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Message-ID: <5f6768e9-a301-f16d-d6c0-218b29eeabeb@arm.com>
Date: Tue, 18 Oct 2022 15:07:49 +0200
From: Pierre Gondois <pierre.gondois@....com>
To: linux-kernel@...r.kernel.org
Cc: James Morse <james.morse@....com>, Will Deacon <will@...nel.org>,
Huacai Chen <chenhuacai@...nel.org>,
John Garry <john.garry@...wei.com>,
Shaokun Zhang <zhangshaokun@...ilicon.com>,
WANG Xuerui <git@...0n.name>, Qi Liu <liuqi115@...wei.com>,
Bharat Bhushan <bbhushan2@...vell.com>,
Huang Ying <ying.huang@...el.com>,
Bibo Mao <maobibo@...ngson.cn>,
"Jason A. Donenfeld" <Jason@...c4.com>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2] firmware: arm_sdei: Fix sleep from invalid context BUG
The changelog was removed:
v2:
- Don't use a raw spin_lock, but move the CPUHP_AP_ARM_SDEI_
cpuhp state to the _ONLINE section.
On 10/18/22 15:04, Pierre Gondois wrote:
> On an Ampere Altra,
> Running a preemp_rt kernel based on v5.19-rc3-rt5 on an
> Ampere Altra triggers:
> [ 15.683141] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
> [ 15.683154] in_atomic(): 0, irqs_disabled(): 128, non_block: 0, pid: 24, name: cpuhp/0
> [ 15.683157] preempt_count: 0, expected: 0
> [ 15.683159] RCU nest depth: 0, expected: 0
> [ 15.683163] 3 locks held by cpuhp/0/24:
> [ 15.683167] #0: ffffda30217c70d0 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x5c/0x248
> [ 15.683201] #1: ffffda30217c7120 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x5c/0x248
> [ 15.683205] #2: ffffda3021c711f0 (sdei_list_lock){....}-{3:3}, at: sdei_cpuhp_up+0x3c/0x130
> [ 15.683224] irq event stamp: 36
> [ 15.683226] hardirqs last enabled at (35): [<ffffda301e85b7bc>] finish_task_switch+0xb4/0x2b0
> [ 15.683236] hardirqs last disabled at (36): [<ffffda301e812fec>] cpuhp_thread_fun+0x21c/0x248
> [ 15.683238] softirqs last enabled at (0): [<ffffda301e80b184>] copy_process+0x63c/0x1ac0
> [ 15.683245] softirqs last disabled at (0): [<0000000000000000>] 0x0
> [ 15.683258] CPU: 0 PID: 24 Comm: cpuhp/0 Not tainted 5.19.0-rc3-rt5-[...]
> [ 15.683265] Hardware name: WIWYNN Mt.Jade Server System B81.03001.0005/Mt.Jade Motherboard, BIOS 1.08.20220218 (SCP: 1.08.20220218) 2022/02/18
> [ 15.683268] Call trace:
> [ 15.683271] dump_backtrace+0x114/0x120
> [ 15.683277] show_stack+0x20/0x70
> [ 15.683279] dump_stack_lvl+0x9c/0xd8
> [ 15.683288] dump_stack+0x18/0x34
> [ 15.683289] __might_resched+0x188/0x228
> [ 15.683292] rt_spin_lock+0x70/0x120
> [ 15.683301] sdei_cpuhp_up+0x3c/0x130
> [ 15.683303] cpuhp_invoke_callback+0x250/0xf08
> [ 15.683305] cpuhp_thread_fun+0x120/0x248
> [ 15.683308] smpboot_thread_fn+0x280/0x320
> [ 15.683315] kthread+0x130/0x140
> [ 15.683321] ret_from_fork+0x10/0x20
>
> sdei_cpuhp_up() is called in the STARTING hotplug section,
> which runs whith interrupts disabled. Move CPUHP_AP_ARM_SDEI_
> state to the _ONLINE section to execute the cpuhp cb with
> preemption enabled.
