arm64: efi: Avoid workqueue to check whether EFI runtime is live

Comparing current_work() against efi_rts_work.work is sufficient to
decide whether current is currently running EFI runtime services

arm64: efi: Avoid workqueue to check whether EFI runtime is live

Comparing current_work() against efi_rts_work.work is sufficient to
decide whether current is currently running EFI runtime services code at
any level in its call stack.

However, there are other potential users of the EFI runtime stack, such
as the ACPI subsystem, which may invoke efi_call_virt_pointer()
directly, and so any sync exceptions occurring in firmware during those
calls are currently misidentified.

So instead, let's check whether the stashed value of the thread stack
pointer points into current's thread stack. This can only be the case if
current was interrupted while running EFI runtime code. Note that this
implies that we should clear the stashed value after switching back, to
avoid false positives.

Reviewed-by: Mark Rutland <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>

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efi: rt-wrapper: Add missing include

Add the missing #include of asm/assembler.h, which is where the ldr_l
macro is defined.

Fixes: ff7a167961d1b97e ("arm64: efi: Execute runtime services from a de

efi: rt-wrapper: Add missing include

Add the missing #include of asm/assembler.h, which is where the ldr_l
macro is defined.

Fixes: ff7a167961d1b97e ("arm64: efi: Execute runtime services from a dedicated stack")
Signed-off-by: Ard Biesheuvel <[email protected]>

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arm64: efi: Recover from synchronous exceptions occurring in firmware

Unlike x86, which has machinery to deal with page faults that occur
during the execution of EFI runtime services, arm64 has noth

arm64: efi: Recover from synchronous exceptions occurring in firmware

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 <[email protected]>
Acked-by: Catalin Marinas <[email protected]>

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arm64: efi: Execute runtime services from a dedicated stack

With the introduction of PRMT in the ACPI subsystem, the EFI rts
workqueue is no longer the only caller of efi_call_virt_pointer() in the

arm64: efi: Execute runtime services from a dedicated stack

With the introduction of PRMT in the ACPI subsystem, the EFI rts
workqueue is no longer the only caller of efi_call_virt_pointer() in the
kernel. This means the EFI runtime services lock is no longer sufficient
to manage concurrent calls into firmware, but also that firmware calls
may occur that are not marshalled via the workqueue mechanism, but
originate directly from the caller context.

For added robustness, and to ensure that the runtime services have 8 KiB
of stack space available as per the EFI spec, introduce a spinlock
protected EFI runtime stack of 8 KiB, where the spinlock also ensures
serialization between the EFI rts workqueue (which itself serializes EFI
runtime calls) and other callers of efi_call_virt_pointer().

While at it, use the stack pivot to avoid reloading the shadow call
stack pointer from the ordinary stack, as doing so could produce a
gadget to defeat it.

Signed-off-by: Ard Biesheuvel <[email protected]>

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arm64: efi: Revert "Recover from synchronous exceptions ..."

This reverts commit 23715a26c8d81291, which introduced some code in
assembler that manipulates both the ordinary and the shadow call stac

arm64: efi: Revert "Recover from synchronous exceptions ..."

This reverts commit 23715a26c8d81291, which introduced some code in
assembler that manipulates both the ordinary and the shadow call stack
pointer in a way that could potentially be taken advantage of. So let's
revert it, and do a better job the next time around.

Signed-off-by: Ard Biesheuvel <[email protected]>

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arm64: efi: Recover from synchronous exceptions occurring in firmware

Unlike x86, which has machinery to deal with page faults that occur
during the execution of EFI runtime services, arm64 has noth

arm64: efi: Recover from synchronous exceptions occurring in firmware

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 <[email protected]>
Acked-by: Catalin Marinas <[email protected]>

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arm64: efi: Restore register x18 if it was corrupted

If we detect a corrupted x18, restore the register before jumping back
to potentially SCS instrumented code. This is safe, because the wrapper
is

arm64: efi: Restore register x18 if it was corrupted

If we detect a corrupted x18, restore the register before jumping back
to potentially SCS instrumented code. This is safe, because the wrapper
is called with preemption disabled and a separate shadow stack is used
for interrupt handling.

Signed-off-by: Sami Tolvanen <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Acked-by: Will Deacon <[email protected]>
Signed-off-by: Will Deacon <[email protected]>

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arm64: kernel: Convert to modern annotations for assembly functions

In an effort to clarify and simplify the annotation of assembly functions
in the kernel new macros have been introduced. These rep

arm64: kernel: Convert to modern annotations for assembly functions

In an effort to clarify and simplify the annotation of assembly functions
in the kernel new macros have been introduced. These replace ENTRY and
ENDPROC and also add a new annotation for static functions which previously
had no ENTRY equivalent. Update the annotations in the core kernel code to
the new macros.

Signed-off-by: Mark Brown <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of th

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Enrico Weigelt <[email protected]>
Reviewed-by: Kate Stewart <[email protected]>
Reviewed-by: Allison Randal <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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efi/arm64: Check whether x18 is preserved by runtime services calls

Whether or not we will ever decide to start using x18 as a platform
register in Linux is uncertain, but by that time, we will need

efi/arm64: Check whether x18 is preserved by runtime services calls

Whether or not we will ever decide to start using x18 as a platform
register in Linux is uncertain, but by that time, we will need to
ensure that UEFI runtime services calls don't corrupt it.

So let's start issuing warnings now for this, and increase the
likelihood that these firmware images have all been replaced by that time.

This has been fixed on the EDK2 side in commit:

6d73863b5464 ("BaseTools/tools_def AARCH64: mark register x18 as reserved")

dated July 13, 2017.

Signed-off-by: Ard Biesheuvel <[email protected]>
Acked-by: Will Deacon <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Matt Fleming <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

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