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SubjectRe: [PATCH v1] arm64: efi: Make efi_rt_lock a raw_spinlock
From
Hello Ard,

On 2/16/23 18:23, Ard Biesheuvel wrote:
> On Thu, 16 Feb 2023 at 17:43, Pierre Gondois <pierre.gondois@arm.com> wrote:
>>
>> Hello,
>> Please ignore this patch for now. While running a kernel with this patch,
>> the following was triggered once (among multiple reboots). IRQ flags might
>> need to be saved, along with this present patch.
>>
>
> Hello Pierre,
>
> This is probably related to the Altra firmware bug that we are trying
> to narrow down and work around.
>
> So when the firmware crashes, it is not entirely unexpected that it
> might do so with the IRQ flags left in a different state, so this we
> should be able to ignore. (Perhaps we should silence that diagnostic
> in this case)
>
> Could you share the output of dmidecode on this platform?

I forgot to mention, this was tested on an Ampere eMAG. I saw that
commit 550b33cfd445 ("arm64: efi: Force the use of SetVirtualAddressMap()
on Altra machines") was solving a similar issue, but this should not impact
this machine.
I ll try to reproduce it and get more information.

# dmidecode 3.2
Getting SMBIOS data from sysfs.
SMBIOS 3.1.1 present.
Table at 0x8FFCAC0000.

Handle 0x0000, DMI type 0, 26 bytes
BIOS Information
Vendor: Ampere(TM)
Version: 1.0
Release Date: 06/28/2019
Address: 0xF0000
Runtime Size: 64 kB
ROM Size: 8192 kB
Characteristics:
PCI is supported
BIOS is upgradeable
Boot from CD is supported
Selectable boot is supported
ACPI is supported
UEFI is supported
BIOS Revision: 5.13
Firmware Revision: 1.0

Handle 0x0001, DMI type 1, 27 bytes
System Information
Manufacturer: MiTAC
Product Name: RAPTOR EV-883832-X3-0001
Version: PR010
Serial Number: 2AC2-B91602C
UUID: dfa0f1d6-835d-11e8-adb0-0cc47ad8d1fc
Wake-up Type: Power Switch
SKU Number: EV-883832-X3-OBX-1
Family: eMAG

Handle 0x0002, DMI type 2, 15 bytes
Base Board Information
Manufacturer: MiTAC
Product Name: RAPTOR
Version: EV-883832-X3-ED0-1
Serial Number: 2AC2-B91602C
Asset Tag: AMPX3A1-A000-0000000000022
Features:
Board is a hosting board
Location In Chassis: Part Component
Chassis Handle: 0x0003
Type: Motherboard
Contained Object Handles: 0

Handle 0x0003, DMI type 3, 22 bytes
Chassis Information
Manufacturer: MiTAC
Type: Rack Mount Chassis
Lock: Not Present
Version: RAPTOR-00000000
Serial Number: A1A1-A000-0000000000022
Asset Tag: AMPX3A1-A000-0000000000022
Boot-up State: Safe
Power Supply State: Safe
Thermal State: Safe
Security Status: None
OEM Information: 0x00000000
Height: Unspecified
Number Of Power Cords: 1
Contained Elements: 0
SKU Number: EV-883832-X3-OBX-1

Handle 0x0004, DMI type 4, 48 bytes
Processor Information
Socket Designation: CPU 1
Type: Central Processor
Family: ARMv8
Manufacturer: Ampere(TM)
ID: 00 00 00 00 02 00 3F 50
Version: eMAG
Voltage: 0.9 V
External Clock: 3000 MHz
Max Speed: 3300 MHz
Current Speed: 3000 MHz
Status: Populated, Enabled
Upgrade: None
L1 Cache Handle: 0x0005
L2 Cache Handle: 0x0006
L3 Cache Handle: 0x0007
Serial Number: 00000000000000005011060302FB0988
Asset Tag: 00000000
Part Number: 00000000
Core Count: 32
Core Enabled: 32
Thread Count: 32
Characteristics:
64-bit capable
Multi-Core
Hardware Thread
Execute Protection
Enhanced Virtualization

[...]




