Currently, we support mixed mode by casting all boot time firmware
calls to 64-bit explicitly on native 64-bit systems, and to 32-bit
on 32-bit systems or 64-bit systems running with 32-bit firmware.
Due to this explicit awareness of the bitness in the code, we do a
lot of casting even on generic code that is shared with other
architectures, where mixed mode does not even exist. This casting
leads to loss of coverage of type checking by the compiler, which
we should try to avoid.
So instead of distinguishing between 32-bit vs 64-bit, distinguish
between native vs mixed, and limit all the nasty casting and
pointer mangling to the code that actually deals with mixed mode.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Borislav Petkov <bp@alien8.de>
Cc: James Morse <james.morse@arm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20191224151025.32482-10-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull ACPI updates from Rafael Wysocki:
"These update the ACPICA code in the kernel to upstream revision
20191018, add support for EFI specific purpose memory, update the ACPI
EC driver to make it work on systems with hardware-reduced ACPI,
improve ACPI-based device enumeration for some platforms, rework the
lid blacklist handling in the button driver and add more lid quirks to
it, unify ACPI _HID/_UID matching, fix assorted issues and clean up
the code and documentation.
Specifics:
- Update the ACPICA code in the kernel to upstream revision 20191018
including:
* Fixes for Clang warnings (Bob Moore)
* Fix for possible overflow in get_tick_count() (Bob Moore)
* Introduction of acpi_unload_table() (Bob Moore)
* Debugger and utilities updates (Erik Schmauss)
* Fix for unloading tables loaded via configfs (Nikolaus Voss)
- Add support for EFI specific purpose memory to optionally allow
either application-exclusive or core-kernel-mm managed access to
differentiated memory (Dan Williams)
- Fix and clean up processing of the HMAT table (Brice Goglin, Qian
Cai, Tao Xu)
- Update the ACPI EC driver to make it work on systems with
hardware-reduced ACPI (Daniel Drake)
- Always build in support for the Generic Event Device (GED) to allow
one kernel binary to work both on systems with full hardware ACPI
and hardware-reduced ACPI (Arjan van de Ven)
- Fix the table unload mechanism to unregister platform devices
created when the given table was loaded (Andy Shevchenko)
- Rework the lid blacklist handling in the button driver and add more
lid quirks to it (Hans de Goede)
- Improve ACPI-based device enumeration for some platforms based on
Intel BayTrail SoCs (Hans de Goede)
- Add an OpRegion driver for the Cherry Trail Crystal Cove PMIC and
prevent handlers from being registered for unhandled PMIC OpRegions
(Hans de Goede)
- Unify ACPI _HID/_UID matching (Andy Shevchenko)
- Clean up documentation and comments (Cao jin, James Pack, Kacper
Piwiński)"
* tag 'acpi-5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (52 commits)
ACPI: OSI: Shoot duplicate word
ACPI: HMAT: use %u instead of %d to print u32 values
ACPI: NUMA: HMAT: fix a section mismatch
ACPI: HMAT: don't mix pxm and nid when setting memory target processor_pxm
ACPI: NUMA: HMAT: Register "soft reserved" memory as an "hmem" device
ACPI: NUMA: HMAT: Register HMAT at device_initcall level
device-dax: Add a driver for "hmem" devices
dax: Fix alloc_dax_region() compile warning
lib: Uplevel the pmem "region" ida to a global allocator
x86/efi: Add efi_fake_mem support for EFI_MEMORY_SP
arm/efi: EFI soft reservation to memblock
x86/efi: EFI soft reservation to E820 enumeration
efi: Common enable/disable infrastructure for EFI soft reservation
x86/efi: Push EFI_MEMMAP check into leaf routines
efi: Enumerate EFI_MEMORY_SP
ACPI: NUMA: Establish a new drivers/acpi/numa/ directory
ACPICA: Update version to 20191018
ACPICA: debugger: remove leading whitespaces when converting a string to a buffer
ACPICA: acpiexec: initialize all simple types and field units from user input
ACPICA: debugger: add field unit support for acpi_db_get_next_token
...
UEFI 2.8 defines an EFI_MEMORY_SP attribute bit to augment the
interpretation of the EFI Memory Types as "reserved for a specific
purpose".
