Messages in this thread | | | From | Song Shuai <> | Subject | [PATCH 0/2] riscv/ftrace: add WITH_DIRECT_CALLS support | Date | Wed, 23 Nov 2022 22:20:23 +0800 |
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This series adds DYNAMIC_FTRACE_WITH_DIRECT_CALLS support for RISC-V. SAMPLE_FTRACE_DIRECT and SAMPLE_FTRACE_DIRECT_MULTI are also included here as the samples for testing DIRECT_CALLS related interface.
First, select the DYNAMIC_FTRACE_WITH_DIRECT_CALLS to provide register_ftrace_direct[_multi] interfaces allowing user to register the customed trampoline (direct_caller) as the mcount for one or more target functions. And modify_ftrace_direct[_multi] are also provided for modify direct_caller.
At the same time, the samples in ./samples/ftrace/ can be built as kerenl module for testing these interfaces with SAMPLE_FTRACE_DIRECT and SAMPLE_FTRACE_DIRECT_MULTI selected.
Second, to make the direct_caller and the other ftrace hooks (eg. function/fgraph tracer, k[ret]probes) co-exist, a temporary register are nominated to store the address of direct_caller in ftrace_regs_caller. After the setting of the address direct_caller by direct_ops->func and the RESTORE_REGS in ftrace_regs_caller, direct_caller will be jumped to by the `jr` inst.
The following tests have been passed in my local qemu-riscv64 virt machine.
1. tests with CONFIG_FTRACE_STARTUP_TEST 2. tests of samples/ftrace/ftrace*.ko 3. manual tests with any combination of the following hooks - function/function_graph tracer - ftrace*.ko - kprobe/kretprobe
For your reference, here is the log when function tracer, kretprobe and ftrace-direct-too.ko co-hooks the handle_mm_fault function.
``` [root@stage4 tracing]# echo handle_mm_fault > set_ftrace_filter [root@stage4 tracing]# echo 'r:myr handle_mm_fault' > kprobe_events [root@stage4 tracing]# echo function > current_tracer [root@stage4 tracing]# echo 1 > events/kprobes/myr/enable [root@stage4 tracing]# insmod /root/ftrace-direct-too.ko [root@stage4 tracing]# [root@stage4 tracing]# cat trace | tail cat-388 [000] ...1. 583.051438: myr: (do_page_fault+0x16c/0x5f2 <- handle_mm_fault) cat-388 [000] ...2. 583.057930: handle_mm_fault <-do_page_fault cat-388 [000] ..... 583.057990: my_direct_func: handle mm fault vma=000000002d9fe19c address=ffffffae9b7000 flags=215 cat-388 [000] ...1. 583.058284: myr: (do_page_fault+0x16c/0x5f2 <- handle_mm_fault) tail-389 [001] ...2. 583.059062: handle_mm_fault <-do_page_fault tail-389 [001] ..... 583.059104: my_direct_func: handle mm fault vma=0000000017f3c48e address=aaaaaabebf3000 flags=215 tail-389 [001] ...1. 583.059325: myr: (do_page_fault+0x16c/0x5f2 <- handle_mm_fault) tail-389 [001] ...2. 583.060371: handle_mm_fault <-do_page_fault tail-389 [001] ..... 583.060410: my_direct_func: handle mm fault vma=0000000017f3c48e address=aaaaaabebf1000 flags=255 tail-389 [001] ...1. 583.060996: myr: (do_page_fault+0x16c/0x5f2 <- handle_mm_fault) ```
Note1:
This series is based on (riscv/ftrace: make ftrace_caller call ftrace_graph_func) in this repo -> https://github.com/guoren83/linux/commits/ftrace_fixup_v3 .
Note2:
The checkpatch.pl will output some warnings on this series, like this
``` WARNING: Prefer using '"%s...", __func__' to using 'my_direct_func2', this function's name, in a string 111: FILE: samples/ftrace/ftrace-direct-multi-modify.c:48: +" call my_direct_func2\n" ```
The reason is that checkpatch depends on patch context providing the function name. In the above warning, my_direct_func2 has some codeline distance with the changed trunk, so its declaration doesn't come into the patch, and then the warning jumps out.
You may notice the location of `my_ip` variable changes in the 2nd patch. I did that for reducing the warnings to some extent. But killing all the warnings will makes the patch less readable, so I stopped here.
-- Song
Song Shuai (2): riscv/ftrace: add DYNAMIC_FTRACE_WITH_DIRECT_CALLS support samples/ftrace: add riscv support for SAMPLE_FTRACE_DIRECT[_MULTI]
arch/riscv/Kconfig | 3 ++ arch/riscv/include/asm/ftrace.h | 6 ++++ arch/riscv/kernel/mcount-dyn.S | 4 +++ samples/ftrace/ftrace-direct-modify.c | 35 ++++++++++++++++++- samples/ftrace/ftrace-direct-multi-modify.c | 37 +++++++++++++++++++++ samples/ftrace/ftrace-direct-multi.c | 22 ++++++++++++ samples/ftrace/ftrace-direct-too.c | 26 +++++++++++++++ samples/ftrace/ftrace-direct.c | 22 ++++++++++++ 8 files changed, 154 insertions(+), 1 deletion(-)
-- 2.20.1
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