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

From: Ian Rogers
Date: Wed Jul 12 2023 - 18:37:55 EST

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On Mon, Jun 5, 2023 at 6:46 PM Leo Yan <leo.yan@xxxxxxxxxx> 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@xxxxxxxxxx/
>
> 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@xxxxxxxxxx>

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.

Thanks!
Ian

> tools/perf/arch/arm/include/perf_regs.h | 3 -
> tools/perf/arch/arm/util/perf_regs.c | 11 +
> tools/perf/arch/arm/util/unwind-libdw.c | 1 +
> tools/perf/arch/arm64/include/perf_regs.h | 3 -
> tools/perf/arch/arm64/util/machine.c | 1 +
> tools/perf/arch/arm64/util/perf_regs.c | 6 +
> tools/perf/arch/arm64/util/unwind-libdw.c | 1 +
> tools/perf/arch/csky/include/perf_regs.h | 3 -
> tools/perf/arch/csky/util/perf_regs.c | 11 +
> tools/perf/arch/csky/util/unwind-libdw.c | 1 +
> tools/perf/arch/loongarch/include/perf_regs.h | 2 -
> tools/perf/arch/loongarch/util/perf_regs.c | 11 +
> tools/perf/arch/loongarch/util/unwind-libdw.c | 1 +
> tools/perf/arch/mips/include/perf_regs.h | 2 -
> tools/perf/arch/mips/util/perf_regs.c | 11 +
> tools/perf/arch/powerpc/include/perf_regs.h | 3 -
> tools/perf/arch/powerpc/util/perf_regs.c | 6 +
> tools/perf/arch/powerpc/util/unwind-libdw.c | 1 +
> tools/perf/arch/riscv/include/perf_regs.h | 3 -
> tools/perf/arch/riscv/util/perf_regs.c | 11 +
> tools/perf/arch/riscv/util/unwind-libdw.c | 1 +
> tools/perf/arch/s390/include/perf_regs.h | 3 -
> tools/perf/arch/s390/util/perf_regs.c | 11 +
> tools/perf/arch/s390/util/unwind-libdw.c | 1 +
> tools/perf/arch/x86/include/perf_regs.h | 2 -
> tools/perf/arch/x86/util/perf_regs.c | 6 +
> tools/perf/arch/x86/util/unwind-libdw.c | 1 +
> tools/perf/util/Build | 1 +
> tools/perf/util/evsel.c | 6 +-
> tools/perf/util/libunwind/arm64.c | 2 -
> tools/perf/util/libunwind/x86_32.c | 2 -
> tools/perf/util/perf-regs-arch/Build | 9 +
> .../util/perf-regs-arch/perf_regs_aarch64.c | 96 +++
> .../perf/util/perf-regs-arch/perf_regs_arm.c | 60 ++
> .../perf/util/perf-regs-arch/perf_regs_csky.c | 100 +++
> .../util/perf-regs-arch/perf_regs_loongarch.c | 91 +++
> .../perf/util/perf-regs-arch/perf_regs_mips.c | 87 ++
> .../util/perf-regs-arch/perf_regs_powerpc.c | 145 ++++
> .../util/perf-regs-arch/perf_regs_riscv.c | 92 +++
> .../perf/util/perf-regs-arch/perf_regs_s390.c | 96 +++
> .../perf/util/perf-regs-arch/perf_regs_x86.c | 98 +++
> tools/perf/util/perf_regs.c | 772 ++----------------
> tools/perf/util/perf_regs.h | 49 +-
> tools/perf/util/unwind-libdw.c | 7 +-
> tools/perf/util/unwind-libunwind-local.c | 6 +-
> tools/perf/util/unwind.h | 8 -
> 46 files changed, 1078 insertions(+), 766 deletions(-)
> create mode 100644 tools/perf/util/perf-regs-arch/Build
> create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_aarch64.c
> create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_arm.c
> create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_csky.c
> create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_loongarch.c
> create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_mips.c
> create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_powerpc.c
> create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_riscv.c
> create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_s390.c
> create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_x86.c
>
> --
> 2.34.1
>

Next message: Kees Cook: "Re: [PATCH 29/32] lib/string_helpers: string_get_size() now returns characters wrote"
Previous message: Jeshua Smith: "[PATCH V2] ACPI: APEI: Use ERST timeout for slow devices"
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