[PATCH] perf/x86/intel: Add cpu_(prepare|starting|dying) for core_pmu

[PATCH] perf/x86/intel: Add cpu_(prepare|starting|dying) for core_pmu

[Jiri Olsa]

The core_pmu does not define cpu_* callbacks, which handles
allocation of 'struct cpu_hw_events::shared_regs' data,
initialization of debug store and PMU_FL_EXCL_CNTRS counters.

While this probably won't happen on bare metal, virtual CPU can
define x86_pmu.extra_regs together with PMU version 1 and thus
be using core_pmu -> using shared_regs data without it being
allocated. That could could leave to following panic:

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8152cd4f>] _spin_lock_irqsave+0x1f/0x40

SNIP

 [<ffffffff81024bd9>] __intel_shared_reg_get_constraints+0x69/0x1e0
 [<ffffffff81024deb>] intel_get_event_constraints+0x9b/0x180
 [<ffffffff8101e815>] x86_schedule_events+0x75/0x1d0
 [<ffffffff810586dc>] ? check_preempt_curr+0x7c/0x90
 [<ffffffff810649fe>] ? try_to_wake_up+0x24e/0x3e0
 [<ffffffff81064ba2>] ? default_wake_function+0x12/0x20
 [<ffffffff8109eb16>] ? autoremove_wake_function+0x16/0x40
 [<ffffffff810577e9>] ? __wake_up_common+0x59/0x90
 [<ffffffff811a9517>] ? __d_lookup+0xa7/0x150
 [<ffffffff8119db5f>] ? do_lookup+0x9f/0x230
 [<ffffffff811a993a>] ? dput+0x9a/0x150
 [<ffffffff8119c8f5>] ? path_to_nameidata+0x25/0x60
 [<ffffffff8119e90a>] ? __link_path_walk+0x7da/0x1000
 [<ffffffff8101d8f9>] ? x86_pmu_add+0xb9/0x170
 [<ffffffff8101d7a7>] x86_pmu_commit_txn+0x67/0xc0
 [<ffffffff811b07b0>] ? mntput_no_expire+0x30/0x110
 [<ffffffff8119c731>] ? path_put+0x31/0x40
 [<ffffffff8107c297>] ? current_fs_time+0x27/0x30
 [<ffffffff8117d170>] ? mem_cgroup_get_reclaim_stat_from_page+0x20/0x70
 [<ffffffff8111b7aa>] group_sched_in+0x13a/0x170
 [<ffffffff81014a29>] ? sched_clock+0x9/0x10
 [<ffffffff8111bac8>] ctx_sched_in+0x2e8/0x330
 [<ffffffff8111bb7b>] perf_event_sched_in+0x6b/0xb0
 [<ffffffff8111bc36>] perf_event_context_sched_in+0x76/0xc0
 [<ffffffff8111eb3b>] perf_event_comm+0x1bb/0x2e0
 [<ffffffff81195ee9>] set_task_comm+0x69/0x80
 [<ffffffff81195fe1>] setup_new_exec+0xe1/0x2e0
 [<ffffffff811ea68e>] load_elf_binary+0x3ce/0x1ab0

Adding cpu_(prepare|starting|dying) for core_pmu to have shared_regs
data allocated for core_pmu. AFAICS there's no harm to initialize
debug store and PMU_FL_EXCL_CNTRS either for core_pmu.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 arch/x86/kernel/cpu/perf_event_intel.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 9da2400c2ec3..0a61a9a021de 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -2533,6 +2533,10 @@ ssize_t intel_event_sysfs_show(char *page, u64 config)
 	return x86_event_sysfs_show(page, config, event);
 }
 
+static int  intel_pmu_cpu_prepare(int cpu);
+static void intel_pmu_cpu_starting(int cpu);
+static void intel_pmu_cpu_dying(int cpu);
+
 static __initconst const struct x86_pmu core_pmu = {
 	.name			= "core",
 	.handle_irq		= x86_pmu_handle_irq,
@@ -2559,6 +2563,9 @@ static __initconst const struct x86_pmu core_pmu = {
 	.guest_get_msrs		= core_guest_get_msrs,
 	.format_attrs		= intel_arch_formats_attr,
 	.events_sysfs_show	= intel_event_sysfs_show,
+	.cpu_prepare		= intel_pmu_cpu_prepare,
+	.cpu_starting		= intel_pmu_cpu_starting,
+	.cpu_dying		= intel_pmu_cpu_dying,
 };
 
 struct intel_shared_regs *allocate_shared_regs(int cpu)
-- 
1.9.3

Re: [PATCH] perf/x86/intel: Add cpu_(prepare|starting|dying) for core_pmu

[Ingo Molnar]

