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Subject[PATCH 4/7] perf, x86: Implement IBS interrupt handler
Date
This patch implements code to handle ibs interrupts. If ibs data is
available a raw perf_event data sample is created and sent back to the
userland. This patch only implements the storage of ibs data in the
raw sample, but this could be extended in a later patch by generating
generic event data such as the rip from the ibs sampling data.

Signed-off-by: Robert Richter <robert.richter@amd.com>
---
arch/x86/include/asm/msr-index.h | 3 +
arch/x86/kernel/cpu/perf_event_amd_ibs.c | 80 ++++++++++++++++++++++++++++++
2 files changed, 83 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 485b4f1..75f131e 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -127,6 +127,7 @@
#define MSR_AMD64_IBSFETCHCTL 0xc0011030
#define MSR_AMD64_IBSFETCHLINAD 0xc0011031
#define MSR_AMD64_IBSFETCHPHYSAD 0xc0011032
+#define MSR_AMD64_IBSFETCH_REG_COUNT 3
#define MSR_AMD64_IBSOPCTL 0xc0011033
#define MSR_AMD64_IBSOPRIP 0xc0011034
#define MSR_AMD64_IBSOPDATA 0xc0011035
@@ -134,6 +135,8 @@
#define MSR_AMD64_IBSOPDATA3 0xc0011037
#define MSR_AMD64_IBSDCLINAD 0xc0011038
#define MSR_AMD64_IBSDCPHYSAD 0xc0011039
+#define MSR_AMD64_IBSOP_REG_COUNT 7
+#define MSR_AMD64_IBS_REG_COUNT_MAX MSR_AMD64_IBSOP_REG_COUNT
#define MSR_AMD64_IBSCTL 0xc001103a
#define MSR_AMD64_IBSBRTARGET 0xc001103b

diff --git a/arch/x86/kernel/cpu/perf_event_amd_ibs.c b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
index bd77209..09311e3 100644
--- a/arch/x86/kernel/cpu/perf_event_amd_ibs.c
+++ b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
@@ -12,6 +12,11 @@

#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_AMD)

+#include <linux/kprobes.h>
+#include <linux/hardirq.h>
+
+#include <asm/nmi.h>
+
#define IBS_FETCH_CONFIG_MASK (IBS_FETCH_RAND_EN | IBS_FETCH_MAX_CNT)
#define IBS_OP_CONFIG_MASK IBS_OP_MAX_CNT

@@ -21,6 +26,8 @@ struct perf_ibs {
u64 config_mask;
u64 cnt_mask;
u64 enable_mask;
+ u64 valid_mask;
+ int reg_count;
};

static struct perf_ibs perf_ibs_fetch;
@@ -102,6 +109,8 @@ static struct perf_ibs perf_ibs_fetch = {
.config_mask = IBS_FETCH_CONFIG_MASK,
.cnt_mask = IBS_FETCH_MAX_CNT,
.enable_mask = IBS_FETCH_ENABLE,
+ .valid_mask = IBS_FETCH_VAL,
+ .reg_count = MSR_AMD64_IBSFETCH_REG_COUNT,
};

static struct perf_ibs perf_ibs_op = {
@@ -114,6 +123,76 @@ static struct perf_ibs perf_ibs_op = {
.config_mask = IBS_OP_CONFIG_MASK,
.cnt_mask = IBS_OP_MAX_CNT,
.enable_mask = IBS_OP_ENABLE,
+ .valid_mask = IBS_OP_VAL,
+ .reg_count = MSR_AMD64_IBSOP_REG_COUNT,
+};
+
+static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
+{
+ struct perf_event *event = NULL;
+ struct hw_perf_event *hwc = &event->hw;
+ struct perf_sample_data data;
+ struct perf_raw_record raw;
+ struct pt_regs regs;
+ u64 buffer[MSR_AMD64_IBS_REG_COUNT_MAX];
+ int i;
+ unsigned int msr;
+ u64 *buf;
+
+ msr = hwc->config_base;
+ buf = buffer;
+ rdmsrl(msr++, *buf);
+ if (!(*buf++ & perf_ibs->valid_mask))
+ return 0;
+
+ perf_sample_data_init(&data, 0);
+ if (event->attr.sample_type & PERF_SAMPLE_RAW) {
+ for (i = 1; i < perf_ibs->reg_count; i++)
+ rdmsrl(msr++, *buf++);
+ raw.size = sizeof(u32) + sizeof(u64) * perf_ibs->reg_count;
+ raw.data = buffer;
+ data.raw = &raw;
+ }
+
+ regs = *iregs; /* XXX: update ip from ibs sample */
+
+ if (perf_event_overflow(event, &data, &regs))
+ ; /* stop */
+ else
+ /* reenable */
+ wrmsrl(hwc->config_base, hwc->config | perf_ibs->enable_mask);
+
+ return 1;
+}
+
+static int __kprobes
+perf_ibs_nmi_handler(struct notifier_block *self,
+ unsigned long cmd, void *__args)
+{
+ struct die_args *args = __args;
+ int handled = 0;
+
+ switch (cmd) {
+ case DIE_NMI:
+ break;
+ default:
+ return NOTIFY_DONE;
+ }
+
+ handled += perf_ibs_handle_irq(&perf_ibs_fetch, args->regs);
+ handled += perf_ibs_handle_irq(&perf_ibs_op, args->regs);
+
+ if (!handled)
+ return NOTIFY_DONE;
+
+ inc_irq_stat(apic_perf_irqs);
+
+ return NOTIFY_STOP;
+}
+
+static __read_mostly struct notifier_block perf_ibs_nmi_notifier = {
+ .notifier_call = perf_ibs_nmi_handler,
+ .priority = NMI_LOCAL_LOW_PRIOR,
};

static __init int perf_event_ibs_init(void)
@@ -126,6 +205,7 @@ static __init int perf_event_ibs_init(void)

perf_pmu_register(&perf_ibs_fetch.pmu, "ibs_fetch", -1);
perf_pmu_register(&perf_ibs_op.pmu, "ibs_op", -1);
+ register_die_notifier(&perf_ibs_nmi_notifier);
printk(KERN_INFO "perf: AMD IBS detected (0x%08x)\n", caps);

return 0;
--
1.7.5.3



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