From: Anshuman Khandual anshuman.khandual@arm.com
maillist inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8EC9K CVE: NA
Reference: https://lore.kernel.org/lkml/20230711082455.215983-7-anshuman.khandual@arm.c...
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This extends recently added branch stack sampling framework in ARMV8 PMU to enable such events via new architecture feature called Branch Record Buffer Extension aka BRBE. This implements all the armv8pmu_branch_xxx() callbacks as expected at ARMV8 PMU level required to drive perf branch stack sampling events. This adds a new config option CONFIG_ARM64_BRBE to encapsulate this BRBE based implementation, available only on ARM64 platforms.
BRBE hardware captures a branch record via three distinct system registers representing branch source address, branch target address, and other branch information. A BRBE buffer implementation is organized as multiple banks of 32 branch records each, which is a collection of BRBSRC_EL1, BRBTGT_EL1 and BRBINF_EL1 registers. Though total BRBE record entries i.e BRBE_MAX_ENTRIES cannot exceed MAX_BRANCH_RECORDS as defined for ARM PMU.
BRBE hardware attributes get captured in a new reg_brbidr element in struct arm_pmu during armv8pmu_branch_probe() which is called from broader probing function __armv8pmu_probe_pmu(). Attributes such as number of branch record entries implemented in the hardware can be derived from armpmu->reg_brbidr.
BRBE gets enabled via armv8pmu_branch_enable() where it also derives branch filter, and additional requirements from event's 'attr.branch_sample_type' and configures them via BRBFCR_EL1 and BRBCR_EL1 registers.
PMU event overflow triggers IRQ, where current branch records get captured, stitched along with older records available in 'task_ctx', before getting processed for core perf ring buffer. Task context switch outs incrementally save current branch records in event's 'pmu_ctx->task_ctx_data' to optimize workload's branch record samples.
In case multiple events with different branch sample type requests converge on the same PMU, BRBE gets enabled for branch filters for the last event's branch sample type. No branch records will be captured and processed for an event if BRBE hardware config does not match its branch sample type, while handling the PMU IRQ.
Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual anshuman.khandual@arm.com Signed-off-by: Junhao He hejunhao3@huawei.com --- arch/arm64/include/asm/perf_event.h | 13 + arch/arm64/include/asm/sysreg.h | 8 + arch/arm64/kernel/head.S | 48 ++ drivers/perf/Kconfig | 11 + drivers/perf/Makefile | 1 + drivers/perf/arm_brbe.c | 779 ++++++++++++++++++++++++++++ drivers/perf/arm_brbe.h | 258 +++++++++ drivers/perf/arm_pmu.c | 6 + include/linux/perf/arm_pmu.h | 5 + 9 files changed, 1129 insertions(+) create mode 100644 drivers/perf/arm_brbe.c create mode 100644 drivers/perf/arm_brbe.h
diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/perf_event.h index c2129b1bf5f0..7053b977c0a2 100644 --- a/arch/arm64/include/asm/perf_event.h +++ b/arch/arm64/include/asm/perf_event.h @@ -250,6 +250,18 @@ extern unsigned long perf_misc_flags(struct pt_regs *regs); #define perf_misc_flags(regs) perf_misc_flags(regs) #define perf_arch_bpf_user_pt_regs(regs) ®s->user_regs
+#ifdef CONFIG_ARM64_BRBE +void armv8pmu_branch_reset(void); +void armv8pmu_branch_probe(struct arm_pmu *arm_pmu); +bool armv8pmu_branch_attr_valid(struct perf_event *event); +void armv8pmu_branch_enable(struct perf_event *event); +void armv8pmu_branch_disable(struct perf_event *event); +void armv8pmu_branch_read(struct pmu_hw_events *cpuc, + struct perf_event *event); +void armv8pmu_branch_save(struct arm_pmu *arm_pmu, void *ctx); +int armv8pmu_task_ctx_cache_alloc(struct arm_pmu *arm_pmu); +void armv8pmu_task_ctx_cache_free(struct arm_pmu *arm_pmu); +#else /* !CONFIG_ARM64_BRBE */ static inline void armv8pmu_branch_reset(void) { } @@ -288,6 +300,7 @@ static inline int armv8pmu_task_ctx_cache_alloc(struct arm_pmu *arm_pmu) static inline void armv8pmu_task_ctx_cache_free(struct arm_pmu *arm_pmu) { } +#endif /* CONFIG_ARM64_BRBE */ #endif
#define perf_arch_fetch_caller_regs(regs, __ip) { \ diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index d25a31f93bbf..4431c92c23bd 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -110,6 +110,14 @@ #define SYS_DC_ISW sys_insn(1, 0, 7, 6, 2) #define SYS_DC_CSW sys_insn(1, 0, 7, 10, 2) #define SYS_DC_CISW sys_insn(1, 0, 7, 14, 2) +#define SYS_BRB_IALL sys_insn(1, 1, 7, 2, 4) +#define SYS_BRB_INJ sys_insn(1, 1, 7, 2, 5) + +/* + * BRBE Instructions + */ +#define BRB_IALL_INSN __emit_inst(0xd5000000 | SYS_BRB_IALL | (0x1f)) +#define BRB_INJ_INSN __emit_inst(0xd5000000 | SYS_BRB_INJ | (0x1f))
/* * System registers, organised loosely by encoding but grouped together diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 5bc343fc2a91..1dc0e60248a3 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -486,6 +486,51 @@ EXPORT_SYMBOL(kimage_vaddr) */ .section ".idmap.text","awx"
+#ifdef CONFIG_ARM64_BRBE +/* + * Enable BRBE cycle count + * + * BRBE requires both BRBCR_EL1.CC and BRBCR_EL2.CC fields, be set + * for the cycle counts to be available in BRBINF<N>_EL1.CC during + * branch record processing after a PMU interrupt. This enables CC + * field on both these registers while still executing inside EL2. + * + * BRBE driver would still be able to toggle branch records cycle + * count support via BRBCR_EL1.CC field regardless of whether the + * kernel ends up executing in EL1 or EL2. + */ +.macro __init_el2_brbe + mrs x1, id_aa64dfr0_el1 + ubfx x1, x1, #ID_AA64DFR0_EL1_BRBE_SHIFT, #4 + cbz x1, .Lskip_brbe_cc_@ + + mrs_s x0, SYS_BRBCR_EL2 + orr x0, x0, BRBCR_ELx_CC + msr_s SYS_BRBCR_EL2, x0 + + /* + * Accessing BRBCR_EL1 register here does not require + * BRBCR_EL12 addressing mode as HCR_EL2.E2H is still + * clear. Regardless, check for HCR_E2H and be on the + * safer side. + */ + mrs x1, hcr_el2 + and x1, x1, #HCR_E2H + cbz x1, .Lset_brbe_el1_direct_@ + + mrs_s x0, SYS_BRBCR_EL12 + orr x0, x0, BRBCR_ELx_CC + msr_s SYS_BRBCR_EL12, x0 + b .Lskip_brbe_cc_@ + +.Lset_brbe_el1_direct_@: + mrs_s x0, SYS_BRBCR_EL1 + orr x0, x0, BRBCR_ELx_CC + msr_s SYS_BRBCR_EL1, x0 +.Lskip_brbe_cc_@: +.endm + +#endif /* * If we're fortunate enough to boot at EL2, ensure that the world is * sane before dropping to EL1. @@ -601,6 +646,9 @@ set_hcr: 7: msr mdcr_el2, x3 // Configure debug traps
+#ifdef CONFIG_ARM64_BRBE + __init_el2_brbe +#endif /* LORegions */ mrs x1, id_aa64mmfr1_el1 ubfx x0, x1, #ID_AA64MMFR1_LOR_SHIFT, 4 diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig index 1e82ab01e75f..25a577530da4 100644 --- a/drivers/perf/Kconfig +++ b/drivers/perf/Kconfig @@ -130,6 +130,17 @@ config ARM_SPE_PMU Extension, which provides periodic sampling of operations in the CPU pipeline and reports this via the perf AUX interface.