* Jiri Olsa <jolsa@kernel.org> wrote:

> The core_pmu does not define cpu_* callbacks, which handles
> allocation of 'struct cpu_hw_events::shared_regs' data,
> initialization of debug store and PMU_FL_EXCL_CNTRS counters.
> 
> While this probably won't happen on bare metal, virtual CPU can
> define x86_pmu.extra_regs together with PMU version 1 and thus
> be using core_pmu -> using shared_regs data without it being
> allocated. That could could leave to following panic:
> 
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [<ffffffff8152cd4f>] _spin_lock_irqsave+0x1f/0x40

ok.

> diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
> index 9da2400c2ec3..0a61a9a021de 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel.c
> @@ -2533,6 +2533,10 @@ ssize_t intel_event_sysfs_show(char *page, u64 config)
>  	return x86_event_sysfs_show(page, config, event);
>  }
>  
> +static int  intel_pmu_cpu_prepare(int cpu);
> +static void intel_pmu_cpu_starting(int cpu);
> +static void intel_pmu_cpu_dying(int cpu);
> +
>  static __initconst const struct x86_pmu core_pmu = {
>  	.name			= "core",
>  	.handle_irq		= x86_pmu_handle_irq,
> @@ -2559,6 +2563,9 @@ static __initconst const struct x86_pmu core_pmu = {
>  	.guest_get_msrs		= core_guest_get_msrs,
>  	.format_attrs		= intel_arch_formats_attr,
>  	.events_sysfs_show	= intel_event_sysfs_show,
> +	.cpu_prepare		= intel_pmu_cpu_prepare,
> +	.cpu_starting		= intel_pmu_cpu_starting,
> +	.cpu_dying		= intel_pmu_cpu_dying,
>  };

Instead of adding prototype declarations, please arrange the x86_pmu 
definition's position so that it comes after the required functions - 
so that no prototypes are needed.

Thanks,

	Ingo

[PATCHv2] perf/x86/intel: Add cpu_(prepare|starting|dying) for core_pmu

[Jiri Olsa]

On Tue, Apr 21, 2015 at 12:52:40PM +0200, Ingo Molnar wrote:
> 
> * Jiri Olsa <jolsa@kernel.org> wrote:

SNIP

> >  	.guest_get_msrs		= core_guest_get_msrs,
> >  	.format_attrs		= intel_arch_formats_attr,
> >  	.events_sysfs_show	= intel_event_sysfs_show,
> > +	.cpu_prepare		= intel_pmu_cpu_prepare,
> > +	.cpu_starting		= intel_pmu_cpu_starting,
> > +	.cpu_dying		= intel_pmu_cpu_dying,
> >  };
> 
> Instead of adding prototype declarations, please arrange the x86_pmu 
> definition's position so that it comes after the required functions - 
> so that no prototypes are needed.

ok, v2 is attached

thanks,
jirka


---
The core_pmu does not define cpu_* callbacks, which handles
allocation of 'struct cpu_hw_events::shared_regs' data,
initialization of debug store and PMU_FL_EXCL_CNTRS counters.

While this probably won't happen on bare metal, virtual CPU can
define x86_pmu.extra_regs together with PMU version 1 and thus
be using core_pmu -> using shared_regs data without it being
allocated. That could could leave to following panic:

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8152cd4f>] _spin_lock_irqsave+0x1f/0x40