The proposed Linux behavior for specific purpose memory is that it is
reserved for direct-access (device-dax) by default and not available for
any kernel usage, not even as an OOM fallback. Later, through udev
scripts or another init mechanism, these device-dax claimed ranges can
be reconfigured and hot-added to the available System-RAM with a unique
node identifier. This device-dax management scheme implements "soft" in
the "soft reserved" designation by allowing some or all of the
reservation to be recovered as typical memory. This policy can be
disabled at compile-time with CONFIG_EFI_SOFT_RESERVE=n, or runtime with
efi=nosoftreserve.
As for this patch, define the common helpers to determine if the
EFI_MEMORY_SP attribute should be honored. The determination needs to be
made early to prevent the kernel from being loaded into soft-reserved
memory, or otherwise allowing early allocations to land there. Follow-on
changes are needed per architecture to leverage these helpers in their
respective mem-init paths.
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In preparation for adding another EFI_MEMMAP dependent call that needs
to occur before e820__memblock_setup() fixup the existing efi calls to
check for EFI_MEMMAP internally. This ends up being cleaner than the
alternative of checking EFI_MEMMAP multiple times in setup_arch().
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
UEFI 2.8 defines an EFI_MEMORY_SP attribute bit to augment the
interpretation of the EFI Memory Types as "reserved for a specific
purpose". The intent of this bit is to allow the OS to identify precious
or scarce memory resources and optionally manage it separately from
EfiConventionalMemory. As defined older OSes that do not know about this
attribute are permitted to ignore it and the memory will be handled
according to the OS default policy for the given memory type.
In other words, this "specific purpose" hint is deliberately weaker than
EfiReservedMemoryType in that the system continues to operate if the OS
takes no action on the attribute. The risk of taking no action is
potentially unwanted / unmovable kernel allocations from the designated
resource that prevent the full realization of the "specific purpose".
For example, consider a system with a high-bandwidth memory pool. Older
kernels are permitted to boot and consume that memory as conventional
"System-RAM" newer kernels may arrange for that memory to be set aside
(soft reserved) by the system administrator for a dedicated
high-bandwidth memory aware application to consume.
Specifically, this mechanism allows for the elimination of scenarios
where platform firmware tries to game OS policy by lying about ACPI SLIT
values, i.e. claiming that a precious memory resource has a high
distance to trigger the OS to avoid it by default. This reservation hint
allows platform-firmware to instead tell the truth about performance
characteristics by indicate to OS memory management to put immovable
allocations elsewhere.
Implement simple detection of the bit for EFI memory table dumps and
save the kernel policy for a follow-on change.
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Invoke the EFI_RNG_PROTOCOL protocol in the context of the x86 EFI stub,
same as is done on arm/arm64 since commit 568bc4e870 ("efi/arm*/libstub:
Invoke EFI_RNG_PROTOCOL to seed the UEFI RNG table"). Within the stub,
a Linux-specific RNG seed UEFI config table will be seeded. The EFI routines
in the core kernel will pick that up later, yet still early during boot,
to seed the kernel entropy pool. If CONFIG_RANDOM_TRUST_BOOTLOADER, entropy
is credited for this seed.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Currently, kernel fails to boot on some HyperV VMs when using EFI.
And it's a potential issue on all x86 platforms.
It's caused by broken kernel relocation on EFI systems, when below three
conditions are met:
1. Kernel image is not loaded to the default address (LOAD_PHYSICAL_ADDR)
by the loader.
2. There isn't enough room to contain the kernel, starting from the
default load address (eg. something else occupied part the region).
3. In the memmap provided by EFI firmware, there is a memory region
starts below LOAD_PHYSICAL_ADDR, and suitable for containing the
kernel.
EFI stub will perform a kernel relocation when condition 1 is met. But
due to condition 2, EFI stub can't relocate kernel to the preferred
address, so it fallback to ask EFI firmware to alloc lowest usable memory
region, got the low region mentioned in condition 3, and relocated
kernel there.
It's incorrect to relocate the kernel below LOAD_PHYSICAL_ADDR. This
is the lowest acceptable kernel relocation address.
The first thing goes wrong is in arch/x86/boot/compressed/head_64.S.
Kernel decompression will force use LOAD_PHYSICAL_ADDR as the output
address if kernel is located below it. Then the relocation before
decompression, which move kernel to the end of the decompression buffer,
will overwrite other memory region, as there is no enough memory there.
To fix it, just don't let EFI stub relocate the kernel to any address
lower than lowest acceptable address.
