[PATCH 0/7] add function arguments to ftrace

[Steven Rostedt]

On Wed,  4 Sep 2024 08:58:54 +0200
Sven Schnelle <svens at linux.ibm.com> wrote:

> These patches add support for printing function arguments in ftrace.
> 
> Example usage:
> 
> function tracer:
> 
> cd /sys/kernel/tracing/
> echo icmp_rcv >set_ftrace_filter
> echo function >current_tracer
> echo 1 >options/func-args
> ping -c 10 127.0.0.1
> [..]
> cat trace
> [..]
>             ping-1277    [030] ..s1.    39.120939: icmp_rcv(skb = 0xa0ecab00) <-ip_protocol_deliver_rcu
>             ping-1277    [030] ..s1.    39.120946: icmp_rcv(skb = 0xa0ecac00) <-ip_protocol_deliver_rcu
>             ping-1277    [030] ..s1.    40.179724: icmp_rcv(skb = 0xa0ecab00) <-ip_protocol_deliver_rcu
>             ping-1277    [030] ..s1.    40.179730: icmp_rcv(skb = 0xa0ecac00) <-ip_protocol_deliver_rcu
>             ping-1277    [030] ..s1.    41.219700: icmp_rcv(skb = 0xa0ecab00) <-ip_protocol_deliver_rcu
>             ping-1277    [030] ..s1.    41.219706: icmp_rcv(skb = 0xa0ecac00) <-ip_protocol_deliver_rcu
>             ping-1277    [030] ..s1.    42.259717: icmp_rcv(skb = 0xa0ecab00) <-ip_protocol_deliver_rcu
>             ping-1277    [030] ..s1.    42.259725: icmp_rcv(skb = 0xa0ecac00) <-ip_protocol_deliver_rcu
>             ping-1277    [030] ..s1.    43.299735: icmp_rcv(skb = 0xa0ecab00) <-ip_protocol_deliver_rcu
>             ping-1277    [030] ..s1.    43.299742: icmp_rcv(skb = 0xa0ecac00) <-ip_protocol_deliver_rcu
> 
> function graph:
> 
> cd /sys/kernel/tracing
> echo icmp_rcv >set_graph_function
> echo function_graph >current_tracer
> echo 1 >options/funcgraph-args
> 
> ping -c 1 127.0.0.1
> 
> cat trace
> 
>  30)               |  icmp_rcv(skb = 0xa0ecab00) {
>  30)               |    __skb_checksum_complete(skb = 0xa0ecab00) {
>  30)               |      skb_checksum(skb = 0xa0ecab00, offset = 0, len = 64, csum = 0) {
>  30)               |        __skb_checksum(skb = 0xa0ecab00, offset = 0, len = 64, csum = 0, ops = 0x232e0327a88) {
>  30)   0.418 us    |          csum_partial(buff = 0xa0d20924, len = 64, sum = 0)
>  30)   0.985 us    |        }
>  30)   1.463 us    |      }
>  30)   2.039 us    |    }
> [..]
> 

First I want to say THANK YOU!!!!

This has been on my TODO list for far too long. I never got the time to
work on it :-p

Anyway, this is something I definitely want added. But I'm going to guess
that there is going to be issues with it and I doubt it will be ready for
the next merge window. I'm currently focused on some other things and also
have to get ready for next weeks travels (I'll be in Prague for GNU Cauldron,
then Vienna for Plumbers and OSS EU, then to Paris for Kernel Recipes!).

But I most definitely want this in. Hopefully by 6.13. This may be
something I can review on the plane (if I get my slides done).

Again, thanks for doing this!

-- Steve

> 
> Sven Schnelle (7):
>   tracing: add ftrace_regs to function_graph_enter()
>   x86/tracing: pass ftrace_regs to function_graph_enter()
>   s390/tracing: pass ftrace_regs to function_graph_enter()
>   Add print_function_args()
>   tracing: add config option for print arguments in ftrace
>   tracing: add support for function argument to graph tracer
>   tracing: add arguments to function tracer
> 
>  arch/arm/kernel/ftrace.c             |  2 +-
>  arch/arm64/kernel/ftrace.c           |  2 +-
>  arch/csky/kernel/ftrace.c            |  2 +-
>  arch/loongarch/kernel/ftrace.c       |  2 +-
>  arch/loongarch/kernel/ftrace_dyn.c   |  2 +-
>  arch/microblaze/kernel/ftrace.c      |  2 +-
>  arch/mips/kernel/ftrace.c            |  2 +-
>  arch/parisc/kernel/ftrace.c          |  2 +-
>  arch/powerpc/kernel/trace/ftrace.c   |  2 +-
>  arch/riscv/kernel/ftrace.c           |  2 +-
>  arch/s390/kernel/entry.h             |  4 +-
>  arch/s390/kernel/ftrace.c            |  4 +-
>  arch/sh/kernel/ftrace.c              |  2 +-
>  arch/sparc/kernel/ftrace.c           |  2 +-
>  arch/x86/include/asm/ftrace.h        |  2 +-
>  arch/x86/kernel/ftrace.c             |  6 +-
>  include/linux/ftrace.h               |  4 +-
>  kernel/trace/Kconfig                 | 12 ++++
>  kernel/trace/fgraph.c                |  7 ++-
>  kernel/trace/trace.c                 |  8 ++-
>  kernel/trace/trace.h                 |  4 +-
>  kernel/trace/trace_entries.h         |  7 ++-
>  kernel/trace/trace_functions.c       | 46 ++++++++++++++--
>  kernel/trace/trace_functions_graph.c | 74 +++++++++++++------------
>  kernel/trace/trace_irqsoff.c         |  4 +-
>  kernel/trace/trace_output.c          | 82 +++++++++++++++++++++++++++-
>  kernel/trace/trace_output.h          |  9 +++
>  kernel/trace/trace_sched_wakeup.c    |  4 +-
>  28 files changed, 228 insertions(+), 73 deletions(-)
> 
> --
> 2.43.0