SNIP

 [<ffffffff81024bd9>] __intel_shared_reg_get_constraints+0x69/0x1e0
 [<ffffffff81024deb>] intel_get_event_constraints+0x9b/0x180
 [<ffffffff8101e815>] x86_schedule_events+0x75/0x1d0
 [<ffffffff810586dc>] ? check_preempt_curr+0x7c/0x90
 [<ffffffff810649fe>] ? try_to_wake_up+0x24e/0x3e0
 [<ffffffff81064ba2>] ? default_wake_function+0x12/0x20
 [<ffffffff8109eb16>] ? autoremove_wake_function+0x16/0x40
 [<ffffffff810577e9>] ? __wake_up_common+0x59/0x90
 [<ffffffff811a9517>] ? __d_lookup+0xa7/0x150
 [<ffffffff8119db5f>] ? do_lookup+0x9f/0x230
 [<ffffffff811a993a>] ? dput+0x9a/0x150
 [<ffffffff8119c8f5>] ? path_to_nameidata+0x25/0x60
 [<ffffffff8119e90a>] ? __link_path_walk+0x7da/0x1000
 [<ffffffff8101d8f9>] ? x86_pmu_add+0xb9/0x170
 [<ffffffff8101d7a7>] x86_pmu_commit_txn+0x67/0xc0
 [<ffffffff811b07b0>] ? mntput_no_expire+0x30/0x110
 [<ffffffff8119c731>] ? path_put+0x31/0x40
 [<ffffffff8107c297>] ? current_fs_time+0x27/0x30
 [<ffffffff8117d170>] ? mem_cgroup_get_reclaim_stat_from_page+0x20/0x70
 [<ffffffff8111b7aa>] group_sched_in+0x13a/0x170
 [<ffffffff81014a29>] ? sched_clock+0x9/0x10
 [<ffffffff8111bac8>] ctx_sched_in+0x2e8/0x330
 [<ffffffff8111bb7b>] perf_event_sched_in+0x6b/0xb0
 [<ffffffff8111bc36>] perf_event_context_sched_in+0x76/0xc0
 [<ffffffff8111eb3b>] perf_event_comm+0x1bb/0x2e0
 [<ffffffff81195ee9>] set_task_comm+0x69/0x80
 [<ffffffff81195fe1>] setup_new_exec+0xe1/0x2e0
 [<ffffffff811ea68e>] load_elf_binary+0x3ce/0x1ab0

Adding cpu_(prepare|starting|dying) for core_pmu to have shared_regs
data allocated for core_pmu. AFAICS there's no harm to initialize
debug store and PMU_FL_EXCL_CNTRS either for core_pmu.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 arch/x86/kernel/cpu/perf_event_intel.c | 59 ++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 28 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 9da2400c2ec3..973abdc796fb 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -2533,34 +2533,6 @@ ssize_t intel_event_sysfs_show(char *page, u64 config)
 	return x86_event_sysfs_show(page, config, event);
 }
 
-static __initconst const struct x86_pmu core_pmu = {
-	.name			= "core",
-	.handle_irq		= x86_pmu_handle_irq,
-	.disable_all		= x86_pmu_disable_all,
-	.enable_all		= core_pmu_enable_all,
-	.enable			= core_pmu_enable_event,
-	.disable		= x86_pmu_disable_event,
-	.hw_config		= x86_pmu_hw_config,
-	.schedule_events	= x86_schedule_events,
-	.eventsel		= MSR_ARCH_PERFMON_EVENTSEL0,
-	.perfctr		= MSR_ARCH_PERFMON_PERFCTR0,
-	.event_map		= intel_pmu_event_map,
-	.max_events		= ARRAY_SIZE(intel_perfmon_event_map),
-	.apic			= 1,
-	/*
-	 * Intel PMCs cannot be accessed sanely above 32 bit width,
-	 * so we install an artificial 1<<31 period regardless of
-	 * the generic event period:
-	 */
-	.max_period		= (1ULL << 31) - 1,
-	.get_event_constraints	= intel_get_event_constraints,
-	.put_event_constraints	= intel_put_event_constraints,
-	.event_constraints	= intel_core_event_constraints,
-	.guest_get_msrs		= core_guest_get_msrs,
-	.format_attrs		= intel_arch_formats_attr,
-	.events_sysfs_show	= intel_event_sysfs_show,
-};
-
 struct intel_shared_regs *allocate_shared_regs(int cpu)
 {
 	struct intel_shared_regs *regs;
@@ -2743,6 +2715,37 @@ static struct attribute *intel_arch3_formats_attr[] = {
 	NULL,
 };
 
+static __initconst const struct x86_pmu core_pmu = {
+	.name			= "core",
+	.handle_irq		= x86_pmu_handle_irq,
+	.disable_all		= x86_pmu_disable_all,
+	.enable_all		= core_pmu_enable_all,
+	.enable			= core_pmu_enable_event,
+	.disable		= x86_pmu_disable_event,
+	.hw_config		= x86_pmu_hw_config,
+	.schedule_events	= x86_schedule_events,
+	.eventsel		= MSR_ARCH_PERFMON_EVENTSEL0,
+	.perfctr		= MSR_ARCH_PERFMON_PERFCTR0,
+	.event_map		= intel_pmu_event_map,
+	.max_events		= ARRAY_SIZE(intel_perfmon_event_map),
+	.apic			= 1,
+	/*
+	 * Intel PMCs cannot be accessed sanely above 32 bit width,
+	 * so we install an artificial 1<<31 period regardless of
+	 * the generic event period:
+	 */
+	.max_period		= (1ULL << 31) - 1,
+	.get_event_constraints	= intel_get_event_constraints,
+	.put_event_constraints	= intel_put_event_constraints,
+	.event_constraints	= intel_core_event_constraints,
+	.guest_get_msrs		= core_guest_get_msrs,
+	.format_attrs		= intel_arch_formats_attr,
+	.events_sysfs_show	= intel_event_sysfs_show,
+	.cpu_prepare		= intel_pmu_cpu_prepare,
+	.cpu_starting		= intel_pmu_cpu_starting,
+	.cpu_dying		= intel_pmu_cpu_dying,
+};
+
 static __initconst const struct x86_pmu intel_pmu = {
 	.name			= "Intel",
 	.handle_irq		= intel_pmu_handle_irq,
-- 
1.9.3

