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- Always try to initialize the idle functions when graph tracer starts A bug was found that when a CPU is offline when graph tracing starts and then comes online, that CPU is not traced. The fix to that was to move the initialization of the idle shadow stack over to the hot plug online logic, which also handle onlined CPUs. The issue was that it removed the initialization of the shadow stack when graph tracing starts, but the callbacks to the hot plug logic do nothing if graph tracing isn't currently running. Although that fix fixed the onlining of a CPU during tracing, it broke the CPUs that were already online. - Have microblaze not try to get the "true parent" in function tracing If function tracing and graph tracing are both enabled at the same time the parent of the functions traced by the function tracer may sometimes be the graph tracing trampoline. The graph tracing hijacks the return pointer of the function to trace it, but that can interfere with the function tracing parent output. This was fixed by using the ftrace_graph_ret_addr() function passing in the kernel stack pointer using the ftrace_regs_get_stack_pointer() function. But Al Viro reported that Microblaze does not implement the kernel_stack_pointer(regs) helper function that ftrace_regs_get_stack_pointer() uses and fails to compile when function graph tracing is enabled. It was first thought that this was a microblaze issue, but the real cause is that this only works when an architecture implements HAVE_DYNAMIC_FTRACE_WITH_ARGS, as a requirement for that config is to have ftrace always pass a valid ftrace_regs to the callbacks. That also means that the architecture supports ftrace_regs_get_stack_pointer() Microblaze does not set HAVE_DYNAMIC_FTRACE_WITH_ARGS nor does it implement ftrace_regs_get_stack_pointer() which caused it to fail to build. Only implement the "true parent" logic if an architecture has that config set. -----BEGIN PGP SIGNATURE----- iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCZ2GoLxQccm9zdGVkdEBn b29kbWlzLm9yZwAKCRAp5XQQmuv6qrooAQCY2e6mwLFIb3HttmC5KikrEE48YLOj QEz3UGb2zrxVTQD/ebYtXTiZSU/oS+CHdDsXhKSq7jKdLlRWjqUTx81PJQs= =mvcR -----END PGP SIGNATURE----- Merge tag 'ftrace-v6.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull ftrace fixes from Steven Rostedt: - Always try to initialize the idle functions when graph tracer starts A bug was found that when a CPU is offline when graph tracing starts and then comes online, that CPU is not traced. The fix to that was to move the initialization of the idle shadow stack over to the hot plug online logic, which also handle onlined CPUs. The issue was that it removed the initialization of the shadow stack when graph tracing starts, but the callbacks to the hot plug logic do nothing if graph tracing isn't currently running. Although that fix fixed the onlining of a CPU during tracing, it broke the CPUs that were already online. - Have microblaze not try to get the "true parent" in function tracing If function tracing and graph tracing are both enabled at the same time the parent of the functions traced by the function tracer may sometimes be the graph tracing trampoline. The graph tracing hijacks the return pointer of the function to trace it, but that can interfere with the function tracing parent output. This was fixed by using the ftrace_graph_ret_addr() function passing in the kernel stack pointer using the ftrace_regs_get_stack_pointer() function. But Al Viro reported that Microblaze does not implement the kernel_stack_pointer(regs) helper function that ftrace_regs_get_stack_pointer() uses and fails to compile when function graph tracing is enabled. It was first thought that this was a microblaze issue, but the real cause is that this only works when an architecture implements HAVE_DYNAMIC_FTRACE_WITH_ARGS, as a requirement for that config is to have ftrace always pass a valid ftrace_regs to the callbacks. That also means that the architecture supports ftrace_regs_get_stack_pointer() Microblaze does not set HAVE_DYNAMIC_FTRACE_WITH_ARGS nor does it implement ftrace_regs_get_stack_pointer() which caused it to fail to build. Only implement the "true parent" logic if an architecture has that config set" * tag 'ftrace-v6.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ftrace: Do not find "true_parent" if HAVE_DYNAMIC_FTRACE_WITH_ARGS is not set fgraph: Still initialize idle shadow stacks when starting |
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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 reStructuredText 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.