+config ARM64_BRBE + bool "Enable support for Branch Record Buffer Extension (BRBE)" + depends on PERF_EVENTS && ARM64 && ARM_PMU + default y + help + Enable perf support for Branch Record Buffer Extension (BRBE) which + records all branches taken in an execution path. This supports some + branch types and privilege based filtering. It captures additional + relevant information such as cycle count, misprediction and branch + type, branch privilege level etc. + source "drivers/perf/hisilicon/Kconfig"
endmenu diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile index 5365fd56f88f..a89359aeac6d 100644 --- a/drivers/perf/Makefile +++ b/drivers/perf/Makefile @@ -13,3 +13,4 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o obj-$(CONFIG_ARM_SPE_PMU) += arm_spe_pmu.o +obj-$(CONFIG_ARM64_BRBE) += arm_brbe.o diff --git a/drivers/perf/arm_brbe.c b/drivers/perf/arm_brbe.c new file mode 100644 index 000000000000..1ffa41e355cf --- /dev/null +++ b/drivers/perf/arm_brbe.c @@ -0,0 +1,779 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Branch Record Buffer Extension Driver. + * + * Copyright (C) 2022-2023 ARM Limited + * + * Author: Anshuman Khandual anshuman.khandual@arm.com + */ +#include "arm_brbe.h" + +void armv8pmu_branch_reset(void) +{ + asm volatile(BRB_IALL_INSN); + isb(); +} + +static bool valid_brbe_nr(int brbe_nr) +{ + return brbe_nr == BRBIDR0_EL1_NUMREC_8 || + brbe_nr == BRBIDR0_EL1_NUMREC_16 || + brbe_nr == BRBIDR0_EL1_NUMREC_32 || + brbe_nr == BRBIDR0_EL1_NUMREC_64; +} + +static bool valid_brbe_cc(int brbe_cc) +{ + return brbe_cc == BRBIDR0_EL1_CC_20_BIT; +} + +static bool valid_brbe_format(int brbe_format) +{ + return brbe_format == BRBIDR0_EL1_FORMAT_0; +} + +static bool valid_brbe_version(int brbe_version) +{ + return brbe_version == ID_AA64DFR0_EL1_BRBE_IMP || + brbe_version == ID_AA64DFR0_EL1_BRBE_BRBE_V1P1; +} + +static void select_brbe_bank(int bank) +{ + u64 brbfcr; + + WARN_ON(bank > BRBE_BANK_IDX_1); + brbfcr = read_sysreg_s(SYS_BRBFCR_EL1); + brbfcr &= ~BRBFCR_EL1_BANK_MASK; + brbfcr |= SYS_FIELD_PREP(BRBFCR_EL1, BANK, bank); + write_sysreg_s(brbfcr, SYS_BRBFCR_EL1); + isb(); +} + +static bool __read_brbe_regset(struct brbe_regset *entry, int idx) +{ + entry->brbinf = get_brbinf_reg(idx); + + if (brbe_invalid(entry->brbinf)) + return false; + + entry->brbsrc = get_brbsrc_reg(idx); + entry->brbtgt = get_brbtgt_reg(idx); + return true; +} + +/* + * Read all BRBE entries in HW until the first invalid entry. + * + * The caller must ensure that the BRBE is not concurrently modifying these + * branch entries. + */ +static int capture_brbe_regset(struct brbe_regset *buf, int nr_hw_entries) +{ + int idx = 0; + + select_brbe_bank(BRBE_BANK_IDX_0); + while (idx < nr_hw_entries && idx <= BRBE_BANK0_IDX_MAX) { + if (!__read_brbe_regset(&buf[idx], idx)) + return idx; + idx++; + } + + select_brbe_bank(BRBE_BANK_IDX_1); + while (idx < nr_hw_entries && idx <= BRBE_BANK1_IDX_MAX) { + if (!__read_brbe_regset(&buf[idx], idx)) + return idx; + idx++; + } + return idx; +} + +/* + * This function concatenates branch records from stored and live buffer + * up to maximum nr_max records and the stored buffer holds the resultant + * buffer. The concatenated buffer contains all the branch records from + * the live buffer but might contain some from stored buffer considering + * the maximum combined length does not exceed 'nr_max'. + * + * Stored records Live records + * ------------------------------------------------^ + * | S0 | L0 | Newest | + * --------------------------------- | + * | S1 | L1 | | + * --------------------------------- | + * | S2 | L2 | | + * --------------------------------- | + * | S3 | L3 | | + * --------------------------------- | + * | S4 | L4 | nr_max + * --------------------------------- | + * | | L5 | | + * --------------------------------- | + * | | L6 | | + * --------------------------------- | + * | | L7 | | + * --------------------------------- | + * | | | | + * --------------------------------- | + * | | | Oldest | + * ------------------------------------------------V + * + * + * S0 is the newest in the stored records, where as L7 is the oldest in + * the live records. Unless the live buffer is detected as being full + * thus potentially dropping off some older records, L7 and S0 records + * are contiguous in time for a user task context. The stitched buffer + * here represents maximum possible branch records, contiguous in time. + * + * Stored records Live records + * ------------------------------------------------^ + * | L0 | L0 | Newest | + * --------------------------------- | + * | L0 | L1 | | + * --------------------------------- | + * | L2 | L2 | | + * --------------------------------- | + * | L3 | L3 | | + * --------------------------------- | + * | L4 | L4 | nr_max + * --------------------------------- | + * | L5 | L5 | | + * --------------------------------- | + * | L6 | L6 | | + * --------------------------------- | + * | L7 | L7 | | + * --------------------------------- | + * | S0 | | | + * --------------------------------- | + * | S1 | | Oldest | + * ------------------------------------------------V + * | S2 | <----| + * ----------------- | + * | S3 | <----| Dropped off after nr_max + * ----------------- | + * | S4 | <----| + * ----------------- + */ +static int stitch_stored_live_entries(struct brbe_regset *stored, + struct brbe_regset *live, + int nr_stored, int nr_live, + int nr_max) +{ + int nr_move = min(nr_stored, nr_max - nr_live); + + /* Move the tail of the buffer to make room for the new entries */ + memmove(&stored[nr_live], &stored[0], nr_move * sizeof(*stored)); + + /* Copy the new entries into the head of the buffer */ + memcpy(&stored[0], &live[0], nr_live * sizeof(*stored)); + + /* Return the number of entries in the stitched buffer */ + return min(nr_live + nr_stored, nr_max); +} + +static int brbe_branch_save(struct brbe_regset *live, int nr_hw_entries) +{ + u64 brbfcr = read_sysreg_s(SYS_BRBFCR_EL1); + int nr_live; + + write_sysreg_s(brbfcr | BRBFCR_EL1_PAUSED, SYS_BRBFCR_EL1); + isb(); + + nr_live = capture_brbe_regset(live, nr_hw_entries); + + write_sysreg_s(brbfcr & ~BRBFCR_EL1_PAUSED, SYS_BRBFCR_EL1); + isb(); + + return nr_live; +} + +void armv8pmu_branch_save(struct arm_pmu *arm_pmu, void *ctx) +{ + struct arm64_perf_task_context *task_ctx = ctx; + struct brbe_regset live[BRBE_MAX_ENTRIES]; + int nr_live, nr_store, nr_hw_entries; + + nr_hw_entries = brbe_get_numrec(arm_pmu->reg_brbidr); + nr_live = brbe_branch_save(live, nr_hw_entries); + nr_store = task_ctx->nr_brbe_records; + nr_store = stitch_stored_live_entries(task_ctx->store, live, nr_store, + nr_live, nr_hw_entries); + task_ctx->nr_brbe_records = nr_store; +} + +/* + * Generic perf branch filters supported on BRBE + * + * New branch filters need to be evaluated whether they could be supported on + * BRBE. This ensures that such branch filters would not just be accepted, to + * fail silently. PERF_SAMPLE_BRANCH_HV is a special case that is selectively + * supported only on platforms where kernel is in hyp mode. + */ +#define BRBE_EXCLUDE_BRANCH_FILTERS (PERF_SAMPLE_BRANCH_ABORT_TX | \ + PERF_SAMPLE_BRANCH_IN_TX | \ + PERF_SAMPLE_BRANCH_NO_TX | \ + PERF_SAMPLE_BRANCH_CALL_STACK) + +#define BRBE_ALLOWED_BRANCH_FILTERS (PERF_SAMPLE_BRANCH_USER | \ + PERF_SAMPLE_BRANCH_KERNEL | \ + PERF_SAMPLE_BRANCH_HV | \ + PERF_SAMPLE_BRANCH_ANY | \ + PERF_SAMPLE_BRANCH_ANY_CALL | \ + PERF_SAMPLE_BRANCH_ANY_RETURN | \ + PERF_SAMPLE_BRANCH_IND_CALL | \ + PERF_SAMPLE_BRANCH_COND | \ + PERF_SAMPLE_BRANCH_IND_JUMP | \ + PERF_SAMPLE_BRANCH_CALL | \ + PERF_SAMPLE_BRANCH_NO_FLAGS | \ + PERF_SAMPLE_BRANCH_NO_CYCLES | \ + PERF_SAMPLE_BRANCH_TYPE_SAVE | \ + PERF_SAMPLE_BRANCH_HW_INDEX | \ + PERF_SAMPLE_BRANCH_PRIV_SAVE) + +#define BRBE_PERF_BRANCH_FILTERS (BRBE_ALLOWED_BRANCH_FILTERS | \ + BRBE_EXCLUDE_BRANCH_FILTERS) + +bool armv8pmu_branch_attr_valid(struct perf_event *event) +{ + u64 branch_type = event->attr.branch_sample_type; + + /* + * Ensure both perf branch filter allowed and exclude + * masks are always in sync with the generic perf ABI. + */ + BUILD_BUG_ON(BRBE_PERF_BRANCH_FILTERS != (PERF_SAMPLE_BRANCH_MAX - 1)); + + if (branch_type & ~BRBE_ALLOWED_BRANCH_FILTERS) { + pr_debug_once("requested branch filter not supported 0x%llx\n", branch_type); + return false; + } + + /* + * If the event does not have at least one of the privilege + * branch filters as in PERF_SAMPLE_BRANCH_PLM_ALL, the core + * perf will adjust its value based on perf event's existing + * privilege level via attr.exclude_[user|kernel|hv]. + * + * As event->attr.branch_sample_type might have been changed + * when the event reaches here, it is not possible to figure + * out whether the event originally had HV privilege request + * or got added via the core perf. Just report this situation + * once and continue ignoring if there are other instances. + */ + if ((branch_type & PERF_SAMPLE_BRANCH_HV) && !is_kernel_in_hyp_mode()) + pr_debug_once("hypervisor privilege filter not supported 0x%llx\n", branch_type); + + return true; +} + +int armv8pmu_task_ctx_cache_alloc(struct arm_pmu *arm_pmu) +{ + size_t size = sizeof(struct arm64_perf_task_context); + + arm_pmu->pmu.task_ctx_cache = kmem_cache_create("arm64_brbe_task_ctx", size, 0, 0, NULL); + if (!arm_pmu->pmu.task_ctx_cache) + return -ENOMEM; + return 0; +} + +void armv8pmu_task_ctx_cache_free(struct arm_pmu *arm_pmu) +{ + kmem_cache_destroy(arm_pmu->pmu.task_ctx_cache); +} + +static