Re: [PATCH] perf/x86/intel: Add cpu_(prepare|starting|dying) for core_pmu

[Peter Zijlstra]

On Tue, Apr 21, 2015 at 10:54:25AM +0200, Jiri Olsa wrote:
> @@ -2559,6 +2563,9 @@ static __initconst const struct x86_pmu core_pmu = {
>  	.guest_get_msrs		= core_guest_get_msrs,
>  	.format_attrs		= intel_arch_formats_attr,
>  	.events_sysfs_show	= intel_event_sysfs_show,

Could you also insert a little comment here how these methods are for
'funny' 'hardware' ?

> +	.cpu_prepare		= intel_pmu_cpu_prepare,
> +	.cpu_starting		= intel_pmu_cpu_starting,
> +	.cpu_dying		= intel_pmu_cpu_dying,
>  };
>  
>  struct intel_shared_regs *allocate_shared_regs(int cpu)
> -- 
> 1.9.3
> 

Re: [PATCH] perf/x86/intel: Add cpu_(prepare|starting|dying) for core_pmu

[Jiri Olsa]

On Tue, Apr 21, 2015 at 05:12:16PM +0200, Peter Zijlstra wrote:
> On Tue, Apr 21, 2015 at 10:54:25AM +0200, Jiri Olsa wrote:
> > @@ -2559,6 +2563,9 @@ static __initconst const struct x86_pmu core_pmu = {
> >  	.guest_get_msrs		= core_guest_get_msrs,
> >  	.format_attrs		= intel_arch_formats_attr,
> >  	.events_sysfs_show	= intel_event_sysfs_show,
> 
> Could you also insert a little comment here how these methods are for
> 'funny' 'hardware' ?

ook, will do v3

jirka

> 
> > +	.cpu_prepare		= intel_pmu_cpu_prepare,
> > +	.cpu_starting		= intel_pmu_cpu_starting,
> > +	.cpu_dying		= intel_pmu_cpu_dying,
> >  };
> >  
> >  struct intel_shared_regs *allocate_shared_regs(int cpu)
> > -- 
> > 1.9.3
> > 

[PATCHv3] perf/x86/intel: Add cpu_(prepare|starting|dying) for core_pmu

[Jiri Olsa]

On Tue, Apr 21, 2015 at 05:18:27PM +0200, Jiri Olsa wrote:
> On Tue, Apr 21, 2015 at 05:12:16PM +0200, Peter Zijlstra wrote:
> > On Tue, Apr 21, 2015 at 10:54:25AM +0200, Jiri Olsa wrote:
> > > @@ -2559,6 +2563,9 @@ static __initconst const struct x86_pmu core_pmu = {
> > >  	.guest_get_msrs		= core_guest_get_msrs,
> > >  	.format_attrs		= intel_arch_formats_attr,
> > >  	.events_sysfs_show	= intel_event_sysfs_show,
> > 
> > Could you also insert a little comment here how these methods are for
> > 'funny' 'hardware' ?
> 
> ook, will do v3

attached,
jirka


---
The core_pmu does not define cpu_* callbacks, which handles
allocation of 'struct cpu_hw_events::shared_regs' data,
initialization of debug store and PMU_FL_EXCL_CNTRS counters.

