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Message-ID: <CAK7LNATzqVAJHFg6OyVR1+YgNKo7S=nN1M7w5GJVG1Ygn0QhUA@mail.gmail.com>
Date: Thu, 10 Oct 2024 00:46:54 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: Hari Bathini <hbathini@...ux.ibm.com>
Cc: linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>, bpf@...r.kernel.org,
linux-trace-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
linux-kernel@...r.kernel.org, "Naveen N. Rao" <naveen@...nel.org>,
Mark Rutland <mark.rutland@....com>, Daniel Borkmann <daniel@...earbox.net>,
Nicholas Piggin <npiggin@...il.com>, Alexei Starovoitov <ast@...nel.org>, Steven Rostedt <rostedt@...dmis.org>,
Andrii Nakryiko <andrii@...nel.org>, Christophe Leroy <christophe.leroy@...roup.eu>,
Vishal Chourasia <vishalc@...ux.ibm.com>, Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [PATCH v5 00/17] powerpc: Core ftrace rework, support for ftrace
direct and bpf trampolines
On Mon, Sep 16, 2024 at 5:57 AM Hari Bathini <hbathini@...ux.ibm.com> wrote:
>
> This is v5 of the series posted here:
> https://lore.kernel.org/all/cover.1720942106.git.naveen@kernel.org/
>
> This series reworks core ftrace support on powerpc to have the function
> profiling sequence moved out of line. This enables us to have a single
> nop at kernel function entry virtually eliminating effect of the
> function tracer when it is not enabled. The function profile sequence is
> moved out of line and is allocated at two separate places depending on a
> new config option.
>
> For 64-bit powerpc, the function profiling sequence is also updated to
> include an additional instruction 'mtlr r0' after the usual
> two-instruction sequence to fix link stack imbalance (return address
> predictor) when ftrace is enabled. This showed an improvement of ~10%
> in null_syscall benchmark (NR_LOOPS=10000000) on a Power 10 system
> with ftrace enabled.
>
> Finally, support for ftrace direct calls is added based on support for
> DYNAMIC_FTRACE_WITH_CALL_OPS. BPF Trampoline support is added atop this.
>
> Support for ftrace direct calls is added for 32-bit powerpc. There is
> some code to enable bpf trampolines for 32-bit powerpc, but it is not
> complete and will need to be pursued separately.
>
> Patches 1 to 10 are independent of this series and can go in separately
> though. Rest of the patches depend on the series from Benjamin Gray
> adding support for patch_uint() and patch_ulong():
> https://lore.kernel.org/all/172474280311.31690.1489687786264785049.b4-ty@ellerman.id.au/
It is getting better.
I attached a diff for improvements.
Also, please run 'shellcheck' and eliminate
as many warnings as you can.
$ shellcheck arch/powerpc/tools/ftrace-gen-ool-stubs.sh
In arch/powerpc/tools/ftrace-gen-ool-stubs.sh line 19:
num_ool_stubs_text=$(${OBJDUMP} -r -j __patchable_function_entries
${vmlinux_o} |
^----------^ SC2086 (info): Double quote to prevent globbing and word
splitting.
Did you mean:
num_ool_stubs_text=$(${OBJDUMP} -r -j __patchable_function_entries
"${vmlinux_o}" |
In arch/powerpc/tools/ftrace-gen-ool-stubs.sh line 20:
grep -v ".init.text" | grep "${RELOCATION}" | wc -l)
^------------------^
SC2126 (style): Consider using 'grep -c' instead of 'grep|wc -l'.
In arch/powerpc/tools/ftrace-gen-ool-stubs.sh line 21:
num_ool_stubs_inittext=$(${OBJDUMP} -r -j __patchable_function_entries
${vmlinux_o} |
^----------^ SC2086 (info): Double quote to prevent globbing and word
splitting.
Did you mean:
num_ool_stubs_inittext=$(${OBJDUMP} -r -j __patchable_function_entries
"${vmlinux_o}" |
In arch/powerpc/tools/ftrace-gen-ool-stubs.sh line 22:
grep ".init.text" | grep "${RELOCATION}" | wc -l)
^------------------^
SC2126 (style): Consider using 'grep -c' instead of 'grep|wc -l'.
In arch/powerpc/tools/ftrace-gen-ool-stubs.sh line 25:
if [ ${num_ool_stubs_text} -gt ${num_ool_stubs_text_builtin} ]; then
^-------------------^ SC2086 (info): Double quote to prevent
globbing and word splitting.
^---------------------------^ SC2086
(info): Double quote to prevent globbing and word splitting.
Did you mean:
if [ "${num_ool_stubs_text}" -gt "${num_ool_stubs_text_builtin}" ]; then
In arch/powerpc/tools/ftrace-gen-ool-stubs.sh line 26:
num_ool_stubs_text_end=$(expr ${num_ool_stubs_text} -
${num_ool_stubs_text_builtin})
^--^ SC2003 (style): expr is
antiquated. Consider rewriting this using $((..)), ${} or [[ ]].
^-------------------^ SC2086
(info): Double quote to prevent globbing and word splitting.
^---------------------------^ SC2086 (info): Double quote to prevent
globbing and word splitting.
Did you mean:
num_ool_stubs_text_end=$(expr "${num_ool_stubs_text}" -
"${num_ool_stubs_text_builtin}")
In arch/powerpc/tools/ftrace-gen-ool-stubs.sh line 31:
cat > ${arch_vmlinux_S} <<EOF
^---------------^ SC2086 (info): Double quote to prevent
globbing and word splitting.
