[PATCH v14 7/8] arm64: mte: Report async tag faults before suspend

From: Vincenzo Frascino
Date: Mon Mar 08 2021 - 11:16:08 EST


When MTE async mode is enabled TFSR_EL1 contains the accumulative
asynchronous tag check faults for EL1 and EL0.

During the suspend/resume operations the firmware might perform some
operations that could change the state of the register resulting in
a spurious tag check fault report.

Report asynchronous tag faults before suspend and clear the TFSR_EL1
register after resume to prevent this to happen.

Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
---
arch/arm64/include/asm/mte.h | 4 ++++
arch/arm64/kernel/mte.c | 16 ++++++++++++++++
arch/arm64/kernel/suspend.c | 3 +++
3 files changed, 23 insertions(+)

diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index 43169b978cd3..33e88a470357 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -41,6 +41,7 @@ void mte_sync_tags(pte_t *ptep, pte_t pte);
void mte_copy_page_tags(void *kto, const void *kfrom);
void flush_mte_state(void);
void mte_thread_switch(struct task_struct *next);
+void mte_suspend_enter(void);
void mte_suspend_exit(void);
long set_mte_ctrl(struct task_struct *task, unsigned long arg);
long get_mte_ctrl(struct task_struct *task);
@@ -66,6 +67,9 @@ static inline void flush_mte_state(void)
static inline void mte_thread_switch(struct task_struct *next)
{
}
+static inline void mte_suspend_enter(void)
+{
+}
static inline void mte_suspend_exit(void)
{
}
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index d6456f2d2306..1979bd9ad09b 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -261,6 +261,22 @@ void mte_thread_switch(struct task_struct *next)
mte_check_tfsr_el1();
}

+void mte_suspend_enter(void)
+{
+ if (!system_supports_mte())
+ return;
+
+ /*
+ * The barriers are required to guarantee that the indirect writes
+ * to TFSR_EL1 are synchronized before we report the state.
+ */
+ dsb(nsh);
+ isb();
+
+ /* Report SYS_TFSR_EL1 before suspend entry */
+ mte_check_tfsr_el1();
+}
+
void mte_suspend_exit(void)
{
if (!system_supports_mte())
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
index d7564891ffe1..6fdc8292b4f5 100644
--- a/arch/arm64/kernel/suspend.c
+++ b/arch/arm64/kernel/suspend.c
@@ -91,6 +91,9 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
unsigned long flags;
struct sleep_stack_data state;

+ /* Report any MTE async fault before going to suspend */
+ mte_suspend_enter();
+
/*
* From this point debug exceptions are disabled to prevent
* updates to mdscr register (saved and restored along with
--
2.30.0