>
> Some SDEI calls (e.g. SDEI_1_0_FN_SDEI_PE_MASK) take actions on the
> calling CPU. It is checked that preemption is disabled for them.
> _ONLINE cpuhp cb are executed in the 'per CPU hotplug thread'.
> Preemption is enabled in those threads, but their cpumask is limited
> to 1 CPU.
> Move 'WARN_ON_ONCE(preemptible())' statements so that SDEI cpuhp cb
> don't trigger them. This means that no check will be done for some
> cases, e.g. sdei_mask_local_cpu() invocations.
>
> Also add a check for the SDEI_1_0_FN_SDEI_PRIVATE_RESET SDEI call
> which acts on the calling CPU.
>
> Suggested-by: James Morse <james.morse@....com>
> Signed-off-by: Pierre Gondois <pierre.gondois@....com>
> ---
> drivers/firmware/arm_sdei.c | 28 ++++++++++++++--------------
> include/linux/cpuhotplug.h | 2 +-
> 2 files changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
> index 1e1a51510e83..9b03e164a37a 100644
> --- a/drivers/firmware/arm_sdei.c
> +++ b/drivers/firmware/arm_sdei.c
> @@ -301,8 +301,6 @@ int sdei_mask_local_cpu(void)
> {
> int err;
>
> - WARN_ON_ONCE(preemptible());
> -
> err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PE_MASK, 0, 0, 0, 0, 0, NULL);
> if (err && err != -EIO) {
> pr_warn_once("failed to mask CPU[%u]: %d\n",
> @@ -315,6 +313,7 @@ int sdei_mask_local_cpu(void)
>
> static void _ipi_mask_cpu(void *ignored)
> {
> + WARN_ON_ONCE(preemptible());
> sdei_mask_local_cpu();
> }
>
> @@ -322,8 +321,6 @@ int sdei_unmask_local_cpu(void)
> {
> int err;
>
> - WARN_ON_ONCE(preemptible());
> -
> err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PE_UNMASK, 0, 0, 0, 0, 0, NULL);
> if (err && err != -EIO) {
> pr_warn_once("failed to unmask CPU[%u]: %d\n",
> @@ -336,6 +333,7 @@ int sdei_unmask_local_cpu(void)
>
> static void _ipi_unmask_cpu(void *ignored)
> {
> + WARN_ON_ONCE(preemptible());
> sdei_unmask_local_cpu();
> }
>
> @@ -343,6 +341,8 @@ static void _ipi_private_reset(void *ignored)
> {
> int err;
>
> + WARN_ON_ONCE(preemptible());
> +
> err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PRIVATE_RESET, 0, 0, 0, 0, 0,
> NULL);
> if (err && err != -EIO)
> @@ -389,8 +389,6 @@ static void _local_event_enable(void *data)
> int err;
> struct sdei_crosscall_args *arg = data;
>
> - WARN_ON_ONCE(preemptible());
> -
> err = sdei_api_event_enable(arg->event->event_num);
>
> sdei_cross_call_return(arg, err);
> @@ -401,6 +399,8 @@ int sdei_event_enable(u32 event_num)
> int err = -EINVAL;
> struct sdei_event *event;
>
> + WARN_ON_ONCE(preemptible());
> +
> mutex_lock(&sdei_events_lock);
> event = sdei_event_find(event_num);
> if (!event) {
> @@ -479,8 +479,6 @@ static void _local_event_unregister(void *data)
> int err;
> struct sdei_crosscall_args *arg = data;
>
> - WARN_ON_ONCE(preemptible());
> -
> err = sdei_api_event_unregister(arg->event->event_num);
>
> sdei_cross_call_return(arg, err);
> @@ -492,6 +490,7 @@ int sdei_event_unregister(u32 event_num)
> struct sdei_event *event;
>
