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>,
linux-kernel@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 4/4] arm64: Rework ARM_ERRATUM_1414080 handling
Date: Mon, 6 Jul 2020 17:38:02 +0100 [thread overview]
Message-ID: <20200706163802.1836732-5-maz@kernel.org> (raw)
In-Reply-To: <20200706163802.1836732-1-maz@kernel.org>
The current handling of erratum 1414080 has the side effect that
cntkctl_el1 can get changed for both 32 and 64bit tasks.
This isn't a problem so far, but if we ever need to mitigate another
of these errata on the 64bit side, we'd better keep the messing with
cntkctl_el1 local to 32bit tasks.
For that, make sure that on entering the kernel from a 32bit tasks,
userspace access to cntvct gets enabled, and disabled returning to
userspace, while it never gets changed for 64bit tasks.
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kernel/entry.S | 40 +++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 5304d193c79d..8f51f3273bc7 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -167,6 +167,19 @@ alternative_cb_end
stp x28, x29, [sp, #16 * 14]
.if \el == 0
+ .if \regsize == 32
+ // If we come back from a 32bit task on a system affected by
+ // 1418040, let's reenable userspace access to the virtual counter.
+#ifdef CONFIG_ARM64_ERRATUM_1418040
+alternative_if_not ARM64_WORKAROUND_1418040
+ b .L__entry_skip_wa_1418040\@
+alternative_else_nop_endif
+ mrs x0, cntkctl_el1
+ orr x0, x0, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN
+ msr cntkctl_el1, x0
+.L__entry_skip_wa_1418040\@:
+#endif
+ .endif
clear_gp_regs
mrs x21, sp_el0
ldr_this_cpu tsk, __entry_task, x20
@@ -318,7 +331,17 @@ alternative_else_nop_endif
ldr x23, [sp, #S_SP] // load return stack pointer
msr sp_el0, x23
tst x22, #PSR_MODE32_BIT // native task?
- b.eq 3f
+ b.eq 4f
+
+#ifdef CONFIG_ARM64_ERRATUM_1418040
+alternative_if_not ARM64_WORKAROUND_1418040
+ b 3f
+alternative_else_nop_endif
+ mrs x1, cntkctl_el1
+ bic x1, x1, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN
+ msr cntkctl_el1, x1
+3:
+#endif
#ifdef CONFIG_ARM64_ERRATUM_845719
alternative_if ARM64_WORKAROUND_845719
@@ -330,22 +353,7 @@ alternative_if ARM64_WORKAROUND_845719
#endif
alternative_else_nop_endif
#endif
-3:
-#ifdef CONFIG_ARM64_ERRATUM_1418040
-alternative_if_not ARM64_WORKAROUND_1418040
- b 4f
-alternative_else_nop_endif
- /*
- * if (x22.mode32 == cntkctl_el1.el0vcten)
- * cntkctl_el1.el0vcten = ~cntkctl_el1.el0vcten
- */
- mrs x1, cntkctl_el1
- eon x0, x1, x22, lsr #3
- tbz x0, #1, 4f
- eor x1, x1, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN
- msr cntkctl_el1, x1
4:
-#endif
scs_save tsk, x0
/* No kernel C function calls after this as user keys are set. */
--
2.27.0
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next prev parent reply other threads:[~2020-07-06 16:39 UTC|newest]
Thread overview: 9+ 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 ` [PATCH v2 1/4] arm64: Introduce a way to disable the 32bit vdso Marc Zyngier
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 16:55 ` 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 16:57 ` Mark Rutland
2020-07-06 16:38 ` Marc Zyngier [this message]
2020-07-06 17:12 ` [PATCH v2 4/4] arm64: Rework ARM_ERRATUM_1414080 handling Mark Rutland
2020-07-08 22:02 ` [PATCH v2 0/4] arm64: Allow the compat vdso to be disabled at runtime Will Deacon
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