This series adds CPU erratum work arounds related to the self-hosted tracing. The list of affected errata handled in this series are :
* TRBE may overwrite trace in FILL mode - Arm Neoverse-N2 #2139208 - Cortex-A710 #211985
* A TSB instruction may not flush the trace completely when executed in trace prohibited region.
- Arm Neoverse-N2 #2067961 - Cortex-A710 #2054223
* TRBE may write to out-of-range address - Arm Neoverse-N2 #2253138 - Cortex-A710 #2224489
The series applies on coresight/next. The series has been reordered to make it easier to merge the patches via arm64 tree and the coresight tree.
Patches 1-4 are could be picked up via arm64 tree. The rest can go via the coresight tree. The Kconfig items for the TRBE errata are initially dropped in with dependency on COMPILE_TEST. These are dropped only after the driver is equipped with the work around in later patches.
A tree is available here :
git@git.gitlab.arm.com:linux-arm/linux-skp.git coresight/errata/trbe-tsb-n2-a710/v4
Changes since v3:
- Fix missing Kconfig selection for TSB flush failure erratum (Will) Merged the Kconfig changes to the core patch for TSB. - Use COMPILE_TEST dependency for the TRBE work arounds instead of delaying the Kconfig entries.
Changes since v2: * https://lkml.kernel.org/r/20210921134121.2423546-1-suzuki.poulose@arm.com - Dropped patch adding a helper to reach cpudata from perf handle - Split the TSB erratum work around patch to split the Kconfig/erratum list update changes(pushed to the end of the series). - Added wrappers to check the erratum : trbe_has_erratum(cpudata, TRBE_ERRATUM_<TITLE>) -> trbe_may_<title> - More ASCII art explanation on workaround.
Changes since v1: * https://lkml.kernel.org/r/20210728135217.591173-1-suzuki.poulose@arm.com - Added a fix to the TRBE driver handling of sink_specific data - Added more description and ASCII art for overwrite in FILL mode work around - Added another TRBE erratum to the list. "TRBE may write to out-of-range address" Patches from 12-17 - Added comment to list the expectations around TSB erratum workaround.
Suzuki K Poulose (15): arm64: Add Neoverse-N2, Cortex-A710 CPU part definition arm64: errata: Add detection for TRBE overwrite in FILL mode arm64: errata: Add workaround for TSB flush failures arm64: errata: Add detection for TRBE write to out-of-range coresight: trbe: Add a helper to calculate the trace generated coresight: trbe: Add a helper to pad a given buffer area coresight: trbe: Decouple buffer base from the hardware base coresight: trbe: Allow driver to choose a different alignment coresight: trbe: Add infrastructure for Errata handling coresight: trbe: Workaround TRBE errata overwrite in FILL mode coresight: trbe: Add a helper to determine the minimum buffer size coresight: trbe: Make sure we have enough space coresight: trbe: Work around write to out of range arm64: errata: Enable workaround for TRBE overwrite in FILL mode arm64: errata: Enable TRBE workaround for write to out-of-range address
Documentation/arm64/silicon-errata.rst | 12 + arch/arm64/Kconfig | 111 ++++++ arch/arm64/include/asm/barrier.h | 16 +- arch/arm64/include/asm/cputype.h | 4 + arch/arm64/kernel/cpu_errata.c | 64 ++++ arch/arm64/tools/cpucaps | 3 + drivers/hwtracing/coresight/coresight-trbe.c | 382 +++++++++++++++++-- 7 files changed, 556 insertions(+), 36 deletions(-)
Add the CPU Partnumbers for the new Arm designs.
Cc: Catalin Marinas catalin.marinas@arm.com Cc: Mark Rutland mark.rutland@arm.com Cc: Will Deacon will@kernel.org Acked-by: Catalin Marinas catalin.marinas@arm.com Reviewed-by: Anshuman Khandual anshuman.khandual@arm.com Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- arch/arm64/include/asm/cputype.h | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h index 6231e1f0abe7..19b8441aa8f2 100644 --- a/arch/arm64/include/asm/cputype.h +++ b/arch/arm64/include/asm/cputype.h @@ -73,6 +73,8 @@ #define ARM_CPU_PART_CORTEX_A76 0xD0B #define ARM_CPU_PART_NEOVERSE_N1 0xD0C #define ARM_CPU_PART_CORTEX_A77 0xD0D +#define ARM_CPU_PART_CORTEX_A710 0xD47 +#define ARM_CPU_PART_NEOVERSE_N2 0xD49
#define APM_CPU_PART_POTENZA 0x000
@@ -113,6 +115,8 @@ #define MIDR_CORTEX_A76 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A76) #define MIDR_NEOVERSE_N1 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_NEOVERSE_N1) #define MIDR_CORTEX_A77 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A77) +#define MIDR_CORTEX_A710 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A710) +#define MIDR_NEOVERSE_N2 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_NEOVERSE_N2) #define MIDR_THUNDERX MIDR_CPU_MODEL(ARM_CPU_IMP_CAVIUM, CAVIUM_CPU_PART_THUNDERX) #define MIDR_THUNDERX_81XX MIDR_CPU_MODEL(ARM_CPU_IMP_CAVIUM, CAVIUM_CPU_PART_THUNDERX_81XX) #define MIDR_THUNDERX_83XX MIDR_CPU_MODEL(ARM_CPU_IMP_CAVIUM, CAVIUM_CPU_PART_THUNDERX_83XX)
Arm Neoverse-N2 and the Cortex-A710 cores are affected by a CPU erratum where the TRBE will overwrite the trace buffer in FILL mode. The TRBE doesn't stop (as expected in FILL mode) when it reaches the limit and wraps to the base to continue writing upto 3 cache lines. This will overwrite any trace that was written previously.
Add the Neoverse-N2 erratumi(#2139208) and Cortex-A710 erratum (#2119858) to the detection logic.
This will be used by the TRBE driver in later patches to work around the issue. The detection has been kept with the core arm64 errata framework list to make sure : - We don't duplicate the framework in TRBE driver - The errata detection is advertised like the rest of the CPU errata.
Note that the Kconfig entries are not fully active until the TRBE driver implements the work around.
Cc: Will Deacon will@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Catalin Marinas catalin.marinas@arm.com Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Mike Leach mike.leach@linaro.org cc: Leo Yan leo.yan@linaro.org Acked-by: Catalin Marinas catalin.marinas@arm.com Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Reviewed-by: Anshuman Khandual anshuman.khandual@arm.com Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- Documentation/arm64/silicon-errata.rst | 4 +++ arch/arm64/Kconfig | 41 ++++++++++++++++++++++++++ arch/arm64/kernel/cpu_errata.c | 25 ++++++++++++++++ arch/arm64/tools/cpucaps | 1 + 4 files changed, 71 insertions(+)
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst index d410a47ffa57..2f99229d993c 100644 --- a/Documentation/arm64/silicon-errata.rst +++ b/Documentation/arm64/silicon-errata.rst @@ -92,12 +92,16 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A77 | #1508412 | ARM64_ERRATUM_1508412 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Cortex-A710 | #2119858 | ARM64_ERRATUM_2119858 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1349291 | N/A | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1542419 | ARM64_ERRATUM_1542419 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Neoverse-N2 | #2139208 | ARM64_ERRATUM_2139208 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | MMU-500 | #841119,826419 | N/A | +----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+ diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 077f2ec4eeb2..404f56e87e93 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -666,6 +666,47 @@ config ARM64_ERRATUM_1508412
If unsure, say Y.