While this probably won't happen on bare metal, virtual CPU can
define x86_pmu.extra_regs together with PMU version 1 and thus
be using core_pmu -> using shared_regs data without it being
allocated. That could could leave to following panic:

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8152cd4f>] _spin_lock_irqsave+0x1f/0x40

SNIP

 [<ffffffff81024bd9>] __intel_shared_reg_get_constraints+0x69/0x1e0
 [<ffffffff81024deb>] intel_get_event_constraints+0x9b/0x180
 [<ffffffff8101e815>] x86_schedule_events+0x75/0x1d0
 [<ffffffff810586dc>] ? check_preempt_curr+0x7c/0x90
 [<ffffffff810649fe>] ? try_to_wake_up+0x24e/0x3e0
 [<ffffffff81064ba2>] ? default_wake_function+0x12/0x20
 [<ffffffff8109eb16>] ? autoremove_wake_function+0x16/0x40
 [<ffffffff810577e9>] ? __wake_up_common+0x59/0x90
 [<ffffffff811a9517>] ? __d_lookup+0xa7/0x150
 [<ffffffff8119db5f>] ? do_lookup+0x9f/0x230
 [<ffffffff811a993a>] ? dput+0x9a/0x150
 [<ffffffff8119c8f5>] ? path_to_nameidata+0x25/0x60
 [<ffffffff8119e90a>] ? __link_path_walk+0x7da/0x1000
 [<ffffffff8101d8f9>] ? x86_pmu_add+0xb9/0x170
 [<ffffffff8101d7a7>] x86_pmu_commit_txn+0x67/0xc0
 [<ffffffff811b07b0>] ? mntput_no_expire+0x30/0x110
 [<ffffffff8119c731>] ? path_put+0x31/0x40
 [<ffffffff8107c297>] ? current_fs_time+0x27/0x30
 [<ffffffff8117d170>] ? mem_cgroup_get_reclaim_stat_from_page+0x20/0x70
 [<ffffffff8111b7aa>] group_sched_in+0x13a/0x170
 [<ffffffff81014a29>] ? sched_clock+0x9/0x10
 [<ffffffff8111bac8>] ctx_sched_in+0x2e8/0x330
 [<ffffffff8111bb7b>] perf_event_sched_in+0x6b/0xb0
 [<ffffffff8111bc36>] perf_event_context_sched_in+0x76/0xc0
 [<ffffffff8111eb3b>] perf_event_comm+0x1bb/0x2e0
 [<ffffffff81195ee9>] set_task_comm+0x69/0x80
 [<ffffffff81195fe1>] setup_new_exec+0xe1/0x2e0
 [<ffffffff811ea68e>] load_elf_binary+0x3ce/0x1ab0

Adding cpu_(prepare|starting|dying) for core_pmu to have shared_regs
data allocated for core_pmu. AFAICS there's no harm to initialize
debug store and PMU_FL_EXCL_CNTRS either for core_pmu.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 arch/x86/kernel/cpu/perf_event_intel.c | 66 +++++++++++++++++++---------------
 1 file changed, 38 insertions(+), 28 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 9da2400c2ec3..8a4e21eb2087 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -2533,34 +2533,6 @@ ssize_t intel_event_sysfs_show(char *page, u64 config)
 	return x86_event_sysfs_show(page, config, event);
 }
 
-static __initconst const struct x86_pmu core_pmu = {
-	.name			= "core",
-	.handle_irq		= x86_pmu_handle_irq,
-	.disable_all		= x86_pmu_disable_all,
-	.enable_all		= core_pmu_enable_all,
-	.enable			= core_pmu_enable_event,
-	.disable		= x86_pmu_disable_event,
-	.hw_config		= x86_pmu_hw_config,
-	.schedule_events	= x86_schedule_events,
-	.eventsel		= MSR_ARCH_PERFMON_EVENTSEL0,
-	.perfctr		= MSR_ARCH_PERFMON_PERFCTR0,
-	.event_map		= intel_pmu_event_map,
-	.max_events		= ARRAY_SIZE(intel_perfmon_event_map),
-	.apic			= 1,
-	/*
-	 * Intel PMCs cannot be accessed sanely above 32 bit width,
-	 * so we install an artificial 1<<31 period regardless of
-	 * the generic event period:
-	 */
-	.max_period		= (1ULL << 31) - 1,
-	.get_event_constraints	= intel_get_event_constraints,
-	.put_event_constraints	= intel_put_event_constraints,
-	.event_constraints	= intel_core_event_constraints,
-	.guest_get_msrs		= core_guest_get_msrs,
-	.format_attrs		= intel_arch_formats_attr,
-	.events_sysfs_show	= intel_event_sysfs_show,
-};
-
 struct intel_shared_regs *allocate_shared_regs(int cpu)
 {
 	struct intel_shared_regs *regs;
@@ -2743,6 +2715,44 @@ static struct attribute *intel_arch3_formats_attr[] = {
 	NULL,
 };
 
