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Improve __kernel_text_address()/kernel_text_address() to return true if the given address is on a kprobe's instruction slot trampoline. This can help stacktraces to determine the address is on a text area or not. To implement this atomically in is_kprobe_*_slot(), also change the insn_cache page list to an RCU list. This changes timings a bit (it delays page freeing to the RCU garbage collection phase), but none of that is in the hot path. Note: this change can add small overhead to stack unwinders because it adds 2 additional checks to __kernel_text_address(). However, the impact should be very small, because kprobe_insn_pages list has 1 entry per 256 probes(on x86, on arm/arm64 it will be 1024 probes), and kprobe_optinsn_pages has 1 entry per 32 probes(on x86). In most use cases, the number of kprobe events may be less than 20, which means that is_kprobe_*_slot() will check just one entry. Tested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/148388747896.6869.6354262871751682264.stgit@devbox [ Improved the changelog and coding style. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.