+config ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE + bool + +config ARM64_ERRATUM_2119858 + bool "Cortex-A710: 2119858: workaround TRBE overwriting trace data in FILL mode" + default y + depends on COMPILE_TEST # Until the CoreSight TRBE driver changes are in + depends on CORESIGHT_TRBE + select ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE + help + This option adds the workaround for ARM Cortex-A710 erratum 2119858. + + Affected Cortex-A710 cores could overwrite upto 3 cache lines of trace + data at the base of the buffer (ponited by TRBASER_EL1) in FILL mode in + the event of a WRAP event. + + Work around the issue by always making sure we move the TRBPTR_EL1 by + 256bytes before enabling the buffer and filling the first 256bytes of + the buffer with ETM ignore packets upon disabling. + + If unsure, say Y. + +config ARM64_ERRATUM_2139208 + bool "Neoverse-N2: 2139208: workaround TRBE overwriting trace data in FILL mode" + default y + depends on COMPILE_TEST # Until the CoreSight TRBE driver changes are in + depends on CORESIGHT_TRBE + select ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE + help + This option adds the workaround for ARM Neoverse-N2 erratum 2139208. + + Affected Neoverse-N2 cores could overwrite upto 3 cache lines of trace + data at the base of the buffer (ponited by TRBASER_EL1) in FILL mode in + the event of a WRAP event. + + Work around the issue by always making sure we move the TRBPTR_EL1 by + 256bytes before enabling the buffer and filling the first 256bytes of + the buffer with ETM ignore packets upon disabling. + + If unsure, say Y. + config CAVIUM_ERRATUM_22375 bool "Cavium erratum 22375, 24313" default y diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index e2c20c036442..ccd757373f36 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -340,6 +340,18 @@ static const struct midr_range erratum_1463225[] = { }; #endif
+#ifdef CONFIG_ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE +static const struct midr_range trbe_overwrite_fill_mode_cpus[] = { +#ifdef CONFIG_ARM64_ERRATUM_2139208 + MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2), +#endif +#ifdef CONFIG_ARM64_ERRATUM_2119858 + MIDR_ALL_VERSIONS(MIDR_CORTEX_A710), +#endif + {}, +}; +#endif /* CONFIG_ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE */ + const struct arm64_cpu_capabilities arm64_errata[] = { #ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE { @@ -533,6 +545,19 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .capability = ARM64_WORKAROUND_NVIDIA_CARMEL_CNP, ERRATA_MIDR_ALL_VERSIONS(MIDR_NVIDIA_CARMEL), }, +#endif +#ifdef CONFIG_ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE + { + /* + * The erratum work around is handled within the TRBE + * driver and can be applied per-cpu. So, we can allow + * a late CPU to come online with this erratum. + */ + .desc = "ARM erratum 2119858 or 2139208", + .capability = ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE, + .type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE, + CAP_MIDR_RANGE_LIST(trbe_overwrite_fill_mode_cpus), + }, #endif { } diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index 49305c2e6dfd..1ccb92165bd8 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -53,6 +53,7 @@ WORKAROUND_1418040 WORKAROUND_1463225 WORKAROUND_1508412 WORKAROUND_1542419 +WORKAROUND_TRBE_OVERWRITE_FILL_MODE WORKAROUND_CAVIUM_23154 WORKAROUND_CAVIUM_27456 WORKAROUND_CAVIUM_30115
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 will@kernel.org Cc: Catalin Marinas catalin.marinas@arm.com Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Mike Leach mike.leach@linaro.org Cc: Mark Rutland mark.rutland@arm.com Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Marc Zyngier maz@kernel.org Acked-by: Catalin Marinas catalin.marinas@arm.com Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- Changes since v3: - Merge the Kconfig changes back. --- Documentation/arm64/silicon-errata.rst | 4 ++++ arch/arm64/Kconfig | 33 ++++++++++++++++++++++++++ arch/arm64/include/asm/barrier.h | 16 ++++++++++++- arch/arm64/kernel/cpu_errata.c | 19 +++++++++++++++ arch/arm64/tools/cpucaps | 1 + 5 files changed, 72 insertions(+), 1 deletion(-)
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst index 2f99229d993c..569a92411dcd 100644 --- a/Documentation/arm64/silicon-errata.rst +++ b/Documentation/arm64/silicon-errata.rst @@ -94,6 +94,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A710 | #2119858 | ARM64_ERRATUM_2119858 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Cortex-A710 | #2054223 | ARM64_ERRATUM_2054223 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1349291 | N/A | @@ -102,6 +104,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N2 | #2139208 | ARM64_ERRATUM_2139208 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Neoverse-N2 | #2067961 | ARM64_ERRATUM_2067961 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | MMU-500 | #841119,826419 | N/A | +----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+ diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 404f56e87e93..b9b181470f0f 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -707,6 +707,39 @@ config ARM64_ERRATUM_2139208
If unsure, say Y.
+config ARM64_WORKAROUND_TSB_FLUSH_FAILURE + bool + +config ARM64_ERRATUM_2054223 + bool "Cortex-A710: 2054223: workaround TSB instruction failing to flush trace" + default y + select ARM64_WORKAROUND_TSB_FLUSH_FAILURE + help + Enable workaround for ARM Cortex-A710 erratum 2054223 + + Affected cores may fail to flush the trace data on a TSB instruction, when + the PE is in trace prohibited state. This will cause losing a few bytes + of the trace cached. + + Workaround is to issue two TSB consecutively on affected cores. + + If unsure, say Y. + +config ARM64_ERRATUM_2067961 + bool "Neoverse-N2: 2067961: workaround TSB instruction failing to flush trace" + default y + select ARM64_WORKAROUND_TSB_FLUSH_FAILURE + help + Enable workaround for ARM Neoverse-N2 erratum 2067961 + + Affected cores may fail to flush the trace data on a TSB instruction, when + the PE is in trace prohibited state. This will cause losing a few bytes + of the trace cached. + + Workaround is to issue two TSB consecutively on affected cores. + + If unsure, say Y. + config CAVIUM_ERRATUM_22375 bool "Cavium erratum 22375, 24313" default y 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. diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index ccd757373f36..bdbeac75ead6 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -352,6 +352,18 @@ static const struct midr_range trbe_overwrite_fill_mode_cpus[] = { }; #endif /* CONFIG_ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE */
+#ifdef CONFIG_ARM64_WORKAROUND_TSB_FLUSH_FAILURE +static const struct midr_range tsb_flush_fail_cpus[] = { +#ifdef CONFIG_ARM64_ERRATUM_2067961 + MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2), +#endif +#ifdef CONFIG_ARM64_ERRATUM_2054223 + MIDR_ALL_VERSIONS(MIDR_CORTEX_A710), +#endif + {}, +}; +#endif /* CONFIG_ARM64_WORKAROUND_TSB_FLUSH_FAILURE */ + const struct arm64_cpu_capabilities arm64_errata[] = { #ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE { @@ -558,6 +570,13 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE, CAP_MIDR_RANGE_LIST(trbe_overwrite_fill_mode_cpus), }, +#endif +#ifdef CONFIG_ARM64_WORKAROUND_TSB_FLUSH_FAILRE + { + .desc = "ARM erratum 2067961 or 2054223", + .capability = ARM64_WORKAROUND_TSB_FLUSH_FAILURE, + ERRATA_MIDR_RANGE_LIST(tsb_flush_fail_cpus), + }, #endif { } diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index 1ccb92165bd8..2102e15af43d 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -54,6 +54,7 @@ WORKAROUND_1463225 WORKAROUND_1508412 WORKAROUND_1542419 WORKAROUND_TRBE_OVERWRITE_FILL_MODE +WORKAROUND_TSB_FLUSH_FAILURE WORKAROUND_CAVIUM_23154 WORKAROUND_CAVIUM_27456 WORKAROUND_CAVIUM_30115
Arm Neoverse-N2 and Cortex-A710 cores are affected by an erratum where the trbe, under some circumstances, might write upto 64bytes to an address after the Limit as programmed by the TRBLIMITR_EL1.LIMIT. This might -
- Corrupt a page in the ring buffer, which may corrupt trace from a previous session, consumed by userspace. - Hit the guard page at the end of the vmalloc area and raise a fault.
