kernel/drivers/firmware/efi/runtime-wrappers.c, branch linux-6.9.y

efi/runtime-wrappers: Clean up white space and add __init annotation

2023-08-22T08:39:26Z

Some cosmetic changes as well as a missing __init annotation. Signed-off-by: Ard Biesheuvel

acpi/prmt: Use EFI runtime sandbox to invoke PRM handlers

2023-08-22T08:39:26Z

Instead of bypassing the kernel's adaptation layer for performing EFI runtime calls, wire up ACPI PRM handling into it. This means these calls can no longer occur concurrently with EFI runtime calls, and will be made from the EFI runtime workqueue. It also means any page faults occurring during PRM handling will be identified correctly as originating in firmware code. Acked-by: Rafael J. Wysocki Signed-off-by: Ard Biesheuvel

efi/runtime-wrappers: Don't duplicate setup/teardown code

2023-08-22T08:39:26Z

Avoid duplicating the EFI arch setup and teardown routine calls numerous times in efi_call_rts(). Instead, expand the efi_call_virt_pointer() macro into efi_call_rts(), taking the pre and post parts out of the switch. Signed-off-by: Ard Biesheuvel

efi/runtime-wrappers: Remove duplicated macro for service returning void

2023-08-22T08:39:26Z

__efi_call_virt() exists as an alternative for efi_call_virt() for the sole reason that ResetSystem() returns void, and so we cannot use a call to it in the RHS of an assignment. Given that there is only a single user, let's drop the macro, and expand it into the caller. That way, the remaining macro can be tightened somewhat in terms of type safety too. Note that the use of typeof() on the runtime service invocation does not result in an actual call being made, but it does require a few pointer types to be fixed up and converted into the proper function pointer prototypes. Signed-off-by: Ard Biesheuvel

efi/runtime-wrapper: Move workqueue manipulation out of line

2023-08-21T15:59:54Z

efi_queue_work() is a macro that implements the non-trivial manipulation of the EFI runtime workqueue and completion data structure, most of which is generic, and could be shared between all the users of the macro. So move it out of the macro and into a new helper function. Signed-off-by: Ard Biesheuvel

efi/runtime-wrappers: Use type safe encapsulation of call arguments

2023-08-21T15:59:54Z

The current code that marshalls the EFI runtime call arguments to hand them off to a async helper does so in a type unsafe and slightly messy manner - everything is cast to void* except for some integral types that are passed by reference and dereferenced on the receiver end. Let's clean this up a bit, and record the arguments of each runtime service invocation exactly as they are issued, in a manner that permits the compiler to check the types of the arguments at both ends. Signed-off-by: Ard Biesheuvel

Change DEFINE_SEMAPHORE() to take a number argument

2023-04-18T18:15:24Z

Fundamentally semaphores are a counted primitive, but DEFINE_SEMAPHORE() does not expose this and explicitly creates a binary semaphore. Change DEFINE_SEMAPHORE() to take a number argument and use that in the few places that open-coded it using __SEMAPHORE_INITIALIZER(). Signed-off-by: Peter Zijlstra (Intel) [mcgrof: add some tribal knowledge about why some folks prefer binary sempahores over mutexes] Reviewed-by: Sergey Senozhatsky Reviewed-by: Davidlohr Bueso Signed-off-by: Luis Chamberlain

efi: fix userspace infinite retry read efivars after EFI runtime services page fault

2023-01-03T09:52:16Z

After [1][2], if we catch exceptions due to EFI runtime service, we will clear EFI_RUNTIME_SERVICES bit to disable EFI runtime service, then the subsequent routine which invoke the EFI runtime service should fail. But the userspace cat efivars through /sys/firmware/efi/efivars/ will stuck and infinite loop calling read() due to efivarfs_file_read() return -EINTR. The -EINTR is converted from EFI_ABORTED by efi_status_to_err(), and is an improper return value in this situation, so let virt_efi_xxx() return EFI_DEVICE_ERROR and converted to -EIO to invoker. Cc: Fixes: 3425d934fc03 ("efi/x86: Handle page faults occurring while running EFI runtime services") Fixes: 23715a26c8d8 ("arm64: efi: Recover from synchronous exceptions occurring in firmware") Signed-off-by: Ding Hui Signed-off-by: Ard Biesheuvel

arm64: efi: Recover from synchronous exceptions occurring in firmware

2022-12-08T17:33:34Z

Unlike x86, which has machinery to deal with page faults that occur during the execution of EFI runtime services, arm64 has nothing like that, and a synchronous exception raised by firmware code brings down the whole system. With more EFI based systems appearing that were not built to run Linux (such as the Windows-on-ARM laptops based on Qualcomm SOCs), as well as the introduction of PRM (platform specific firmware routines that are callable just like EFI runtime services), we are more likely to run into issues of this sort, and it is much more likely that we can identify and work around such issues if they don't bring down the system entirely. Since we already use a EFI runtime services call wrapper in assembler, we can quite easily add some code that captures the execution state at the point where the call is made, allowing us to revert to this state and proceed execution if the call triggered a synchronous exception. Given that the kernel and the firmware don't share any data structures that could end up in an indeterminate state, we can happily continue running, as long as we mark the EFI runtime services as unavailable from that point on. Signed-off-by: Ard Biesheuvel Acked-by: Catalin Marinas

efi: Change down_interruptible() in virt_efi_reset_system() to down_trylock()

2021-10-05T11:07:01Z

While reboot the system by sysrq, the following bug will be occur. BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:90 in_atomic(): 0, irqs_disabled(): 128, non_block: 0, pid: 10052, name: rc.shutdown CPU: 3 PID: 10052 Comm: rc.shutdown Tainted: G W O 5.10.0 #1 Call trace: dump_backtrace+0x0/0x1c8 show_stack+0x18/0x28 dump_stack+0xd0/0x110 ___might_sleep+0x14c/0x160 __might_sleep+0x74/0x88 down_interruptible+0x40/0x118 virt_efi_reset_system+0x3c/0xd0 efi_reboot+0xd4/0x11c machine_restart+0x60/0x9c emergency_restart+0x1c/0x2c sysrq_handle_reboot+0x1c/0x2c __handle_sysrq+0xd0/0x194 write_sysrq_trigger+0xbc/0xe4 proc_reg_write+0xd4/0xf0 vfs_write+0xa8/0x148 ksys_write+0x6c/0xd8 __arm64_sys_write+0x18/0x28 el0_svc_common.constprop.3+0xe4/0x16c do_el0_svc+0x1c/0x2c el0_svc+0x20/0x30 el0_sync_handler+0x80/0x17c el0_sync+0x158/0x180 The reason for this problem is that irq has been disabled in machine_restart() and then it calls down_interruptible() in virt_efi_reset_system(), which would occur sleep in irq context, it is dangerous! Commit 99409b935c9a("locking/semaphore: Add might_sleep() to down_*() family") add might_sleep() in down_interruptible(), so the bug info is here. down_trylock() can solve this problem, cause there is no might_sleep. -------- Cc: Signed-off-by: Zhang Jianhua Signed-off-by: Ard Biesheuvel