Messages in this thread | | | From | Guo Ren <> | Date | Wed, 30 Nov 2022 15:29:52 +0800 | Subject | Re: [PATCH V4 6/7] riscv: ftrace: Add DYNAMIC_FTRACE_WITH_DIRECT_CALLS support |
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On Tue, Nov 29, 2022 at 8:03 PM Song Shuai <suagrfillet@gmail.com> wrote: > > <guoren@kernel.org> 于2022年11月29日周二 03:33写道: > > > > From: Song Shuai <suagrfillet@gmail.com> > > > > This patch adds DYNAMIC_FTRACE_WITH_DIRECT_CALLS support for RISC-V. > > > > select the DYNAMIC_FTRACE_WITH_DIRECT_CALLS to provide the > > register_ftrace_direct[_multi] interfaces allowing users 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 modifying direct_caller. > > > > To make the direct_caller and the other ftrace hooks (eg. function/fgraph > > tracer, k[ret]probes) co-exist, a temporary register is 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. > > > > Signed-off-by: Song Shuai <suagrfillet@gmail.com> > > Tested-by: Guo Ren <guoren@kernel.org> > > Signed-off-by: Guo Ren <guoren@kernel.org> > > --- > > arch/riscv/Kconfig | 1 + > > arch/riscv/include/asm/ftrace.h | 6 ++++++ > > arch/riscv/kernel/mcount-dyn.S | 4 ++++ > > 3 files changed, 11 insertions(+) > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > index 1d0e5838b11b..2828537abfcd 100644 > > --- a/arch/riscv/Kconfig > > +++ b/arch/riscv/Kconfig > > @@ -278,6 +278,7 @@ config ARCH_RV64I > > select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 > > select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && $(cc-option,-fpatchable-function-entry=8) > I noticed this cc-option uses the '-fpatchable-function-entry=8' to > judge if the compiler supports this option. > Should we keep up with the CC_FLAGS_FTRACE modified in ("riscv: > ftrace: Reduce the detour code size to half"), > or follow the parisc architecture to set the value as '1,1' in the > case of the CC_FLAGS_FTRACE is not constant. > ``` > ./arch/parisc/Makefile:75:CC_FLAGS_FTRACE := > -fpatchable-function-entry=$(NOP_COUNT),$(shell echo > $$(($(NOP_COUNT)-1))) > ./arch/parisc/Kconfig:70: select HAVE_DYNAMIC_FTRACE if > $(cc-option,-fpatchable-function-entry=1,1) The -fpatchable-function-entry=8 is still okay for riscv because it's big enough. Your proposal could be another optimization patch, not a fixup (No bug happens :).
> ``` > > select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE > > + select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS > > select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL > > select HAVE_FUNCTION_GRAPH_TRACER > > select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION > > diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h > > index 84f856a3286e..4539f10fea56 100644 > > --- a/arch/riscv/include/asm/ftrace.h > > +++ b/arch/riscv/include/asm/ftrace.h > > @@ -114,6 +114,12 @@ struct ftrace_regs; > > void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, > > struct ftrace_ops *op, struct ftrace_regs *fregs); > > #define ftrace_graph_func ftrace_graph_func > > + > > +static inline void arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigned long addr) > > +{ > > + regs->t1 = addr; > > +} > > + > > #endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ > > > > #endif /* __ASSEMBLY__ */ > > diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S > > index 466c6ef217b1..fef7c460f991 100644 > > --- a/arch/riscv/kernel/mcount-dyn.S > > +++ b/arch/riscv/kernel/mcount-dyn.S > > @@ -232,6 +232,7 @@ ENDPROC(ftrace_caller) > > > > #else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ > > ENTRY(ftrace_regs_caller) > > + move t1, zero > > SAVE_ABI_REGS 1 > > PREPARE_ARGS > > > > @@ -241,7 +242,10 @@ ftrace_regs_call: > > > > > > RESTORE_ABI_REGS 1 > > + bnez t1,.Ldirect > > jr t0 > > +.Ldirect: > > + jr t1 > > ENDPROC(ftrace_regs_caller) > > > > ENTRY(ftrace_caller) > > -- > > 2.36.1 > > > > > -- > Thanks, > Song
-- Best Regards Guo Ren
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