| Message ID | 20220426015751.88582-1-lihuafei1@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] riscv: ftrace: Fix the comments about the number of ftrace instruction | expand |
On Tue, Apr 26, 2022 at 9:59 AM Li Huafei <lihuafei1@huawei.com> wrote: > > When DYNAMIC_FTRACE is enabled, we put four instructions in front of the > function for ftrace use, not five. > > Signed-off-by: Li Huafei <lihuafei1@huawei.com> > --- > arch/riscv/kernel/ftrace.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c > index 4716f4cdc038..63f457650fa4 100644 > --- a/arch/riscv/kernel/ftrace.c > +++ b/arch/riscv/kernel/ftrace.c > @@ -73,7 +73,7 @@ static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target, > } > > /* > - * Put 5 instructions with 16 bytes at the front of function within > + * Put 4 instructions with 16 bytes at the front of function within Yeah, 5 instructions are for mcount, -fpatchable-function-entry=8 cause 8 16bit instructions. Fixes: afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT") I recommend just delete "4 instructions with" - * Put 5 instructions with 16 bytes at the front of function within - * patchable function entry nops' area. + * Put 16 bytes at the front of the function within the patchable + * function entry nops' area. > * patchable function entry nops' area. > * > * 0: REG_S ra, -SZREG(sp) > -- > 2.17.1 >
On 2022/4/26 14:22, Guo Ren wrote: > On Tue, Apr 26, 2022 at 9:59 AM Li Huafei <lihuafei1@huawei.com> wrote: >> When DYNAMIC_FTRACE is enabled, we put four instructions in front of the >> function for ftrace use, not five. >> >> Signed-off-by: Li Huafei <lihuafei1@huawei.com> >> --- >> arch/riscv/kernel/ftrace.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c >> index 4716f4cdc038..63f457650fa4 100644 >> --- a/arch/riscv/kernel/ftrace.c >> +++ b/arch/riscv/kernel/ftrace.c >> @@ -73,7 +73,7 @@ static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target, >> } >> >> /* >> - * Put 5 instructions with 16 bytes at the front of function within >> + * Put 4 instructions with 16 bytes at the front of function within > Yeah, 5 instructions are for mcount, -fpatchable-function-entry=8 > cause 8 16bit instructions. I misunderstood, thanks for the clarification. > > Fixes: afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT") There is no functional fix here, do we need to add the fix tag? > > I recommend just delete "4 instructions with" > - * Put 5 instructions with 16 bytes at the front of function within > - * patchable function entry nops' area. > + * Put 16 bytes at the front of the function within the patchable > + * function entry nops' area. I agree and will use this modification for the next version, thanks! Huafei > >> * patchable function entry nops' area. >> * >> * 0: REG_S ra, -SZREG(sp) >> -- >> 2.17.1 >> >
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c index 4716f4cdc038..63f457650fa4 100644 --- a/arch/riscv/kernel/ftrace.c +++ b/arch/riscv/kernel/ftrace.c @@ -73,7 +73,7 @@ static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target, } /* - * Put 5 instructions with 16 bytes at the front of function within + * Put 4 instructions with 16 bytes at the front of function within * patchable function entry nops' area. * * 0: REG_S ra, -SZREG(sp)
When DYNAMIC_FTRACE is enabled, we put four instructions in front of the function for ftrace use, not five. Signed-off-by: Li Huafei <lihuafei1@huawei.com> --- arch/riscv/kernel/ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)