>
> Obviously, there is a related issue where some process keeps hitting
> on the RTC. Mind testing the below to see if the system is usable
> beyond the EFI problems, and perhaps have a stab at figuring out which
> process keeps hitting on the RTC like that?
>
> diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c
> index 1e8bc6cc1e12d855..cc4edb85841e8f67 100644
> --- a/drivers/rtc/rtc-efi.c
> +++ b/drivers/rtc/rtc-efi.c
> @@ -164,7 +164,7 @@ static int efi_read_time(struct device *dev,
> struct rtc_time *tm)
>
> if (status != EFI_SUCCESS) {
> /* should never happen */
> - dev_err(dev, "can't read time\n");
> + dev_err_ratelimited(dev, "can't read time\n");
> return -EINVAL;
> }
>
>
>
>>
>> random: crng init done
>> [Firmware Bug]: Unable to handle write to read-only memory in EFI runtime service
>> ------------[ cut here ]------------
>> WARNING: CPU: 7 PID: 325 at drivers/firmware/efi/runtime-wrappers.c:113 efi_call_virt_check_flags+0x48/0xb0
>> Modules linked in: btrfs blake2b_generic libcrc32c xor xor_neon raid6_pq crct10dif_ce
>> CPU: 7 PID: 325 Comm: kworker/u64:1 Tainted: G W I 6.2.0-rc8-rt1-[...]
>> Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 1.0 06/28/2019
>> Workqueue: efi_rts_wq efi_call_rts
>> pstate: 00000085 (nzcv daIf -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>> pc : efi_call_virt_check_flags+0x48/0xb0
>> lr : efi_call_rts+0x240/0x4b0
>> sp : ffff80000def3cf0
>> x29: ffff80000def3cf0 x28: ffff000801d10b05 x27: ffff80000b16d000
>> x26: 0000000000000000 x25: ffff80000b17e4a0 x24: ffff80000c84bd48
>> x23: ffff80000c84bd00 x22: ffff80000c84bd0c x21: 0000000000000080
>> x20: ffff80000a41d0e0 x19: 0000000000000000 x18: ffff80000a22b3a8
>> x17: 0000000000000000 x16: ffff80000d2dc000 x15: 0000000000000000
>> x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
>> x11: 0000000000000000 x10: 0000000000000000 x9 : ffff80000927cd60
>> x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
>> x5 : ffff80000a7d1008 x4 : 0000008ffd1d0018 x3 : 0000000000000000
>> x2 : 0000000000000001 x1 : ffff80000a41d0e0 x0 : 0000000000000080
>> Call trace:
>> efi_call_virt_check_flags+0x48/0xb0
>> efi_call_rts+0x240/0x4b0
>> process_one_work+0x2c8/0x7a0
>> worker_thread+0x54/0x410
>> kthread+0x130/0x140
>> ret_from_fork+0x10/0x20
>> irq event stamp: 540538
>> hardirqs last enabled at (540537): [<ffff80000927d97c>] efi_virtmap_load+0x28c/0x328
>> hardirqs last disabled at (540538): [<ffff8000095c8590>] el1_abort+0x28/0x100
>> softirqs last enabled at (534078): [<ffff80000819cec8>] __local_bh_enable_ip+0xa8/0x2a8
>> softirqs last disabled at (534066): [<ffff80000934b408>] neigh_managed_work+0x8/0x100
>> ---[ end trace 0000000000000000 ]---
>> Disabling lock debugging due to kernel taint
>> efi: [Firmware Bug]: IRQ flags corrupted (0x00000000=>0x00000080) by EFI set_variable
>> ------------[ cut here ]------------
>> WARNING: CPU: 0 PID: 14 at drivers/firmware/efi/runtime-wrappers.c:341 virt_efi_set_variable+0x164/0x1c0
>> Modules linked in: btrfs blake2b_generic libcrc32c xor xor_neon raid6_pq crct10dif_ce
>> CPU: 0 PID: 14 Comm: kworker/0:1 Tainted: G W I 6.2.0-rc8-rt1-custom-[...]
>> Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 1.0 06/28/2019
>> Workqueue: events refresh_nv_rng_seed
>> pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>> pc : virt_efi_set_variable+0x164/0x1c0
>> lr : virt_efi_set_variable+0x150/0x1c0
>> sp : ffff80000c84bcc0
>> x29: ffff80000c84bcc0 x28: ffff008f35feb905 x27: ffff80000b16d000
>> x26: ffff80000b16ced0 x25: 0000000000000000 x24: ffff80000c344000
>> x23: ffff80000a41b2b0 x22: ffff80000c84bd38 x21: 8000000000000015
>> x20: ffff80000b63ecf8 x19: ffff80000c344480 x18: ffff80000a22b3a8
>> x17: 000000005a8ae2d0 x16: 0000000000000000 x15: ffff80000b16cfb8
>> x14: 0000000000000001 x13: 0000000000000030 x12: 0101010101010101
>> x11: 0000000571f160b9 x10: 0000000000002460 x9 : ffff8000095e2064
>> x8 : ffff80000a7d1008 x7 : 0000000000000004 x6 : ffff80000c84bb28
>> x5 : ffff80000c84c000 x4 : ffff80000c848000 x3 : ffff80000c84bc40
>> x2 : 0000000000000001 x1 : 0000000000000000 x0 : 8000000000000015
>> Call trace:
>> virt_efi_set_variable+0x164/0x1c0
>> refresh_nv_rng_seed+0x84/0xb8
>> process_one_work+0x2c8/0x7a0
