lkml.org 
[lkml]   [2021]   [Feb]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v12 6/7] arm64: mte: Save/Restore TFSR_EL1 during suspend
Date
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.

Save/restore the state of the TFSR_EL1 register during the
suspend/resume operations to prevent this to happen.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
arch/arm64/include/asm/mte.h | 4 ++++
arch/arm64/kernel/mte.c | 22 ++++++++++++++++++++++
arch/arm64/kernel/suspend.c | 3 +++
3 files changed, 29 insertions(+)

diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index 237bb2f7309d..2d79bcaaeb30 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -43,6 +43,7 @@ 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);
@@ -68,6 +69,9 @@ 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 3332aabda466..5c440967721b 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -25,6 +25,7 @@

u64 gcr_kernel_excl __ro_after_init;

+static u64 mte_suspend_tfsr_el1;
static bool report_fault_once = true;

/* Whether the MTE asynchronous mode is enabled. */
@@ -295,12 +296,33 @@ 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 save the state.
+ */
+ dsb(nsh);
+ isb();
+
+ /* Save SYS_TFSR_EL1 before suspend entry */
+ mte_suspend_tfsr_el1 = read_sysreg_s(SYS_TFSR_EL1);
+}
+
void mte_suspend_exit(void)
{
if (!system_supports_mte())
return;

update_gcr_el1_excl(gcr_kernel_excl);
+
+ /* Resume SYS_TFSR_EL1 after suspend exit */
+ write_sysreg_s(mte_suspend_tfsr_el1, SYS_TFSR_EL1);
+
+ mte_check_tfsr_el1();
}

long set_mte_ctrl(struct task_struct *task, unsigned long arg)
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
index a67b37a7a47e..16caa9b32dae 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
\
 
 \ /
  Last update: 2022-09-17 16:09    [W:0.100 / U:5.136 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site