To keep the handling simpler, we always leave the last page from the range, which TRBE is allowed to write. This can be achieved by ensuring that we always have more than a PAGE worth space in the range, while calculating the LIMIT for TRBE. And then the LIMIT pointer can be adjusted to leave the PAGE (TRBLIMITR.LIMIT -= PAGE_SIZE), out of the TRBE range while enabling it. This makes sure that the TRBE will only write to an area within its allowed limit (i.e, [head-head+size]) and we do not have to handle address faults within the driver.
Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Mike Leach mike.leach@linaro.org Cc: Leo Yan leo.yan@linaro.org Cc: Will Deacon will@kernel.org Cc: Mark Rutland mark.rutland@arm.com Reviewed-by: Anshuman Khandual anshuman.khandual@arm.com Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Acked-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- Documentation/arm64/silicon-errata.rst | 4 +++ arch/arm64/Kconfig | 41 ++++++++++++++++++++++++++ arch/arm64/kernel/cpu_errata.c | 20 +++++++++++++ arch/arm64/tools/cpucaps | 1 + 4 files changed, 66 insertions(+)
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst index 569a92411dcd..5342e895fb60 100644 --- a/Documentation/arm64/silicon-errata.rst +++ b/Documentation/arm64/silicon-errata.rst @@ -96,6 +96,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A710 | #2054223 | ARM64_ERRATUM_2054223 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Cortex-A710 | #2224489 | ARM64_ERRATUM_2224489 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1349291 | N/A | @@ -106,6 +108,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N2 | #2067961 | ARM64_ERRATUM_2067961 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Neoverse-N2 | #2253138 | ARM64_ERRATUM_2253138 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | MMU-500 | #841119,826419 | N/A | +----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+ diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index b9b181470f0f..87a07e895db9 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -740,6 +740,47 @@ config ARM64_ERRATUM_2067961
If unsure, say Y.
+config ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE + bool + +config ARM64_ERRATUM_2253138 + bool "Neoverse-N2: 2253138: workaround TRBE writing to address out-of-range" + depends on COMPILE_TEST # Until the CoreSight TRBE driver changes are in + depends on CORESIGHT_TRBE + default y + select ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE + help + This option adds the workaround for ARM Neoverse-N2 erratum 2253138. + + Affected Neoverse-N2 cores might write to an out-of-range address, not reserved + for TRBE. Under some conditions, the TRBE might generate a write to the next + virtually addressed page following the last page of the TRBE address space + (i.e, the TRBLIMITR_EL1.LIMIT), instead of wrapping around to the base. + + We work around this in the driver by, always making sure that there is a + page beyond the TRBLIMITR_EL1.LIMIT, within the space allowed for the TRBE. + + If unsure, say Y. + +config ARM64_ERRATUM_2224489 + bool "Cortex-A710: 2224489: workaround TRBE writing to address out-of-range" + depends on COMPILE_TEST # Until the CoreSight TRBE driver changes are in + depends on CORESIGHT_TRBE + default y + select ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE + help + This option adds the workaround for ARM Cortex-A710 erratum 2224489. + + Affected Cortex-A710 cores might write to an out-of-range address, not reserved + for TRBE. Under some conditions, the TRBE might generate a write to the next + virtually addressed page following the last page of the TRBE address space + (i.e, the TRBLIMITR_EL1.LIMIT), instead of wrapping around to the base. + + We work around this in the driver by, always making sure that there is a + page beyond the TRBLIMITR_EL1.LIMIT, within the space allowed for the TRBE. + + If unsure, say Y. + config CAVIUM_ERRATUM_22375 bool "Cavium erratum 22375, 24313" default y diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index bdbeac75ead6..e2978b89d4b8 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -364,6 +364,18 @@ static const struct midr_range tsb_flush_fail_cpus[] = { }; #endif /* CONFIG_ARM64_WORKAROUND_TSB_FLUSH_FAILURE */
+#ifdef CONFIG_ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE +static struct midr_range trbe_write_out_of_range_cpus[] = { +#ifdef CONFIG_ARM64_ERRATUM_2253138 + MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2), +#endif +#ifdef CONFIG_ARM64_ERRATUM_2224489 + MIDR_ALL_VERSIONS(MIDR_CORTEX_A710), +#endif + {}, +}; +#endif /* CONFIG_ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE */ + const struct arm64_cpu_capabilities arm64_errata[] = { #ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE { @@ -577,6 +589,14 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .capability = ARM64_WORKAROUND_TSB_FLUSH_FAILURE, ERRATA_MIDR_RANGE_LIST(tsb_flush_fail_cpus), }, +#endif +#ifdef CONFIG_ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE + { + .desc = "ARM erratum 2253138 or 2224489", + .capability = ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE, + .type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE, + CAP_MIDR_RANGE_LIST(trbe_write_out_of_range_cpus), + }, #endif { } diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index 2102e15af43d..90628638e0f9 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -55,6 +55,7 @@ WORKAROUND_1508412 WORKAROUND_1542419 WORKAROUND_TRBE_OVERWRITE_FILL_MODE WORKAROUND_TSB_FLUSH_FAILURE +WORKAROUND_TRBE_WRITE_OUT_OF_RANGE WORKAROUND_CAVIUM_23154 WORKAROUND_CAVIUM_27456 WORKAROUND_CAVIUM_30115
We collect the trace from the TRBE on FILL event from IRQ context and via update_buffer(), when the event is stopped. Let us consolidate how we calculate the trace generated into a helper.
Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Mike Leach mike.leach@linaro.org Cc: Leo Yan leo.yan@linaro.org Reviewed-by: Anshuman Khandual anshuman.khandual@arm.com Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- Changes since v2: - Fix code style issues - Read base pointer directly now. Switch to using cached value of the base of the ring buffer, when this changes. --- drivers/hwtracing/coresight/coresight-trbe.c | 47 ++++++++++++-------- 1 file changed, 29 insertions(+), 18 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index 2825ccb0cf39..5902ef41bfb8 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -499,6 +499,29 @@ static enum trbe_fault_action trbe_get_fault_act(u64 trbsr) return TRBE_FAULT_ACT_SPURIOUS; }
+static unsigned long trbe_get_trace_size(struct perf_output_handle *handle, + struct trbe_buf *buf, bool wrap) +{ + u64 write; + u64 start_off, end_off; + + /* + * If the TRBE has wrapped around the write pointer has + * wrapped and should be treated as limit. + */ + if (wrap) + write = get_trbe_limit_pointer(); + else + write = get_trbe_write_pointer(); + + end_off = write - get_trbe_base_pointer(); + start_off = PERF_IDX2OFF(handle->head, buf); + + if (WARN_ON_ONCE(end_off < start_off)) + return 0; + return (end_off - start_off); +} + static void *arm_trbe_alloc_buffer(struct coresight_device *csdev, struct perf_event *event, void **pages, int nr_pages, bool snapshot) @@ -560,9 +583,9 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev, struct trbe_cpudata *cpudata = dev_get_drvdata(&csdev->dev); struct trbe_buf *buf = config; enum trbe_fault_action act; - unsigned long size, offset; - unsigned long write, base, status; + unsigned long size, status; unsigned long flags; + bool wrap = false;
WARN_ON(buf->cpudata != cpudata); WARN_ON(cpudata->cpu != smp_processor_id()); @@ -602,8 +625,6 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev, * handle gets freed in etm_event_stop(). */ trbe_drain_and_disable_local(); - write = get_trbe_write_pointer(); - base = get_trbe_base_pointer();
/* Check if there is a pending interrupt and handle it here */ status = read_sysreg_s(SYS_TRBSR_EL1); @@ -627,20 +648,11 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev, goto done; }
- /* - * Otherwise, the buffer is full and the write pointer - * has reached base. Adjust this back to the Limit pointer - * for correct size. Also, mark the buffer truncated. - */ - write = get_trbe_limit_pointer(); trbe_report_wrap_event(handle); + wrap = true; }
- offset = write - base; - if (WARN_ON_ONCE(offset < PERF_IDX2OFF(handle->head, buf))) - size = 0; - else - size = offset - PERF_IDX2OFF(handle->head, buf); + size = trbe_get_trace_size(handle, buf, wrap);
done: local_irq_restore(flags); @@ -721,11 +733,10 @@ static int trbe_handle_overflow(struct perf_output_handle *handle) { struct perf_event *event = handle->event; struct trbe_buf *buf = etm_perf_sink_config(handle); - unsigned long offset, size; + unsigned long size; struct etm_event_data *event_data;
- offset = get_trbe_limit_pointer() - get_trbe_base_pointer(); - size = offset - PERF_IDX2OFF(handle->head, buf); + size = trbe_get_trace_size(handle, buf, true); if (buf->snapshot) handle->head += size;
Refactor the helper to pad a given AUX buffer area to allow "filling" ignore packets, without moving any handle pointers. This will be useful in working around errata, where we may have to fill the buffer after a session.
Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Mike Leach mike.leach@linaro.org Cc: Leo Yan leo.yan@linaro.org Reviewed-by: Anshuman Khandual anshuman.khandual@arm.com Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- drivers/hwtracing/coresight/coresight-trbe.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index 5902ef41bfb8..3de03136285f 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -199,12 +199,18 @@ static void trbe_stop_and_truncate_event(struct perf_output_handle *handle) * consumed from the user space. The enabled TRBE buffer area is a moving subset of * the allocated perf auxiliary buffer. */ + +static void __trbe_pad_buf(struct trbe_buf *buf, u64 offset, int len) +{ + memset((void *)buf->trbe_base + offset, ETE_IGNORE_PACKET, len); +} + static void trbe_pad_buf(struct perf_output_handle *handle, int len) { struct trbe_buf *buf = etm_perf_sink_config(handle); u64 head = PERF_IDX2OFF(handle->head, buf);
- memset((void *)buf->trbe_base + head, ETE_IGNORE_PACKET, len); + __trbe_pad_buf(buf, head, len); if (!buf->snapshot) perf_aux_output_skip(handle, len); }
We always set the TRBBASER_EL1 to the base of the virtual ring buffer. We are about to change this for working around an erratum. So, in preparation to that, allow the driver to choose a different base for the TRBBASER_EL1 (which is within the buffer range).
Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Mike Leach mike.leach@linaro.org Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Leo Yan leo.yan@linaro.org Reviewed-by: Anshuman Khandual anshuman.khandual@arm.com Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- drivers/hwtracing/coresight/coresight-trbe.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index 3de03136285f..58796ff425a4 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -57,6 +57,8 @@ struct trbe_buf { * trbe_limit sibling pointers. */ unsigned long trbe_base; + /* The base programmed into the TRBE */ + unsigned long trbe_hw_base; unsigned long trbe_limit; unsigned long trbe_write; int nr_pages; @@ -470,12 +472,13 @@ static void set_trbe_limit_pointer_enabled(unsigned long addr)
static void trbe_enable_hw(struct trbe_buf *buf) { - WARN_ON(buf->trbe_write < buf->trbe_base); + WARN_ON(buf->trbe_hw_base < buf->trbe_base); + WARN_ON(buf->trbe_write < buf->trbe_hw_base); WARN_ON(buf->trbe_write >= buf->trbe_limit); set_trbe_disabled(); isb(); clr_trbe_status(); - set_trbe_base_pointer(buf->trbe_base); + set_trbe_base_pointer(buf->trbe_hw_base); set_trbe_write_pointer(buf->trbe_write);
/* @@ -520,7 +523,12 @@ static unsigned long trbe_get_trace_size(struct perf_output_handle *handle, else write = get_trbe_write_pointer();
- end_off = write - get_trbe_base_pointer(); + /* + * TRBE may use a different base address than the base + * of the ring buffer. Thus use the beginning of the ring + * buffer to compute the offsets. + */ + end_off = write - buf->trbe_base; start_off = PERF_IDX2OFF(handle->head, buf);
if (WARN_ON_ONCE(end_off < start_off)) @@ -678,6 +686,8 @@ static int __arm_trbe_enable(struct trbe_buf *buf, trbe_stop_and_truncate_event(handle); return -ENOSPC; } + /* Set the base of the TRBE to the buffer base */ + buf->trbe_hw_base = buf->trbe_base; *this_cpu_ptr(buf->cpudata->drvdata->handle) = handle; trbe_enable_hw(buf); return 0; @@ -771,7 +781,7 @@ static bool is_perf_trbe(struct perf_output_handle *handle) struct trbe_drvdata *drvdata = cpudata->drvdata; int cpu = smp_processor_id();
- WARN_ON(buf->trbe_base != get_trbe_base_pointer()); + WARN_ON(buf->trbe_hw_base != get_trbe_base_pointer()); WARN_ON(buf->trbe_limit != get_trbe_limit_pointer());
if (cpudata->mode != CS_MODE_PERF)
The TRBE hardware mandates a minimum alignment for the TRBPTR_EL1, advertised via the TRBIDR_EL1. This is used by the driver to align the buffer write head. This patch allows the driver to choose a different alignment from that of the hardware, by decoupling the alignment tracking. This will be useful for working around errata.
Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Mike Leach mike.leach@linaro.org Cc: Leo Yan leo.yan@linaro.org Reviewed-by: Anshuman Khandual anshuman.khandual@arm.com Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- drivers/hwtracing/coresight/coresight-trbe.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index 58796ff425a4..f8c04c428780 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -67,8 +67,18 @@ struct trbe_buf { struct trbe_cpudata *cpudata; };
+/* + * struct trbe_cpudata: TRBE instance specific data + * @trbe_flag - TRBE dirty/access flag support + * @trbe_hw_align - Actual TRBE alignment required for TRBPTR_EL1. + * @trbe_align - Software alignment used for the TRBPTR_EL1, + * @cpu - CPU this TRBE belongs to. + * @mode - Mode of current operation. (perf/disabled) + * @drvdata - TRBE specific drvdata + */ struct trbe_cpudata { bool trbe_flag; + u64 trbe_hw_align; u64 trbe_align; int cpu; enum cs_mode mode; @@ -875,7 +885,7 @@ static ssize_t align_show(struct device *dev, struct device_attribute *attr, cha { struct trbe_cpudata *cpudata = dev_get_drvdata(dev);
- return sprintf(buf, "%llx\n", cpudata->trbe_align); + return sprintf(buf, "%llx\n", cpudata->trbe_hw_align); } static DEVICE_ATTR_RO(align);
@@ -963,11 +973,13 @@ static void arm_trbe_probe_cpu(void *info) goto cpu_clear; }
- cpudata->trbe_align = 1ULL << get_trbe_address_align(trbidr); - if (cpudata->trbe_align > SZ_2K) { + cpudata->trbe_hw_align = 1ULL << get_trbe_address_align(trbidr); + if (cpudata->trbe_hw_align > SZ_2K) { pr_err("Unsupported alignment on cpu %d\n", cpu); goto cpu_clear; } + + cpudata->trbe_align = cpudata->trbe_hw_align; cpudata->trbe_flag = get_trbe_flag_update(trbidr); cpudata->cpu = cpu; cpudata->drvdata = drvdata;
Add a minimal infrastructure to keep track of the errata affecting the given TRBE instance. Given that we have heterogeneous CPUs, we have to manage the list per-TRBE instance to be able to apply the work around as needed. Thus we will need to check if individual CPUs are affected by the erratum.
We rely on the arm64 errata framework for the actual description and the discovery of a given erratum, to keep the Erratum work around at a central place and benefit from the code and the advertisement from the kernel. Though we could reuse the "this_cpu_has_cap()" to apply an erratum work around, it is a bit of a heavy operation, as it must go through the "erratum" detection check on the CPU every time it is called (e.g, scanning through a table of affected MIDRs). Since we need to do this check for every session, may be multiple times (depending on the wrok around), we could save the cycles by caching the affected errata per-CPU instance in the per-CPU struct trbe_cpudata.
Since we are only interested in the errata affecting the TRBE driver, we only need to track a very few of them per-CPU. Thus we use a local mapping of the CPUCAP for the erratum to avoid bloating up a bitmap for trbe_cpudata.
i.e, each arm64 TRBE erratum bit is assigned a "index" within the driver to track. Each trbe instance updates the list of affected erratum at probe time on the CPU. This makes sure that we can easily access the list of errata on a given TRBE instance without much overhead.
Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Mike Leach mike.leach@linaro.org Cc: Leo Yan leo.yan@linaro.org Cc: Anshuman Khandual anshuman.khandual@arm.com Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- Changes since v2: - Automatically define TRBE_ERRATA_MAX - Add some basic sanity check to make sure the new entries are added in order. - Describe the design choice of caching CPU local errata in trbe_cpudata instead of using this_cpu_has_cap() Changes since v1: - Flip the order of args for trbe_has_erratum() - Move erratum detection further down in the sequence --- drivers/hwtracing/coresight/coresight-trbe.c | 58 +++++++++++++++++++- 1 file changed, 57 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index f8c04c428780..443194114eb3 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -16,6 +16,7 @@ #define pr_fmt(fmt) DRVNAME ": " fmt
#include <asm/barrier.h> + #include "coresight-self-hosted-trace.h" #include "coresight-trbe.h"
@@ -67,14 +68,43 @@ struct trbe_buf { struct trbe_cpudata *cpudata; };
+/* + * TRBE erratum list + * + * The errata are defined in arm64 generic cpu_errata framework. + * Since the errata work arounds could be applied individually + * to the affected CPUs inside the TRBE driver, we need to know if + * a given CPU is affected by the erratum. Unlike the other erratum + * work arounds, TRBE driver needs to check multiple times during + * a trace session. Thus we need a quicker access to per-CPU + * errata and not issue costly this_cpu_has_cap() everytime. + * We keep a set of the affected errata in trbe_cpudata, per TRBE. + * + * We rely on the corresponding cpucaps to be defined for a given + * TRBE erratum. We map the given cpucap into a TRBE internal number + * to make the tracking of the errata lean. + * + * This helps in : + * - Not duplicating the detection logic + * - Streamlined detection of erratum across the system + */ + +static int trbe_errata_cpucaps[] = { + -1, /* Sentinel, must be the last entry */ +}; + +/* The total number of listed errata in trbe_errata_cpucaps */ +#define TRBE_ERRATA_MAX (ARRAY_SIZE(trbe_errata_cpucaps) - 1) + /* * struct trbe_cpudata: TRBE instance specific data * @trbe_flag - TRBE dirty/access flag support * @trbe_hw_align - Actual TRBE alignment required for TRBPTR_EL1. - * @trbe_align - Software alignment used for the TRBPTR_EL1, + * @trbe_align - Software alignment used for the TRBPTR_EL1 * @cpu - CPU this TRBE belongs to. * @mode - Mode of current operation. (perf/disabled) * @drvdata - TRBE specific drvdata + * @errata - Bit map for the errata on this TRBE. */ struct trbe_cpudata { bool trbe_flag; @@ -84,6 +114,7 @@ struct trbe_cpudata { enum cs_mode mode; struct trbe_buf *buf; struct trbe_drvdata *drvdata; + DECLARE_BITMAP(errata, TRBE_ERRATA_MAX); };
struct trbe_drvdata { @@ -96,6 +127,25 @@ struct trbe_drvdata { struct platform_device *pdev; };
+static void trbe_check_errata(struct trbe_cpudata *cpudata) +{ + int i; + + for (i = 0; i < TRBE_ERRATA_MAX; i++) { + int cap = trbe_errata_cpucaps[i]; + + if (WARN_ON_ONCE(cap < 0)) + return; + if (this_cpu_has_cap(cap)) + set_bit(i, cpudata->errata); + } +} + +static inline bool trbe_has_erratum(struct trbe_cpudata *cpudata, int i) +{ + return (i < TRBE_ERRATA_MAX) && test_bit(i, cpudata->errata); +} + static int trbe_alloc_node(struct perf_event *event) { if (event->cpu == -1) @@ -979,6 +1029,12 @@ static void arm_trbe_probe_cpu(void *info) goto cpu_clear; }
+ /* + * Run the TRBE erratum checks, now that we know + * this instance is about to be registered. + */ + trbe_check_errata(cpudata); + cpudata->trbe_align = cpudata->trbe_hw_align; cpudata->trbe_flag = get_trbe_flag_update(trbidr); cpudata->cpu = cpu;
ARM Neoverse-N2 (#2139208) and Cortex-A710(##2119858) suffers from an erratum, which when triggered, might cause the TRBE to overwrite the trace data already collected in FILL mode, in the event of a WRAP. i.e, the TRBE doesn't stop writing the data, instead wraps to the base and could write upto 3 cache line size worth trace. Thus, this could corrupt the trace at the "BASE" pointer.
