Messages in this thread Patch in this message | | | Date | Fri, 12 Feb 2021 12:30:29 +0000 | From | Lorenzo Pieralisi <> | Subject | Re: [PATCH v13 6/7] arm64: mte: Report async tag faults before suspend |
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On Fri, Feb 12, 2021 at 12:00:15PM +0000, Lorenzo Pieralisi wrote: > On Thu, Feb 11, 2021 at 03:33:52PM +0000, Vincenzo Frascino wrote: > > 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@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 | 20 ++++++++++++++++++++ > > arch/arm64/kernel/suspend.c | 3 +++ > > 3 files changed, 27 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 f5aa5bea6dfe..de905102245a 100644 > > --- a/arch/arm64/kernel/mte.c > > +++ b/arch/arm64/kernel/mte.c > > @@ -258,12 +258,32 @@ 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()) > > return; > > > > update_gcr_el1_excl(gcr_kernel_excl); > > + > > + /* Clear SYS_TFSR_EL1 after suspend exit */ > > + write_sysreg_s(0, SYS_TFSR_EL1); > > AFAICS it is not needed, it is done already in __cpu_setup() (that is > called by cpu_resume on return from cpu_suspend() from firmware). > > However, I have a question. We are relying on context switch to set > sctlr_el1_tfc0 right ? If that's the case, till the thread resuming from > low power switches context we are running with SCTLR_EL1_TCF0 not > reflecting the actual value.
Forget this, we obviously restore sctlr_el1 on resume (cpu_do_resume()).
With the line above removed:
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Just making sure that I understand it correctly, I need to check the > resume from suspend-to-RAM path, it is something that came up with perf > save/restore already in the past. > > Lorenzo > > > + > > } > > > > 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..25a02926ad88 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 > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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