[PATCH v3 00/13] Cleanup recordmcount and begin objtool conversion

From: Matt Helsley
Date: Wed Jul 24 2019 - 17:06:19 EST

This series cleans up recordmcount and then makes it into
an objtool subcommand.

The series starts with 8 cleanup patches which make recordmcount
easier to review and integrate with objtool. The final 5 patches
show the beginning steps of converting recordmcount to use objtool's
ELF code rather than its own open-coded methods of accessing ELF


Rebased on mainline. s/elf_open/elf_read/ in recordmcount.c

Fix whitespace before line continuation

Add ftrace/mcount/record.h to objtool_dep

Rename the Makefile variable BUILD_C_RECORDMCOUNT to
better reflect its purpose

Similar: rename recordmcount_source => recordmcount_dep
When using objtool we can just depend on the
binary rather than the source the binary is
built from. This should address Josh's feedback and
make the Makefile code a bit clearer

Add a comment to make reading the Makefile a little

Rebased to latest mainline -rc

Collected some build time measurements

Build times measurements (measured for v2 posting) -- median of multiple
runs in a VM measured with "time":

mainline (5.2.0-rc4) build times (median of 3 runs):
real 2m58.379s
user 2m29.621s
sys 1m35.116s

Post recordmcount-cleanup build times (median of 5 runs):
real 2m51.973s
user 2m29.094s
sys 1m33.688s

objtool mcount build times (median of 7 runs):
real 2m57.92s
user 2m33.73s
sys 1m37.06s

Note: I saw some significant variation especially in the "real" time
measurements probably because it was in a VM on a machine with
various "idle" GUI tasks running. This is why I took the median
rather than the mean. Though I haven't run the statistics, my
sense is the numbers don't support concluding that things really
got any faster or slower.

Matt Helsley (13):
recordmcount: Remove redundant strcmp
recordmcount: Remove uread()
recordmcount: Remove unused fd from uwrite() and ulseek()
recordmcount: Rewrite error/success handling
recordmcount: Kernel style function signature formatting
recordmcount: Kernel style formatting
recordmcount: Remove redundant cleanup() calls
recordmcount: Clarify what cleanup() does
objtool: Prepare to merge recordmcount
objtool: Make recordmcount into an objtool subcmd
objtool: recordmcount: Start using objtool's elf wrapper
objtool: recordmcount: Search for __mcount_loc before walking the
objtool: recordmcount: Convert do_func() relhdrs

Makefile | 6 +-
scripts/.gitignore | 1 -
scripts/Makefile | 1 -
scripts/Makefile.build | 25 +-
tools/objtool/.gitignore | 1 +
tools/objtool/Build | 1 +
tools/objtool/Makefile | 1 +
tools/objtool/builtin-mcount.c | 72 +++++
tools/objtool/builtin-mcount.h | 23 ++
tools/objtool/builtin.h | 1 +
tools/objtool/objtool.c | 1 +
{scripts => tools/objtool}/recordmcount.c | 350 ++++++++++-----------
{scripts => tools/objtool}/recordmcount.h | 197 +++++++-----
{scripts => tools/objtool}/recordmcount.pl | 0
14 files changed, 406 insertions(+), 274 deletions(-)
create mode 100644 tools/objtool/builtin-mcount.c
create mode 100644 tools/objtool/builtin-mcount.h
rename {scripts => tools/objtool}/recordmcount.c (78%)
rename {scripts => tools/objtool}/recordmcount.h (78%)
rename {scripts => tools/objtool}/recordmcount.pl (100%)