在 2024/6/28 15:02, Michael Ellerman 写道:
Jialong Yang <[email protected]> writes:
mmiotrace is a useful tool to trace MMIO accesses. Nowadays, it only
supported on x86 and x86_64 platforms.
I've never used mmiotrace, and don't know it well.
I'm not necessarily opposed to merging it, but AFAIK it was mostly used
for reverse engineering proprietary drivers, where the driver itself
couldn't be easily instrumented. Is that what you're using it for?
Yes. Just like you think. We have used it for network stack debug in
ppc64le.
For drivers where we have the source wouldn't it be easier to just use
tracepoints in the MMIO accessors?
Tracepoints need pre-defined. And in some big driver, it's not easy to
overwrite
all points where access registers in io area. And tracepoint is C
function level filter.
mmiotrace is similar to set tracepoints in writel/readl... But it can do
deeperly.
mmiotrace is a asm level filter tool. It doesn't care what have done in
C level. It will
only find what have done by asm, such as stw(store word)/lw(load word),
just like standing
in the view of device.
Is it still in-use/maintained on the x86 side?
Here is some core file patches number in x86:
| | mmio_mod.c | kmmio.c | pf_in.* | testmmiotrace.c |
|------+------------+---------+---------+-----------------|
| 2022 | 1 | 3 | | |
| 2021 | 2 | 1 | | |
| 2020 | 4 | 4 | | 1 |
| 2019 | 2 | 1 | 1 | 4 |
| 2018 | | 2 | | |
| 2017 | 2 | 2 | | 1 |
| 2016 | 1 | 2 | 1 | |
| 2014 | | 1 | | |
| 2013 | 1 | | | |
| 2012 | 1 | | | |
| 2011 | 3 | | 1 | |
| 2010 | 1 | 3 | 2 | 1 |
| 2009 | 4 | 19 | | 3 |
| 2008 | 13 | 5 | 2 | 3 |
Here is a support for powerpc.
The manual is located at Documentation/trace/mmiotrace.rst which means
I have not changed user API. People will be easy to use it.
Almost all files are copied from x86/mm, there are only some
differences from hardware and architectures software.
LINK: https://lore.kernel.org/lkml/[email protected]/
Signed-off-by: Jialong Yang <[email protected]>
---
arch/powerpc/Kconfig.debug | 3 +
arch/powerpc/mm/Makefile | 1 +
arch/powerpc/mm/kmmio.c | 649 +++++++++++++++++++++++++++++++
arch/powerpc/mm/mmio-mod.c | 414 ++++++++++++++++++++
arch/powerpc/mm/mmiotrace_arch.c | 149 +++++++
arch/powerpc/mm/mmiotrace_arch.h | 25 ++
arch/powerpc/mm/pf_in.c | 185 +++++++++
arch/powerpc/mm/pf_in.h | 33 ++
8 files changed, 1459 insertions(+)
At a glance most of that code could be shared between arches. I don't
think I can merge that as-is, without some attempt to split the generic
parts out.
Right.
I just copy them from arch/x86/mm. There are many code not arch specific.
cheers
