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Subject[PATCH 4.19 009/131] arm64: compat: Workaround Neoverse-N1 #1542419 for compat user-space
Date
From: James Morse <james.morse@arm.com>

[ Upstream commit: 222fc0c8503d98cec3cb2bac2780cdd21a6e31c0 ]

Compat user-space is unable to perform ICIMVAU instructions from
user-space. Instead it uses a compat-syscall. Add the workaround for
Neoverse-N1 #1542419 to this code path.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/kernel/sys_compat.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/arch/arm64/kernel/sys_compat.c b/arch/arm64/kernel/sys_compat.c
index 010212d35700e..5a9b220aef6cf 100644
--- a/arch/arm64/kernel/sys_compat.c
+++ b/arch/arm64/kernel/sys_compat.c
@@ -19,6 +19,7 @@
*/

#include <linux/compat.h>
+#include <linux/cpufeature.h>
#include <linux/personality.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
@@ -28,6 +29,7 @@

#include <asm/cacheflush.h>
#include <asm/system_misc.h>
+#include <asm/tlbflush.h>
#include <asm/unistd.h>

static long
@@ -41,6 +43,15 @@ __do_compat_cache_op(unsigned long start, unsigned long end)
if (fatal_signal_pending(current))
return 0;

+ if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) {
+ /*
+ * The workaround requires an inner-shareable tlbi.
+ * We pick the reserved-ASID to minimise the impact.
+ */
+ __tlbi(aside1is, 0);
+ dsb(ish);
+ }
+
ret = __flush_cache_user_range(start, start + chunk);
if (ret)
return ret;
--
2.20.1


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