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augmented_raw_syscalls.c defines the bpf map 'syscalls' which is initialized by perf tool in user space to indicate which system calls are enabled for tracing, on the other flip eBPF program relies on the map to filter out the trace events which are not enabled. The map also includes a field 'string_args_len[6]' which presents the string length if the corresponding argument is a string type. Now the map 'syscalls' is not used, bpf program doesn't use it as filter anymore, this is replaced by using the function bpf_tail_call() and PROG_ARRAY syscalls map. And we don't need to explicitly set the string length anymore, bpf_probe_read_str() is smart to copy the string and return string length. Therefore, it's safe to remove the bpf map 'syscalls'. To consolidate the code, this patch removes the definition of map 'syscalls' from augmented_raw_syscalls.c and drops code for using the map in the perf trace. Note, since function trace__set_ev_qualifier_bpf_filter() is removed, calling trace__init_syscall_bpf_progs() from it is also removed. We don't need to worry it because trace__init_syscall_bpf_progs() is still invoked from trace__init_syscalls_bpf_prog_array_maps() for initialization the system call's bpf program callback. After: # perf trace -e examples/bpf/augmented_raw_syscalls.c,open* --max-events 10 perf stat --quiet sleep 0.001 openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libm.so.6", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libelf.so.1", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libdw.so.1", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libunwind.so.8", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libunwind-aarch64.so.8", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libcrypto.so.3", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libslang.so.2", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libperl.so.5.34", O_RDONLY|O_CLOEXEC) = 3 openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3 # perf trace -e examples/bpf/augmented_raw_syscalls.c --max-events 10 perf stat --quiet sleep 0.001 ... [continued]: execve()) = 0 brk(NULL) = 0xaaaab1d28000 faccessat(-100, "/etc/ld.so.preload", 4) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3 close(3</usr/lib/aarch64-linux-gnu/libcrypto.so.3>) = 0 openat(AT_FDCWD, "/lib/aarch64-linux-gnu/libm.so.6", O_RDONLY|O_CLOEXEC) = 3 read(3</usr/lib/aarch64-linux-gnu/libcrypto.so.3>, 0xfffff33f70d0, 832) = 832 munmap(0xffffb5519000, 28672) = 0 munmap(0xffffb55b7000, 32880) = 0 mprotect(0xffffb55a6000, 61440, PROT_NONE) = 0 Signed-off-by: Leo Yan <leo.yan@linaro.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Acked-by: Ian Rogers <irogers@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221121075237.127706-6-leo.yan@linaro.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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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 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.