[RFC PATCH 02/12] perf/x86: Setup the regs data

From: kan . liang
Date: Fri Jun 13 2025 - 10:04:17 EST


From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>

The current code relies on the generic code to setup the regs data.
It will not work well when there are more regs introduced.
Introduce a X86-specific x86_pmu_setup_regs_data().
Now, it's the same as the generic code. More X86-specific codes will be
added later with the new regs.

Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
---
arch/x86/events/core.c | 32 ++++++++++++++++++++++++++++++++
arch/x86/events/intel/ds.c | 4 +++-
arch/x86/events/perf_event.h | 4 ++++
3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 64a7a8aa2e38..c601ad761534 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1685,6 +1685,38 @@ static void x86_pmu_del(struct perf_event *event, int flags)
static_call_cond(x86_pmu_del)(event);
}

+void x86_pmu_setup_regs_data(struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ u64 sample_type = event->attr.sample_type;
+
+ if (sample_type & PERF_SAMPLE_REGS_USER) {
+ if (user_mode(regs)) {
+ data->regs_user.abi = perf_reg_abi(current);
+ data->regs_user.regs = regs;
+ } else if (!(current->flags & PF_KTHREAD)) {
+ perf_get_regs_user(&data->regs_user, regs);
+ } else {
+ data->regs_user.abi = PERF_SAMPLE_REGS_ABI_NONE;
+ data->regs_user.regs = NULL;
+ }
+ data->dyn_size += sizeof(u64);
+ if (data->regs_user.regs)
+ data->dyn_size += hweight64(event->attr.sample_regs_user) * sizeof(u64);
+ data->sample_flags |= PERF_SAMPLE_REGS_USER;
+ }
+
+ if (sample_type & PERF_SAMPLE_REGS_INTR) {
+ data->regs_intr.regs = regs;
+ data->regs_intr.abi = perf_reg_abi(current);
+ data->dyn_size += sizeof(u64);
+ if (data->regs_intr.regs)
+ data->dyn_size += hweight64(event->attr.sample_regs_intr) * sizeof(u64);
+ data->sample_flags |= PERF_SAMPLE_REGS_INTR;
+ }
+}
+
int x86_pmu_handle_irq(struct pt_regs *regs)
{
struct perf_sample_data data;
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index c0b7ac1c7594..e67d8a03ddfe 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -2126,8 +2126,10 @@ static void setup_pebs_adaptive_sample_data(struct perf_event *event,
regs->flags &= ~PERF_EFLAGS_EXACT;
}

- if (sample_type & (PERF_SAMPLE_REGS_INTR | PERF_SAMPLE_REGS_USER))
+ if (sample_type & (PERF_SAMPLE_REGS_INTR | PERF_SAMPLE_REGS_USER)) {
adaptive_pebs_save_regs(regs, gprs);
+ x86_pmu_setup_regs_data(event, data, regs);
+ }
}

if (format_group & PEBS_DATACFG_MEMINFO) {
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index 2b969386dcdd..12682a059608 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -1278,6 +1278,10 @@ void x86_pmu_enable_event(struct perf_event *event);

int x86_pmu_handle_irq(struct pt_regs *regs);

+void x86_pmu_setup_regs_data(struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs);
+
void x86_pmu_show_pmu_cap(struct pmu *pmu);

static inline int x86_pmu_num_counters(struct pmu *pmu)
--
2.38.1