Samuel reported that the static branch usage in cpu_relax() breaks
building with CONFIG_CC_OPTIMIZE_FOR_SIZE:
In file included from <command-line>:
./arch/riscv/include/asm/jump_label.h: In function 'cpu_relax':
././include/linux/compiler_types.h:285:33: warning: 'asm' operand 0
probably does not match constraints
285 | #define asm_volatile_goto(x...) asm goto(x)
| ^~~
./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
'asm_volatile_goto'
41 | asm_volatile_goto(
| ^~~~~~~~~~~~~~~~~
././include/linux/compiler_types.h:285:33: error: impossible constraint
in 'asm'
285 | #define asm_volatile_goto(x...) asm goto(x)
| ^~~
./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
'asm_volatile_goto'
41 | asm_volatile_goto(
| ^~~~~~~~~~~~~~~~~
make[1]: *** [scripts/Makefile.build:249:
arch/riscv/kernel/vdso/vgettimeofday.o] Error 1
make: *** [arch/riscv/Makefile:128: vdso_prepare] Error 2
Maybe "-Os" prevents GCC from detecting that the key/branch arguments
can be treated as constants and used as immediate operands. Inspired
by x86's commit 864b435514b2("x86/jump_label: Mark arguments as const to
satisfy asm constraints"), and as pointed out by Steven: "The "i"
constraint needs to be a constant.", let's do similar modifications to
riscv.
Tested by CC_OPTIMIZE_FOR_SIZE + gcc and CC_OPTIMIZE_FOR_SIZE + clang.
Link: https://lore.kernel.org/linux-riscv/[email protected]/
Link: https://lore.kernel.org/all/[email protected]/
Fixes: 8eb060e10185 ("arch/riscv: add Zihintpause support")
Reported-by: Samuel Holland <[email protected]>
Signed-off-by: Jisheng Zhang <[email protected]>
Reviewed-by: Andrew Jones <[email protected]>
---
since v1:
- add Reported-by, Reviewed-by, Fixes and Link tag
arch/riscv/include/asm/jump_label.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
index 38af2ec7b9bf..6d58bbb5da46 100644
--- a/arch/riscv/include/asm/jump_label.h
+++ b/arch/riscv/include/asm/jump_label.h
@@ -14,8 +14,8 @@
#define JUMP_LABEL_NOP_SIZE 4
-static __always_inline bool arch_static_branch(struct static_key *key,
- bool branch)
+static __always_inline bool arch_static_branch(struct static_key * const key,
+ const bool branch)
{
asm_volatile_goto(
" .option push \n\t"
@@ -35,8 +35,8 @@ static __always_inline bool arch_static_branch(struct static_key *key,
return true;
}
-static __always_inline bool arch_static_branch_jump(struct static_key *key,
- bool branch)
+static __always_inline bool arch_static_branch_jump(struct static_key * const key,
+ const bool branch)
{
asm_volatile_goto(
" .option push \n\t"
--
2.37.2
Am Samstag, 8. Oktober 2022, 16:54:37 CEST schrieb Jisheng Zhang:
> Samuel reported that the static branch usage in cpu_relax() breaks
> building with CONFIG_CC_OPTIMIZE_FOR_SIZE:
>
> In file included from <command-line>:
> ./arch/riscv/include/asm/jump_label.h: In function 'cpu_relax':
> ././include/linux/compiler_types.h:285:33: warning: 'asm' operand 0
> probably does not match constraints
> 285 | #define asm_volatile_goto(x...) asm goto(x)
> | ^~~
> ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
> 'asm_volatile_goto'
> 41 | asm_volatile_goto(
> | ^~~~~~~~~~~~~~~~~
> ././include/linux/compiler_types.h:285:33: error: impossible constraint
> in 'asm'
> 285 | #define asm_volatile_goto(x...) asm goto(x)
> | ^~~
> ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
> 'asm_volatile_goto'
> 41 | asm_volatile_goto(
> | ^~~~~~~~~~~~~~~~~
> make[1]: *** [scripts/Makefile.build:249:
> arch/riscv/kernel/vdso/vgettimeofday.o] Error 1
> make: *** [arch/riscv/Makefile:128: vdso_prepare] Error 2
>
> Maybe "-Os" prevents GCC from detecting that the key/branch arguments
> can be treated as constants and used as immediate operands. Inspired
> by x86's commit 864b435514b2("x86/jump_label: Mark arguments as const to
> satisfy asm constraints"), and as pointed out by Steven: "The "i"
> constraint needs to be a constant.", let's do similar modifications to
> riscv.
>
> Tested by CC_OPTIMIZE_FOR_SIZE + gcc and CC_OPTIMIZE_FOR_SIZE + clang.
>
> Link: https://lore.kernel.org/linux-riscv/[email protected]/
> Link: https://lore.kernel.org/all/[email protected]/
> Fixes: 8eb060e10185 ("arch/riscv: add Zihintpause support")
> Reported-by: Samuel Holland <[email protected]>
> Signed-off-by: Jisheng Zhang <[email protected]>
> Reviewed-by: Andrew Jones <[email protected]>
I ran into the same build-issue when enabling CC_OPTIMIZE_FOR_SIZE
and this patch fixes it, so
Tested-by: Heiko Stuebner <[email protected]>
Hey Jisheng,
LKP reported an error that seems to only have gone to myself & Samuel,
but the branch it's complaining about is your v1:
https://lore.kernel.org/lkml/[email protected]/
Any idea what the story is here?
Thanks,
Conor.
On Sat, Oct 08, 2022 at 10:54:37PM +0800, Jisheng Zhang wrote:
> Samuel reported that the static branch usage in cpu_relax() breaks
> building with CONFIG_CC_OPTIMIZE_FOR_SIZE:
>
> In file included from <command-line>:
> ./arch/riscv/include/asm/jump_label.h: In function 'cpu_relax':
> ././include/linux/compiler_types.h:285:33: warning: 'asm' operand 0
> probably does not match constraints
> 285 | #define asm_volatile_goto(x...) asm goto(x)
> | ^~~
> ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
> 'asm_volatile_goto'
> 41 | asm_volatile_goto(
> | ^~~~~~~~~~~~~~~~~
> ././include/linux/compiler_types.h:285:33: error: impossible constraint
> in 'asm'
> 285 | #define asm_volatile_goto(x...) asm goto(x)
> | ^~~
> ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
> 'asm_volatile_goto'
> 41 | asm_volatile_goto(
> | ^~~~~~~~~~~~~~~~~
> make[1]: *** [scripts/Makefile.build:249:
> arch/riscv/kernel/vdso/vgettimeofday.o] Error 1
> make: *** [arch/riscv/Makefile:128: vdso_prepare] Error 2
>
> Maybe "-Os" prevents GCC from detecting that the key/branch arguments
> can be treated as constants and used as immediate operands. Inspired
> by x86's commit 864b435514b2("x86/jump_label: Mark arguments as const to
> satisfy asm constraints"), and as pointed out by Steven: "The "i"
> constraint needs to be a constant.", let's do similar modifications to
> riscv.
>
> Tested by CC_OPTIMIZE_FOR_SIZE + gcc and CC_OPTIMIZE_FOR_SIZE + clang.
>
> Link: https://lore.kernel.org/linux-riscv/[email protected]/
> Link: https://lore.kernel.org/all/[email protected]/
> Fixes: 8eb060e10185 ("arch/riscv: add Zihintpause support")
> Reported-by: Samuel Holland <[email protected]>
> Signed-off-by: Jisheng Zhang <[email protected]>
> Reviewed-by: Andrew Jones <[email protected]>
> ---
>
> since v1:
> - add Reported-by, Reviewed-by, Fixes and Link tag
>
> arch/riscv/include/asm/jump_label.h | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
> index 38af2ec7b9bf..6d58bbb5da46 100644
> --- a/arch/riscv/include/asm/jump_label.h
> +++ b/arch/riscv/include/asm/jump_label.h
> @@ -14,8 +14,8 @@
>
> #define JUMP_LABEL_NOP_SIZE 4
>
> -static __always_inline bool arch_static_branch(struct static_key *key,
> - bool branch)
> +static __always_inline bool arch_static_branch(struct static_key * const key,
> + const bool branch)
> {
> asm_volatile_goto(
> " .option push \n\t"
> @@ -35,8 +35,8 @@ static __always_inline bool arch_static_branch(struct static_key *key,
> return true;
> }
>
> -static __always_inline bool arch_static_branch_jump(struct static_key *key,
> - bool branch)
> +static __always_inline bool arch_static_branch_jump(struct static_key * const key,
> + const bool branch)
> {
> asm_volatile_goto(
> " .option push \n\t"
> --
> 2.37.2
>
On Sat, 8 Oct 2022 22:54:37 +0800, Jisheng Zhang wrote:
> Samuel reported that the static branch usage in cpu_relax() breaks
> building with CONFIG_CC_OPTIMIZE_FOR_SIZE:
>
> In file included from <command-line>:
> ./arch/riscv/include/asm/jump_label.h: In function 'cpu_relax':
> ././include/linux/compiler_types.h:285:33: warning: 'asm' operand 0
> probably does not match constraints
> 285 | #define asm_volatile_goto(x...) asm goto(x)
> | ^~~
> ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
> 'asm_volatile_goto'
> 41 | asm_volatile_goto(
> | ^~~~~~~~~~~~~~~~~
> ././include/linux/compiler_types.h:285:33: error: impossible constraint
> in 'asm'
> 285 | #define asm_volatile_goto(x...) asm goto(x)
> | ^~~
> ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
> 'asm_volatile_goto'
> 41 | asm_volatile_goto(
> | ^~~~~~~~~~~~~~~~~
> make[1]: *** [scripts/Makefile.build:249:
> arch/riscv/kernel/vdso/vgettimeofday.o] Error 1
> make: *** [arch/riscv/Makefile:128: vdso_prepare] Error 2
>
> [...]
