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Ard Biesheuvel
2e6eb40ca5
The following commit:
2c3625cb9f ("efi/x86: Fold __setup_efi_pci32() and __setup_efi_pci64() into one function")
... merged the two versions of __setup_efi_pciXX(), without taking into
account that the 32-bit version used a rather dodgy trick to pass an
immediate 0 constant as argument for a uint64_t parameter.
The issue is caused by the fact that on x86, UEFI protocol method calls
are redirected via struct efi_config::call(), which is a variadic function,
and so the compiler has to infer the types of the parameters from the
arguments rather than from the prototype.
As the 32-bit x86 calling convention passes arguments via the stack,
passing the unqualified constant 0 twice is the same as passing 0ULL,
which is why the 32-bit code in __setup_efi_pci32() contained the
following call:
status = efi_early->call(pci->attributes, pci,
EfiPciIoAttributeOperationGet, 0, 0,
&attributes);
to invoke this UEFI protocol method:
typedef
EFI_STATUS
(EFIAPI *EFI_PCI_IO_PROTOCOL_ATTRIBUTES) (
IN EFI_PCI_IO_PROTOCOL *This,
IN EFI_PCI_IO_PROTOCOL_ATTRIBUTE_OPERATION Operation,
IN UINT64 Attributes,
OUT UINT64 *Result OPTIONAL
);
After the merge, we inadvertently ended up with this version for both
32-bit and 64-bit builds, breaking the latter.
So replace the two zeroes with the explicitly typed constant 0ULL,
which works as expected on both 32-bit and 64-bit builds.
Wilfried tested the 64-bit build, and I checked the generated assembly
of a 32-bit build with and without this patch, and they are identical.
Reported-by: Wilfried Klaebe <linux-kernel@lebenslange-mailadresse.de>
Tested-by: Wilfried Klaebe <linux-kernel@lebenslange-mailadresse.de>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdegoede@redhat.com
Cc: linux-efi@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.