Messages in this thread | | | From | Song Shuai <> | Subject | [PATCH v4 0/2] riscv/ftrace: make function graph use ftrace directly | Date | Sun, 20 Nov 2022 16:42:28 +0800 |
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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.
This series of patches makes function graph use ftrace directly for riscv.
If FTRACE_WITH_REGS isn't defined, ftrace_caller keeps ftrace_graph_call so that it can be replaced with the calling of prepare_ftrace_return by the enable/disable helper.
As for defining FTRACE_WITH_REGS, ftrace_caller is adjusted to save the necessary regs against the pt_regs layout, so it can reasonably call the graph_ops::func function - ftrace_graph_func. And ftrace_graph_[regs]_call and its enable/disable helper aren't needed.
The tests generated by CONFIG_FTRACE_STARTUP_TEST have passed in the local qemu-system-riscv64 virt machine. The following is the log during startup.
``` Nov 15 03:07:13 stage4 kernel: Testing tracer function: PASSED Nov 15 03:07:13 stage4 kernel: Testing dynamic ftrace: PASSED Nov 15 03:07:13 stage4 kernel: Testing dynamic ftrace ops #1: Nov 15 03:07:13 stage4 kernel: (1 0 1 0 0) Nov 15 03:07:13 stage4 kernel: (1 1 2 0 0) Nov 15 03:07:13 stage4 kernel: (2 1 3 0 365) Nov 15 03:07:13 stage4 kernel: (2 2 4 0 399) Nov 15 03:07:13 stage4 kernel: (3 2 4 0 146071) Nov 15 03:07:13 stage4 kernel: (3 3 5 0 146105) PASSED Nov 15 03:07:13 stage4 kernel: Testing dynamic ftrace ops #2: Nov 15 03:07:13 stage4 kernel: (1 0 1 589 0) Nov 15 03:07:13 stage4 kernel: (1 1 2 635 0) Nov 15 03:07:13 stage4 kernel: (2 1 3 1 2) Nov 15 03:07:13 stage4 kernel: (2 2 4 125 126) Nov 15 03:07:13 stage4 kernel: (3 2 4 146001 146078) Nov 15 03:07:13 stage4 kernel: (3 3 5 146035 146112) PASSED Nov 15 03:07:13 stage4 kernel: Testing ftrace recursion: PASSED Nov 15 03:07:13 stage4 kernel: Testing ftrace recursion safe: PASSED Nov 15 03:07:13 stage4 kernel: Testing ftrace regs: PASSED Nov 15 03:07:13 stage4 kernel: Testing tracer nop: PASSED Nov 15 03:07:13 stage4 kernel: Testing tracer irqsoff: PASSED Nov 15 03:07:13 stage4 kernel: Testing tracer wakeup: Nov 15 03:07:13 stage4 kernel: sched: DL replenish lagged too much Nov 15 03:07:13 stage4 kernel: PASSED Nov 15 03:07:13 stage4 kernel: Testing tracer wakeup_rt: PASSED Nov 15 03:07:13 stage4 kernel: Testing tracer wakeup_dl: PASSED Nov 15 03:07:13 stage4 kernel: Testing tracer function_graph: PASSED ```
Note that the changes of mcount-dyn.S conflicts with this unmerged commit (riscv: entry: consolidate general regs saving/restoring). https://lore.kernel.org/linux-riscv/20221103075047.1634923-15-guoren@kernel.org
Changes since v3: - separate parameters preparation as PREPARE_ARGS [Guo Ren] v3 link: https://lore.kernel.org/linux-riscv/20221118173217.888077-1-suagrfillet@gmail.com/
Changes since v2: - line up the comments [Andrew] - rename SAVE_ALL as SAVE_ABI_REGS [Guo Ren] - consolidate the modifications of mcount-dyn.S into one patch [Guo Ren] - adapt this series based on [riscv: ftrace: Fixup ftrace detour code][1] [Guo Ren]
[1]: https://lore.kernel.org/linux-riscv/20220921034910.3142465-1-guoren@kernel.org/ v2 Link: https://lore.kernel.org/linux-riscv/20221116031305.286634-1-suagrfillet@gmail.com/
Changes since v1: - fix the checkpatch warnings in patch 1 v1 Link: https://lore.kernel.org/linux-riscv/20221115061525.112757-1-suagrfillet@gmail.com
Song Shuai (2): riscv/ftrace: add ftrace_graph_func riscv/ftrace: make ftrace_caller call ftrace_graph_func
arch/riscv/include/asm/ftrace.h | 13 ++- arch/riscv/kernel/ftrace.c | 30 +++---- arch/riscv/kernel/mcount-dyn.S | 142 +++++++++++++++++++++++--------- 3 files changed, 128 insertions(+), 57 deletions(-)
-- 2.20.1
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