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 <[email protected]>
Tested-by: Guo Ren <[email protected]>
Signed-off-by: Guo Ren <[email protected]>
---
arch/riscv/Kconfig | 1 +
arch/riscv/include/asm/ftrace.h | 8 ++++++++
arch/riscv/kernel/mcount-dyn.S | 10 ++++++++++
3 files changed, 19 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index e0632493482f..fdf0b219a02c 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -144,6 +144,7 @@ config RISCV
select UACCESS_MEMCPY if !MMU
select ZONE_DMA32 if 64BIT
select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE)
+ select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
select HAVE_FUNCTION_GRAPH_TRACER
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 84f856a3286e..84904c1e4369 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -114,6 +114,14 @@ 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;
+}
+#define arch_ftrace_set_direct_caller(fregs, addr) \
+ __arch_ftrace_set_direct_caller(&(fregs)->regs, 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 f26e9f6e2fed..9d405baedb52 100644
--- a/arch/riscv/kernel/mcount-dyn.S
+++ b/arch/riscv/kernel/mcount-dyn.S
@@ -231,6 +231,7 @@ ENDPROC(ftrace_caller)
#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
ENTRY(ftrace_regs_caller)
+ move t1, zero
SAVE_ABI_REGS 1
PREPARE_ARGS
@@ -239,7 +240,10 @@ ftrace_regs_call:
call ftrace_stub
RESTORE_ABI_REGS 1
+ bnez t1,.Ldirect
jr t0
+.Ldirect:
+ jr t1
ENDPROC(ftrace_regs_caller)
ENTRY(ftrace_caller)
@@ -254,3 +258,9 @@ ftrace_call:
jr t0
ENDPROC(ftrace_caller)
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
+SYM_CODE_START(ftrace_stub_direct_tramp)
+ jr t0
+SYM_CODE_END(ftrace_stub_direct_tramp)
+#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
--
2.20.1
Song Shuai <[email protected]> writes:
> 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 <[email protected]>
> Tested-by: Guo Ren <[email protected]>
> Signed-off-by: Guo Ren <[email protected]>
> ---
> arch/riscv/Kconfig | 1 +
> arch/riscv/include/asm/ftrace.h | 8 ++++++++
> arch/riscv/kernel/mcount-dyn.S | 10 ++++++++++
> 3 files changed, 19 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index e0632493482f..fdf0b219a02c 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -144,6 +144,7 @@ config RISCV
> select UACCESS_MEMCPY if !MMU
> select ZONE_DMA32 if 64BIT
> select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE)
> + select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
> select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
> select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
> select HAVE_FUNCTION_GRAPH_TRACER
> diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
> index 84f856a3286e..84904c1e4369 100644
> --- a/arch/riscv/include/asm/ftrace.h
> +++ b/arch/riscv/include/asm/ftrace.h
> @@ -114,6 +114,14 @@ 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;
> +}
> +#define arch_ftrace_set_direct_caller(fregs, addr) \
> + __arch_ftrace_set_direct_caller(&(fregs)->regs, 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 f26e9f6e2fed..9d405baedb52 100644
> --- a/arch/riscv/kernel/mcount-dyn.S
> +++ b/arch/riscv/kernel/mcount-dyn.S
> @@ -231,6 +231,7 @@ ENDPROC(ftrace_caller)
>
> #else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
> ENTRY(ftrace_regs_caller)
> + move t1, zero
Please use "mv", and not "move" [1].
> SAVE_ABI_REGS 1
> PREPARE_ARGS
>
> @@ -239,7 +240,10 @@ ftrace_regs_call:
> call ftrace_stub
>
> RESTORE_ABI_REGS 1
> + bnez t1,.Ldirect
> jr t0
> +.Ldirect:
> + jr t1
Again, while you're doing changes here, please try to align op/operands.
Wearing my BPF hat, I'm happy to finally get DIRECT_CALLS support!
This does not take the WITH_CALL_OPS approach Mark suggested in the v7
threads, but given that text patching story on RISC-V is still a bit sad
(inconsistency in the RV tree, no specification, cannot work with
preempt, ...) I'd say this approach is OK for now, and we can change to
WITH_CALL_OPS later in a wider "let's improve RISC-V textpatching" work.
Thoughts?
