Arnaldo Carvalho de Melo 5834da7f10 perf trace: Add BPF handler for unaugmented syscalls ... Will be used to assign to syscalls that don't need augmentation, i.e. those with just integer args. All syscalls will be in a BPF_MAP_TYPE_PROG_ARRAY, and the bpf_tail_call() keyed by the syscall id will either find nothing in place, which means the syscall is being filtered, or a function that will either add things like filenames to the ring buffer, right after the raw syscall args, or be this unaugmented handler that will just return 1, meaning don't filter the original raw_syscalls:sys_{enter,exit} tracepoint. For now it is not really being used, this is just leg work to break the patch into smaller pieces. It introduces a trace__find_bpf_program_by_title() helper that in turn uses libbpf's bpf_object__find_program_by_title() on the BPF object with the __augmented_syscalls__ map. "title" is how libbpf calls the SEC() argument for functions, i.e. the ELF section that follows a convention to specify what BPF program (a function with this SEC() marking) should be connected to which tracepoint, kprobes, etc. In perf anything that is of the form SEC("sys:event_name") will be connected to that tracepoint by perf's BPF loader. In this case its something that will be bpf_tail_call()ed from either the "raw_syscalls:sys_enter" or "raw_syscall:sys_exit" tracepoints, so its named "!raw_syscalls:unaugmented" to convey that idea, i.e. its not going to be directly attached to a tracepoint, thus it starts with a "!". Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Link: https://lkml.kernel.org/n/tip-meucpjx2u0slpkayx56lxqq6@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>		2019-07-29 18:34:41 -03:00
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bpf	perf trace: Add BPF handler for unaugmented syscalls	2019-07-29 18:34:41 -03:00