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Subject[tip:perf/urgent] perf/x86: Disable extended registers for non-supported PMUs
Commit-ID:  e321d02db87af7840da29ef833a2a71fc0eab198
Gitweb: https://git.kernel.org/tip/e321d02db87af7840da29ef833a2a71fc0eab198
Author: Kan Liang <kan.liang@linux.intel.com>
AuthorDate: Tue, 28 May 2019 15:08:30 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 24 Jun 2019 19:19:23 +0200

perf/x86: Disable extended registers for non-supported PMUs

The perf fuzzer caused Skylake machine to crash:

[ 9680.085831] Call Trace:
[ 9680.088301] <IRQ>
[ 9680.090363] perf_output_sample_regs+0x43/0xa0
[ 9680.094928] perf_output_sample+0x3aa/0x7a0
[ 9680.099181] perf_event_output_forward+0x53/0x80
[ 9680.103917] __perf_event_overflow+0x52/0xf0
[ 9680.108266] ? perf_trace_run_bpf_submit+0xc0/0xc0
[ 9680.113108] perf_swevent_hrtimer+0xe2/0x150
[ 9680.117475] ? check_preempt_wakeup+0x181/0x230
[ 9680.122091] ? check_preempt_curr+0x62/0x90
[ 9680.126361] ? ttwu_do_wakeup+0x19/0x140
[ 9680.130355] ? try_to_wake_up+0x54/0x460
[ 9680.134366] ? reweight_entity+0x15b/0x1a0
[ 9680.138559] ? __queue_work+0x103/0x3f0
[ 9680.142472] ? update_dl_rq_load_avg+0x1cd/0x270
[ 9680.147194] ? timerqueue_del+0x1e/0x40
[ 9680.151092] ? __remove_hrtimer+0x35/0x70
[ 9680.155191] __hrtimer_run_queues+0x100/0x280
[ 9680.159658] hrtimer_interrupt+0x100/0x220
[ 9680.163835] smp_apic_timer_interrupt+0x6a/0x140
[ 9680.168555] apic_timer_interrupt+0xf/0x20
[ 9680.172756] </IRQ>

The XMM registers can only be collected by PEBS hardware events on the
platforms with PEBS baseline support, e.g. Icelake, not software/probe
events.

Add capabilities flag PERF_PMU_CAP_EXTENDED_REGS to indicate the PMU
which support extended registers. For X86, the extended registers are
XMM registers.

Add has_extended_regs() to check if extended registers are applied.

The generic code define the mask of extended registers as 0 if arch
headers haven't overridden it.

Originally-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 878068ea270e ("perf/x86: Support outputting XMM registers")
Link: https://lkml.kernel.org/r/1559081314-9714-1-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/events/intel/ds.c | 1 +
arch/x86/include/uapi/asm/perf_regs.h | 3 +++
include/linux/perf_event.h | 1 +
include/linux/perf_regs.h | 8 ++++++++
kernel/events/core.c | 18 ++++++++++++++----
5 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 7acc526b4ad2..6cb38ab02c8a 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -2020,6 +2020,7 @@ void __init intel_ds_init(void)
PERF_SAMPLE_TIME;
x86_pmu.flags |= PMU_FL_PEBS_ALL;
pebs_qual = "-baseline";
+ x86_get_pmu()->capabilities |= PERF_PMU_CAP_EXTENDED_REGS;
} else {
/* Only basic record supported */
x86_pmu.pebs_no_xmm_regs = 1;
diff --git a/arch/x86/include/uapi/asm/perf_regs.h b/arch/x86/include/uapi/asm/perf_regs.h
index ac67bbea10ca..7c9d2bb3833b 100644
--- a/arch/x86/include/uapi/asm/perf_regs.h
+++ b/arch/x86/include/uapi/asm/perf_regs.h
@@ -52,4 +52,7 @@ enum perf_event_x86_regs {
/* These include both GPRs and XMMX registers */
PERF_REG_X86_XMM_MAX = PERF_REG_X86_XMM15 + 2,
};
+
+#define PERF_REG_EXTENDED_MASK (~((1ULL << PERF_REG_X86_XMM0) - 1))
+
#endif /* _ASM_X86_PERF_REGS_H */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 0ab99c7b652d..2bca72f3028b 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -241,6 +241,7 @@ struct perf_event;
#define PERF_PMU_CAP_NO_INTERRUPT 0x01
#define PERF_PMU_CAP_NO_NMI 0x02
#define PERF_PMU_CAP_AUX_NO_SG 0x04
+#define PERF_PMU_CAP_EXTENDED_REGS 0x08
#define PERF_PMU_CAP_EXCLUSIVE 0x10
#define PERF_PMU_CAP_ITRACE 0x20
#define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x40
diff --git a/include/linux/perf_regs.h b/include/linux/perf_regs.h
index 476747456bca..2d12e97d5e7b 100644
--- a/include/linux/perf_regs.h
+++ b/include/linux/perf_regs.h
@@ -11,6 +11,11 @@ struct perf_regs {

#ifdef CONFIG_HAVE_PERF_REGS
#include <asm/perf_regs.h>
+
+#ifndef PERF_REG_EXTENDED_MASK
+#define PERF_REG_EXTENDED_MASK 0
+#endif
+
u64 perf_reg_value(struct pt_regs *regs, int idx);
int perf_reg_validate(u64 mask);
u64 perf_reg_abi(struct task_struct *task);
@@ -18,6 +23,9 @@ void perf_get_regs_user(struct perf_regs *regs_user,
struct pt_regs *regs,
struct pt_regs *regs_user_copy);
#else
+
+#define PERF_REG_EXTENDED_MASK 0
+
static inline u64 perf_reg_value(struct pt_regs *regs, int idx)
{
return 0;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8d1c62df20a7..f85929ce13be 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10036,6 +10036,12 @@ void perf_pmu_unregister(struct pmu *pmu)
}
EXPORT_SYMBOL_GPL(perf_pmu_unregister);

+static inline bool has_extended_regs(struct perf_event *event)
+{
+ return (event->attr.sample_regs_user & PERF_REG_EXTENDED_MASK) ||
+ (event->attr.sample_regs_intr & PERF_REG_EXTENDED_MASK);
+}
+
static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
{
struct perf_event_context *ctx = NULL;
@@ -10067,12 +10073,16 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
perf_event_ctx_unlock(event->group_leader, ctx);

if (!ret) {
+ if (!(pmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS) &&
+ has_extended_regs(event))
+ ret = -EOPNOTSUPP;
+
if (pmu->capabilities & PERF_PMU_CAP_NO_EXCLUDE &&
- event_has_any_exclude_flag(event)) {
- if (event->destroy)
- event->destroy(event);
+ event_has_any_exclude_flag(event))
ret = -EINVAL;
- }
+
+ if (ret && event->destroy)
+ event->destroy(event);
}

if (ret)
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