[ ardb: introduce efi_low_alloc_above() to reduce the scope of the change ]
Signed-off-by: Kairui Song <kasong@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20191029173755.27149-6-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
System firmware advertises the address of the 'Runtime
Configuration Interface table version 2 (RCI2)' via
an EFI Configuration Table entry. This code retrieves the RCI2
table from the address and exports it to sysfs as a binary
attribute 'rci2' under /sys/firmware/efi/tables directory.
The approach adopted is similar to the attribute 'DMI' under
/sys/firmware/dmi/tables.
RCI2 table contains BIOS HII in XML format and is used to populate
BIOS setup page in Dell EMC OpenManage Server Administrator tool.
The BIOS setup page contains BIOS tokens which can be configured.
Signed-off-by: Narendra K <Narendra.K@dell.com>
Reviewed-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
The SAL systab is an Itanium specific EFI configuration table, so
move its handling into arch/ia64 where it belongs.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
The SGI UV UEFI machines are tightly coupled to the x86 architecture
so there is no need to keep any awareness of its existence in the
generic EFI layer, especially since we already have the infrastructure
to handle arch-specific configuration tables, and were even already
using it to some extent.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
The function efi_is_table_address() and the associated array of table
pointers is specific to x86. Since we will be adding some more x86
specific tables, let's move this code out of the generic code first.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
After the first call to GetEventLog() on UEFI systems using the TCG2
crypto agile log format, any further log events (other than those
triggered by ExitBootServices()) will be logged in both the main log and
also in the Final Events Log. While the kernel only calls GetEventLog()
immediately before ExitBootServices(), we can't control whether earlier
parts of the boot process have done so. This will result in log entries
that exist in both logs, and so the current approach of simply appending
the Final Event Log to the main log will result in events being
duplicated.
We can avoid this problem by looking at the size of the Final Event Log
just before we call ExitBootServices() and exporting this to the main
kernel. The kernel can then skip over all events that occured before
ExitBootServices() and only append events that were not also logged to
the main log.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reported-by: Joe Richey <joerichey@google.com>
Suggested-by: Joe Richey <joerichey@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
UEFI systems provide a boot services protocol for obtaining the TPM
event log, but this is unusable after ExitBootServices() is called.
Unfortunately ExitBootServices() itself triggers additional TPM events
that then can't be obtained using this protocol. The platform provides a
mechanism for the OS to obtain these events by recording them to a
separate UEFI configuration table which the OS can then map.
Unfortunately this table isn't self describing in terms of providing its
length, so we need to parse the events inside it to figure out how long
it is. Since the table isn't mapped at this point, we need to extend the
length calculation function to be able to map the event as it goes
along.
(Fixes by Bartosz Szczepanek <bsz@semihalf.com>)
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Bartosz Szczepanek <bsz@semihalf.com>
Tested-by: Bartosz Szczepanek <bsz@semihalf.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Pull arm64 updates from Catalin Marinas:
- Pseudo NMI support for arm64 using GICv3 interrupt priorities
- uaccess macros clean-up (unsafe user accessors also merged but
reverted, waiting for objtool support on arm64)
- ptrace regsets for Pointer Authentication (ARMv8.3) key management
- inX() ordering w.r.t. delay() on arm64 and riscv (acks in place by
the riscv maintainers)
- arm64/perf updates: PMU bindings converted to json-schema, unused
variable and misleading comment removed
- arm64/debug fixes to ensure checking of the triggering exception
level and to avoid the propagation of the UNKNOWN FAR value into the
si_code for debug signals
- Workaround for Fujitsu A64FX erratum 010001
- lib/raid6 ARM NEON optimisations
- NR_CPUS now defaults to 256 on arm64
- Minor clean-ups (documentation/comments, Kconfig warning, unused
asm-offsets, clang warnings)
- MAINTAINERS update for list information to the ARM64 ACPI entry
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (54 commits)
arm64: mmu: drop paging_init comments
arm64: debug: Ensure debug handlers check triggering exception level
arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals
Revert "arm64: uaccess: Implement unsafe accessors"
arm64: avoid clang warning about self-assignment
arm64: Kconfig.platforms: fix warning unmet direct dependencies
lib/raid6: arm: optimize away a mask operation in NEON recovery routine
lib/raid6: use vdupq_n_u8 to avoid endianness warnings
arm64: io: Hook up __io_par() for inX() ordering
riscv: io: Update __io_[p]ar() macros to take an argument
asm-generic/io: Pass result of I/O accessor to __io_[p]ar()
arm64: Add workaround for Fujitsu A64FX erratum 010001
arm64: Rename get_thread_info()
arm64: Remove documentation about TIF_USEDFPU
arm64: irqflags: Fix clang build warnings
arm64: Enable the support of pseudo-NMIs
arm64: Skip irqflags tracing for NMI in IRQs disabled context
arm64: Skip preemption when exiting an NMI
arm64: Handle serror in NMI context
irqchip/gic-v3: Allow interrupts to be set as pseudo-NMI
...
