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From: Marc Zyngier <maz@kernel.org>
To: Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, kernel-team@android.com,
	stable@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>
Subject: [PATCH v2 1/4] arm64: Introduce a way to disable the 32bit vdso
Date: Mon,  6 Jul 2020 17:37:59 +0100	[thread overview]
Message-ID: <20200706163802.1836732-2-maz@kernel.org> (raw)
In-Reply-To: <20200706163802.1836732-1-maz@kernel.org>

We have a class of errata (grouped under the ARM64_WORKAROUND_1418040
banner) that force the trapping of counter access from 32bit EL0.

We would normally disable the whole vdso for such defect, except that
it would disable it for 64bit userspace as well, which is a shame.

Instead, add a new vdso_clock_mode, which signals that the vdso
isn't usable for compat tasks.  This gets checked in the new
vdso_clocksource_ok() helper, now provided for the 32bit vdso.

Cc: stable@vger.kernel.org
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/include/asm/vdso/clocksource.h         | 7 +++++--
 arch/arm64/include/asm/vdso/compat_gettimeofday.h | 8 +++++++-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/vdso/clocksource.h b/arch/arm64/include/asm/vdso/clocksource.h
index df6ea65c1dec..b054d9febfb5 100644
--- a/arch/arm64/include/asm/vdso/clocksource.h
+++ b/arch/arm64/include/asm/vdso/clocksource.h
@@ -2,7 +2,10 @@
 #ifndef __ASM_VDSOCLOCKSOURCE_H
 #define __ASM_VDSOCLOCKSOURCE_H
 
-#define VDSO_ARCH_CLOCKMODES	\
-	VDSO_CLOCKMODE_ARCHTIMER
+#define VDSO_ARCH_CLOCKMODES					\
+	/* vdso clocksource for both 32 and 64bit tasks */	\
+	VDSO_CLOCKMODE_ARCHTIMER,				\
+	/* vdso clocksource for 64bit tasks only */		\
+	VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT
 
 #endif
diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h
index b6907ae78e53..9a625e8947ff 100644
--- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h
+++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h
@@ -111,7 +111,7 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
 	 * update. Return something. Core will do another round and then
 	 * see the mode change and fallback to the syscall.
 	 */
-	if (clock_mode == VDSO_CLOCKMODE_NONE)
+	if (clock_mode != VDSO_CLOCKMODE_ARCHTIMER)
 		return 0;
 
 	/*
@@ -152,6 +152,12 @@ static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
 	return ret;
 }
 
+static inline bool vdso_clocksource_ok(const struct vdso_data *vd)
+{
+	return vd->clock_mode == VDSO_CLOCKMODE_ARCHTIMER;
+}
+#define vdso_clocksource_ok	vdso_clocksource_ok
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_VDSO_GETTIMEOFDAY_H */
-- 
2.27.0


WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	kernel-team@android.com, linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 1/4] arm64: Introduce a way to disable the 32bit vdso
Date: Mon,  6 Jul 2020 17:37:59 +0100	[thread overview]
Message-ID: <20200706163802.1836732-2-maz@kernel.org> (raw)
In-Reply-To: <20200706163802.1836732-1-maz@kernel.org>

We have a class of errata (grouped under the ARM64_WORKAROUND_1418040
banner) that force the trapping of counter access from 32bit EL0.

We would normally disable the whole vdso for such defect, except that
it would disable it for 64bit userspace as well, which is a shame.

Instead, add a new vdso_clock_mode, which signals that the vdso
isn't usable for compat tasks.  This gets checked in the new
vdso_clocksource_ok() helper, now provided for the 32bit vdso.

Cc: stable@vger.kernel.org
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/include/asm/vdso/clocksource.h         | 7 +++++--
 arch/arm64/include/asm/vdso/compat_gettimeofday.h | 8 +++++++-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/vdso/clocksource.h b/arch/arm64/include/asm/vdso/clocksource.h
index df6ea65c1dec..b054d9febfb5 100644
--- a/arch/arm64/include/asm/vdso/clocksource.h
+++ b/arch/arm64/include/asm/vdso/clocksource.h
@@ -2,7 +2,10 @@
 #ifndef __ASM_VDSOCLOCKSOURCE_H
 #define __ASM_VDSOCLOCKSOURCE_H
 
-#define VDSO_ARCH_CLOCKMODES	\
-	VDSO_CLOCKMODE_ARCHTIMER
+#define VDSO_ARCH_CLOCKMODES					\
+	/* vdso clocksource for both 32 and 64bit tasks */	\
+	VDSO_CLOCKMODE_ARCHTIMER,				\
+	/* vdso clocksource for 64bit tasks only */		\
+	VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT
 
 #endif
diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h
index b6907ae78e53..9a625e8947ff 100644
--- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h
+++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h
@@ -111,7 +111,7 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
 	 * update. Return something. Core will do another round and then
 	 * see the mode change and fallback to the syscall.
 	 */
-	if (clock_mode == VDSO_CLOCKMODE_NONE)
+	if (clock_mode != VDSO_CLOCKMODE_ARCHTIMER)
 		return 0;
 
 	/*
@@ -152,6 +152,12 @@ static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
 	return ret;
 }
 
+static inline bool vdso_clocksource_ok(const struct vdso_data *vd)
+{
+	return vd->clock_mode == VDSO_CLOCKMODE_ARCHTIMER;
+}
+#define vdso_clocksource_ok	vdso_clocksource_ok
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_VDSO_GETTIMEOFDAY_H */
-- 
2.27.0


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  reply	other threads:[~2020-07-06 16:38 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-06 16:37 [PATCH v2 0/4] arm64: Allow the compat vdso to be disabled at runtime Marc Zyngier
2020-07-06 16:37 ` Marc Zyngier
2020-07-06 16:37 ` Marc Zyngier [this message]
2020-07-06 16:37   ` [PATCH v2 1/4] arm64: Introduce a way to disable the 32bit vdso Marc Zyngier
2020-07-10 14:02   ` Sasha Levin
2020-07-06 16:38 ` [PATCH v2 2/4] arm64: arch_timer: Allow an workaround descriptor to disable compat vdso Marc Zyngier
2020-07-06 16:38   ` Marc Zyngier
2020-07-06 16:55   ` Mark Rutland
2020-07-06 16:55     ` Mark Rutland
2020-07-06 16:38 ` [PATCH v2 3/4] arm64: arch_timer: Disable the compat vdso for cores affected by ARM64_WORKAROUND_1418040 Marc Zyngier
2020-07-06 16:38   ` Marc Zyngier
2020-07-06 16:57   ` Mark Rutland
2020-07-06 16:57     ` Mark Rutland
2020-07-06 16:38 ` [PATCH v2 4/4] arm64: Rework ARM_ERRATUM_1414080 handling Marc Zyngier
2020-07-06 16:38   ` Marc Zyngier
2020-07-06 17:12   ` Mark Rutland
2020-07-06 17:12     ` Mark Rutland
2020-07-08 22:02 ` [PATCH v2 0/4] arm64: Allow the compat vdso to be disabled at runtime Will Deacon
2020-07-08 22:02   ` Will Deacon

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