>> worker_thread+0x54/0x410
>> kthread+0x130/0x140
>> ret_from_fork+0x10/0x20
>> irq event stamp: 35886
>> hardirqs last enabled at (35885): [<ffff8000095e2050>] _raw_spin_unlock_irq+0x40/0xb8
>> hardirqs last disabled at (35886): [<ffff8000095e215c>] _raw_spin_lock_irq+0x94/0x98
>> softirqs last enabled at (10754): [<ffff80000819cec8>] __local_bh_enable_ip+0xa8/0x2a8
>> softirqs last disabled at (10746): [<ffff800008256de0>] srcu_invoke_callbacks+0x100/0x1a8
>> ---[ end trace 0000000000000000 ]---
>> [...]
>> In-situ OAM (IOAM) with IPv6
>> efi: EFI Runtime Services are disabled!
>> efivars: get_next_variable: status=8000000000000007
>> [...]
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> rtc-efi rtc-efi.0: can't read time
>> [...]
>>
>>
>> On 2/15/23 17:10, Pierre Gondois wrote:
>>> Running a rt-kernel base on 6.2.0-rc3-rt1 on an Ampere Altra outputs
>>> the following:
>>> BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
>>> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 9, name: kworker/u320:0
>>> preempt_count: 2, expected: 0
>>> RCU nest depth: 0, expected: 0
>>> 3 locks held by kworker/u320:0/9:
>>> #0: ffff3fff8c27d128 ((wq_completion)efi_rts_wq){+.+.}-{0:0}, at: process_one_work (./include/linux/atomic/atomic-long.h:41)
>>> #1: ffff80000861bdd0 ((work_completion)(&efi_rts_work.work)){+.+.}-{0:0}, at: process_one_work (./include/linux/atomic/atomic-long.h:41)
>>> #2: ffffdf7e1ed3e460 (efi_rt_lock){+.+.}-{3:3}, at: efi_call_rts (drivers/firmware/efi/runtime-wrappers.c:101)
>>> Preemption disabled at:
>>> efi_virtmap_load (./arch/arm64/include/asm/mmu_context.h:248)
>>> CPU: 0 PID: 9 Comm: kworker/u320:0 Tainted: G W 6.2.0-rc3-rt1
>>> Hardware name: WIWYNN Mt.Jade Server System B81.03001.0005/Mt.Jade Motherboard, BIOS 1.08.20220218 (SCP: 1.08.20220218) 2022/02/18
>>> Workqueue: efi_rts_wq efi_call_rts
>>> Call trace:
>>> dump_backtrace (arch/arm64/kernel/stacktrace.c:158)
>>> show_stack (arch/arm64/kernel/stacktrace.c:165)
>>> dump_stack_lvl (lib/dump_stack.c:107 (discriminator 4))
>>> dump_stack (lib/dump_stack.c:114)
>>> __might_resched (kernel/sched/core.c:10134)
>>> rt_spin_lock (kernel/locking/rtmutex.c:1769 (discriminator 4))
>>> efi_call_rts (drivers/firmware/efi/runtime-wrappers.c:101)
>>> [...]
>>>
>>> This seems to come from commit ff7a167961d1 ("arm64: efi: Execute
>>> runtime services from a dedicated stack") which adds a spinlock. This
>>> spinlock is taken through:
>>> efi_call_rts()
>>> \-efi_call_virt()
>>> \-efi_call_virt_pointer()
>>> \-arch_efi_call_virt_setup()
>>>
>>> Make 'efi_rt_lock' a raw_spinlock to avoid being preempted.
>>>
>>> Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
>>> ---
>>> arch/arm64/include/asm/efi.h | 6 +++---
>>> arch/arm64/kernel/efi.c | 2 +-
>>> 2 files changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
>>> index 31d13a6001df..37dc2e8c3500 100644
>>> --- a/arch/arm64/include/asm/efi.h
>>> +++ b/arch/arm64/include/asm/efi.h
>>> @@ -33,7 +33,7 @@ int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md);
>>> ({ \
>>> efi_virtmap_load(); \
>>> __efi_fpsimd_begin(); \
>>> - spin_lock(&efi_rt_lock); \
>>> + raw_spin_lock(&efi_rt_lock); \
>>> })
>>>
>>> #undef arch_efi_call_virt
>>> @@ -42,12 +42,12 @@ int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md);
>>>
>>> #define arch_efi_call_virt_teardown() \
>>> ({ \
>>> - spin_unlock(&efi_rt_lock); \
>>> + raw_spin_unlock(&efi_rt_lock); \
>>> __efi_fpsimd_end(); \
>>> efi_virtmap_unload(); \
>>> })
>>>
>>> -extern spinlock_t efi_rt_lock;
>>> +extern raw_spinlock_t efi_rt_lock;
>>> efi_status_t __efi_rt_asm_wrapper(void *, const char *, ...);
>>>
>>> #define ARCH_EFI_IRQ_FLAGS_MASK (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)
>>> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
>>> index fab05de2e12d..216933cf47ee 100644
>>> --- a/arch/arm64/kernel/efi.c
>>> +++ b/arch/arm64/kernel/efi.c
>>> @@ -145,7 +145,7 @@ asmlinkage efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f)
>>> return s;
>>> }
>>>
>>> -DEFINE_SPINLOCK(efi_rt_lock);
>>> +DEFINE_RAW_SPINLOCK(efi_rt_lock);
>>>
>>> asmlinkage u64 *efi_rt_stack_top __ro_after_init;
>>>

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