Pull EFI updates from Ingo Molnar:
"The main EFI changes in this cycle were:
- Use 32-bit alignment for efi_guid_t
- Allow the SetVirtualAddressMap() call to be omitted
- Implement earlycon=efifb based on existing earlyprintk code
- Various minor fixes and code cleanups from Sai, Ard and me"
* 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
efi: Fix build error due to enum collision between efi.h and ima.h
efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation
x86: Make ARCH_USE_MEMREMAP_PROT a generic Kconfig symbol
efi/arm/arm64: Allow SetVirtualAddressMap() to be omitted
efi: Replace GPL license boilerplate with SPDX headers
efi/fdt: Apply more cleanups
efi: Use 32-bit alignment for efi_guid_t
efi/memattr: Don't bail on zero VA if it equals the region's PA
x86/efi: Mark can_free_region() as an __init function
The following commit:
a893ea15d764 ("tpm: move tpm_chip definition to include/linux/tpm.h")
introduced a build error when both IMA and EFI are enabled:
In file included from ../security/integrity/ima/ima_fs.c:30:
../security/integrity/ima/ima.h:176:7: error: redeclaration of enumerator "NONE"
What happens is that both headers (ima.h and efi.h) defines the same
'NONE' constant, and it broke when they started getting included from
the same file:
Rework to prefix the EFI enum with 'EFI_*'.
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20190215165551.12220-2-ard.biesheuvel@linaro.org
[ Cleaned up the changelog a bit. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull integrity updates from James Morris:
"In Linux 4.19, a new LSM hook named security_kernel_load_data was
upstreamed, allowing LSMs and IMA to prevent the kexec_load syscall.
Different signature verification methods exist for verifying the
kexec'ed kernel image. This adds additional support in IMA to prevent
loading unsigned kernel images via the kexec_load syscall,
independently of the IMA policy rules, based on the runtime "secure
boot" flag. An initial IMA kselftest is included.
In addition, this pull request defines a new, separate keyring named
".platform" for storing the preboot/firmware keys needed for verifying
the kexec'ed kernel image's signature and includes the associated IMA
kexec usage of the ".platform" keyring.
(David Howell's and Josh Boyer's patches for reading the
preboot/firmware keys, which were previously posted for a different
use case scenario, are included here)"
* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
integrity: Remove references to module keyring
ima: Use inode_is_open_for_write
ima: Support platform keyring for kernel appraisal
efi: Allow the "db" UEFI variable to be suppressed
efi: Import certificates from UEFI Secure Boot
efi: Add an EFI signature blob parser
efi: Add EFI signature data types
integrity: Load certs to the platform keyring
integrity: Define a trusted platform keyring
selftests/ima: kexec_load syscall test
ima: don't measure/appraise files on efivarfs
x86/ima: retry detecting secure boot mode
docs: Extend trusted keys documentation for TPM 2.0
x86/ima: define arch_get_ima_policy() for x86
ima: add support for arch specific policies
ima: refactor ima_init_policy()
ima: prevent kexec_load syscall based on runtime secureboot flag
x86/ima: define arch_ima_get_secureboot
integrity: support new struct public_key_signature encoding field
From Mimi:
In Linux 4.19, a new LSM hook named security_kernel_load_data was
upstreamed, allowing LSMs and IMA to prevent the kexec_load
syscall. Different signature verification methods exist for verifying
the kexec'ed kernel image. This pull request adds additional support
in IMA to prevent loading unsigned kernel images via the kexec_load
syscall, independently of the IMA policy rules, based on the runtime
"secure boot" flag. An initial IMA kselftest is included.
In addition, this pull request defines a new, separate keyring named
".platform" for storing the preboot/firmware keys needed for verifying
the kexec'ed kernel image's signature and includes the associated IMA
kexec usage of the ".platform" keyring.
(David Howell's and Josh Boyer's patches for reading the
preboot/firmware keys, which were previously posted for a different
use case scenario, are included here.)
Add a function to parse an EFI signature blob looking for elements of
interest. A list is made up of a series of sublists, where all the
elements in a sublist are of the same type, but sublists can be of
different types.
