Messages in this thread | | | From | Guo Ren <> | Date | Sun, 20 Nov 2022 11:38:30 +0800 | Subject | Re: [PATCH v3 2/2] riscv/ftrace: make ftrace_caller call ftrace_graph_func |
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On Sat, Nov 19, 2022 at 1:32 AM Song Shuai <suagrfillet@gmail.com> wrote: > > In order to make the function graph use ftrace directly, ftrace_caller > should be adjusted to save the necessary regs against the pt_regs layout > so it can call ftrace_graph_func reasonably. > > SAVE_ALL now saves all the regs according to the pt_regs struct. Here > supersedes SAVE_ALL by SAVE_ABI_REGS which has an extra option to allow > saving only the necessary ABI-related regs for ftrace_caller. > > ftrace_caller and ftrace_regs_caller save their regs with the respective > option of SAVE_ABI_REGS, then call the tracing function, especially > graph_ops's ftrace_graph_func. So the ftrace_graph_[regs]_call labels > aren't needed anymore if FTRACE_WITH_REGS is defined. > > As the previous patch described, the ftrace_caller remains with its > ftrace_graph_call if FTRACE_WITH_REGS isn't defined, > > For convenience, the original argument setup for the tracing function in > ftrace_[regs]_caller is killed and appended to the tail of SAVE_ABI_REGS. > > Signed-off-by: Song Shuai <suagrfillet@gmail.com> > --- > arch/riscv/kernel/mcount-dyn.S | 143 ++++++++++++++++++++++++--------- > 1 file changed, 105 insertions(+), 38 deletions(-) > > diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S > index 64bc79816f5e..c70f04711a2e 100644 > --- a/arch/riscv/kernel/mcount-dyn.S > +++ b/arch/riscv/kernel/mcount-dyn.S > @@ -57,19 +57,55 @@ > .endm > > #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > - .macro SAVE_ALL > + > +/** > +* SAVE_ABI_REGS - save regs against the pt_regs struct > +* > +* @all: tell if saving all the regs > +* > +* If all is set, all the regs will be saved, otherwise only ABI > +* related regs (a0-a7,epc,ra and optional s0) will be saved. > +* > +* For convenience the argument setup for tracing function is appended here. > +* Especially $sp is passed as the 4th argument of the tracing function. > +* > +* After the stack is established, > +* > +* 0(sp) stores the PC of the traced function which can be accessed > +* by &(fregs)->regs->epc in tracing function. Note that the real > +* function entry address should be computed with -FENTRY_RA_OFFSET. > +* > +* 8(sp) stores the function return address (i.e. parent IP) that > +* can be accessed by &(fregs)->regs->ra in tracing function. > +* > +* The other regs are saved at the respective localtion and accessed > +* by the respective pt_regs member. > +* > +* Here is the layout of stack for your reference. > +* > +* PT_SIZE_ON_STACK -> +++++++++ > +* + ..... + > +* + t3-t6 + > +* + s2-s11+ > +* + a0-a7 + --++++-> ftrace_caller saved > +* + s1 + + > +* + s0 + --+ > +* + t0-t2 + + > +* + tp + + > +* + gp + + > +* + sp + + > +* + ra + --+ // parent IP > +* sp -> + epc + --+ // PC > +* +++++++++ > +**/ > + .macro SAVE_ABI_REGS, all=0 > addi sp, sp, -PT_SIZE_ON_STACK > > REG_S t0, PT_EPC(sp) > REG_S x1, PT_RA(sp) > - REG_S x2, PT_SP(sp) > - REG_S x3, PT_GP(sp) > - REG_S x4, PT_TP(sp) > - REG_S x5, PT_T0(sp) > - REG_S x6, PT_T1(sp) > - REG_S x7, PT_T2(sp) > - REG_S x8, PT_S0(sp) > - REG_S x9, PT_S1(sp) > + > + // always save the ABI regs > + > REG_S x10, PT_A0(sp) > REG_S x11, PT_A1(sp) > REG_S x12, PT_A2(sp) > @@ -78,6 +114,18 @@ > REG_S x15, PT_A5(sp) > REG_S x16, PT_A6(sp) > REG_S x17, PT_A7(sp) > + > + // save the leftover regs > + > + .if \all == 1 > + REG_S x2, PT_SP(sp) > + REG_S x3, PT_GP(sp) > + REG_S x4, PT_TP(sp) > + REG_S x5, PT_T0(sp) > + REG_S x6, PT_T1(sp) > + REG_S x7, PT_T2(sp) > + REG_S x8, PT_S0(sp) > + REG_S x9, PT_S1(sp) > REG_S x18, PT_S2(sp) > REG_S x19, PT_S3(sp) > REG_S x20, PT_S4(sp) > @@ -92,19 +140,28 @@ > REG_S x29, PT_T4(sp) > REG_S x30, PT_T5(sp) > REG_S x31, PT_T6(sp) > + > + // save s0 if FP_TEST defined > + > + .else > +#ifdef HAVE_FUNCTION_GRAPH_FP_TEST > + REG_S x8, PT_S0(sp) > +#endif > + .endif > + > + // setup 4 args for tracing functions > + > + addi a0, t0, -FENTRY_RA_OFFSET // ip > + la a1, function_trace_op > + REG_L a2, 0(a1) // op > + REG_L a1, PT_RA(sp) // parent_ip > + mv a3, sp // fregs Moving parameters preparation into SAVE_ABI_REGS is not a good idea. Give them a separate .macro: PREPARE_ARGS.
