Messages in this thread | | | From | Huacai Chen <> | Date | Tue, 15 Nov 2022 18:55:44 +0800 | Subject | Re: [PATCH v6 5/9] LoongArch/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support |
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On Tue, Nov 15, 2022 at 6:44 PM Qing Zhang <zhangqing@loongson.cn> wrote: > > > Hi, huacai > On 2022/11/15 下午5:24, Huacai Chen wrote: > > On Tue, Nov 15, 2022 at 5:22 PM Qing Zhang <zhangqing@loongson.cn> wrote: > >> > >> Hi, Huacai > >> > >> On 2022/11/15 下午4:41, Huacai Chen wrote: > >>> Hi, Qing, > >>> > >>> Patch5 and Patch6 are small and related, maybe they can be combined > >>> with a name "LoongArch/ftrace: Add DYNAMIC_FTRACE_WITH_{ARGS,REGS} > >>> support" > >> I think they should be independent due to different use scenarios. > > From the commit message it seems DYNAMIC_FTRACE_WITH_ARGS depend on > > DYNAMIC_FTRACE_WITH_REGS. > > DYNAMIC_FTRACE_WITH_REGS : which allows trace function saved registers, > It means that these registers can be modified, eg: Kprobe、Livepatch. > > DYNAMIC_FTRACE_WITH_ARGS: uses pt_regs as a parameter for get sp, > which means it can be used to access registers on the stack, and > use graph_ops::func to install return_hooker to replace the special > hook, eg: Livepatch. > > From the following Kconfig, they are reasonable as separate patches. > config LIVEPATCH > bool "Kernel Live Patching" > depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS > OK, then keeping them separately is reasonable.
Huacai > Thanks > - Qing > > > > Huacai > >> > >> Thanks, > >> -Qing > >>> > >>> Huacai > >>> > >>> On Tue, Nov 15, 2022 at 10:55 AM Qing Zhang <zhangqing@loongson.cn> wrote: > >>>> > >>>> This patch implements DYNAMIC_FTRACE_WITH_REGS on LoongArch, which allows > >>>> a traced function's arguments (and some other registers) to be captured > >>>> into a struct pt_regs, allowing these to be inspected and modified. > >>>> > >>>> Co-developed-by: Jinyang He <hejinyang@loongson.cn> > >>>> Signed-off-by: Jinyang He <hejinyang@loongson.cn> > >>>> Signed-off-by: Qing Zhang <zhangqing@loongson.cn> > >>>> --- > >>>> arch/loongarch/Kconfig | 1 + > >>>> arch/loongarch/include/asm/ftrace.h | 3 +++ > >>>> arch/loongarch/kernel/ftrace_dyn.c | 17 ++++++++++++++ > >>>> arch/loongarch/kernel/mcount-dyn.S | 36 +++++++++++++++++++++++++++-- > >>>> 4 files changed, 55 insertions(+), 2 deletions(-) > >>>> > >>>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig > >>>> index 615ce62422b8..12e3e91a68ae 100644 > >>>> --- a/arch/loongarch/Kconfig > >>>> +++ b/arch/loongarch/Kconfig > >>>> @@ -90,6 +90,7 @@ config LOONGARCH > >>>> select HAVE_DEBUG_STACKOVERFLOW > >>>> select HAVE_DMA_CONTIGUOUS > >>>> select HAVE_DYNAMIC_FTRACE > >>>> + select HAVE_DYNAMIC_FTRACE_WITH_REGS > >>>> select HAVE_EBPF_JIT > >>>> select HAVE_EXIT_THREAD > >>>> select HAVE_FAST_GUP > >>>> diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h > >>>> index 76ca58767f4d..a3f974a7a5ce 100644 > >>>> --- a/arch/loongarch/include/asm/ftrace.h > >>>> +++ b/arch/loongarch/include/asm/ftrace.h > >>>> @@ -28,6 +28,9 @@ struct dyn_ftrace; > >>>> int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); > >>>> #define ftrace_init_nop ftrace_init_nop > >>>> > >>>> +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > >>>> +#define ARCH_SUPPORTS_FTRACE_OPS 1 > >>>> +#endif > >>>> #endif /* CONFIG_DYNAMIC_FTRACE */ > >>>> #endif /* __ASSEMBLY__ */ > >>>> #endif /* CONFIG_FUNCTION_TRACER */ > >>>> diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c > >>>> index 3fe791b6783e..ec3d951be50c 100644 > >>>> --- a/arch/loongarch/kernel/ftrace_dyn.c > >>>> +++ b/arch/loongarch/kernel/ftrace_dyn.c > >>>> @@ -99,6 +99,23 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, > >>>> return ftrace_modify_code(pc, old, new, true); > >>>> } > >>>> > >>>> +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > >>>> +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, > >>>> + unsigned long addr) > >>>> +{ > >>>> + unsigned long pc; > >>>> + long offset; > >>>> + u32 old, new; > >>>> + > >>>> + pc = rec->ip + LOONGARCH_INSN_SIZE; > >>>> + > >>>> + old = larch_insn_gen_bl(pc, old_addr); > >>>> + new = larch_insn_gen_bl(pc, addr); > >>>> + > >>>> + return ftrace_modify_code(pc, old, new, true); > >>>> +} > >>>> +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ > >>>> + > >>>> void arch_ftrace_update_code(int command) > >>>> { > >>>> command |= FTRACE_MAY_SLEEP; > >>>> diff --git a/arch/loongarch/kernel/mcount-dyn.S b/arch/loongarch/kernel/mcount-dyn.S > >>>> index 0c12cc108e6f..02835186b463 100644 > >>>> --- a/arch/loongarch/kernel/mcount-dyn.S > >>>> +++ b/arch/loongarch/kernel/mcount-dyn.S > >>>> @@ -27,7 +27,7 @@ > >>>> * follows the LoongArch psABI well. > >>>> */ > >>>> > >>>> - .macro ftrace_regs_entry > >>>> + .macro ftrace_regs_entry allregs=0 > >>>> PTR_ADDI sp, sp, -PT_SIZE > >>>> /* Save trace function ra at PT_ERA */ > >>>> PTR_S ra, sp, PT_ERA > >>>> @@ -43,16 +43,48 @@ > >>>> PTR_S a7, sp, PT_R11 > >>>> PTR_S fp, sp, PT_R22 > >>>> > >>>> + .if \allregs > >>>> + PTR_S t0, sp, PT_R12 > >>>> + PTR_S t1, sp, PT_R13 > >>>> + PTR_S t2, sp, PT_R14 > >>>> + PTR_S t3, sp, PT_R15 > >>>> + PTR_S t4, sp, PT_R16 > >>>> + PTR_S t5, sp, PT_R17 > >>>> + PTR_S t6, sp, PT_R18 > >>>> + PTR_S t7, sp, PT_R19 > >>>> + PTR_S t8, sp, PT_R20 > >>>> + PTR_S s0, sp, PT_R23 > >>>> + PTR_S s1, sp, PT_R24 > >>>> + PTR_S s2, sp, PT_R25 > >>>> + PTR_S s3, sp, PT_R26 > >>>> + PTR_S s4, sp, PT_R27 > >>>> + PTR_S s5, sp, PT_R28 > >>>> + PTR_S s6, sp, PT_R29 > >>>> + PTR_S s7, sp, PT_R30 > >>>> + PTR_S s8, sp, PT_R31 > >>>> + PTR_S tp, sp, PT_R2 > >>>> + /* Clear it for later use as a flag sometimes. */ > >>>> + PTR_S zero, sp, PT_R0 > >>>> + PTR_S $r21, sp, PT_R21 > >>>> + .endif > >>>> + > >>>> PTR_ADDI t8, sp, PT_SIZE > >>>> PTR_S t8, sp, PT_R3 > >>>> > >>>> .endm > >>>> > >>>> SYM_CODE_START(ftrace_caller) > >>>> - ftrace_regs_entry > >>>> + ftrace_regs_entry allregs=0 > >>>> b ftrace_common > >>>> SYM_CODE_END(ftrace_caller) > >>>> > >>>> +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > >>>> +SYM_CODE_START(ftrace_regs_caller) > >>>> + ftrace_regs_entry allregs=1 > >>>> + b ftrace_common > >>>> +SYM_CODE_END(ftrace_regs_caller) > >>>> +#endif > >>>> + > >>>> SYM_CODE_START(ftrace_common) > >>>> PTR_ADDI a0, ra, -8 /* arg0: ip */ > >>>> move a1, t0 /* arg1: parent_ip */ > >>>> -- > >>>> 2.36.0 > >>>> > >>>> > >> > >> > >
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