+static __initconst const struct x86_pmu core_pmu = {
+	.name			= "core",
+	.handle_irq		= x86_pmu_handle_irq,
+	.disable_all		= x86_pmu_disable_all,
+	.enable_all		= core_pmu_enable_all,
+	.enable			= core_pmu_enable_event,
+	.disable		= x86_pmu_disable_event,
+	.hw_config		= x86_pmu_hw_config,
+	.schedule_events	= x86_schedule_events,
+	.eventsel		= MSR_ARCH_PERFMON_EVENTSEL0,
+	.perfctr		= MSR_ARCH_PERFMON_PERFCTR0,
+	.event_map		= intel_pmu_event_map,
+	.max_events		= ARRAY_SIZE(intel_perfmon_event_map),
+	.apic			= 1,
+	/*
+	 * Intel PMCs cannot be accessed sanely above 32 bit width,
+	 * so we install an artificial 1<<31 period regardless of
+	 * the generic event period:
+	 */
+	.max_period		= (1ULL << 31) - 1,
+	.get_event_constraints	= intel_get_event_constraints,
+	.put_event_constraints	= intel_put_event_constraints,
+	.event_constraints	= intel_core_event_constraints,
+	.guest_get_msrs		= core_guest_get_msrs,
+	.format_attrs		= intel_arch_formats_attr,
+	.events_sysfs_show	= intel_event_sysfs_show,
+
+	/*
+	 * Virtual (or funny metal) CPU can define x86_pmu.extra_regs
+	 * together with PMU version 1 and thus be using core_pmu with
+	 * shared_regs. We need following callbacks here to allocate
+	 * it properly.
+	 */
+	.cpu_prepare		= intel_pmu_cpu_prepare,
+	.cpu_starting		= intel_pmu_cpu_starting,
+	.cpu_dying		= intel_pmu_cpu_dying,
+};
+
 static __initconst const struct x86_pmu intel_pmu = {
 	.name			= "Intel",
 	.handle_irq		= intel_pmu_handle_irq,
-- 
1.9.3

Re: [PATCHv3] perf/x86/intel: Add cpu_(prepare|starting|dying) for core_pmu

[Peter Zijlstra]

On Tue, Apr 21, 2015 at 05:26:23PM +0200, Jiri Olsa wrote:
> The core_pmu does not define cpu_* callbacks, which handles
> allocation of 'struct cpu_hw_events::shared_regs' data,
> initialization of debug store and PMU_FL_EXCL_CNTRS counters.
> 
> While this probably won't happen on bare metal, virtual CPU can
> define x86_pmu.extra_regs together with PMU version 1 and thus
> be using core_pmu -> using shared_regs data without it being
> allocated. That could could leave to following panic:
> 
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [<ffffffff8152cd4f>] _spin_lock_irqsave+0x1f/0x40
> 
> SNIP
> 
>  [<ffffffff81024bd9>] __intel_shared_reg_get_constraints+0x69/0x1e0
>  [<ffffffff81024deb>] intel_get_event_constraints+0x9b/0x180
>  [<ffffffff8101e815>] x86_schedule_events+0x75/0x1d0
>  [<ffffffff810586dc>] ? check_preempt_curr+0x7c/0x90
>  [<ffffffff810649fe>] ? try_to_wake_up+0x24e/0x3e0
>  [<ffffffff81064ba2>] ? default_wake_function+0x12/0x20
>  [<ffffffff8109eb16>] ? autoremove_wake_function+0x16/0x40
>  [<ffffffff810577e9>] ? __wake_up_common+0x59/0x90
>  [<ffffffff811a9517>] ? __d_lookup+0xa7/0x150
>  [<ffffffff8119db5f>] ? do_lookup+0x9f/0x230
>  [<ffffffff811a993a>] ? dput+0x9a/0x150
>  [<ffffffff8119c8f5>] ? path_to_nameidata+0x25/0x60
>  [<ffffffff8119e90a>] ? __link_path_walk+0x7da/0x1000
>  [<ffffffff8101d8f9>] ? x86_pmu_add+0xb9/0x170
>  [<ffffffff8101d7a7>] x86_pmu_commit_txn+0x67/0xc0
>  [<ffffffff811b07b0>] ? mntput_no_expire+0x30/0x110
>  [<ffffffff8119c731>] ? path_put+0x31/0x40
>  [<ffffffff8107c297>] ? current_fs_time+0x27/0x30
>  [<ffffffff8117d170>] ? mem_cgroup_get_reclaim_stat_from_page+0x20/0x70
>  [<ffffffff8111b7aa>] group_sched_in+0x13a/0x170
>  [<ffffffff81014a29>] ? sched_clock+0x9/0x10
>  [<ffffffff8111bac8>] ctx_sched_in+0x2e8/0x330
>  [<ffffffff8111bb7b>] perf_event_sched_in+0x6b/0xb0
>  [<ffffffff8111bc36>] perf_event_context_sched_in+0x76/0xc0
>  [<ffffffff8111eb3b>] perf_event_comm+0x1bb/0x2e0
>  [<ffffffff81195ee9>] set_task_comm+0x69/0x80
>  [<ffffffff81195fe1>] setup_new_exec+0xe1/0x2e0
>  [<ffffffff811ea68e>] load_elf_binary+0x3ce/0x1ab0
> 
> Adding cpu_(prepare|starting|dying) for core_pmu to have shared_regs
> data allocated for core_pmu. AFAICS there's no harm to initialize
> debug store and PMU_FL_EXCL_CNTRS either for core_pmu.
> 
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