The workaround is to program the write pointer 256bytes from the base, such that if the erratum is triggered, it doesn't overwrite the trace data that was captured. This skipped region could be padded with ignore packets at the end of the session, so that the decoder sees a continuous buffer with some padding at the beginning. The trace data written at the base is considered lost as the limit could have been in the middle of the perf ring buffer, and jumping to the "base" is not acceptable. We set the flags already to indicate that some amount of trace was lost during the FILL event IRQ. So this is fine.
One important change with the work around is, we program the TRBBASER_EL1 to current page where we are allowed to write. Otherwise, it could overwrite a region that may be consumed by the perf. Towards this, we always make sure that the "handle->head" and thus the trbe_write is PAGE_SIZE aligned, so that we can set the BASE to the PAGE base and move the TRBPTR to the 256bytes offset.
Cc: Mike Leach mike.leach@linaro.org Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Leo Yan leo.yan@linaro.org Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- Changes since v2: - Updated the ASCII art to include better description of all the steps in the work around Change since v1: - Updated comment with ASCII art - Add _BYTES suffix for the space to skip for the work around. --- drivers/hwtracing/coresight/coresight-trbe.c | 169 +++++++++++++++++-- 1 file changed, 158 insertions(+), 11 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index 443194114eb3..2a1656902836 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -16,6 +16,7 @@ #define pr_fmt(fmt) DRVNAME ": " fmt
#include <asm/barrier.h> +#include <asm/cpufeature.h>
#include "coresight-self-hosted-trace.h" #include "coresight-trbe.h" @@ -88,14 +89,22 @@ struct trbe_buf { * - Not duplicating the detection logic * - Streamlined detection of erratum across the system */ +#define TRBE_WORKAROUND_OVERWRITE_FILL_MODE 0
static int trbe_errata_cpucaps[] = { + [TRBE_WORKAROUND_OVERWRITE_FILL_MODE] = ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE, -1, /* Sentinel, must be the last entry */ };
/* The total number of listed errata in trbe_errata_cpucaps */ #define TRBE_ERRATA_MAX (ARRAY_SIZE(trbe_errata_cpucaps) - 1)
+/* + * Safe limit for the number of bytes that may be overwritten + * when ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE is triggered. + */ +#define TRBE_WORKAROUND_OVERWRITE_FILL_MODE_SKIP_BYTES 256 + /* * struct trbe_cpudata: TRBE instance specific data * @trbe_flag - TRBE dirty/access flag support @@ -146,6 +155,11 @@ static inline bool trbe_has_erratum(struct trbe_cpudata *cpudata, int i) return (i < TRBE_ERRATA_MAX) && test_bit(i, cpudata->errata); }
+static inline bool trbe_may_overwrite_in_fill_mode(struct trbe_cpudata *cpudata) +{ + return trbe_has_erratum(cpudata, TRBE_WORKAROUND_OVERWRITE_FILL_MODE); +} + static int trbe_alloc_node(struct perf_event *event) { if (event->cpu == -1) @@ -549,10 +563,13 @@ static void trbe_enable_hw(struct trbe_buf *buf) set_trbe_limit_pointer_enabled(buf->trbe_limit); }
-static enum trbe_fault_action trbe_get_fault_act(u64 trbsr) +static enum trbe_fault_action trbe_get_fault_act(struct perf_output_handle *handle, + u64 trbsr) { int ec = get_trbe_ec(trbsr); int bsc = get_trbe_bsc(trbsr); + struct trbe_buf *buf = etm_perf_sink_config(handle); + struct trbe_cpudata *cpudata = buf->cpudata;
WARN_ON(is_trbe_running(trbsr)); if (is_trbe_trg(trbsr) || is_trbe_abort(trbsr)) @@ -561,10 +578,16 @@ static enum trbe_fault_action trbe_get_fault_act(u64 trbsr) if ((ec == TRBE_EC_STAGE1_ABORT) || (ec == TRBE_EC_STAGE2_ABORT)) return TRBE_FAULT_ACT_FATAL;
- if (is_trbe_wrap(trbsr) && (ec == TRBE_EC_OTHERS) && (bsc == TRBE_BSC_FILLED)) { - if (get_trbe_write_pointer() == get_trbe_base_pointer()) - return TRBE_FAULT_ACT_WRAP; - } + /* + * If the trbe is affected by TRBE_WORKAROUND_OVERWRITE_FILL_MODE, + * it might write data after a WRAP event in the fill mode. + * Thus the check TRBPTR == TRBBASER will not be honored. + */ + if ((is_trbe_wrap(trbsr) && (ec == TRBE_EC_OTHERS) && (bsc == TRBE_BSC_FILLED)) && + (trbe_may_overwrite_in_fill_mode(cpudata) || + get_trbe_write_pointer() == get_trbe_base_pointer())) + return TRBE_FAULT_ACT_WRAP; + return TRBE_FAULT_ACT_SPURIOUS; }
@@ -573,6 +596,8 @@ static unsigned long trbe_get_trace_size(struct perf_output_handle *handle, { u64 write; u64 start_off, end_off; + u64 size; + u64 overwrite_skip = TRBE_WORKAROUND_OVERWRITE_FILL_MODE_SKIP_BYTES;
/* * If the TRBE has wrapped around the write pointer has @@ -593,7 +618,18 @@ static unsigned long trbe_get_trace_size(struct perf_output_handle *handle,
if (WARN_ON_ONCE(end_off < start_off)) return 0; - return (end_off - start_off); + + size = end_off - start_off; + /* + * If the TRBE is affected by the following erratum, we must fill + * the space we skipped with IGNORE packets. And we are always + * guaranteed to have at least a PAGE_SIZE space in the buffer. + */ + if (trbe_has_erratum(buf->cpudata, TRBE_WORKAROUND_OVERWRITE_FILL_MODE) && + !WARN_ON(size < overwrite_skip)) + __trbe_pad_buf(buf, start_off, overwrite_skip); + + return size; }
static void *arm_trbe_alloc_buffer(struct coresight_device *csdev, @@ -712,7 +748,7 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev, clr_trbe_irq(); isb();
- act = trbe_get_fault_act(status); + act = trbe_get_fault_act(handle, status); /* * If this was not due to a WRAP event, we have some * errors and as such buffer is empty. @@ -736,21 +772,117 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev, return size; }
+ +static int trbe_apply_work_around_before_enable(struct trbe_buf *buf) +{ + /* + * TRBE_WORKAROUND_OVERWRITE_FILL_MODE causes the TRBE to overwrite a few cache + * line size from the "TRBBASER_EL1" in the event of a "FILL". + * Thus, we could loose some amount of the trace at the base. + * + * Before Fix: + * + * normal-BASE head (normal-TRBPTR) tail (normal-LIMIT) + * | / / + * ------------------------------------------------------------- + * | Pg0 | Pg1 | | | PgN | + * ------------------------------------------------------------- + * + * In the normal course of action, we would set the TRBBASER to the + * beginning of the ring-buffer (normal-BASE). But with the erratum, + * the TRBE could overwrite the contents at the "normal-BASE", after + * hitting the "normal-LIMIT", since it doesn't stop as expected. And + * this is wrong. This could result in overwriting trace collected in + * one of the previous runs, being consumed by the user. So we must + * always make sure that the TRBBASER is within the region + * [head, head+size]. Note that TRBBASER must be PAGE aligned, + * + * After moving the BASE: + * + * normal-BASE head (normal-TRBPTR) tail (normal-LIMIT) + * | / / + * ------------------------------------------------------------- + * | | |xyzdef. |.. tuvw| | + * ------------------------------------------------------------- + * / + * New-BASER + * + * Also, we would set the TRBPTR to head (after adjusting