arm64: mte: Report async tag faults before suspend

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: Will Deacon <will@kernel.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20210315132019.33202-9-vincenzo.frascino@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index 9a92962..a38abc1 100644 (file)
--- 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 b6336fb..820bad9 100644 (file)
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -265,6 +265,22 @@ 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 d756489..6fdc829 100644 (file)
--- 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