linux.git/arch/arm64/kernel/efi.c, branch v5.10.258

arm64: efi: Make efi_rt_lock a raw_spinlock

2023-03-17T07:45:08+00:00

[ Upstream commit 0e68b5517d3767562889f1d83fdb828c26adb24f ]

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.

[ardb: The EFI runtime services are called with a different set of
       translation tables, and are permitted to use the SIMD registers.
       The context switch code preserves/restores neither, and so EFI
       calls must be made with preemption disabled, rather than only
       disabling migration.]

Fixes: ff7a167961d1 ("arm64: efi: Execute runtime services from a dedicated stack")
Signed-off-by: Pierre Gondois 
Cc:  # v6.1+
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Sasha Levin

arm64: efi: Execute runtime services from a dedicated stack

2023-01-24T06:20:01+00:00

commit ff7a167961d1b97e0e205f245f806e564d3505e7 upstream.

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 
Cc: Lee Jones 
Signed-off-by: Greg Kroah-Hartman

arm64: efi: Fix handling of misaligned runtime regions and drop warning

2022-11-16T08:57:14+00:00

commit 9b9eaee9828fe98b030cf43ac50065a54a2f5d52 upstream.

Currently, when mapping the EFI runtime regions in the EFI page tables,
we complain about misaligned regions in a rather noisy way, using
WARN().

Not only does this produce a lot of irrelevant clutter in the log, it is
factually incorrect, as misaligned runtime regions are actually allowed
by the EFI spec as long as they don't require conflicting memory types
within the same 64k page.

So let's drop the warning, and tweak the code so that we
- take both the start and end of the region into account when checking
  for misalignment
- only revert to RWX mappings for non-code regions if misaligned code
  regions are also known to exist.

Cc: 
Acked-by: Linus Torvalds 
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Greg Kroah-Hartman

treewide: Convert macro and uses of section(foo) to section("foo")

2020-10-25T21:51:49+00:00

Use a more generic form for __section that requires quotes to avoid
complications with clang and gcc differences.

Remove the quote operator # from compiler_attributes.h __section macro.

Convert all unquoted __section(foo) uses to quoted __section("foo").
Also convert __attribute__((section("foo"))) uses to __section("foo")
even if the __attribute__ has multiple list entry forms.

Conversion done using the script at:

    https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl

Signed-off-by: Joe Perches 
Reviewed-by: Nick Desaulniers 
Reviewed-by: Miguel Ojeda 
Signed-off-by: Linus Torvalds

mm/pgtable: drop pgtable_t variable from pte_fn_t functions

2019-07-12T18:05:46+00:00

Drop the pgtable_t variable from all implementation for pte_fn_t as none
of them use it.  apply_to_pte_range() should stop computing it as well.
Should help us save some cycles.

Link: http://lkml.kernel.org/r/1556803126-26596-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual 
Acked-by: Matthew Wilcox 
Cc: Ard Biesheuvel 
Cc: Russell King 
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Michal Hocko 
Cc: Logan Gunthorpe 
Cc: "Kirill A. Shutemov" 
Cc: Dan Williams 
Cc: 
Cc: Mike Rapoport 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

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

2019-06-19T15:09:55+00:00

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 
Reviewed-by: Enrico Weigelt 
Reviewed-by: Kate Stewart 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman

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

2018-03-09T07:58:22+00:00

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 
Acked-by: Will Deacon 
Cc: Linus Torvalds 
Cc: Matt Fleming 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180308080020.22828-6-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar

arm64: mm: Use READ_ONCE/WRITE_ONCE when accessing page tables

2018-02-16T18:13:57+00:00

In many cases, page tables can be accessed concurrently by either another
CPU (due to things like fast gup) or by the hardware page table walker
itself, which may set access/dirty bits. In such cases, it is important
to use READ_ONCE/WRITE_ONCE when accessing page table entries so that
entries cannot be torn, merged or subject to apparent loss of coherence
due to compiler transformations.

Whilst there are some scenarios where this cannot happen (e.g. pinned
kernel mappings for the linear region), the overhead of using READ_ONCE
/WRITE_ONCE everywhere is minimal and makes the code an awful lot easier
to reason about. This patch consistently uses these macros in the arch
code, as well as explicitly namespacing pointers to page table entries
from the entries themselves by using adopting a 'p' suffix for the former
(as is sometimes used elsewhere in the kernel source).

Tested-by: Yury Norov 
Tested-by: Richard Ruigrok 
Reviewed-by: Marc Zyngier 
Signed-off-by: Will Deacon 
Signed-off-by: Catalin Marinas

arm64/efi: Ignore EFI_MEMORY_XP attribute if RP and/or WP are set

2018-01-03T13:03:48+00:00

The UEFI memory map is a bit vague about how to interpret the
EFI_MEMORY_XP attribute when it is combined with EFI_MEMORY_RP and/or
EFI_MEMORY_WP, which have retroactively been redefined as cacheability
attributes rather than permission attributes.

So let's ignore EFI_MEMORY_XP if _RP and/or _WP are also set. In this
case, it is likely that they are being used to describe the capability
of the region (i.e., whether it has the controls to reconfigure it as
non-executable) rather than the nature of the contents of the region
(i.e., whether it contains data that we will never attempt to execute)

Reported-by: Stephen Boyd 
Tested-by: Stephen Boyd 
Signed-off-by: Ard Biesheuvel 
Cc: Arvind Yadav 
Cc: Linus Torvalds 
Cc: Matt Fleming 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Tyler Baicar 
Cc: Vasyl Gomonovych 
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180102181042.19074-3-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar

efi/arm: Enable DMI/SMBIOS

2017-06-05T15:50:44+00:00

Wire up the existing arm64 support for SMBIOS tables (aka DMI) for ARM as
well, by moving the arm64 init code to drivers/firmware/efi/arm-runtime.c
(which is shared between ARM and arm64), and adding a asm/dmi.h header to
ARM that defines the mapping routines for the firmware tables.

This allows userspace to access these tables to discover system information
exposed by the firmware. It also sets the hardware name used in crash
dumps, e.g.:

  Unable to handle kernel NULL pointer dereference at virtual address 00000000
  pgd = ed3c0000
  [00000000] *pgd=bf1f3835
  Internal error: Oops: 817 [#1] SMP THUMB2
  Modules linked in:
  CPU: 0 PID: 759 Comm: bash Not tainted 4.10.0-09601-g0e8f38792120-dirty #112
  Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
  ^^^

NOTE: This does *NOT* enable or encourage the use of DMI quirks, i.e., the
      the practice of identifying the platform via DMI to decide whether
      certain workarounds for buggy hardware and/or firmware need to be
      enabled. This would require the DMI subsystem to be enabled much
      earlier than we do on ARM, which is non-trivial.

Signed-off-by: Ard Biesheuvel 
Acked-by: Russell King 
Cc: Linus Torvalds 
Cc: Matt Fleming 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170602135207.21708-14-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar