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SubjectRe: [PATCH v6 5/9] LoongArch/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support
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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.

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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