| Message ID | 20230510101857.2953955-4-suagrfillet@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | riscv: Optimize function trace | expand |
Song Shuai <suagrfillet@gmail.com> 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 <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 | 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 <bjorn@kernel.org> 于2023年5月11日周四 07:19写道： > > Song Shuai <suagrfillet@gmail.com> 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 <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 | 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 <suagrfillet@gmail.com> 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 <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 | 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 <e.shatokhin@yadro.com> wrote: > > Hi, > > On 11.05.2023 10:19, Björn Töpel wrote: > > Song Shuai <suagrfillet@gmail.com> 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 <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 | 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 > >
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 */