for + * alignment) at normal-PTR. This would mean that the last few bytes + * of the trace (say, "xyz") might overwrite the first few bytes of + * trace written ("abc"). More importantly they will appear in what + * userspace sees as the beginning of the trace, which is wrong. We may + * not always have space to move the latest trace "xyz" to the correct + * order as it must appear beyond the LIMIT. (i.e, [head..head+size]). + * Thus it is easier to ignore those bytes than to complicate the + * driver to move it, assuming that the erratum was triggered and + * doing additional checks to see if there is indeed allowed space at + * TRBLIMITR.LIMIT. + * + * Thus the full workaround will move the BASE and the PTR and would + * look like (after padding at the skipped bytes at the end of + * session) : + * + * normal-BASE head (normal-TRBPTR) tail (normal-LIMIT) + * | / / + * ------------------------------------------------------------- + * | | |///abc.. |.. rst| | + * ------------------------------------------------------------- + * / | + * New-BASER New-TRBPTR + * + * To summarize, with the work around: + * + * - We always align the offset for the next session to PAGE_SIZE + * (This is to ensure we can program the TRBBASER to this offset + * within the region [head...head+size]). + * + * - At TRBE enable: + * - Set the TRBBASER to the page aligned offset of the current + * proposed write offset. (which is guaranteed to be aligned + * as above) + * - Move the TRBPTR to skip first 256bytes (that might be + * overwritten with the erratum). This ensures that the trace + * generated in the session is not re-written. + * + * - At trace collection: + * - Pad the 256bytes skipped above again with IGNORE packets. + */ + if (trbe_has_erratum(buf->cpudata, TRBE_WORKAROUND_OVERWRITE_FILL_MODE)) { + if (WARN_ON(!IS_ALIGNED(buf->trbe_write, PAGE_SIZE))) + return -EINVAL; + buf->trbe_hw_base = buf->trbe_write; + buf->trbe_write += TRBE_WORKAROUND_OVERWRITE_FILL_MODE_SKIP_BYTES; + } + + return 0; +} + static int __arm_trbe_enable(struct trbe_buf *buf, struct perf_output_handle *handle) { + int ret = 0; + perf_aux_output_flag(handle, PERF_AUX_FLAG_CORESIGHT_FORMAT_RAW); buf->trbe_limit = compute_trbe_buffer_limit(handle); buf->trbe_write = buf->trbe_base + PERF_IDX2OFF(handle->head, buf); if (buf->trbe_limit == buf->trbe_base) { - trbe_stop_and_truncate_event(handle); - return -ENOSPC; + ret = -ENOSPC; + goto err; } /* Set the base of the TRBE to the buffer base */ buf->trbe_hw_base = buf->trbe_base; + + ret = trbe_apply_work_around_before_enable(buf); + if (ret) + goto err; + *this_cpu_ptr(buf->cpudata->drvdata->handle) = handle; trbe_enable_hw(buf); return 0; +err: + trbe_stop_and_truncate_event(handle); + return ret; }
static int arm_trbe_enable(struct coresight_device *csdev, u32 mode, void *data) @@ -890,7 +1022,7 @@ static irqreturn_t arm_trbe_irq_handler(int irq, void *dev) if (!is_perf_trbe(handle)) return IRQ_NONE;
- act = trbe_get_fault_act(status); + act = trbe_get_fault_act(handle, status); switch (act) { case TRBE_FAULT_ACT_WRAP: truncated = !!trbe_handle_overflow(handle); @@ -1035,7 +1167,22 @@ static void arm_trbe_probe_cpu(void *info) */ trbe_check_errata(cpudata);
- cpudata->trbe_align = cpudata->trbe_hw_align; + /* + * If the TRBE is affected by erratum TRBE_WORKAROUND_OVERWRITE_FILL_MODE, + * we must always program the TBRPTR_EL1, 256bytes from a page + * boundary, with TRBBASER_EL1 set to the page, to prevent + * TRBE over-writing 256bytes at TRBBASER_EL1 on FILL event. + * + * Thus make sure we always align our write pointer to a PAGE_SIZE, + * which also guarantees that we have at least a PAGE_SIZE space in + * the buffer (TRBLIMITR is PAGE aligned) and thus we can skip + * the required bytes at the base. + */ + if (trbe_may_overwrite_in_fill_mode(cpudata)) + cpudata->trbe_align = PAGE_SIZE; + else + cpudata->trbe_align = cpudata->trbe_hw_align; + cpudata->trbe_flag = get_trbe_flag_update(trbidr); cpudata->cpu = cpu; cpudata->drvdata = drvdata;
For the TRBE to operate, we need a minimum space available to collect meaningful trace session. This is currently a few bytes, but we may need to extend this for working around errata. So, abstract this into a helper function.
Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Mike Leach mike.leach@linaro.org Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Leo Yan leo.yan@linaro.org Reviewed-by: Anshuman Khandual anshuman.khandual@arm.com Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- drivers/hwtracing/coresight/coresight-trbe.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index 2a1656902836..c2ab4351e80b 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -303,6 +303,11 @@ static unsigned long trbe_snapshot_offset(struct perf_output_handle *handle) return buf->nr_pages * PAGE_SIZE; }
+static u64 trbe_min_trace_buf_size(struct perf_output_handle *handle) +{ + return TRBE_TRACE_MIN_BUF_SIZE; +} + /* * TRBE Limit Calculation * @@ -473,7 +478,7 @@ static unsigned long trbe_normal_offset(struct perf_output_handle *handle) * have space for a meaningful run, we rather pad it * and start fresh. */ - if (limit && (limit - head < TRBE_TRACE_MIN_BUF_SIZE)) { + if (limit && ((limit - head) < trbe_min_trace_buf_size(handle))) { trbe_pad_buf(handle, limit - head); limit = __trbe_normal_offset(handle); }
The TRBE driver makes sure that there is enough space for a meaningful run, otherwise pads the given space and restarts the offset calculation once. But there is no guarantee that we may find space or hit "no space". Make sure that we repeat the step until, either : - We have the minimum space OR - There is NO space at all.
Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Mike Leach mike.leach@linaro.org Cc: Leo Yan leo.yan@linaro.org Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- drivers/hwtracing/coresight/coresight-trbe.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index c2ab4351e80b..46d23fbfd5f7 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -477,10 +477,14 @@ static unsigned long trbe_normal_offset(struct perf_output_handle *handle) * If the head is too close to the limit and we don't * have space for a meaningful run, we rather pad it * and start fresh. + * + * We might have to do this more than once to make sure + * we have enough required space. */ - if (limit && ((limit - head) < trbe_min_trace_buf_size(handle))) { + while (limit && ((limit - head) < trbe_min_trace_buf_size(handle))) { trbe_pad_buf(handle, limit - head); limit = __trbe_normal_offset(handle); + head = PERF_IDX2OFF(handle->head, buf); } return limit; }
TRBE implementations affected by Arm erratum (2253138 or 2224489), could write to the next address after the TRBLIMITR.LIMIT, instead of wrapping to the TRBBASER. This implies that the TRBE could potentially corrupt :
- A page used by the rest of the kernel/user (if the LIMIT = end of perf ring buffer) - A page within the ring buffer, but outside the driver's range. [head, head + size]. This may contain some trace data, may be consumed by the userspace.