> WARN_ON(in_nmi());
> + WARN_ON_ONCE(preemptible());
>
> mutex_lock(&sdei_events_lock);
> event = sdei_event_find(event_num);
> @@ -561,8 +560,6 @@ static void _local_event_register(void *data)
> struct sdei_registered_event *reg;
> struct sdei_crosscall_args *arg = data;
>
> - WARN_ON(preemptible());
> -
> reg = per_cpu_ptr(arg->event->private_registered, smp_processor_id());
> err = sdei_api_event_register(arg->event->event_num, sdei_entry_point,
> reg, 0, 0);
> @@ -576,6 +573,7 @@ int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg)
> struct sdei_event *event;
>
> WARN_ON(in_nmi());
> + WARN_ON_ONCE(preemptible());
>
> mutex_lock(&sdei_events_lock);
> if (sdei_event_find(event_num)) {
> @@ -717,6 +715,8 @@ static int sdei_pm_notifier(struct notifier_block *nb, unsigned long action,
> {
> int rv;
>
> + WARN_ON_ONCE(preemptible());
> +
> switch (action) {
> case CPU_PM_ENTER:
> rv = sdei_mask_local_cpu();
> @@ -765,7 +765,7 @@ static int sdei_device_freeze(struct device *dev)
> int err;
>
> /* unregister private events */
> - cpuhp_remove_state(CPUHP_AP_ARM_SDEI_STARTING);
> + cpuhp_remove_state(CPUHP_AP_ARM_SDEI_ONLINE);
>
> err = sdei_unregister_shared();
> if (err)
> @@ -786,7 +786,7 @@ static int sdei_device_thaw(struct device *dev)
> return err;
> }
>
> - err = cpuhp_setup_state(CPUHP_AP_ARM_SDEI_STARTING, "SDEI",
> + err = cpuhp_setup_state(CPUHP_AP_ARM_SDEI_ONLINE, "SDEI",
> &sdei_cpuhp_up, &sdei_cpuhp_down);
> if (err)
> pr_warn("Failed to re-register CPU hotplug notifier...\n");
> @@ -823,7 +823,7 @@ static int sdei_reboot_notifier(struct notifier_block *nb, unsigned long action,
> * We are going to reset the interface, after this there is no point
> * doing work when we take CPUs offline.
> */
> - cpuhp_remove_state(CPUHP_AP_ARM_SDEI_STARTING);
> + cpuhp_remove_state(CPUHP_AP_ARM_SDEI_ONLINE);
>
> sdei_platform_reset();
>
> @@ -1003,7 +1003,7 @@ static int sdei_probe(struct platform_device *pdev)
> goto remove_cpupm;
> }
>
> - err = cpuhp_setup_state(CPUHP_AP_ARM_SDEI_STARTING, "SDEI",
> + err = cpuhp_setup_state(CPUHP_AP_ARM_SDEI_ONLINE, "SDEI",
> &sdei_cpuhp_up, &sdei_cpuhp_down);
> if (err) {
> pr_warn("Failed to register CPU hotplug notifier...\n");
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index f61447913db9..63b89e00a4c3 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -161,7 +161,6 @@ enum cpuhp_state {
> CPUHP_AP_PERF_X86_CSTATE_STARTING,
> CPUHP_AP_PERF_XTENSA_STARTING,
> CPUHP_AP_MIPS_OP_LOONGSON3_STARTING,
> - CPUHP_AP_ARM_SDEI_STARTING,
> CPUHP_AP_ARM_VFP_STARTING,
> CPUHP_AP_ARM64_DEBUG_MONITORS_STARTING,
> CPUHP_AP_PERF_ARM_HW_BREAKPOINT_STARTING,
> @@ -209,6 +208,7 @@ enum cpuhp_state {
> CPUHP_AP_IRQ_AFFINITY_ONLINE,
> CPUHP_AP_BLK_MQ_ONLINE,
> CPUHP_AP_ARM_MVEBU_SYNC_CLOCKS,
> + CPUHP_AP_ARM_SDEI_ONLINE,
> CPUHP_AP_X86_INTEL_EPB_ONLINE,
> CPUHP_AP_PERF_ONLINE,
> CPUHP_AP_PERF_X86_ONLINE,
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