On 03. 05. 21, 8:11, Jiri Slaby wrote:
looks like vfs_truncate did not get into BTF data,
I'll try to reproduce
_None_ of the functions are generated by pahole -J from debuginfo on
ppc64. debuginfo appears to be correct. Neither pahole -J fs/open.o
works correctly. collect_functions in dwarves seems to be defunct on
ppc64... "functions" array is bogus (so find_function -- the bsearch
-- fails).
It's not that bogus. I forgot an asterisk:
#0 find_function (btfe=0x100269f80, name=0x10024631c "stream_open")
at /usr/src/debug/dwarves-1.21-1.1.ppc64/btf_encoder.c:350
(gdb) p (*functions)@84
$5 = {{name = 0x7ffff68e0922 ".__se_compat_sys_ftruncate", addr =
75232, size = 72, sh_addr = 65536, generated = false}, {
name = 0x7ffff68e019e ".__se_compat_sys_open", addr = 80592, size
= 216, sh_addr = 65536, generated = false}, {
name = 0x7ffff68e0076 ".__se_compat_sys_openat", addr = 80816,
size = 232, sh_addr = 65536, generated = false}, {
name = 0x7ffff68e0908 ".__se_compat_sys_truncate", addr = 74304,
size = 100, sh_addr = 65536, generated = false}, {
...
name = 0x7ffff68e0808 ".stream_open", addr = 65824, size = 72,
sh_addr = 65536, generated = false}, {
...
name = 0x7ffff68e0751 ".vfs_truncate", addr = 73392, size = 544,
sh_addr = 65536, generated = false}}
The dot makes the difference, of course. The question is why is it
there? I keep looking into it. Only if someone has an immediate idea...
Well, .vfs_truncate is in .text (and contains an ._mcount call). And
vfs_truncate is in .opd (w/o an ._mcount call). Since setup_functions
excludes all functions without the ._mcount call, is_ftrace_func later
returns false for such functions and they are filtered before the BTF
processing.
Technically, get_vmlinux_addrs looks at a list of functions between
__start_mcount_loc and __stop_mcount_loc and considers only the listed.
I don't know what the correct fix is (exclude .opd functions from the
filter?). Neither why cross compiler doesn't fail, nor why ebi v2 avoids
this too.
regards,
--
js