Did you mean:
cat > "${arch_vmlinux_S}" <<EOF
For more information:
https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...
https://www.shellcheck.net/wiki/SC2003 -- expr is antiquated. Consider rewr...
https://www.shellcheck.net/wiki/SC2126 -- Consider using 'grep -c' instead ...
> Changelog v5:
> * Intermediate files named .vmlinux.arch.* instead of .arch.vmlinux.*
> * Fixed ftrace stack tracer failure due to inadvertent use of
> 'add r7, r3, MCOUNT_INSN_SIZE' instruction instead of
> 'addi r7, r3, MCOUNT_INSN_SIZE'
> * Fixed build error for !CONFIG_MODULES case.
> * .vmlinux.arch.* files compiled under arch/powerpc/tools
> * Made sure .vmlinux.arch.* files are cleaned with `make clean`
> * num_ool_stubs_text_end used for setting up ftrace_ool_stub_text_end
> set to zero instead of computing to some random negative value when
> not required.
> * Resolved checkpatch.pl warnings.
> * Dropped RFC tag.
>
> Changelog v4:
> - Patches 1, 10 and 13 are new.
> - Address review comments from Nick. Numerous changes throughout the
> patch series.
> - Extend support for ftrace ool to vmlinux text up to 64MB (patch 13).
> - Address remaining TODOs in support for BPF Trampolines.
> - Update synchronization when patching instructions during trampoline
> attach/detach.
>
>
> Naveen N Rao (17):
> powerpc/trace: Account for -fpatchable-function-entry support by
> toolchain
> powerpc/kprobes: Use ftrace to determine if a probe is at function
> entry
> powerpc64/ftrace: Nop out additional 'std' instruction emitted by gcc
> v5.x
> powerpc32/ftrace: Unify 32-bit and 64-bit ftrace entry code
> powerpc/module_64: Convert #ifdef to IS_ENABLED()
> powerpc/ftrace: Remove pointer to struct module from dyn_arch_ftrace
> powerpc/ftrace: Skip instruction patching if the instructions are the
> same
> powerpc/ftrace: Move ftrace stub used for init text before _einittext
> powerpc64/bpf: Fold bpf_jit_emit_func_call_hlp() into
> bpf_jit_emit_func_call_rel()
> powerpc/ftrace: Add a postlink script to validate function tracer
> kbuild: Add generic hook for architectures to use before the final
> vmlinux link
> powerpc64/ftrace: Move ftrace sequence out of line
> powerpc64/ftrace: Support .text larger than 32MB with out-of-line
> stubs
> powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPS
> powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_DIRECT_CALLS
> samples/ftrace: Add support for ftrace direct samples on powerpc
> powerpc64/bpf: Add support for bpf trampolines
>
> arch/Kconfig | 6 +
> arch/powerpc/Kbuild | 2 +-
> arch/powerpc/Kconfig | 23 +-
> arch/powerpc/Makefile | 8 +
> arch/powerpc/Makefile.postlink | 8 +
> arch/powerpc/include/asm/ftrace.h | 33 +-
> arch/powerpc/include/asm/module.h | 5 +
> arch/powerpc/include/asm/ppc-opcode.h | 14 +
> arch/powerpc/kernel/asm-offsets.c | 11 +
> arch/powerpc/kernel/kprobes.c | 18 +-
> arch/powerpc/kernel/module_64.c | 66 +-
> arch/powerpc/kernel/trace/Makefile | 11 +-
> arch/powerpc/kernel/trace/ftrace.c | 298 ++++++-
> arch/powerpc/kernel/trace/ftrace_64_pg.c | 69 +-
> arch/powerpc/kernel/trace/ftrace_entry.S | 244 ++++--
> arch/powerpc/kernel/vmlinux.lds.S | 3 +-
> arch/powerpc/net/bpf_jit.h | 12 +
> arch/powerpc/net/bpf_jit_comp.c | 847 +++++++++++++++++++-
> arch/powerpc/net/bpf_jit_comp32.c | 7 +-
> arch/powerpc/net/bpf_jit_comp64.c | 68 +-
> arch/powerpc/tools/Makefile | 12 +
> arch/powerpc/tools/ftrace-gen-ool-stubs.sh | 52 ++
> arch/powerpc/tools/ftrace_check.sh | 50 ++
> samples/ftrace/ftrace-direct-modify.c | 85 +-
> samples/ftrace/ftrace-direct-multi-modify.c | 101 ++-
> samples/ftrace/ftrace-direct-multi.c | 79 +-
> samples/ftrace/ftrace-direct-too.c | 83 +-
> samples/ftrace/ftrace-direct.c | 69 +-
> scripts/Makefile.vmlinux | 7 +
> scripts/link-vmlinux.sh | 7 +-
> 30 files changed, 2098 insertions(+), 200 deletions(-)
> create mode 100644 arch/powerpc/tools/Makefile
> create mode 100755 arch/powerpc/tools/ftrace-gen-ool-stubs.sh
> create mode 100755 arch/powerpc/tools/ftrace_check.sh
>
> --
> 2.46.0
>
--
Best Regards
Masahiro Yamada
View attachment "0001-fixup.patch" of type "text/x-patch" (4765 bytes)
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