[tip:perf/urgent] perf/x86/intel: Add cpu_(prepare|starting|dying ) for core_pmu

[tip-bot for Jiri Olsa]

Commit-ID:  3b6e042188994466ec257b71296b5f85b894dcd9
Gitweb:     http://git.kernel.org/tip/3b6e042188994466ec257b71296b5f85b894dcd9
Author:     Jiri Olsa <jolsa@redhat.com>
AuthorDate: Tue, 21 Apr 2015 17:26:23 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 22 Apr 2015 08:24:33 +0200

perf/x86/intel: Add cpu_(prepare|starting|dying) for core_pmu

The core_pmu does not define cpu_* callbacks, which handles
allocation of 'struct cpu_hw_events::shared_regs' data,
initialization of debug store and PMU_FL_EXCL_CNTRS counters.

While this probably won't happen on bare metal, virtual CPU can
define x86_pmu.extra_regs together with PMU version 1 and thus
be using core_pmu -> using shared_regs data without it being
allocated. That could could leave to following panic:

	BUG: unable to handle kernel NULL pointer dereference at (null)
	IP: [<ffffffff8152cd4f>] _spin_lock_irqsave+0x1f/0x40

	SNIP

	 [<ffffffff81024bd9>] __intel_shared_reg_get_constraints+0x69/0x1e0
	 [<ffffffff81024deb>] intel_get_event_constraints+0x9b/0x180
	 [<ffffffff8101e815>] x86_schedule_events+0x75/0x1d0
	 [<ffffffff810586dc>] ? check_preempt_curr+0x7c/0x90
	 [<ffffffff810649fe>] ? try_to_wake_up+0x24e/0x3e0
	 [<ffffffff81064ba2>] ? default_wake_function+0x12/0x20
	 [<ffffffff8109eb16>] ? autoremove_wake_function+0x16/0x40
	 [<ffffffff810577e9>] ? __wake_up_common+0x59/0x90
	 [<ffffffff811a9517>] ? __d_lookup+0xa7/0x150
	 [<ffffffff8119db5f>] ? do_lookup+0x9f/0x230
	 [<ffffffff811a993a>] ? dput+0x9a/0x150
	 [<ffffffff8119c8f5>] ? path_to_nameidata+0x25/0x60
	 [<ffffffff8119e90a>] ? __link_path_walk+0x7da/0x1000
	 [<ffffffff8101d8f9>] ? x86_pmu_add+0xb9/0x170
	 [<ffffffff8101d7a7>] x86_pmu_commit_txn+0x67/0xc0
	 [<ffffffff811b07b0>] ? mntput_no_expire+0x30/0x110
	 [<ffffffff8119c731>] ? path_put+0x31/0x40
	 [<ffffffff8107c297>] ? current_fs_time+0x27/0x30
	 [<ffffffff8117d170>] ? mem_cgroup_get_reclaim_stat_from_page+0x20/0x70
	 [<ffffffff8111b7aa>] group_sched_in+0x13a/0x170
	 [<ffffffff81014a29>] ? sched_clock+0x9/0x10
	 [<ffffffff8111bac8>] ctx_sched_in+0x2e8/0x330
	 [<ffffffff8111bb7b>] perf_event_sched_in+0x6b/0xb0
	 [<ffffffff8111bc36>] perf_event_context_sched_in+0x76/0xc0
	 [<ffffffff8111eb3b>] perf_event_comm+0x1bb/0x2e0
	 [<ffffffff81195ee9>] set_task_comm+0x69/0x80
	 [<ffffffff81195fe1>] setup_new_exec+0xe1/0x2e0
	 [<ffffffff811ea68e>] load_elf_binary+0x3ce/0x1ab0

