From fa82d0b4b833790ac4572377fb777dcea24a9d69 Mon Sep 17 00:00:00 2001 From: Suzuki K Poulose Date: Tue, 19 Oct 2021 17:31:41 +0100 Subject: arm64: errata: Add workaround for TSB flush failures Arm Neoverse-N2 (#2067961) and Cortex-A710 (#2054223) suffers from errata, where a TSB (trace synchronization barrier) fails to flush the trace data completely, when executed from a trace prohibited region. In Linux we always execute it after we have moved the PE to trace prohibited region. So, we can apply the workaround every time a TSB is executed. The work around is to issue two TSB consecutively. NOTE: This errata is defined as LOCAL_CPU_ERRATUM, implying that a late CPU could be blocked from booting if it is the first CPU that requires the workaround. This is because we do not allow setting a cpu_hwcaps after the SMP boot. The other alternative is to use "this_cpu_has_cap()" instead of the faster system wide check, which may be a bit of an overhead, given we may have to do this in nvhe KVM host before a guest entry. Cc: Will Deacon Cc: Catalin Marinas Cc: Mathieu Poirier Cc: Mike Leach Cc: Mark Rutland Cc: Anshuman Khandual Cc: Marc Zyngier Acked-by: Catalin Marinas Reviewed-by: Mathieu Poirier Reviewed-by: Anshuman Khandual Signed-off-by: Suzuki K Poulose Link: https://lore.kernel.org/r/20211019163153.3692640-4-suzuki.poulose@arm.com Signed-off-by: Will Deacon --- arch/arm64/include/asm/barrier.h | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'arch/arm64/include/asm/barrier.h') diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h index 451e11e5fd23..1c5a00598458 100644 --- a/arch/arm64/include/asm/barrier.h +++ b/arch/arm64/include/asm/barrier.h @@ -23,7 +23,7 @@ #define dsb(opt) asm volatile("dsb " #opt : : : "memory") #define psb_csync() asm volatile("hint #17" : : : "memory") -#define tsb_csync() asm volatile("hint #18" : : : "memory") +#define __tsb_csync() asm volatile("hint #18" : : : "memory") #define csdb() asm volatile("hint #20" : : : "memory") #ifdef CONFIG_ARM64_PSEUDO_NMI @@ -46,6 +46,20 @@ #define dma_rmb() dmb(oshld) #define dma_wmb() dmb(oshst) + +#define tsb_csync() \ + do { \ + /* \ + * CPUs affected by Arm Erratum 2054223 or 2067961 needs \ + * another TSB to ensure the trace is flushed. The barriers \ + * don't have to be strictly back to back, as long as the \ + * CPU is in trace prohibited state. \ + */ \ + if (cpus_have_final_cap(ARM64_WORKAROUND_TSB_FLUSH_FAILURE)) \ + __tsb_csync(); \ + __tsb_csync(); \ + } while (0) + /* * Generate a mask for array_index__nospec() that is ~0UL when 0 <= idx < sz * and 0 otherwise. -- cgit v1.2.3