Re: [PATCH v2 0/6] perf parse-regs: Refactor architecture functions

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Aug 15, 2023 at 03:24:04PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Wed, Jul 12, 2023 at 03:37:36PM -0700, Ian Rogers escreveu:
> > On Mon, Jun 5, 2023 at 6:46 PM Leo Yan <leo.yan@linaro.org> wrote:
> > >
> > > This patch series is to refactor arch related functions for register
> > > parsing, which follows up the discussion for v1:
> > > https://lore.kernel.org/lkml/20230520025537.1811986-1-leo.yan@linaro.org/
> > >
> > > Compared to patch series v1, this patch series introduces new functions
> > > perf_arch_reg_{ip|sp}(), so this can allow the tool to support cross
> > > analysis.
> > >
> > > To verify the cross analysis, I used below steps:
> > >
> > > - Firstly, I captured perf data on Arm64 machine:
> > >
> > >   $ perf record --call-graph fp -- ./test_program
> > >
> > >   Or ...
> > >
> > >   $ perf record --call-graph dwarf -- ./test_program
> > >
> > >   Then, I also archived associated debug data:
> > >
> > >   $ perf archive
> > >
> > > - Secondly, I copied the perf data file and debug tar file on my x86
> > >   machine:
> > >
> > >   $ scp perf.data perf.data.tar.bz2 leoy@IP_ADDRESS:/target/path/
> > >
> > > - On x86 machine, I need to build perf for support multi-arch unwinding:
> > >
> > >   $ git clone http://git.savannah.gnu.org/r/libunwind.git
> > >   $ cd libunwind
> > >   $ autoreconf -i
> > >
> > >   # Build and install libunwind aarch64:
> > >   $ ./configure prefix=/home/leoy/Work/tools/libunwind/install/ \
> > >         --target=aarch64-linux-gnu CC=x86_64-linux-gnu-gcc
> > >   $ make && make install
> > >
> > >   # Build and install libunwind x86:
> > >   $ ./configure prefix=/home/leoy/Work/tools/libunwind/install/ \
> > >         --target=x86_64-linux-gnu CC=x86_64-linux-gnu-gcc
> > >   $ make && make install
> > >
> > > - Build perf tool for support multi-archs:
> > >
> > >   $ cd $LINUX/tools/perf
> > >   $ make VF=1 DEBUG=1 LIBUNWIND_DIR=/home/leoy/Work/tools/libunwind/install
> > >
> > > At the end, I verified the x86 perf tool can do cross analysis for aarch64's
> > > perf data file.
> > >
> > > Note, I still see x86 perf tool cannot display the complete callgraph
> > > for aarch64, but it should not the issue caused by this series, which
> > > will be addressed by separate patches.
> > >
> > > I also built this patch series on my Arm64 and x86 machines, both can
> > > compile perf tool successfully; but I have no chance to build other
> > > archs natively.
> > >
> > > Changes from v1:
> > > - For support cross analysis for IP/SP registers, introduced patch 0002
> > >   (James Clark, Ian Rogers).
> > >
> > >
> > > Leo Yan (6):
> > >   perf parse-regs: Refactor arch register parsing functions
> > >   perf parse-regs: Introduce functions perf_arch_reg_{ip|sp}()
> > >   perf unwind: Use perf_arch_reg_{ip|sp}() to substitute macros
> > >   perf parse-regs: Remove unused macros PERF_REG_{IP|SP}
> > >   perf parse-regs: Remove PERF_REGS_{MAX|MASK} from common code
> > >   perf parse-regs: Move out arch specific header from util/perf_regs.h
> > 
> > Sorry for the slow review. For the series:
> > Acked-by: Ian Rogers <irogers@google.com>
> > 
> > Some thoughts:
> > uint64_t __perf_reg_ip_arm(void)
> > uint64_t seems like we're giving a lot of space for future register
> > encodings. I think some of the other functions use this size of value
> > due to returning a bitmap/mask, but here it isn't clear and just feels
> > excessive.
> > 
> > Do we need the "__" prefix on all the functions?
> > 
> > In Makefile.config there are NO_PERF_REGS and CONFIG_PERF_REGS then
> > the define HAVE_PERF_REGS_SUPPORT. Is this still relevant? If we had
> > an architecture with no support, couldn't it still read a perf.data
> > file from a supported architecture? It would be nice to remove at
> > least NO_PERF_REGS and HAVE_PERF_REGS_SUPPORT.
> > 
> > This change is very worthwhile fix and cleanup, it didn't introduce
> > what is pondered above, hence the acked-by.
> 
> Agreed, applied to perf-tools-next, sorry for the delay.

Had to add this to make 'perf test python' to work. Please run 'perf
test' before sending patches.

- Arnaldo

diff --git a/tools/perf/util/python-ext-sources b/tools/perf/util/python-ext-sources
index d4c9b4cd35efa556..26e1c8d973ea0b95 100644
--- a/tools/perf/util/python-ext-sources
+++ b/tools/perf/util/python-ext-sources
@@ -40,3 +40,12 @@ util/rwsem.c
 util/hashmap.c
 util/perf_regs.c
 util/fncache.c
+util/perf-regs-arch/perf_regs_aarch64.c
+util/perf-regs-arch/perf_regs_arm.c
+util/perf-regs-arch/perf_regs_csky.c
+util/perf-regs-arch/perf_regs_loongarch.c
+util/perf-regs-arch/perf_regs_mips.c
+util/perf-regs-arch/perf_regs_powerpc.c
+util/perf-regs-arch/perf_regs_riscv.c
+util/perf-regs-arch/perf_regs_s390.c
+util/perf-regs-arch/perf_regs_x86.c