Björn
[1] https://github.com/riscv-non-isa/riscv-asm-manual/blob/master/riscv-asm.md#-a-listing-of-standard-risc-v-pseudoinstructions
Björn Töpel <[email protected]> 于2023年5月11日周四 07:19写道：
>
> Song Shuai <[email protected]> writes:
>
> > 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 <[email protected]>
> > Tested-by: Guo Ren <[email protected]>
> > Signed-off-by: Guo Ren <[email protected]>
> > ---
> > arch/riscv/Kconfig | 1 +
> > arch/riscv/include/asm/ftrace.h | 8 ++++++++
> > arch/riscv/kernel/mcount-dyn.S | 10 ++++++++++
> > 3 files changed, 19 insertions(+)
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index e0632493482f..fdf0b219a02c 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -144,6 +144,7 @@ config RISCV
> > select UACCESS_MEMCPY if !MMU
> > select ZONE_DMA32 if 64BIT
> > select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE)
> > + select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
> > select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
> > select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
> > select HAVE_FUNCTION_GRAPH_TRACER
> > diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
> > index 84f856a3286e..84904c1e4369 100644
> > --- a/arch/riscv/include/asm/ftrace.h
> > +++ b/arch/riscv/include/asm/ftrace.h
> > @@ -114,6 +114,14 @@ 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;
> > +}
> > +#define arch_ftrace_set_direct_caller(fregs, addr) \
> > + __arch_ftrace_set_direct_caller(&(fregs)->regs, 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 f26e9f6e2fed..9d405baedb52 100644
> > --- a/arch/riscv/kernel/mcount-dyn.S
> > +++ b/arch/riscv/kernel/mcount-dyn.S
> > @@ -231,6 +231,7 @@ ENDPROC(ftrace_caller)
> >
> > #else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
> > ENTRY(ftrace_regs_caller)
> > + move t1, zero
>
> Please use "mv", and not "move" [1].
Will fix it up in the next version
>
> > SAVE_ABI_REGS 1
> > PREPARE_ARGS
> >
> > @@ -239,7 +240,10 @@ ftrace_regs_call:
> > call ftrace_stub
> >
> > RESTORE_ABI_REGS 1
> > + bnez t1,.Ldirect
> > jr t0
> > +.Ldirect:
> > + jr t1
>
> Again, while you're doing changes here, please try to align op/operands.
>
> Wearing my BPF hat, I'm happy to finally get DIRECT_CALLS support!
>
> This does not take the WITH_CALL_OPS approach Mark suggested in the v7
> threads, but given that text patching story on RISC-V is still a bit sad
> (inconsistency in the RV tree, no specification, cannot work with
> preempt, ...) I'd say this approach is OK for now, and we can change to
> WITH_CALL_OPS later in a wider "let's improve RISC-V textpatching" work.
>
> Thoughts?
>
>
> Björn
>
> [1] https://github.com/riscv-non-isa/riscv-asm-manual/blob/master/riscv-asm.md#-a-listing-of-standard-risc-v-pseudoinstructions
--
Thanks,
Song
Hi,
On 11.05.2023 10:19, Björn Töpel wrote:
> Song Shuai <[email protected]> writes:
>
>> 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 <[email protected]>
>> Tested-by: Guo Ren <[email protected]>
>> Signed-off-by: Guo Ren <[email protected]>
>> ---
>> arch/riscv/Kconfig | 1 +
>> arch/riscv/include/asm/ftrace.h | 8 ++++++++
>> arch/riscv/kernel/mcount-dyn.S | 10 ++++++++++
>> 3 files changed, 19 insertions(+)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index e0632493482f..fdf0b219a02c 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -144,6 +144,7 @@ config RISCV
>> select UACCESS_MEMCPY if !MMU
>> select ZONE_DMA32 if 64BIT
>> select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE)
>> + select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
>> select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
>> select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
>> select HAVE_FUNCTION_GRAPH_TRACER
>> diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
>> index 84f856a3286e..84904c1e4369 100644
>> --- a/arch/riscv/include/asm/ftrace.h
>> +++ b/arch/riscv/include/asm/ftrace.h
>> @@ -114,6 +114,14 @@ 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;
>> +}
>> +#define arch_ftrace_set_direct_caller(fregs, addr) \
>> + __arch_ftrace_set_direct_caller(&(fregs)->regs, 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 f26e9f6e2fed..9d405baedb52 100644
>> --- a/arch/riscv/kernel/mcount-dyn.S
>> +++ b/arch/riscv/kernel/mcount-dyn.S
>> @@ -231,6 +231,7 @@ ENDPROC(ftrace_caller)
>>
>> #else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
>> ENTRY(ftrace_regs_caller)
>> + move t1, zero
>
> Please use "mv", and not "move" [1].
>
>> SAVE_ABI_REGS 1
>> PREPARE_ARGS
>>
>> @@ -239,7 +240,10 @@ ftrace_regs_call:
>> call ftrace_stub
>>
>> RESTORE_ABI_REGS 1
>> + bnez t1,.Ldirect
>> jr t0
>> +.Ldirect:
>> + jr t1
>
> Again, while you're doing changes here, please try to align op/operands.
>
> Wearing my BPF hat, I'm happy to finally get DIRECT_CALLS support!
>
> This does not take the WITH_CALL_OPS approach Mark suggested in the v7
> threads, but given that text patching story on RISC-V is still a bit sad
> (inconsistency in the RV tree, no specification, cannot work with
> preempt, ...) I'd say this approach is OK for now, and we can change to
> WITH_CALL_OPS later in a wider "let's improve RISC-V textpatching" work.
