linux-imx

perf thread-stack: Fix thread stack return from kernel for kernel-only case

Commit f08046cb3082 ("perf thread-stack: Represent jmps to the start of a
different symbol") had the side-effect of introducing more stack entries
before return from kernel space.

When user space is also traced, those entries are popped before entry to
user space, but when user space is not traced, they get stuck at the
bottom of the stack, making the stack grow progressively larger.

Fix by detecting a return-from-kernel branch type, and popping kernel
addresses from the stack then.

Note, the problem and fix affect the exported Call Graph / Tree but not
the callindent option used by "perf script --call-trace".

Example:

  perf-with-kcore record example -e intel_pt//k -- ls
  perf-with-kcore script example --itrace=bep -s ~/libexec/perf-core/scripts/python/export-to-sqlite.py example.db branches calls
  ~/libexec/perf-core/scripts/python/exported-sql-viewer.py example.db

  Menu option: Reports -> Context-Sensitive Call Graph

  Before: (showing Call Path column only)

    Call Path
    ▶ perf
    ▼ ls
      ▼ 12111:12111
        ▶ setup_new_exec
        ▶ __task_pid_nr_ns
        ▶ perf_event_pid_type
        ▶ perf_event_comm_output
        ▶ perf_iterate_ctx
        ▶ perf_iterate_sb
        ▶ perf_event_comm
        ▶ __set_task_comm
        ▶ load_elf_binary
        ▶ search_binary_handler
        ▶ __do_execve_file.isra.41
        ▶ __x64_sys_execve
        ▶ do_syscall_64
        ▼ entry_SYSCALL_64_after_hwframe
          ▼ swapgs_restore_regs_and_return_to_usermode
            ▼ native_iret
              ▶ error_entry
              ▶ do_page_fault
              ▼ error_exit
                ▼ retint_user
                  ▶ prepare_exit_to_usermode
                  ▼ native_iret
                    ▶ error_entry
                    ▶ do_page_fault
                    ▼ error_exit
                      ▼ retint_user
                        ▶ prepare_exit_to_usermode
                        ▼ native_iret
                          ▶ error_entry
                          ▶ do_page_fault
                          ▼ error_exit
                            ▼ retint_user
                              ▶ prepare_exit_to_usermode
                              ▶ native_iret

  After: (showing Call Path column only)

    Call Path
    ▶ perf
    ▼ ls
      ▼ 12111:12111
        ▶ setup_new_exec
        ▶ __task_pid_nr_ns
        ▶ perf_event_pid_type
        ▶ perf_event_comm_output
        ▶ perf_iterate_ctx
        ▶ perf_iterate_sb
        ▶ perf_event_comm
        ▶ __set_task_comm
        ▶ load_elf_binary
        ▶ search_binary_handler
        ▶ __do_execve_file.isra.41
        ▶ __x64_sys_execve
        ▶ do_syscall_64
        ▶ entry_SYSCALL_64_after_hwframe
        ▶ page_fault
        ▼ entry_SYSCALL_64
          ▼ do_syscall_64
            ▶ __x64_sys_brk
            ▶ __x64_sys_access
            ▶ __x64_sys_openat
            ▶ __x64_sys_newfstat
            ▶ __x64_sys_mmap
            ▶ __x64_sys_close
            ▶ __x64_sys_read
            ▶ __x64_sys_mprotect
            ▶ __x64_sys_arch_prctl
            ▶ __x64_sys_munmap
            ▶ exit_to_usermode_loop
            ▶ __x64_sys_set_tid_address
            ▶ __x64_sys_set_robust_list
            ▶ __x64_sys_rt_sigaction
            ▶ __x64_sys_rt_sigprocmask
            ▶ __x64_sys_prlimit64
            ▶ __x64_sys_statfs
            ▶ __x64_sys_ioctl
            ▶ __x64_sys_getdents64
            ▶ __x64_sys_write
            ▶ __x64_sys_exit_group

Committer notes:

The first arg to the perf-with-kcore needs to be the same for the
'record' and 'script' lines, otherwise we'll record the perf.data file
and kcore_dir/ files in one directory ('example') to then try to use it
from the 'bep' directory, fix the instructions above it so that both use
'example'.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org
Fixes: f08046cb3082 ("perf thread-stack: Represent jmps to the start of a different symbol")
Link: http://lkml.kernel.org/r/20190619064429.14940-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>