[PATCH 0/2] libtraceevent: Add BTF parsing for function arguments

From: "Steven Rostedt (Google)" <[email protected]>

Now that functions can save the first 6 registers of their args during a
trace, and BTF can be used to decipher those arguments, have libtraceevent
handle this as well.

Add a tep_load_btf() function that loads the content of /sys/kernel/btf/vmlinux
and then uses that to parse it to show the arguments of functions in the trace.

When trace-cmd supports this, it would look like:

 # trace-cmd record -p function -O func-args cat /etc/passwd
 # trace-cmd report
             cat-33501 [005] ..... 136155.767937: function:             mutex_unlock(lock=0xffffffff831dbbe0)
             cat-33501 [005] ..... 136155.767939: function:             __mutex_unlock_slowpath(lock=0xffffffff831dbbe0, ip=0xffffffff814a7154)
             cat-33501 [005] ..... 136155.767940: function:             __f_unlock_pos(f=0xffff8881538de000)
             cat-33501 [005] ..... 136155.767940: function:             mutex_unlock(lock=0xffff8881538de090)
             cat-33501 [005] ..... 136155.767940: function:             __mutex_unlock_slowpath(lock=0xffff8881538de090, ip=0xffffffff816e8ed1)
             cat-33501 [005] ..... 136155.767941: function:             mem_cgroup_handle_over_high(gfp_mask=0xcc0)
             cat-33501 [005] ..... 136155.767941: function:             blkcg_maybe_throttle_current()
             cat-33501 [005] ..... 136155.767942: function:             __rseq_handle_notify_resume(ksig=0x0, regs=0xffffc9000e3eff58)
             cat-33501 [005] d.... 136155.767943: function:             fpregs_assert_state_consistent()
             cat-33501 [005] d.... 136155.767943: function:             switch_fpu_return()
             cat-33501 [005] ..... 136155.767950: function:             __x64_sys_execve(regs=0xffffc9000e3eff58)
             cat-33501 [005] ..... 136155.767951: function:                getname_flags(filename=0x7ffe7d33f3d0, flags=0)
             cat-33501 [005] ..... 136155.767951: function:                getname_flags.part.0(7ffe7d33f3d0, 0, 0, 0, 0, 0)
             cat-33501 [005] ..... 136155.767951: function:                   kmem_cache_alloc_noprof(s=0xffff8881001d3800, gfpflags=0xcc0)
             cat-33501 [005] ..... 136155.767951: function:                      fs_reclaim_acquire(gfp_mask=0xcc0)
             cat-33501 [005] ..... 136155.767952: function:                      fs_reclaim_release(gfp_mask=0xcc0)
             cat-33501 [005] ..... 136155.767953: function:                      kmemleak_alloc(ptr=0xffff8881114a0000, size=0x1000, min_count=1, gfp=0xcc0)
             cat-33501 [005] ..... 136155.767953: function:                      __create_object(ptr=0xffff8881114a0000, size=0x1000, min_count=1, gfp=0xcc0, objflags=0x0)
             cat-33501 [005] ..... 136155.767954: function:                         __alloc_object(gfp=0xcc0)


Steven Rostedt (Google) (2):
  libtraceevent: Add loading of BTF to the tep handle
  libtraceevent: Add man page for the new BTF functions

 Documentation/libtraceevent-btf.txt | 158 ++++++++++
 Documentation/libtraceevent.txt     |   5 +
 include/traceevent/event-parse.h    |   5 +
 plugins/plugin_function.c           |  15 +-
 src/Makefile                        |   1 +
 src/event-parse-local.h             |   6 +
 src/event-parse.c                   |   2 +
 src/trace-btf.c                     | 449 ++++++++++++++++++++++++++++
 8 files changed, 631 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/libtraceevent-btf.txt
 create mode 100644 src/trace-btf.c

-- 
2.47.2