From: rusty@rustcorp•com.au (Rusty Russell)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM: test for PMU feature on v7 (v2 with typo fix)
Date: Fri, 23 Mar 2012 11:04:57 +1030 [thread overview]
Message-ID: <87r4wk889a.fsf@rustcorp.com.au> (raw)
In-Reply-To: <87ty1g88dv.fsf@rustcorp.com.au>
The v7 ARM (B4.1.82) specifies that bits 27-24 of the ID_DFR0 reg show
what performance monitoring (if any) is available. We should test this
before assuming (useful for inside virtualized environments, for example).
Signed-off-by: Rusty Russell <rusty.russell@linaro•org>
diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
index 6933244..303d1e1 100644
--- a/arch/arm/kernel/perf_event_v7.c
+++ b/arch/arm/kernel/perf_event_v7.c
@@ -1108,6 +1108,12 @@ static struct arm_pmu armv7pmu = {
.max_period = (1LLU << 32) - 1,
};
+static bool armv7_pmu_avail(void)
+{
+ /* 0 means unknown (maybe v1), 1 means v1, 2 means v2, 15 means none */
+ return ((read_cpuid_ext(CPUID_EXT_DFR0) >> 24) & 0xF) != 0xF;
+}
+
static u32 __init armv7_read_num_pmnc_events(void)
{
u32 nb_cnt;
@@ -1121,6 +1127,8 @@ static u32 __init armv7_read_num_pmnc_events(void)
static struct arm_pmu *__init armv7_a8_pmu_init(void)
{
+ if (!armv7_pmu_avail())
+ return NULL;
armv7pmu.id = ARM_PERF_PMU_ID_CA8;
armv7pmu.name = "ARMv7 Cortex-A8";
armv7pmu.map_event = armv7_a8_map_event;
@@ -1130,6 +1138,8 @@ static struct arm_pmu *__init armv7_a8_pmu_init(void)
static struct arm_pmu *__init armv7_a9_pmu_init(void)
{
+ if (!armv7_pmu_avail())
+ return NULL;
armv7pmu.id = ARM_PERF_PMU_ID_CA9;
armv7pmu.name = "ARMv7 Cortex-A9";
armv7pmu.map_event = armv7_a9_map_event;
@@ -1139,6 +1149,8 @@ static struct arm_pmu *__init armv7_a9_pmu_init(void)
static struct arm_pmu *__init armv7_a5_pmu_init(void)
{
+ if (!armv7_pmu_avail())
+ return NULL;
armv7pmu.id = ARM_PERF_PMU_ID_CA5;
armv7pmu.name = "ARMv7 Cortex-A5";
armv7pmu.map_event = armv7_a5_map_event;
@@ -1148,6 +1160,8 @@ static struct arm_pmu *__init armv7_a5_pmu_init(void)
static struct arm_pmu *__init armv7_a15_pmu_init(void)
{
+ if (!armv7_pmu_avail())
+ return NULL;
armv7pmu.id = ARM_PERF_PMU_ID_CA15;
armv7pmu.name = "ARMv7 Cortex-A15";
armv7pmu.map_event = armv7_a15_map_event;
next prev parent reply other threads:[~2012-03-23 0:34 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4F590411.9060201@arm.com>
2012-03-23 0:32 ` [PATCH] ARM: test for PMU feature on v7 Rusty Russell
2012-03-23 0:34 ` Rusty Russell [this message]
2012-03-23 9:53 ` [PATCH] ARM: test for PMU feature on v7 (v2 with typo fix) Will Deacon
2012-03-23 23:17 ` Rusty Russell
2012-03-26 9:40 ` Will Deacon
2012-03-26 9:50 ` [Android-virt] " Peter Maydell
2012-03-26 15:15 ` Will Deacon
2012-03-28 6:09 ` Rusty Russell
2012-03-28 14:17 ` Nicolas Pitre
2012-03-30 17:04 ` Will Deacon
2012-03-30 17:40 ` Nicolas Pitre
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87r4wk889a.fsf@rustcorp.com.au \
--to=rusty@rustcorp$(echo .)com.au \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox