perf bpf examples: With no BPF events remove examples

endif

	$(call QUIET_INSTALL, libexec) \

		$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(perfexec_instdir_SQ)'

ifndef NO_LIBBPF

	$(call QUIET_INSTALL, bpf-examples) \

		$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(perf_examples_instdir_SQ)/bpf'; \

		$(INSTALL) examples/bpf/*.c -m 644 -t '$(DESTDIR_SQ)$(perf_examples_instdir_SQ)/bpf'

endif

	$(call QUIET_INSTALL, perf-archive) \

		$(INSTALL) $(OUTPUT)perf-archive -t '$(DESTDIR_SQ)$(perfexec_instdir_SQ)'

	$(call QUIET_INSTALL, perf-iostat) \

// SPDX-License-Identifier: GPL-2.0

/*

    Description:

    . Disable strace like syscall tracing (--no-syscalls), or try tracing

      just some (-e *sleep).

    . Attach a filter function to a kernel function, returning when it should

      be considered, i.e. appear on the output.

    . Run it system wide, so that any sleep of >= 5 seconds and < than 6

      seconds gets caught.

    . Ask for callgraphs using DWARF info, so that userspace can be unwound

    . While this is running, run something like "sleep 5s".

    . If we decide to add tv_nsec as well, then it becomes:

      int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec)

      I.e. add where it comes from (rqtp->tv_nsec) and where it will be

      accessible in the function body (nsec)

    # perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/

         0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5

                                           hrtimer_nanosleep ([kernel.kallsyms])

                                           __x64_sys_nanosleep ([kernel.kallsyms])

                                           do_syscall_64 ([kernel.kallsyms])

                                           entry_SYSCALL_64 ([kernel.kallsyms])

                                           __GI___nanosleep (/usr/lib64/libc-2.26.so)

                                           rpl_nanosleep (/usr/bin/sleep)

                                           xnanosleep (/usr/bin/sleep)

                                           main (/usr/bin/sleep)

                                           __libc_start_main (/usr/lib64/libc-2.26.so)

                                           _start (/usr/bin/sleep)

    ^C#

   Copyright (C) 2018 Red Hat, Inc., Arnaldo Carvalho de Melo <acme@redhat.com>

*/

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#define NSEC_PER_SEC	1000000000L

SEC("hrtimer_nanosleep=hrtimer_nanosleep rqtp")

int hrtimer_nanosleep(void *ctx, int err, long long sec)

{

	return sec / NSEC_PER_SEC == 5ULL;

}

char _license[] SEC("license") = "GPL";

// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

struct syscall_enter_args;

SEC("raw_syscalls:sys_enter")

int sys_enter(struct syscall_enter_args *args)

{

	return 0;

}

char _license[] SEC("license") = "GPL";

// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

struct __bpf_stdout__ {

	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);

	__type(key, int);

	__type(value, __u32);

	__uint(max_entries, __NR_CPUS__);

} __bpf_stdout__ SEC(".maps");

#define puts(from) \

	({ const int __len = sizeof(from); \

	   char __from[sizeof(from)] = from;			\

	   bpf_perf_event_output(args, &__bpf_stdout__, BPF_F_CURRENT_CPU, \

			  &__from, __len & (sizeof(from) - 1)); })

struct syscall_enter_args;

SEC("raw_syscalls:sys_enter")

int sys_enter(struct syscall_enter_args *args)

{

	puts("Hello, world\n");

	return 0;

}

char _license[] SEC("license") = "GPL";

// SPDX-License-Identifier: GPL-2.0

/*

 * Hook into 'openat' syscall entry tracepoint

 *

 * Test it with:

 *

 * perf trace -e tools/perf/examples/bpf/sys_enter_openat.c cat /etc/passwd > /dev/null

 *

 * It'll catch some openat syscalls related to the dynamic linked and

 * the last one should be the one for '/etc/passwd'.

 *

 * The syscall_enter_openat_args can be used to get the syscall fields

 * and use them for filtering calls, i.e. use in expressions for

 * the return value.

 */

#include <bpf/bpf.h>

struct syscall_enter_openat_args {

	unsigned long long unused;

	long		   syscall_nr;

	long		   dfd;

	char		   *filename_ptr;

	long		   flags;

	long		   mode;

};

int syscall_enter(openat)(struct syscall_enter_openat_args *args)

{

	return 1;

}

license(GPL);