[PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang

[Sedat Dilek]

On Fri, Mar 26, 2021 at 2:07 PM Nathan Chancellor <nathan at kernel.org> wrote:
>
> On Fri, Mar 26, 2021 at 09:37:55AM +0100, Sedat Dilek wrote:
> > On Thu, Mar 25, 2021 at 11:38 PM Nathan Chancellor <nathan at kernel.org> wrote:
> > >
> > > Hi all,
> > >
> > > This series fixes function tracing with clang.
> > >
> > > Patch 1 adjusts the mcount regex in scripts/recordmcount.pl to handle
> > > the presence of PLT relocations, which happen with clang. Without this,
> > > the mcount_loc section will not be created properly.
> > >
> > > Patch 2 adds a workaround for clang less than 13.0.0 in relation to the
> > > mcount symbol name, which was "mcount" rather than "_mcount". This was
> > > written as a separate patch so that it can be reverted when the minimum
> > > clang version is bumped to clang 13.0.0.
> > >
> > > Patch 3 avoids a build error when -fpatchable-function-entry is not
> > > available, which is the case with clang less than 13.0.0. This will make
> > > dynamic ftrace unavailable but all of the other function tracing should
> > > work due to the prescence of the previous patch.
> > >
> > > I am hoping this series can go in as fixes for 5.12, due to patch 3, but
> > > if not, they can always be backported (patches 1 and 2 are already
> > > marked for stable).
> > >
> > > This series has been build tested with gcc-8 through gcc-10 and clang-11
> > > through clang-13 with defconfig and nommu_virt_defconfig plus
> > > CONFIG_FTRACE=y and CONFIG_FUNCTION_TRACER=y then boot tested under
> > > QEMU.
> > >
> > > Cheers,
> > > Nathan
> > >
> > > Nathan Chancellor (3):
> > >   scripts/recordmcount.pl: Fix RISC-V regex for clang
> > >   riscv: Workaround mcount name prior to clang-13
> > >   riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is
> > >     available
> > >
> >
> > Does this only fixes stuff for clang + riscv?
>
> Yes.
>
> > If so, please put a label "riscv" also in the cover-letter.
>
> Sure, my apologies for not doing that in the first place, I must have
> been in a rush with the cover letter.
>
> In my defense, I think the titles of my commit messages and the diffstat
> below make that obvious without the tag :)
>

No need for any apologies.
I was fooled as you sent two triple-patchset nearly simultaneously.
This riscv patchset here was not of interest to me.

- Sedat -

>
> > - Sedat -
> >
> > >  arch/riscv/Kconfig              |  2 +-
> > >  arch/riscv/include/asm/ftrace.h | 14 ++++++++++++--
> > >  arch/riscv/kernel/mcount.S      | 10 +++++-----
> > >  scripts/recordmcount.pl         |  2 +-
> > >  4 files changed, 19 insertions(+), 9 deletions(-)
> > >
> > > --
> > > 2.31.0
> > >