Adding cpu_(prepare|starting|dying) for core_pmu to have
shared_regs data allocated for core_pmu. AFAICS there's no harm
to initialize debug store and PMU_FL_EXCL_CNTRS either for
core_pmu.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20150421152623.GC13169@krava.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/cpu/perf_event_intel.c | 66 +++++++++++++++++++---------------
 1 file changed, 38 insertions(+), 28 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 219d3fb..960e85d 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -2533,34 +2533,6 @@ ssize_t intel_event_sysfs_show(char *page, u64 config)
 	return x86_event_sysfs_show(page, config, event);
 }
 
-static __initconst const struct x86_pmu core_pmu = {
-	.name			= "core",
-	.handle_irq		= x86_pmu_handle_irq,
-	.disable_all		= x86_pmu_disable_all,
-	.enable_all		= core_pmu_enable_all,
-	.enable			= core_pmu_enable_event,
-	.disable		= x86_pmu_disable_event,
-	.hw_config		= x86_pmu_hw_config,
-	.schedule_events	= x86_schedule_events,
-	.eventsel		= MSR_ARCH_PERFMON_EVENTSEL0,
-	.perfctr		= MSR_ARCH_PERFMON_PERFCTR0,
-	.event_map		= intel_pmu_event_map,
-	.max_events		= ARRAY_SIZE(intel_perfmon_event_map),
-	.apic			= 1,
-	/*
-	 * Intel PMCs cannot be accessed sanely above 32 bit width,
-	 * so we install an artificial 1<<31 period regardless of
-	 * the generic event period:
-	 */
-	.max_period		= (1ULL << 31) - 1,
-	.get_event_constraints	= intel_get_event_constraints,
-	.put_event_constraints	= intel_put_event_constraints,
-	.event_constraints	= intel_core_event_constraints,
-	.guest_get_msrs		= core_guest_get_msrs,
-	.format_attrs		= intel_arch_formats_attr,
-	.events_sysfs_show	= intel_event_sysfs_show,
-};
-
 struct intel_shared_regs *allocate_shared_regs(int cpu)
 {
 	struct intel_shared_regs *regs;
@@ -2743,6 +2715,44 @@ static struct attribute *intel_arch3_formats_attr[] = {
 	NULL,
 };
 
+static __initconst const struct x86_pmu core_pmu = {
+	.name			= "core",
+	.handle_irq		= x86_pmu_handle_irq,
+	.disable_all		= x86_pmu_disable_all,
+	.enable_all		= core_pmu_enable_all,
+	.enable			= core_pmu_enable_event,
+	.disable		= x86_pmu_disable_event,
+	.hw_config		= x86_pmu_hw_config,
+	.schedule_events	= x86_schedule_events,
+	.eventsel		= MSR_ARCH_PERFMON_EVENTSEL0,
+	.perfctr		= MSR_ARCH_PERFMON_PERFCTR0,
+	.event_map		= intel_pmu_event_map,
+	.max_events		= ARRAY_SIZE(intel_perfmon_event_map),
+	.apic			= 1,
+	/*
+	 * Intel PMCs cannot be accessed sanely above 32-bit width,
+	 * so we install an artificial 1<<31 period regardless of
+	 * the generic event period:
+	 */
+	.max_period		= (1ULL<<31) - 1,
+	.get_event_constraints	= intel_get_event_constraints,
+	.put_event_constraints	= intel_put_event_constraints,
+	.event_constraints	= intel_core_event_constraints,
+	.guest_get_msrs		= core_guest_get_msrs,
+	.format_attrs		= intel_arch_formats_attr,
+	.events_sysfs_show	= intel_event_sysfs_show,
+
+	/*
+	 * Virtual (or funny metal) CPU can define x86_pmu.extra_regs
+	 * together with PMU version 1 and thus be using core_pmu with
+	 * shared_regs. We need following callbacks here to allocate
+	 * it properly.
+	 */
+	.cpu_prepare		= intel_pmu_cpu_prepare,
+	.cpu_starting		= intel_pmu_cpu_starting,
+	.cpu_dying		= intel_pmu_cpu_dying,
+};
+
 static __initconst const struct x86_pmu intel_pmu = {
 	.name			= "Intel",
 	.handle_irq		= intel_pmu_handle_irq,