Applied, thanks!
[1/1] riscv: jump_label: mark arguments as const to satisfy asm constraints
commit: 89fd4a1df829187d4d35f6a520cc531de622e6f0
Best regards,
--
Palmer Dabbelt <[email protected]>
On Wed, Oct 12, 2022 at 02:28:16PM +0100, Conor Dooley wrote:
> Hey Jisheng,
Hi Conor,
> LKP reported an error that seems to only have gone to myself & Samuel,
> but the branch it's complaining about is your v1:
> https://lore.kernel.org/lkml/[email protected]/
>
> Any idea what the story is here?
I tried the config in the link, I can reproduce the build error w/
and w/o the my patch. So I think the root cause of the build error
is a different story. I have a fix in local repo, will send it out
soon.
Thanks
>
> Thanks,
> Conor.
>
> On Sat, Oct 08, 2022 at 10:54:37PM +0800, Jisheng Zhang wrote:
> > Samuel reported that the static branch usage in cpu_relax() breaks
> > building with CONFIG_CC_OPTIMIZE_FOR_SIZE:
> >
> > In file included from <command-line>:
> > ./arch/riscv/include/asm/jump_label.h: In function 'cpu_relax':
> > ././include/linux/compiler_types.h:285:33: warning: 'asm' operand 0
> > probably does not match constraints
> > 285 | #define asm_volatile_goto(x...) asm goto(x)
> > | ^~~
> > ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
> > 'asm_volatile_goto'
> > 41 | asm_volatile_goto(
> > | ^~~~~~~~~~~~~~~~~
> > ././include/linux/compiler_types.h:285:33: error: impossible constraint
> > in 'asm'
> > 285 | #define asm_volatile_goto(x...) asm goto(x)
> > | ^~~
> > ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
> > 'asm_volatile_goto'
> > 41 | asm_volatile_goto(
> > | ^~~~~~~~~~~~~~~~~
> > make[1]: *** [scripts/Makefile.build:249:
> > arch/riscv/kernel/vdso/vgettimeofday.o] Error 1
> > make: *** [arch/riscv/Makefile:128: vdso_prepare] Error 2
> >
> > Maybe "-Os" prevents GCC from detecting that the key/branch arguments
> > can be treated as constants and used as immediate operands. Inspired
> > by x86's commit 864b435514b2("x86/jump_label: Mark arguments as const to
> > satisfy asm constraints"), and as pointed out by Steven: "The "i"
> > constraint needs to be a constant.", let's do similar modifications to
> > riscv.
> >
> > Tested by CC_OPTIMIZE_FOR_SIZE + gcc and CC_OPTIMIZE_FOR_SIZE + clang.
> >
> > Link: https://lore.kernel.org/linux-riscv/[email protected]/
> > Link: https://lore.kernel.org/all/[email protected]/
> > Fixes: 8eb060e10185 ("arch/riscv: add Zihintpause support")
> > Reported-by: Samuel Holland <[email protected]>
> > Signed-off-by: Jisheng Zhang <[email protected]>
> > Reviewed-by: Andrew Jones <[email protected]>
> > ---
> >
> > since v1:
> > - add Reported-by, Reviewed-by, Fixes and Link tag
> >
> > arch/riscv/include/asm/jump_label.h | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
> > index 38af2ec7b9bf..6d58bbb5da46 100644
> > --- a/arch/riscv/include/asm/jump_label.h
> > +++ b/arch/riscv/include/asm/jump_label.h
> > @@ -14,8 +14,8 @@
> >
> > #define JUMP_LABEL_NOP_SIZE 4
> >
> > -static __always_inline bool arch_static_branch(struct static_key *key,
> > - bool branch)
> > +static __always_inline bool arch_static_branch(struct static_key * const key,
> > + const bool branch)
> > {
> > asm_volatile_goto(
> > " .option push \n\t"
> > @@ -35,8 +35,8 @@ static __always_inline bool arch_static_branch(struct static_key *key,
> > return true;
> > }
> >
> > -static __always_inline bool arch_static_branch_jump(struct static_key *key,
> > - bool branch)
> > +static __always_inline bool arch_static_branch_jump(struct static_key * const key,
> > + const bool branch)
> > {
> > asm_volatile_goto(
> > " .option push \n\t"
> > --
> > 2.37.2
> >