int brbe_attributes_probe(struct arm_pmu *armpmu, u32 brbe) +{ + u64 brbidr = read_sysreg_s(SYS_BRBIDR0_EL1); + int brbe_version, brbe_format, brbe_cc, brbe_nr; + + brbe_version = brbe; + brbe_format = brbe_get_format(brbidr); + brbe_cc = brbe_get_cc_bits(brbidr); + brbe_nr = brbe_get_numrec(brbidr); + armpmu->reg_brbidr = brbidr; + + if (!valid_brbe_version(brbe_version) || + !valid_brbe_format(brbe_format) || + !valid_brbe_cc(brbe_cc) || + !valid_brbe_nr(brbe_nr)) + return -EOPNOTSUPP; + return 0; +} + +void armv8pmu_branch_probe(struct arm_pmu *armpmu) +{ + u64 aa64dfr0 = read_sysreg_s(SYS_ID_AA64DFR0_EL1); + u32 brbe; + + /* + * BRBE implementation's branch entries cannot exceed maximum + * branch records supported at the ARM PMU level abstraction. + * Otherwise there is always a possibility of array overflow, + * while processing BRBE branch records. + */ + BUILD_BUG_ON(BRBE_BANK_MAX_ENTRIES > MAX_BRANCH_RECORDS); + + brbe = cpuid_feature_extract_unsigned_field(aa64dfr0, ID_AA64DFR0_EL1_BRBE_SHIFT); + if (!brbe) + return; + + if (brbe_attributes_probe(armpmu, brbe)) + return; + + armpmu->has_branch_stack = 1; +} + +/* + * BRBE supports the following functional branch type filters while + * generating branch records. These branch filters can be enabled, + * either individually or as a group i.e ORing multiple filters + * with each other. + * + * BRBFCR_EL1_CONDDIR - Conditional direct branch + * BRBFCR_EL1_DIRCALL - Direct call + * BRBFCR_EL1_INDCALL - Indirect call + * BRBFCR_EL1_INDIRECT - Indirect branch + * BRBFCR_EL1_DIRECT - Direct branch + * BRBFCR_EL1_RTN - Subroutine return + */ +static u64 branch_type_to_brbfcr(int branch_type) +{ + u64 brbfcr = 0; + + if (branch_type & PERF_SAMPLE_BRANCH_ANY) { + brbfcr |= BRBFCR_EL1_BRANCH_FILTERS; + return brbfcr; + } + + if (branch_type & PERF_SAMPLE_BRANCH_ANY_CALL) { + brbfcr |= BRBFCR_EL1_INDCALL; + brbfcr |= BRBFCR_EL1_DIRCALL; + } + + if (branch_type & PERF_SAMPLE_BRANCH_ANY_RETURN) + brbfcr |= BRBFCR_EL1_RTN; + + if (branch_type & PERF_SAMPLE_BRANCH_IND_CALL) + brbfcr |= BRBFCR_EL1_INDCALL; + + if (branch_type & PERF_SAMPLE_BRANCH_COND) + brbfcr |= BRBFCR_EL1_CONDDIR; + + if (branch_type & PERF_SAMPLE_BRANCH_IND_JUMP) + brbfcr |= BRBFCR_EL1_INDIRECT; + + if (branch_type & PERF_SAMPLE_BRANCH_CALL) + brbfcr |= BRBFCR_EL1_DIRCALL; + + return brbfcr; +} + +/* + * BRBE supports the following privilege mode filters while generating + * branch records. + * + * BRBCR_ELx_E0BRE - EL0 branch records + * BRBCR_ELx_ExBRE - EL1/EL2 branch records + * + * BRBE also supports the following additional functional branch type + * filters while generating branch records. + * + * BRBCR_ELx_EXCEPTION - Exception + * BRBCR_ELx_ERTN - Exception return + */ +static u64 branch_type_to_brbcr(int branch_type) +{ + u64 brbcr = BRBCR_ELx_DEFAULT_TS; + + /* + * BRBE should be paused on PMU interrupt while tracing kernel + * space to stop capturing further branch records. Otherwise + * interrupt handler branch records might get into the samples + * which is not desired. + * + * BRBE need not be paused on PMU interrupt while tracing only + * the user space, because it will automatically be inside the + * prohibited region. But even after PMU overflow occurs, the + * interrupt could still take much more cycles, before it can + * be taken and by that time BRBE will have been overwritten. + * Hence enable pause on PMU interrupt mechanism even for user + * only traces as well. + */ + brbcr |= BRBCR_ELx_FZP; + + if (branch_type & PERF_SAMPLE_BRANCH_USER) + brbcr |= BRBCR_ELx_E0BRE; + + /* + * When running in the hyp mode, writing into BRBCR_EL1 + * actually writes into BRBCR_EL2 instead. Field E2BRE + * is also at the same position as E1BRE. + */ + if (branch_type & PERF_SAMPLE_BRANCH_KERNEL) + brbcr |= BRBCR_ELx_ExBRE; + + if (branch_type & PERF_SAMPLE_BRANCH_HV) { + if (is_kernel_in_hyp_mode()) + brbcr |= BRBCR_ELx_ExBRE; + } + + if (!(branch_type & PERF_SAMPLE_BRANCH_NO_CYCLES)) + brbcr |= BRBCR_ELx_CC; + + if (!