b190bc4ac9
branch_entry.type now has ran out of space to accommodate more branch types classification. This will prevent perf branch stack implementation on arm64 (via BRBE) to capture all available branch types. Extending this bit field i.e branch_entry.type [4 bits] is not an option as it will break user space ABI both for little and big endian perf tools. Extend branch classification with a new field branch_entry.new_type via a new branch type PERF_BR_EXTEND_ABI in branch_entry.type. Perf tools which could decode PERF_BR_EXTEND_ABI, will then parse branch_entry.new_type as well. branch_entry.new_type is a 4 bit field which can hold upto 16 branch types. The first three branch types will hold various generic page faults followed by five architecture specific branch types, which can be overridden by the platform for specific use cases. These architecture specific branch types gets overridden on arm64 platform for BRBE implementation. New generic branch types - PERF_BR_NEW_FAULT_ALGN - PERF_BR_NEW_FAULT_DATA - PERF_BR_NEW_FAULT_INST New arch specific branch types - PERF_BR_NEW_ARCH_1 - PERF_BR_NEW_ARCH_2 - PERF_BR_NEW_ARCH_3 - PERF_BR_NEW_ARCH_4 - PERF_BR_NEW_ARCH_5 Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: James Clark <james.clark@arm.com> Link: https://lkml.kernel.org/r/20220824044822.70230-3-anshuman.khandual@arm.com
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.