4c4dcd3541
The AArch64 asm syntax has this slightly tedious property that the names used in mnemonics to refer to registers depend on whether the opcode in question targets the entire 64-bits (xN), or only the least significant 8, 16 or 32 bits (wN). When writing parameterized code such as macros, this can be annoying, as macro arguments don't lend themselves to indexed lookups, and so generating a reference to wN in a macro that receives xN as an argument is problematic. For instance, an upcoming patch that modifies the implementation of the cond_yield macro to be able to refer to 32-bit registers would need to modify invocations such as cond_yield 3f, x8 to cond_yield 3f, 8 so that the second argument can be token pasted after x or w to emit the correct register reference. Unfortunately, this interferes with the self documenting nature of the first example, where the second argument is obviously a register, whereas in the second example, one would need to go and look at the code to find out what '8' means. So let's fix this by defining wxN aliases for all xN registers, which resolve to the 32-bit alias of each respective 64-bit register. This allows the macro implementation to paste the xN reference after a w to obtain the correct register name. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20210302090118.30666-3-ardb@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> |
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| arch | ||
| block | ||
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| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
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| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| .gitignore | ||
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| Kbuild | ||
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| Makefile | ||
| README | ||
README
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.
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.