(branch_type & PERF_SAMPLE_BRANCH_NO_FLAGS)) + brbcr |= BRBCR_ELx_MPRED; + + /* + * The exception and exception return branches could be + * captured, irrespective of the perf event's privilege. + * If the perf event does not have enough privilege for + * a given exception level, then addresses which falls + * under that exception level will be reported as zero + * for the captured branch record, creating source only + * or target only records. + */ + if (branch_type & PERF_SAMPLE_BRANCH_ANY) { + brbcr |= BRBCR_ELx_EXCEPTION; + brbcr |= BRBCR_ELx_ERTN; + } + + if (branch_type & PERF_SAMPLE_BRANCH_ANY_CALL) + brbcr |= BRBCR_ELx_EXCEPTION; + + if (branch_type & PERF_SAMPLE_BRANCH_ANY_RETURN) + brbcr |= BRBCR_ELx_ERTN; + + return brbcr & BRBCR_ELx_CONFIG_MASK; +} + +void armv8pmu_branch_enable(struct perf_event *event) +{ + struct arm_pmu *cpu_pmu = to_arm_pmu(event->pmu); + struct pmu_hw_events *cpuc = this_cpu_ptr(cpu_pmu->hw_events); + u64 brbfcr, brbcr; + + if (!cpuc->brbe_users) + return; + + /* + * Skip enabling BRBE again with same filters and configs + */ + if (cpuc->brbe_sample_type == event->attr.branch_sample_type) + return; + + /* + * BRBE gets configured with a new mismatched branch sample + * type request, overriding any previous branch filters. + */ + cpuc->brbe_sample_type = event->attr.branch_sample_type; + brbfcr = read_sysreg_s(SYS_BRBFCR_EL1); + brbfcr &= ~BRBFCR_EL1_DEFAULT_CONFIG; + brbfcr |= branch_type_to_brbfcr(cpuc->brbe_sample_type); + write_sysreg_s(brbfcr, SYS_BRBFCR_EL1); + isb(); + + brbcr = read_sysreg_s(SYS_BRBCR_EL1); + brbcr &= ~BRBCR_ELx_CONFIG_MASK; + brbcr |= branch_type_to_brbcr(cpuc->brbe_sample_type); + write_sysreg_s(brbcr, SYS_BRBCR_EL1); + isb(); +} + +void armv8pmu_branch_disable(struct perf_event *event) +{ + struct arm_pmu *cpu_pmu = to_arm_pmu(event->pmu); + struct pmu_hw_events *cpuc = this_cpu_ptr(cpu_pmu->hw_events); + u64 brbfcr, brbcr; + + if (cpuc->brbe_users) + return; + + cpuc->brbe_sample_type = 0; + brbcr = read_sysreg_s(SYS_BRBCR_EL1); + brbfcr = read_sysreg_s(SYS_BRBFCR_EL1); + brbcr &= ~(BRBCR_ELx_E0BRE | BRBCR_ELx_ExBRE); + brbfcr |= BRBFCR_EL1_PAUSED; + write_sysreg_s(brbcr, SYS_BRBCR_EL1); + write_sysreg_s(brbfcr, SYS_BRBFCR_EL1); + isb(); +} + +static void brbe_set_perf_entry_type(struct perf_branch_entry *entry, u64 brbinf) +{ + int brbe_type = brbe_get_type(brbinf); + + switch (brbe_type) { + case BRBINFx_EL1_TYPE_UNCOND_DIRECT: + entry->type = PERF_BR_UNCOND; + break; + case BRBINFx_EL1_TYPE_INDIRECT: + entry->type = PERF_BR_IND; + break; + case BRBINFx_EL1_TYPE_DIRECT_LINK: + entry->type = PERF_BR_CALL; + break; + case BRBINFx_EL1_TYPE_INDIRECT_LINK: + entry->type = PERF_BR_IND_CALL; + break; + case BRBINFx_EL1_TYPE_RET: + entry->type = PERF_BR_RET; + break; + case BRBINFx_EL1_TYPE_COND_DIRECT: + entry->type = PERF_BR_COND; + break; + case BRBINFx_EL1_TYPE_CALL: + entry->type = PERF_BR_CALL; + break; + case BRBINFx_EL1_TYPE_TRAP: + entry->type = PERF_BR_SYSCALL; + break; + case BRBINFx_EL1_TYPE_ERET: + entry->type = PERF_BR_ERET; + break; + case BRBINFx_EL1_TYPE_IRQ: + entry->type = PERF_BR_IRQ; + break; + case BRBINFx_EL1_TYPE_DEBUG_HALT: + entry->type = PERF_BR_EXTEND_ABI; + entry->new_type = PERF_BR_ARM64_DEBUG_HALT; + break; + case BRBINFx_EL1_TYPE_SERROR: + entry->type = PERF_BR_SERROR; + break; + case BRBINFx_EL1_TYPE_INSN_DEBUG: + entry->type = PERF_BR_EXTEND_ABI; + entry->new_type = PERF_BR_ARM64_DEBUG_INST; + break; + case BRBINFx_EL1_TYPE_DATA_DEBUG: + entry->type = PERF_BR_EXTEND_ABI; + entry->new_type = PERF_BR_ARM64_DEBUG_DATA; + break; + case BRBINFx_EL1_TYPE_ALIGN_FAULT: + entry->type = PERF_BR_EXTEND_ABI; + entry->new_type = PERF_BR_NEW_FAULT_ALGN; + break; + case BRBINFx_EL1_TYPE_INSN_FAULT: + entry->type = PERF_BR_EXTEND_ABI; + entry->new_type = PERF_BR_NEW_FAULT_INST; + break; + case BRBINFx_EL1_TYPE_DATA_FAULT: + entry->type = PERF_BR_EXTEND_ABI; + entry->new_type = PERF_BR_NEW_FAULT_DATA; + break; + case BRBINFx_EL1_TYPE_FIQ: + entry->type = PERF_BR_EXTEND_ABI; + entry->new_type = PERF_BR_ARM64_FIQ; + break; + case BRBINFx_EL1_TYPE_DEBUG_EXIT: + entry->type = PERF_BR_EXTEND_ABI; + entry->new_type = PERF_BR_ARM64_DEBUG_EXIT; + break; + default: + pr_warn_once("%d - unknown branch type captured\n", brbe_type); + entry->type = PERF_BR_UNKNOWN; + break; + } +} + +static int brbe_get_perf_priv(u64 brbinf) +{ + int brbe_el = brbe_get_el(brbinf); + + switch (brbe_el) { + case BRBINFx_EL1_EL_EL0: + return PERF_BR_PRIV_USER; + case BRBINFx_EL1_EL_EL1: + return PERF_BR_PRIV_KERNEL; + case BRBINFx_EL1_EL_EL2: + if (is_kernel_in_hyp_mode()) + return PERF_BR_PRIV_KERNEL; + return PERF_BR_PRIV_HV; + default: + pr_warn_once("%d - unknown branch privilege captured\n", brbe_el); + return PERF_BR_PRIV_UNKNOWN; + } +} + +static void capture_brbe_flags(struct perf_branch_entry *entry, struct perf_event *event, + u64 brbinf) +{ + if (branch_sample_type(event)) + brbe_set_perf_entry_type(entry, brbinf); + + if (!branch_sample_no_cycles(event)) + entry->cycles = brbe_get_cycles(brbinf); + + if (!branch_sample_no_flags(event)) { + /* + * BRBINFx_EL1.LASTFAILED indicates that a TME transaction failed (or + * was cancelled) prior to this record, and some number of records + * prior to this one, may have been generated during an attempt to + * execute the transaction. + * + * We will remove such entries later in process_branch_aborts(). + */ + entry->abort = brbe_get_lastfailed(brbinf); + + /* + * All these information (i.e transaction state and mispredicts) + * are available for source only and complete branch records. + */ + if (brbe_record_is_complete(brbinf) || + brbe_record_is_source_only(brbinf)) { + entry->mispred = brbe_get_mispredict(brbinf); + entry->predicted = !entry->mispred; + entry->in_tx = brbe_get_in_tx(brbinf); + } + } + + if (branch_sample_priv(event)) { + /* + * All these information (i.e branch privilege level) are + * available for target only and complete branch records. + */ + if (brbe_record_is_complete(brbinf) || + brbe_record_is_target_only(brbinf)) + entry->priv = brbe_get_perf_priv(brbinf); + } +} + +/* + * A branch record with BRBINFx_EL1.LASTFAILED set, implies that all + * preceding consecutive branch records, that were in a transaction + * (i.e their BRBINFx_EL1.TX set) have been aborted. + * + * Similarly BRBFCR_EL1.LASTFAILED set, indicate that all preceding + * consecutive branch records up to the last record, which were in a + * transaction (i.e their BRBINFx_EL1.TX set) have been aborted. + * + * --------------------------------- ------------------- + * | 00 | BRBSRC | BRBTGT | BRBINF | | TX = 1 | LF = 0 | [TX success] + * --------------------------------- ------------------- + * | 01 | BRBSRC | BRBTGT | BRBINF | | TX = 1 | LF = 0 | [TX success] + * --------------------------------- ------------------- + * | 02 | BRBSRC | BRBTGT | BRBINF | | TX = 0 | LF = 0 | + * --------------------------------- ------------------- + * | 03 | BRBSRC | BRBTGT | BRBINF | | TX = 1 | LF = 0 | [TX failed] + * --------------------------------- ------------------- + * | 04 | BRBSRC | BRBTGT | BRBINF | | TX = 1 | LF = 0 | [TX failed] + * --------------------------------- ------------------- + * | 05 | BRBSRC | BRBTGT | BRBINF | | TX = 0 | LF = 1 | + * --------------------------------- ------------------- + * | .. | BRBSRC | BRBTGT | BRBINF | | TX = 0 | LF = 0 | + * --------------------------------- ------------------- + * | 61 | BRBSRC | BRBTGT | BRBINF | | TX = 1 | LF = 0 | [TX failed] + * --------------------------------- ------------------- + * | 62 | BRBSRC | BRBTGT | BRBINF | | TX = 1 | LF = 0 | [TX failed] + * --------------------------------- ------------------- + * | 63 | BRBSRC | BRBTGT | BRBINF | | TX = 1 | LF = 0 | [TX failed] + * --------------------------------- ------------------- + * + * BRBFCR_EL1.LASTFAILED == 1 + * + * BRBFCR_EL1.LASTFAILED fails all those consecutive, in transaction + * branches records near the end of the BRBE buffer. + * + * Architecture does not guarantee a non transaction (TX = 0) branch + * record between two different transactions. So it is possible that + * a subsequent lastfailed record (TX = 0, LF = 1) might erroneously + * mark more than required transactions as aborted. + */ +static void process_branch_aborts(struct pmu_hw_events *cpuc) +{ + u64 brbfcr = read_sysreg_s(SYS_BRBFCR_EL1); + bool lastfailed = !!(brbfcr & BRBFCR_EL1_LASTFAILED); + int idx = brbe_get_numrec(cpuc->percpu_pmu->reg_brbidr) - 1; + struct perf_branch_entry *entry; + + do { + entry = &cpuc->branches->branch_entries[idx]; + if (entry->in_tx) { + entry->abort = lastfailed; + } else { + lastfailed = entry->abort; + entry->abort = false; + } + } while (idx--, idx >= 0); +} + +static void brbe_regset_branch_entries(struct pmu_hw_events *cpuc, struct perf_event *event, + struct brbe_regset *regset, int idx) +{ + struct perf_branch_entry *entry = &cpuc->branches->branch_entries[idx]; + u64 brbinf = regset[idx].brbinf; + + perf_clear_branch_entry_bitfields(entry); + if (brbe_record_is_complete(brbinf)) { + entry->from = regset[idx].brbsrc; + entry->to = regset[idx].brbtgt; + } else if (brbe_record_is_source_only(brbinf)) { + entry->from = regset[idx].brbsrc; + entry->to = 0; + } else if (brbe_record_is_target_only(brbinf)) { + entry->from = 0; + entry->to = regset[idx].brbtgt; + } + capture_brbe_flags(entry, event, brbinf); +} + +static void process_branch_entries(struct pmu_hw_events *cpuc, struct perf_event *event, + struct brbe_regset *regset, int nr_regset) +{ + int idx; + + for (idx = 0; idx < nr_regset; idx++) + brbe_regset_branch_entries(cpuc, event, regset, idx); + + cpuc->branches->branch_stack.nr = nr_regset; + cpuc->branches->branch_stack.hw_idx = -1ULL; +} + +void armv8pmu_branch_read(struct pmu_hw_events *cpuc, struct perf_event *event) +{ + struct arm64_perf_task_context *task_ctx = event->ctx->task_ctx_data; + struct brbe_regset live[BRBE_MAX_ENTRIES]; + int nr_live, nr_store, nr_hw_entries; + u64 brbfcr, brbcr; + + brbcr = read_sysreg_s(SYS_BRBCR_EL1); + brbfcr = read_sysreg_s(SYS_BRBFCR_EL1); + + /* Ensure pause on PMU interrupt is enabled */ + WARN_ON_ONCE(!