arm/arm64: clocksource: Introduce vclock_mode Boqun Feng
2019-12-16 0:19 ` [RFC 4/6] arm64: vdso: hyperv: Map tsc page into vDSO if enabled Boqun Feng
2019-12-16 0:19 ` [RFC 5/6] arm64: hyperv: Enable userspace to read cntvct Boqun Feng
2019-12-16 0:19 ` [RFC 6/6] arm64: hyperv: Enable vDSO Boqun Feng
2019-12-17 14:10 ` Vitaly Kuznetsov
2019-12-18 5:47 ` Boqun Feng
2020-01-23 10:48 ` [RFC 0/6] vDSO support for Hyper-V guest on ARM64 Vincenzo Frascino
2020-01-24 6:32 ` Boqun Feng
2020-01-24 10:24 ` Vincenzo Frascino
2020-01-28 5:58 ` Boqun Feng
2020-01-28 11:48 ` Marc Zyngier
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