linux/tools/perf/include/bpf/stdio.h

// SPDX-License-Identifier: GPL-2.0

#include <bpf.h>

struct bpf_map SEC("maps") __bpf_stdout__ = {
       .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
       .key_size = sizeof(int),
       .value_size = sizeof(u32),
       .max_entries = __NR_CPUS__,
};

#define puts(from) \
	({ const int __len = sizeof(from); \
	   char __from[__len] = from; \
	   perf_event_output(args, &__bpf_stdout__, BPF_F_CURRENT_CPU, \
			  &__from, __len & (sizeof(from) - 1)); })
perf bpf: Add bpf/stdio.h wrapper to bpf_perf_event_output function That, together with the map __bpf_output__ that is already handled by 'perf trace' to print that event's contents as strings provides a debugging facility, to show it in use, print a simple string everytime the syscalls:sys_enter_openat() syscall tracepoint is hit: # cat tools/perf/examples/bpf/hello.c #include <stdio.h> int syscall_enter(openat)(void *args) { puts("Hello, world\n"); return 0; } license(GPL); # # perf trace -e openat,tools/perf/examples/bpf/hello.c cat /etc/passwd > /dev/null 0.016 ( ): __bpf_stdout__:Hello, world 0.018 ( 0.010 ms): cat/9079 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3 0.057 ( ): __bpf_stdout__:Hello, world 0.059 ( 0.011 ms): cat/9079 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC) = 3 0.417 ( ): __bpf_stdout__:Hello, world 0.419 ( 0.009 ms): cat/9079 openat(dfd: CWD, filename: /etc/passwd) = 3 # This is part of an ongoing experimentation on making eBPF scripts as consumed by perf to be as concise as possible and using familiar concepts such as stdio.h functions, that end up just wrapping the existing BPF functions, trying to hide as much boilerplate as possible while using just conventions and C preprocessor tricks. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Link: https://lkml.kernel.org/n/tip-4tiaqlx5crf0fwpe7a6j84x7@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> 2018-08-06 12:15:18 +00:00			`// SPDX-License-Identifier: GPL-2.0`

perf bpf: Remove bpf/ subdir from bpf.h headers used to build bpf events The bpf.h file needed gets installed in /usr/lib/include/perf/bpf/bpf.h, and /usr/lib/include/perf/ is added to the include path passed to clang to build the eBPF bytecode, so just remove "bpf/", its directly in the path passed already. This was working by accident, fix it. I.e. now this is back working: # cat /home/acme/git/perf/tools/perf/examples/bpf/hello.c #include <stdio.h> int syscall_enter(openat)(void *args) { puts("Hello, world\n"); return 0; } license(GPL); # perf trace -e /home/acme/git/perf/tools/perf/examples/bpf/hello.c 0.000 pickup/21493 __bpf_stdout__(Hello, world) 56.462 sh/13539 __bpf_stdout__(Hello, world) 56.536 sh/13539 __bpf_stdout__(Hello, world) 56.673 sh/13539 __bpf_stdout__(Hello, world) 56.781 sh/13539 __bpf_stdout__(Hello, world) 56.707 perf/13182 __bpf_stdout__(Hello, world) 56.849 perf/13182 __bpf_stdout__(Hello, world) ^C # Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Link: https://lkml.kernel.org/n/tip-d9myswhgo8gfi3vmehdqpxa7@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> 2020-02-14 19:21:40 +00:00			`#include <bpf.h>`
perf bpf: Add bpf/stdio.h wrapper to bpf_perf_event_output function That, together with the map __bpf_output__ that is already handled by 'perf trace' to print that event's contents as strings provides a debugging facility, to show it in use, print a simple string everytime the syscalls:sys_enter_openat() syscall tracepoint is hit: # cat tools/perf/examples/bpf/hello.c #include <stdio.h> int syscall_enter(openat)(void *args) { puts("Hello, world\n"); return 0; } license(GPL); # # perf trace -e openat,tools/perf/examples/bpf/hello.c cat /etc/passwd > /dev/null 0.016 ( ): __bpf_stdout__:Hello, world 0.018 ( 0.010 ms): cat/9079 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3 0.057 ( ): __bpf_stdout__:Hello, world 0.059 ( 0.011 ms): cat/9079 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC) = 3 0.417 ( ): __bpf_stdout__:Hello, world 0.419 ( 0.009 ms): cat/9079 openat(dfd: CWD, filename: /etc/passwd) = 3 # This is part of an ongoing experimentation on making eBPF scripts as consumed by perf to be as concise as possible and using familiar concepts such as stdio.h functions, that end up just wrapping the existing BPF functions, trying to hide as much boilerplate as possible while using just conventions and C preprocessor tricks. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Link: https://lkml.kernel.org/n/tip-4tiaqlx5crf0fwpe7a6j84x7@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> 2018-08-06 12:15:18 +00:00
			`struct bpf_map SEC("maps") __bpf_stdout__ = {`
			`.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,`
			`.key_size = sizeof(int),`
			`.value_size = sizeof(u32),`
			`.max_entries = __NR_CPUS__,`
			`};`

			`#define puts(from) \`
			`({ const int __len = sizeof(from); \`
			`char __from[__len] = from; \`
			`perf_event_output(args, &__bpf_stdout__, BPF_F_CURRENT_CPU, \`
			`&__from, __len & (sizeof(from) - 1)); })`