We workaround this erratum by : - Making sure that there is at least an extra PAGE space left in the TRBE's range than we normally assign. This will be additional to other restrictions (e.g, the TRBE alignment for working around TRBE_WORKAROUND_OVERWRITE_IN_FILL_MODE, where there is a minimum of PAGE_SIZE. Thus we would have 2 * PAGE_SIZE)
- Adjust the LIMIT to leave the last PAGE_SIZE out of the TRBE's allowed range (i.e, TRBEBASER...TRBLIMITR.LIMIT), by :
TRBLIMITR.LIMIT -= PAGE_SIZE
Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Mike Leach mike.leach@linaro.org Cc: Leo Yan leo.yan@linaro.org Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- drivers/hwtracing/coresight/coresight-trbe.c | 63 +++++++++++++++++++- 1 file changed, 62 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index 46d23fbfd5f7..5d350acef798 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -90,9 +90,11 @@ struct trbe_buf { * - Streamlined detection of erratum across the system */ #define TRBE_WORKAROUND_OVERWRITE_FILL_MODE 0 +#define TRBE_WORKAROUND_WRITE_OUT_OF_RANGE 1
static int trbe_errata_cpucaps[] = { [TRBE_WORKAROUND_OVERWRITE_FILL_MODE] = ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE, + [TRBE_WORKAROUND_WRITE_OUT_OF_RANGE] = ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE, -1, /* Sentinel, must be the last entry */ };
@@ -160,6 +162,11 @@ static inline bool trbe_may_overwrite_in_fill_mode(struct trbe_cpudata *cpudata) return trbe_has_erratum(cpudata, TRBE_WORKAROUND_OVERWRITE_FILL_MODE); }
+static inline bool trbe_may_write_out_of_range(struct trbe_cpudata *cpudata) +{ + return trbe_has_erratum(cpudata, TRBE_WORKAROUND_WRITE_OUT_OF_RANGE); +} + static int trbe_alloc_node(struct perf_event *event) { if (event->cpu == -1) @@ -305,7 +312,21 @@ static unsigned long trbe_snapshot_offset(struct perf_output_handle *handle)
static u64 trbe_min_trace_buf_size(struct perf_output_handle *handle) { - return TRBE_TRACE_MIN_BUF_SIZE; + u64 size = TRBE_TRACE_MIN_BUF_SIZE; + struct trbe_buf *buf = etm_perf_sink_config(handle); + struct trbe_cpudata *cpudata = buf->cpudata; + + /* + * When the TRBE is affected by an erratum that could make it + * write to the next "virtually addressed" page beyond the LIMIT. + * We need to make sure there is always a PAGE after the LIMIT, + * within the buffer. Thus we ensure there is at least an extra + * page than normal. With this we could then adjust the LIMIT + * pointer down by a PAGE later. + */ + if (trbe_may_write_out_of_range(cpudata)) + size += PAGE_SIZE; + return size; }
/* @@ -611,6 +632,17 @@ static unsigned long trbe_get_trace_size(struct perf_output_handle *handle, /* * If the TRBE has wrapped around the write pointer has * wrapped and should be treated as limit. + * + * When the TRBE is affected by TRBE_WORKAROUND_WRITE_OUT_OF_RANGE, + * it may write upto 64bytes beyond the "LIMIT". The driver already + * keeps a valid page next to the LIMIT and we could potentially + * consume the trace data that may have been collected there. But we + * cannot be really sure it is available, and the TRBPTR may not + * indicate the same. Also, affected cores are also affected by another + * erratum which forces the PAGE_SIZE alignment on the TRBPTR, and thus + * could potentially pad an entire PAGE_SIZE - 64bytes, to get those + * 64bytes. Thus we ignore the potential triggering of the erratum + * on WRAP and limit the data to LIMIT. */ if (wrap) write = get_trbe_limit_pointer(); @@ -864,6 +896,35 @@ static int trbe_apply_work_around_before_enable(struct trbe_buf *buf) buf->trbe_write += TRBE_WORKAROUND_OVERWRITE_FILL_MODE_SKIP_BYTES; }
+ /* + * TRBE_WORKAROUND_WRITE_OUT_OF_RANGE could cause the TRBE to write to + * the next page after the TRBLIMITR.LIMIT. For perf, the "next page" + * may be: + * - The page beyond the ring buffer. This could mean, TRBE could + * corrupt another entity (kernel / user) + * - A portion of the "ring buffer" consumed by the userspace. + * i.e, a page outisde [head, head + size]. + * + * We work around this by: + * - Making sure that we have at least an extra space of PAGE left + * in the ring buffer [head, head + size], than we normally do + * without the erratum. See trbe_min_trace_buf_size(). + * + * - Adjust the TRBLIMITR.LIMIT to leave the extra PAGE outside + * the TRBE's range (i.e [TRBBASER, TRBLIMITR.LIMI] ). + */ + if (trbe_has_erratum(buf->cpudata, TRBE_WORKAROUND_WRITE_OUT_OF_RANGE)) { + s64 space = buf->trbe_limit - buf->trbe_write; + /* + * We must have more than a PAGE_SIZE worth space in the proposed + * range for the TRBE. + */ + if (WARN_ON(space <= PAGE_SIZE || + !IS_ALIGNED(buf->trbe_limit, PAGE_SIZE))) + return -EINVAL; + buf->trbe_limit -= PAGE_SIZE; + } + return 0; }
With the workaround enabled in TRBE, enable the config entries to be built without COMPILE_TEST
Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- arch/arm64/Kconfig | 2 -- 1 file changed, 2 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 87a07e895db9..c0f7c8d19aea 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -672,7 +672,6 @@ config ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE config ARM64_ERRATUM_2119858 bool "Cortex-A710: 2119858: workaround TRBE overwriting trace data in FILL mode" default y - depends on COMPILE_TEST # Until the CoreSight TRBE driver changes are in depends on CORESIGHT_TRBE select ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE help @@ -691,7 +690,6 @@ config ARM64_ERRATUM_2119858 config ARM64_ERRATUM_2139208 bool "Neoverse-N2: 2139208: workaround TRBE overwriting trace data in FILL mode" default y - depends on COMPILE_TEST # Until the CoreSight TRBE driver changes are in depends on CORESIGHT_TRBE select ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE help
With the TRBE driver workaround available, enable the config symbols to be built without COMPILE_TEST
Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- arch/arm64/Kconfig | 2 -- 1 file changed, 2 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index c0f7c8d19aea..a8c10fac8f6b 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -743,7 +743,6 @@ config ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE
config ARM64_ERRATUM_2253138 bool "Neoverse-N2: 2253138: workaround TRBE writing to address out-of-range" - depends on COMPILE_TEST # Until the CoreSight TRBE driver changes are in depends on CORESIGHT_TRBE default y select ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE @@ -762,7 +761,6 @@ config ARM64_ERRATUM_2253138
config ARM64_ERRATUM_2224489 bool "Cortex-A710: 2224489: workaround TRBE writing to address out-of-range" - depends on COMPILE_TEST # Until the CoreSight TRBE driver changes are in depends on CORESIGHT_TRBE default y select ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE
-
Suzuki K Poulose