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Subject[PATCH v3] mips-specific ftrace support
From: Wu Zhangjin <>

ftrace is a mcount based kernel tracing tool/framework, which is originally

ftrace is short for function tracer, this is its original name, but now, it
becomes a kernel tracing framework, lots of kernel tracers are built on it,
such as irqoff tracer, wakeup tracer and so forth. these tracers are
arch-independent(?), but some of them are arch-dependent, such as the original
ftrace: function tracer, and dynamic function tracer, function graph tracer,
and also, system call tracer.

here is the mips porting of these four arch-dependent tracers, it will enable
the following new kernel config options in linux-mips system.

kernel hacking --->
Tracers -->
[*] Kernel Function Tracer
[*] Kernel Function Graph Tracer
[*] Trace syscalls
[*] enable/disable ftrace tracepoints dynamically

in reality, because the timestamp getting function are arch-dependent, lots of
the tracers are arch-dependent. the arch-dependent part is that: sched_clock().
the original sched_clock() in mips is jiffes based, only give 10ms precision in
1000HZ, which is not enough for ftrace. to get high-precise timestamp, we must
implement a new native_sched_clock() via reading the MIPS clock counter, but
since it is only 32bit long, so, overflow should be handled carefully.

this -v3 patch series is based on the -v2 patch series and incorporates the
feedback from Steven Rostedt and Thomas Gleixner.


this -v3 not support modules yet, really hope this can be fixed in -v4 patch.

read the following document, and play with it:

Wu Zhangjin (7):
mips static function tracer support
add an endian argument to scripts/
mips dynamic function tracer support
filter local function prefixed by $L
mips function graph tracer support
mips specific clock function to get precise timestamp
mips specific system call tracer

arch/mips/Kconfig | 7 +
arch/mips/Makefile | 2 +
arch/mips/include/asm/ftrace.h | 35 ++++-
arch/mips/include/asm/ptrace.h | 2 +
arch/mips/include/asm/reg.h | 5 +
arch/mips/include/asm/syscall.h | 84 +++++++++
arch/mips/include/asm/thread_info.h | 5 +-
arch/mips/kernel/Makefile | 12 ++
arch/mips/kernel/csrc-r4k.c | 2 +-
arch/mips/kernel/entry.S | 2 +-
arch/mips/kernel/ftrace.c | 344 +++++++++++++++++++++++++++++++++++
arch/mips/kernel/ftrace_clock.c | 71 +++++++
arch/mips/kernel/mcount.S | 184 +++++++++++++++++++
arch/mips/kernel/mips_ksyms.c | 5 +
arch/mips/kernel/ptrace.c | 14 ++-
arch/mips/kernel/scall64-o32.S | 2 +-
arch/mips/kernel/ | 1 +
kernel/trace/trace_clock.c | 2 +-
scripts/ | 1 +
scripts/ | 30 +++-
20 files changed, 799 insertions(+), 11 deletions(-)
create mode 100644 arch/mips/include/asm/syscall.h
create mode 100644 arch/mips/kernel/ftrace.c
create mode 100644 arch/mips/kernel/ftrace_clock.c
create mode 100644 arch/mips/kernel/mcount.S

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