Messages in this thread | | | From | Song Shuai <> | Subject | [PATCH V9 0/4] riscv: Optimize function trace | Date | Wed, 10 May 2023 18:18:53 +0800 |
| |
Changes in v9:
1. add Acked-by from Björn Töpel in patch 1
2. rebase patch2/patch3 on Linux v6.4-rc1
- patch 2: to make the `SAVE_ABI_REGS` configurable, revert the modification of mcount-dyn.S from commit (45b32b946a97 "riscv: entry: Consolidate general regs saving/restoring")
- patch 3: to pass the trace_selftest, add the implement of `ftrace_stub_direct_tramp` from commit (fee86a4ed536 "ftrace: selftest: remove broken trace_direct_tramp") ; and fixup the context conflict in Kconfig
You can directly try it with:
https://github.com/sugarfillet/linux/tree/6.4-rc1-rv-ftrace-v9
This series optimizes function trace. The first 3 independent patches has been picked in the V7 version of this series, the subsequent version continues the following 4 patches:
select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY [1] (patch 1) ==========================================================
In RISC-V, -fpatchable-function-entry option is used to support dynamic ftrace in this commit afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT"). So recordmcount don't have to be called to create the __mcount_loc section before the vmlinux linking.
Here selects FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY to tell Makefile not to run recordmcount.
Make function graph use ftrace directly [2] (patch 2) ========================================================
In RISC-V architecture, when we enable the ftrace_graph tracer on some functions, the function tracings on other functions will suffer extra graph tracing work. In essence, graph_ops isn't limited by its func_hash due to the global ftrace_graph_[regs]_call label. That should be corrected.
What inspires me is the commit 0c0593b45c9b ("x86/ftrace: Make function graph use ftrace directly") that uses graph_ops::func function to install return_hooker and makes the function called against its func_hash.
Add WITH_DIRECT_CALLS support [3] (patch 3, 4) ==============================================
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 series's old changes related these patches ==========================================
Changes in v8: https://lore.kernel.org/linux-riscv/20230324033342.3177979-1-suagrfillet@gmail.com/ - Fix incorrect address values in the 4nd patch - Rebased on v6.3-rc2
Changes in v7: https://lore.kernel.org/linux-riscv/20230112090603.1295340-1-guoren@kernel.org/ - Fixup RESTORE_ABI_REGS by remove PT_T0(sp) overwrite. - Add FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY [1] - Fixup kconfig with HAVE_SAMPLE_FTRACE_DIRECT & HAVE_SAMPLE_FTRACE_DIRECT_MULTI
Changes in v6: https://lore.kernel.org/linux-riscv/20230107133549.4192639-1-guoren@kernel.org/ - Replace 8 with MCOUNT_INSN_SIZE - Replace "REG_L a1, PT_RA(sp)" with "mv a1, ra" - Add Evgenii Shatokhin comment
Changes in v5: https://lore.kernel.org/linux-riscv/20221208091244.203407-1-guoren@kernel.org/ - Sort Kconfig entries in alphabetical order.
Changes in v4: https://lore.kernel.org/linux-riscv/20221129033230.255947-1-guoren@kernel.org/ - Include [3] for maintenance. [Song Shuai]
Changes in V3: https://lore.kernel.org/linux-riscv/20221123153950.2911981-1-guoren@kernel.org/ - Include [2] for maintenance. [Song Shuai]
[1]: https://lore.kernel.org/linux-riscv/CAAYs2=j3Eak9vU6xbAw0zPuoh00rh8v5C2U3fePkokZFibWs2g@mail.gmail.com/T/#t [2]: https://lore.kernel.org/lkml/20221120084230.910152-1-suagrfillet@gmail.com/ [3]: https://lore.kernel.org/linux-riscv/20221123142025.1504030-1-suagrfillet@gmail.com/
Song Shuai (4): riscv: select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY riscv: ftrace: Add ftrace_graph_func riscv: ftrace: Add DYNAMIC_FTRACE_WITH_DIRECT_CALLS support samples: ftrace: Add riscv support for SAMPLE_FTRACE_DIRECT[_MULTI]
arch/riscv/Kconfig | 4 + arch/riscv/include/asm/ftrace.h | 19 ++- arch/riscv/kernel/ftrace.c | 30 ++-- arch/riscv/kernel/mcount-dyn.S | 176 +++++++++++++++++--- samples/ftrace/ftrace-direct-modify.c | 33 ++++ samples/ftrace/ftrace-direct-multi-modify.c | 39 +++++ samples/ftrace/ftrace-direct-multi.c | 23 +++ samples/ftrace/ftrace-direct-too.c | 26 +++ samples/ftrace/ftrace-direct.c | 22 +++ 9 files changed, 328 insertions(+), 44 deletions(-)
-- 2.20.1
| |