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Linux kernel source tree
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Ard Biesheuvel says: ==================== On arm64, modules are allocated from a 128 MB window which is close to the core kernel, so that relative direct branches are guaranteed to be in range (except in some KASLR configurations). Also, module_alloc() is in charge of allocating KASAN shadow memory when running with KASAN enabled. This means that the way BPF reuses module_alloc()/module_memfree() is undesirable on arm64 (and potentially other architectures as well), and so this series refactors BPF's use of those functions to permit architectures to change this behavior. Patch #1 breaks out the module_alloc() and module_memfree() calls into __weak functions so they can be overridden. Patch #2 implements the new alloc/free overrides for arm64 Changes since v3: - drop 'const' modifier for free() hook void* argument - move the dedicated BPF region to before the module region, putting it within 4GB of the module and kernel regions on non-KASLR kernels Changes since v2: - properly build time and runtime tested this time (log after the diffstat) - create a dedicated 128 MB region at the top of the vmalloc space for BPF programs, ensuring that the programs will be in branching range of each other (which we currently rely upon) but at an arbitrary distance from the kernel and modules (which we don't care about) Changes since v1: - Drop misguided attempt to 'fix' and refactor the free path. Instead, just add another __weak wrapper for the invocation of module_memfree() ==================== Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Rick Edgecombe <rick.p.edgecombe@intel.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Jann Horn <jannh@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Jessica Yu <jeyu@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> |
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| 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.