Re: [PATCH] perf, riscv: Wire up perf trace support for RISC-V

Alexandre Ghiti
2024-10-30T07:31:42Z

Hi Bjorn, Namhyung,

On 30/10/2024 01:37, Namhyung Kim wrote:
> Hello,
>
> On Thu, Oct 24, 2024 at 12:03:51PM -0700, Björn Töpel wrote:
>> From: Björn Töpel <bjorn@rivosinc.com>
>>
>> RISC-V does not currently support perf trace, since the system call
>> table is not generated.
>>
>> Perform the copy/paste exercise, wiring up RISC-V system call table
>> generation.
> Can anybody with RISC-V please test this?

So before this patch, I get:

Error::5File /sys/kernel/tracing//events/raw_syscalls/sys_(enter|exit)
not found.
Hint:    Perhaps this kernel misses some CONFIG_ setting to enable this
feature?.

After applying this patch, I get a proper trace:
....

7.435 ( 0.332 ms): ls/1307 openat(dfd: CWD, filename: 0xb36ef668,
flags: RDONLY|CLOEXEC)         = 3
8.023 ( 0.454 ms): ls/1307 mmap(len: 23171, prot: READ, flags:
PRIVATE, fd: 3)                   = 0x7fffb36cd000
8.558 ( 0.065 ms): ls/1307 close(fd:
3)                                                          = 0
8.850 ( 0.294 ms): ls/1307 openat(dfd: CWD, filename: 0xb36f9f80,
flags: RDONLY|CLOEXEC)         = 3
9.223 ( 0.152 ms): ls/1307 read(fd: 3, buf: 0x7fffe27b3c20, count:
832)

...

So you can add:

Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex

>
> Thanks,
> Namhyung
>
>> Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
>> ---
>> tools/perf/Makefile.config | 6 ++-
>> tools/perf/arch/riscv/Makefile | 22 +++++++++
>> .../arch/riscv/entry/syscalls/mksyscalltbl | 47 +++++++++++++++++++
>> tools/perf/util/syscalltbl.c | 4 ++
>> 4 files changed, 78 insertions(+), 1 deletion(-)
>> create mode 100755 tools/perf/arch/riscv/entry/syscalls/mksyscalltbl
>>
>> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
>> index 4ddb27a48eed..1d388e71e0cc 100644
>> --- a/tools/perf/Makefile.config
>> +++ b/tools/perf/Makefile.config
>> @@ -31,7 +31,7 @@ $(call detected_var,SRCARCH)
>> ifneq ($(NO_SYSCALL_TABLE),1)
>> NO_SYSCALL_TABLE := 1
>>
>> - ifeq ($(SRCARCH),$(filter $(SRCARCH),x86 powerpc arm64 s390 mips loongarch))
>> + ifeq ($(SRCARCH),$(filter $(SRCARCH),x86 powerpc arm64 s390 mips loongarch riscv))
>> NO_SYSCALL_TABLE := 0
>> endif
>>
>> @@ -83,6 +83,10 @@ ifeq ($(ARCH),mips)
>> LIBUNWIND_LIBS = -lunwind -lunwind-mips
>> endif
>>
>> +ifeq ($(ARCH),riscv)
>> + CFLAGS += -I$(OUTPUT)arch/riscv/include/generated
>> +endif
>> +
>> # So far there's only x86 and arm libdw unwind support merged in perf.
>> # Disable it on all other architectures in case libdw unwind
>> # support is detected in system. Add supported architectures
>> diff --git a/tools/perf/arch/riscv/Makefile b/tools/perf/arch/riscv/Makefile
>> index 90c3c476a242..481da4518695 100644
>> --- a/tools/perf/arch/riscv/Makefile
>> +++ b/tools/perf/arch/riscv/Makefile
>> @@ -4,3 +4,25 @@ endif
>> PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET := 1
>> PERF_HAVE_JITDUMP := 1
>> HAVE_KVM_STAT_SUPPORT := 1
>> +
>> +#
>> +# Syscall table generation for perf
>> +#
>> +
>> +out := $(OUTPUT)arch/riscv/include/generated/asm
>> +header := $(out)/syscalls.c
>> +incpath := $(srctree)/tools
>> +sysdef := $(srctree)/tools/arch/riscv/include/uapi/asm/unistd.h
>> +sysprf := $(srctree)/tools/perf/arch/riscv/entry/syscalls/
>> +systbl := $(sysprf)/mksyscalltbl
>> +
>> +# Create output directory if not already present
>> +$(shell [ -d '$(out)' ] || mkdir -p '$(out)')
>> +
>> +$(header): $(sysdef) $(systbl)
>> + $(Q)$(SHELL) '$(systbl)' '$(CC)' '$(HOSTCC)' $(incpath) $(sysdef) > $@
>> +
>> +clean::
>> + $(call QUIET_CLEAN, riscv) $(RM) $(header)
>> +
>> +archheaders: $(header)
>> diff --git a/tools/perf/arch/riscv/entry/syscalls/mksyscalltbl b/tools/perf/arch/riscv/entry/syscalls/mksyscalltbl
>> new file mode 100755
>> index 000000000000..c59f5e852b97
>> --- /dev/null
>> +++ b/tools/perf/arch/riscv/entry/syscalls/mksyscalltbl
>> @@ -0,0 +1,47 @@
>> +#!/bin/sh
>> +# SPDX-License-Identifier: GPL-2.0
>> +#
>> +# Generate system call table for perf. Derived from
>> +# powerpc script.
>> +#
>> +# Copyright IBM Corp. 2017
>> +# Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
>> +# Changed by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
>> +# Changed by: Kim Phillips <kim.phillips@arm.com>
>> +# Changed by: Björn Töpel <bjorn@rivosinc.com>
>> +
>> +gcc=$1
>> +hostcc=$2
>> +incpath=$3
>> +input=$4
>> +
>> +if ! test -r $input; then
>> + echo "Could not read input file" >&2
>> + exit 1
>> +fi
>> +
>> +create_sc_table()
>> +{
>> + local sc nr max_nr
>> +
>> + while read sc nr; do
>> + printf "%s\n" " [$nr] = \"$sc\","
>> + max_nr=$nr
>> + done
>> +
>> + echo "#define SYSCALLTBL_RISCV_MAX_ID $max_nr"
>> +}
>> +
>> +create_table()
>> +{
>> + echo "#include \"$input\""
>> + echo "static const char *const syscalltbl_riscv[] = {"
>> + create_sc_table
>> + echo "};"
>> +}
>> +
>> +$gcc -E -dM -x c -I $incpath/include/uapi $input \
>> + |awk '$2 ~ "__NR" && $3 !~ "__NR3264_" {
>> + sub("^#define __NR(3264)?_", "");
>> + print | "sort -k2 -n"}' \
>> + |create_table
>> diff --git a/tools/perf/util/syscalltbl.c b/tools/perf/util/syscalltbl.c
>> index 7c15dec6900d..349986f6e5f5 100644
>> --- a/tools/perf/util/syscalltbl.c
>> +++ b/tools/perf/util/syscalltbl.c
>> @@ -46,6 +46,10 @@ static const char *const *syscalltbl_native = syscalltbl_mips_n64;
>> #include <asm/syscalls.c>
>> const int syscalltbl_native_max_id = SYSCALLTBL_LOONGARCH_MAX_ID;
>> static const char *const *syscalltbl_native = syscalltbl_loongarch;
>> +#elif defined(__riscv)
>> +#include <asm/syscalls.c>
>> +const int syscalltbl_native_max_id = SYSCALLTBL_RISCV_MAX_ID;
>> +static const char *const *syscalltbl_native = syscalltbl_riscv;
>> #endif
>>
>> struct syscall {
>>
>> base-commit: c2ee9f594da826bea183ed14f2cc029c719bf4da
>> --
>> 2.45.2
>>
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