(brbcr & BRBCR_ELx_FZP)); + + /* Pause the buffer */ + write_sysreg_s(brbfcr | BRBFCR_EL1_PAUSED, SYS_BRBFCR_EL1); + isb(); + + /* + * Overflown event's branch_sample_type does not match the configured + * branch filters in the BRBE HW. So the captured branch records here + * cannot be co-related to the overflown event. Report to the user as + * if no branch records have been captured, and flush branch records. + */ + if ((cpuc->brbe_sample_type != event->attr.branch_sample_type) || + (event->ctx->task && cpuc->brbe_context != event->ctx)) { + cpuc->branches->branch_stack.nr = 0; + cpuc->branches->branch_stack.hw_idx = -1ULL; + goto unpause_reset; + } + + nr_hw_entries = brbe_get_numrec(cpuc->percpu_pmu->reg_brbidr); + nr_live = capture_brbe_regset(live, nr_hw_entries); + if (event->ctx->task) { + nr_store = task_ctx->nr_brbe_records; + nr_store = stitch_stored_live_entries(task_ctx->store, live, nr_store, + nr_live, nr_hw_entries); + process_branch_entries(cpuc, event, task_ctx->store, nr_store); + task_ctx->nr_brbe_records = 0; + } else { + process_branch_entries(cpuc, event, live, nr_live); + } + process_branch_aborts(cpuc); + +unpause_reset: + /* Unpause the buffer */ + write_sysreg_s(brbfcr & ~BRBFCR_EL1_PAUSED, SYS_BRBFCR_EL1); + isb(); + armv8pmu_branch_reset(); +} diff --git a/drivers/perf/arm_brbe.h b/drivers/perf/arm_brbe.h new file mode 100644 index 000000000000..5ba6cf1b0099 --- /dev/null +++ b/drivers/perf/arm_brbe.h @@ -0,0 +1,258 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Branch Record Buffer Extension Helpers. + * + * Copyright (C) 2022-2023 ARM Limited + * + * Author: Anshuman Khandual anshuman.khandual@arm.com + */ +#define pr_fmt(fmt) "brbe: " fmt + +#include <linux/perf/arm_pmu.h> + +#define BRBFCR_EL1_BRANCH_FILTERS (BRBFCR_EL1_DIRECT | \ + BRBFCR_EL1_INDIRECT | \ + BRBFCR_EL1_RTN | \ + BRBFCR_EL1_INDCALL | \ + BRBFCR_EL1_DIRCALL | \ + BRBFCR_EL1_CONDDIR) + +#define BRBFCR_EL1_DEFAULT_CONFIG (BRBFCR_EL1_BANK_MASK | \ + BRBFCR_EL1_PAUSED | \ + BRBFCR_EL1_EnI | \ + BRBFCR_EL1_BRANCH_FILTERS) + +/* + * BRBTS_EL1 is currently not used for branch stack implementation + * purpose but BRBCR_ELx.TS needs to have a valid value from all + * available options. BRBCR_ELx_TS_VIRTUAL is selected for this. + */ +#define BRBCR_ELx_DEFAULT_TS FIELD_PREP(BRBCR_ELx_TS_MASK, BRBCR_ELx_TS_VIRTUAL) + +#define BRBCR_ELx_CONFIG_MASK (BRBCR_ELx_EXCEPTION | \ + BRBCR_ELx_ERTN | \ + BRBCR_ELx_CC | \ + BRBCR_ELx_MPRED | \ + BRBCR_ELx_ExBRE | \ + BRBCR_ELx_E0BRE | \ + BRBCR_ELx_FZP | \ + BRBCR_ELx_TS_MASK) +/* + * BRBE Buffer Organization + * + * BRBE buffer is arranged as multiple banks of 32 branch record + * entries each. An individual branch record in a given bank could + * be accessed, after selecting the bank in BRBFCR_EL1.BANK and + * accessing the registers i.e [BRBSRC, BRBTGT, BRBINF] set with + * indices [0..31]. + * + * Bank 0 + * + * --------------------------------- ------ + * | 00 | BRBSRC | BRBTGT | BRBINF | | 00 | + * --------------------------------- ------ + * | 01 | BRBSRC | BRBTGT | BRBINF | | 01 | + * --------------------------------- ------ + * | .. | BRBSRC | BRBTGT | BRBINF | | .. | + * --------------------------------- ------ + * | 31 | BRBSRC | BRBTGT | BRBINF | | 31 | + * --------------------------------- ------ + * + * Bank 1 + * + * --------------------------------- ------ + * | 32 | BRBSRC | BRBTGT | BRBINF | | 00 | + * --------------------------------- ------ + * | 33 | BRBSRC | BRBTGT | BRBINF | | 01 | + * --------------------------------- ------ + * | .. | BRBSRC | BRBTGT | BRBINF | | .. | + * --------------------------------- ------ + * | 63 | BRBSRC | BRBTGT | BRBINF | | 31 | + * --------------------------------- ------ + */ +#define BRBE_BANK_MAX_ENTRIES 32 +#define BRBE_MAX_BANK 2 +#define BRBE_MAX_ENTRIES (BRBE_BANK_MAX_ENTRIES * BRBE_MAX_BANK) + +#define BRBE_BANK0_IDX_MIN 0 +#define BRBE_BANK0_IDX_MAX 31 +#define BRBE_BANK1_IDX_MIN 32 +#define BRBE_BANK1_IDX_MAX 63 + +struct brbe_regset { + unsigned long brbsrc; + unsigned long brbtgt; + unsigned long brbinf; +}; + +struct arm64_perf_task_context { + struct brbe_regset store[BRBE_MAX_ENTRIES]; + int nr_brbe_records; +}; + +struct brbe_hw_attr { + int brbe_version; + int brbe_cc; + int brbe_nr; + int brbe_format; +}; + +enum brbe_bank_idx { + BRBE_BANK_IDX_INVALID = -1, + BRBE_BANK_IDX_0, + BRBE_BANK_IDX_1, + BRBE_BANK_IDX_MAX +}; + +#define RETURN_READ_BRBSRCN(n) \ + read_sysreg_s(SYS_BRBSRC##n##_EL1) + +#define RETURN_READ_BRBTGTN(n) \ + read_sysreg_s(SYS_BRBTGT##n##_EL1) + +#define RETURN_READ_BRBINFN(n) \ + read_sysreg_s(SYS_BRBINF##n##_EL1) + +#define BRBE_REGN_SWITCH(x, case_macro) \ + do { \ + switch (x) { \ + case 0: return case_macro(0); break; \ + case 1: return case_macro(1); break; \ + case 2: return case_macro(2); break; \ + case 3: return case_macro(3); break; \ + case 4: return case_macro(4); break; \ + case 5: return case_macro(5); break; \ + case 6: return case_macro(6); break; \ + case 7: return case_macro(7); break; \ + case 8: return case_macro(8); break; \ + case 9: return case_macro(9); break; \ + case 10: return case_macro(10); break; \ + case 11: return case_macro(11); break; \ + case 12: return case_macro(12); break; \ + case 13: return case_macro(13); break; \ + case 14: return case_macro(14); break; \ + case 15: return case_macro(15); break; \ + case 16: return case_macro(16); break; \ + case 17: return case_macro(17); break; \ + case 18: return case_macro(18); break; \ + case 19: return case_macro(19); break; \ + case 20: return case_macro(20); break; \ + case 21: return case_macro(21); break; \ + case 22: return case_macro(22); break; \ + case 23: return case_macro(23); break; \ + case 24: return case_macro(24); break; \ + case 25: return case_macro(25); break; \ + case 26: return case_macro(26); break; \ + case 27: return case_macro(27); break; \ + case 28: return case_macro(28); break; \ + case 29: return case_macro(29); break; \ + case 30: return case_macro(30); break; \ + case 31: return case_macro(31); break; \ + default: \ + pr_warn("unknown register index\n"); \ + return -1; \ + } \ + } while (0) + +static inline int buffer_to_brbe_idx(int buffer_idx) +{ + return buffer_idx % BRBE_BANK_MAX_ENTRIES; +} + +static inline u64 get_brbsrc_reg(int buffer_idx) +{ + int brbe_idx = buffer_to_brbe_idx(buffer_idx); + + BRBE_REGN_SWITCH(brbe_idx, RETURN_READ_BRBSRCN); +} + +static inline u64 get_brbtgt_reg(int buffer_idx) +{ + int brbe_idx = buffer_to_brbe_idx(buffer_idx); + + BRBE_REGN_SWITCH(brbe_idx, RETURN_READ_BRBTGTN); +} + +static inline u64 get_brbinf_reg(int buffer_idx) +{ + int brbe_idx = buffer_to_brbe_idx(buffer_idx); + + BRBE_REGN_SWITCH(brbe_idx, RETURN_READ_BRBINFN); +} + +static inline u64 brbe_record_valid(u64 brbinf) +{ + return FIELD_GET(BRBINFx_EL1_VALID_MASK, brbinf); +} + +static inline bool brbe_invalid(u64 brbinf) +{ + return brbe_record_valid(brbinf) == BRBINFx_EL1_VALID_NONE; +} + +static inline bool brbe_record_is_complete(u64 brbinf) +{ + return brbe_record_valid(brbinf) == BRBINFx_EL1_VALID_FULL; +} + +static inline bool brbe_record_is_source_only(u64 brbinf) +{ + return brbe_record_valid(brbinf) == BRBINFx_EL1_VALID_SOURCE; +} + +static inline bool brbe_record_is_target_only(u64 brbinf) +{ + return brbe_record_valid(brbinf) == BRBINFx_EL1_VALID_TARGET; +} + +static inline int brbe_get_in_tx(u64 brbinf) +{ + return FIELD_GET(BRBINFx_EL1_T_MASK, brbinf); +} + +static inline int brbe_get_mispredict(u64 brbinf) +{ + return FIELD_GET(BRBINFx_EL1_MPRED_MASK, brbinf); +} + +static inline int brbe_get_lastfailed(u64 brbinf) +{ + return FIELD_GET(BRBINFx_EL1_LASTFAILED_MASK, brbinf); +} + +static inline int brbe_get_cycles(u64 brbinf) +{ + /* + * Captured cycle count is unknown and hence + * should not be passed on to the user space. + */ + if (brbinf & BRBINFx_EL1_CCU) + return 0; + + return FIELD_GET(BRBINFx_EL1_CC_MASK, brbinf); +} + +static inline int brbe_get_type(u64 brbinf) +{ + return FIELD_GET(BRBINFx_EL1_TYPE_MASK, brbinf); +} + +static inline int brbe_get_el(u64 brbinf) +{ + return FIELD_GET(BRBINFx_EL1_EL_MASK, brbinf); +} + +static inline int brbe_get_numrec(u64 brbidr) +{ + return FIELD_GET(BRBIDR0_EL1_NUMREC_MASK, brbidr); +} + +static inline int brbe_get_format(u64 brbidr) +{ + return FIELD_GET(BRBIDR0_EL1_FORMAT_MASK, brbidr); +} + +static inline int brbe_get_cc_bits(u64 brbidr) +{ + return FIELD_GET(BRBIDR0_EL1_CC_MASK, brbidr); +} diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c index 3df2f9ba388c..d02a85c0bedc 100644 --- a/drivers/perf/arm_pmu.c +++ b/drivers/perf/arm_pmu.c @@ -334,6 +334,12 @@ armpmu_add(struct perf_event *event, int flags) struct hw_perf_event *hwc = &event->hw; int idx;
+ /* + * Reset branch records buffer if a new task event gets + * scheduled on a PMU which might have existing records. + * Otherwise older branch records present in the buffer + * might leak into the new task event. + */ if (event->ctx->task && hw_events->brbe_context != event->ctx) { hw_events->brbe_context = event->ctx; if (armpmu->branch_reset) diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index 9ec6c259ea68..6fd58c8f93f9 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -134,6 +134,11 @@ struct arm_pmu { /* store the PMMIR_EL1 to expose slots */ u64 reg_pmmir;
+#ifdef CONFIG_ARM64_BRBE + /* store the BRBIDR0_EL1 capturing attributes */ + u64 reg_brbidr; +#endif + /* Only to be used by ACPI probing code */ unsigned long acpi_cpuid; };