>
> Thoughts?
The WITH_CALL_OPS approach seems to need much more time and effort, so,
yes, I'd also use this implementation of DIRECT_CALLS for now. Other
improvements could wait for the future "big patching rework".
FWIW, the implementation of kprobes for RISC-V has been improving
gradually too, not everything was done in the first very patchset, but
it was usable nonetheless.
I have not tested this particular version of this
DYNAMIC_FTRACE_WITH_DIRECT_CALLS series, only some previous ones - there
were no outstanding problems there. The code looks sane to me.
>
>
> Björn
>
> [1] https://github.com/riscv-non-isa/riscv-asm-manual/blob/master/riscv-asm.md#-a-listing-of-standard-risc-v-pseudoinstructions
>
Regards,
Evgenii
On Thu, May 11, 2023 at 9:30 PM Evgenii Shatokhin <[email protected]> wrote:
>
> Hi,
>
> On 11.05.2023 10:19, Björn Töpel wrote:
> > Song Shuai <[email protected]> writes:
> >
> >> 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 <[email protected]>
> >> Tested-by: Guo Ren <[email protected]>
> >> Signed-off-by: Guo Ren <[email protected]>
> >> ---
> >> arch/riscv/Kconfig | 1 +
> >> arch/riscv/include/asm/ftrace.h | 8 ++++++++
> >> arch/riscv/kernel/mcount-dyn.S | 10 ++++++++++
> >> 3 files changed, 19 insertions(+)
> >>
> >> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> >> index e0632493482f..fdf0b219a02c 100644
> >> --- a/arch/riscv/Kconfig
> >> +++ b/arch/riscv/Kconfig
> >> @@ -144,6 +144,7 @@ config RISCV
> >> select UACCESS_MEMCPY if !MMU
> >> select ZONE_DMA32 if 64BIT
> >> select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE)
> >> + select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
> >> select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
> >> select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
> >> select HAVE_FUNCTION_GRAPH_TRACER
> >> diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
> >> index 84f856a3286e..84904c1e4369 100644
> >> --- a/arch/riscv/include/asm/ftrace.h
> >> +++ b/arch/riscv/include/asm/ftrace.h
> >> @@ -114,6 +114,14 @@ 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;
> >> +}
> >> +#define arch_ftrace_set_direct_caller(fregs, addr) \
> >> + __arch_ftrace_set_direct_caller(&(fregs)->regs, 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 f26e9f6e2fed..9d405baedb52 100644
> >> --- a/arch/riscv/kernel/mcount-dyn.S
> >> +++ b/arch/riscv/kernel/mcount-dyn.S
> >> @@ -231,6 +231,7 @@ ENDPROC(ftrace_caller)
> >>
> >> #else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
> >> ENTRY(ftrace_regs_caller)
> >> + move t1, zero
> >
> > Please use "mv", and not "move" [1].
> >
> >> SAVE_ABI_REGS 1
> >> PREPARE_ARGS
> >>
> >> @@ -239,7 +240,10 @@ ftrace_regs_call:
> >> call ftrace_stub
> >>
> >> RESTORE_ABI_REGS 1
> >> + bnez t1,.Ldirect
> >> jr t0
> >> +.Ldirect:
> >> + jr t1
> >
> > Again, while you're doing changes here, please try to align op/operands.
> >
> > Wearing my BPF hat, I'm happy to finally get DIRECT_CALLS support!
> >
> > This does not take the WITH_CALL_OPS approach Mark suggested in the v7
> > threads, but given that text patching story on RISC-V is still a bit sad
> > (inconsistency in the RV tree, no specification, cannot work with
> > preempt, ...) I'd say this approach is OK for now, and we can change to
> > WITH_CALL_OPS later in a wider "let's improve RISC-V textpatching" work.
> >
> > Thoughts?
>
> The WITH_CALL_OPS approach seems to need much more time and effort, so,
> yes, I'd also use this implementation of DIRECT_CALLS for now. Other
> improvements could wait for the future "big patching rework".
I agree to make DIRECT_CALLS merged first, WITH_CALL_OPS is another
"big patching rework".
>
> FWIW, the implementation of kprobes for RISC-V has been improving
> gradually too, not everything was done in the first very patchset, but
> it was usable nonetheless.
>
> I have not tested this particular version of this
> DYNAMIC_FTRACE_WITH_DIRECT_CALLS series, only some previous ones - there
> were no outstanding problems there. The code looks sane to me.
>
> >
> >
> > Björn
> >
> > [1] https://github.com/riscv-non-isa/riscv-asm-manual/blob/master/riscv-asm.md#-a-listing-of-standard-risc-v-pseudoinstructions
> >
>
> Regards,
> Evgenii
>
>
--
Best Regards
Guo Ren