> + > .endm > > - .macro RESTORE_ALL > + .macro RESTORE_ABI_REGS, all=0 > REG_L t0, PT_EPC(sp) > REG_L x1, PT_RA(sp) > - REG_L x2, PT_SP(sp) > - REG_L x3, PT_GP(sp) > - REG_L x4, PT_TP(sp) > - REG_L x5, PT_T0(sp) > - REG_L x6, PT_T1(sp) > - REG_L x7, PT_T2(sp) > - REG_L x8, PT_S0(sp) > - REG_L x9, PT_S1(sp) > REG_L x10, PT_A0(sp) > REG_L x11, PT_A1(sp) > REG_L x12, PT_A2(sp) > @@ -113,6 +170,16 @@ > REG_L x15, PT_A5(sp) > REG_L x16, PT_A6(sp) > REG_L x17, PT_A7(sp) > + > + .if \all == 1 > + REG_L x2, PT_SP(sp) > + REG_L x3, PT_GP(sp) > + REG_L x4, PT_TP(sp) > + REG_L x5, PT_T0(sp) > + REG_L x6, PT_T1(sp) > + REG_L x7, PT_T2(sp) > + REG_L x8, PT_S0(sp) > + REG_L x9, PT_S1(sp) > REG_L x18, PT_S2(sp) > REG_L x19, PT_S3(sp) > REG_L x20, PT_S4(sp) > @@ -128,10 +195,16 @@ > REG_L x30, PT_T5(sp) > REG_L x31, PT_T6(sp) > > + .else > +#ifdef HAVE_FUNCTION_GRAPH_FP_TEST > + REG_L x8, PT_S0(sp) > +#endif > + .endif > addi sp, sp, PT_SIZE_ON_STACK > .endm > #endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ > > +#ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS > ENTRY(ftrace_caller) > SAVE_ABI > > @@ -160,33 +233,27 @@ ftrace_graph_call: > jr t0 > ENDPROC(ftrace_caller) > > -#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > +#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ > ENTRY(ftrace_regs_caller) > - SAVE_ALL > - > - addi a0, t0, -FENTRY_RA_OFFSET > - la a1, function_trace_op > - REG_L a2, 0(a1) > - REG_L a1, PT_RA(sp) > - mv a3, sp > + SAVE_ABI_REGS 1 > > ftrace_regs_call: > .global ftrace_regs_call > call ftrace_stub > > -#ifdef CONFIG_FUNCTION_GRAPH_TRACER > - addi a0, sp, PT_RA > - REG_L a1, PT_T0(sp) > - addi a1, a1, -FENTRY_RA_OFFSET > -#ifdef HAVE_FUNCTION_GRAPH_FP_TEST > - mv a2, s0 > -#endif > -ftrace_graph_regs_call: > - .global ftrace_graph_regs_call > - call ftrace_stub > -#endif > > - RESTORE_ALL > + RESTORE_ABI_REGS 1 > jr t0 > ENDPROC(ftrace_regs_caller) > + > +ENTRY(ftrace_caller) > + SAVE_ABI_REGS 0 > + > +ftrace_call: > + .global ftrace_call > + call ftrace_stub > + > + RESTORE_ABI_REGS 0 > + jr t0 > +ENDPROC(ftrace_caller) > #endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ > -- > 2.20.1 >
-- Best Regards Guo Ren
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