For each sublist encountered, the function pointed to by the
get_handler_for_guid argument is called with the type specifier GUID and
returns either a pointer to a function to handle elements of that type or
NULL if the type is not of interest.
If the sublist is of interest, each element is passed to the handler
function in turn.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
The new memory EFI reservation feature we introduced to allow memory
reservations to persist across kexec may trigger an unbounded number
of calls to memblock_reserve(). The memblock subsystem can deal with
this fine, but not before memblock resizing is enabled, which we can
only do after paging_init(), when the memory we reallocate the array
into is actually mapped.
So break out the memreserve table processing into a separate routine
and call it after paging_init() on arm64. On ARM, because of limited
reviewing bandwidth of the maintainer, we cannot currently fix this,
so instead, disable the EFI persistent memreserve entirely on ARM so
we can fix it later.
Tested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20181114175544.12860-5-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Memory accesses performed by UEFI runtime services should be limited to:
- reading/executing from EFI_RUNTIME_SERVICES_CODE memory regions
- reading/writing from/to EFI_RUNTIME_SERVICES_DATA memory regions
- reading/writing by-ref arguments
- reading/writing from/to the stack.
Accesses outside these regions may cause the kernel to hang because the
memory region requested by the firmware isn't mapped in efi_pgd, which
causes a page fault in ring 0 and the kernel fails to handle it, leading
to die(). To save kernel from hanging, add an EFI specific page fault
handler which recovers from such faults by
1. If the efi runtime service is efi_reset_system(), reboot the machine
through BIOS.
2. If the efi runtime service is _not_ efi_reset_system(), then freeze
efi_rts_wq and schedule a new process.
The EFI page fault handler offers us two advantages:
1. Avoid potential hangs caused by buggy firmware.
2. Shout loud that the firmware is buggy and hence is not a kernel bug.
Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Suggested-by: Matt Fleming <matt@codeblueprint.co.uk>
Based-on-code-from: Ricardo Neri <ricardo.neri@intel.com>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
[ardb: clarify commit log]
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
After the kernel has booted, if any accesses by firmware causes a page
fault, the efi page fault handler would freeze efi_rts_wq and schedules
a new process. To do this, the efi page fault handler needs
efi_rts_work. Hence, make it accessible.
There will be no race conditions in accessing this structure, because
all the calls to efi runtime services are already serialized.
Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Suggested-by: Matt Fleming <matt@codeblueprint.co.uk>
Based-on-code-from: Ricardo Neri <ricardo.neri@intel.com>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Add kernel plumbing to reserve memory regions persistently on a EFI
system by adding entries to the MEMRESERVE linked list.
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
In order to allow the OS to reserve memory persistently across a
kexec, introduce a Linux-specific UEFI configuration table that
points to the head of a linked list in memory, allowing each kernel
to add list items describing memory regions that the next kernel
should treat as reserved.
This is useful, e.g., for GICv3 based ARM systems that cannot disable
DMA access to the LPI tables, forcing them to reuse the same memory
region again after a kexec reboot.
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Presently, when a user process requests the kernel to execute any
UEFI runtime service, the kernel temporarily switches to a separate
set of page tables that describe the virtual mapping of the UEFI
runtime services regions in memory. Since UEFI runtime services are
typically invoked with interrupts enabled, any code that may be called
during this time, will have an incorrect view of the process's address
space. Although it is unusual for code running in interrupt context to
make assumptions about the process context it runs in, there are cases
(such as the perf subsystem taking samples) where this causes problems.
So let's set up a work queue for calling UEFI runtime services, so that
the actual calls are made when the work queue items are dispatched by a
work queue worker running in a separate kernel thread. Such threads are
not expected to have userland mappings in the first place, and so the
additional mappings created for the UEFI runtime services can never
clash with any.
The ResetSystem() runtime service is not covered by the work queue
handling, since it is not expected to return, and may be called at a
time when the kernel is torn down to the point where we cannot expect
work queues to still be operational.
The non-blocking variants of SetVariable() and QueryVariableInfo()
are also excluded: these are intended to be used from atomic context,
which obviously rules out waiting for a completion to be signalled by
another thread. Note that these variants are currently only used for
UEFI runtime services calls that occur very early in the boot, and
for ones that occur in critical conditions, e.g., to flush kernel logs
to UEFI variables via efi-pstore.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
[ardb: exclude ResetSystem() from the workqueue treatment
merge from 2 separate patches and rewrite commit log]
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180711094040.12506-4-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
