2019-10-02 19:19:29

by KP Singh

Subject: [PATCH v2] samples/bpf: Add a workaround for asm_inline

From: KP Singh <[email protected]>

This was added in:

commit eb111869301e ("compiler-types.h: add asm_inline definition")

and breaks samples/bpf as clang does not support asm __inline.

Co-developed-by: Florent Revest <[email protected]>
Signed-off-by: Florent Revest <[email protected]>
Signed-off-by: KP Singh <[email protected]>
---

Changes since v1:

- Dropped the rename from asm_workaround.h to asm_goto_workaround.h
- Dropped the fix for task_fd_query_user.c as it is updated in
https://lore.kernel.org/bpf/[email protected]/

samples/bpf/asm_goto_workaround.h | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/samples/bpf/asm_goto_workaround.h b/samples/bpf/asm_goto_workaround.h
index 7409722727ca..7048bb3594d6 100644
--- a/samples/bpf/asm_goto_workaround.h
+++ b/samples/bpf/asm_goto_workaround.h
@@ -3,7 +3,8 @@
#ifndef __ASM_GOTO_WORKAROUND_H
#define __ASM_GOTO_WORKAROUND_H

-/* this will bring in asm_volatile_goto macro definition
+/*
+ * This will bring in asm_volatile_goto and asm_inline macro definitions
* if enabled by compiler and config options.
*/
#include <linux/types.h>
@@ -13,5 +14,15 @@
#define asm_volatile_goto(x...) asm volatile("invalid use of asm_volatile_goto")
#endif

+/*
+ * asm_inline is defined as asm __inline in "include/linux/compiler_types.h"
+ * if supported by the kernel's CC (i.e CONFIG_CC_HAS_ASM_INLINE) which is not
+ * supported by CLANG.
+ */
+#ifdef asm_inline
+#undef asm_inline
+#define asm_inline asm
+#endif
+
#define volatile(x...) volatile("")
#endif
--
2.20.1

2019-10-02 21:51:24

by Andrii Nakryiko

Subject: Re: [PATCH v2] samples/bpf: Add a workaround for asm_inline

On Wed, Oct 2, 2019 at 12:17 PM KP Singh <[email protected]> wrote:
>
> From: KP Singh <[email protected]>
>
> This was added in:
>
> commit eb111869301e ("compiler-types.h: add asm_inline definition")
>
> and breaks samples/bpf as clang does not support asm __inline.
>
> Co-developed-by: Florent Revest <[email protected]>
> Signed-off-by: Florent Revest <[email protected]>
> Signed-off-by: KP Singh <[email protected]>
> ---
>
> Changes since v1:
>
> - Dropped the rename from asm_workaround.h to asm_goto_workaround.h
> - Dropped the fix for task_fd_query_user.c as it is updated in
> https://lore.kernel.org/bpf/[email protected]/
>
> samples/bpf/asm_goto_workaround.h | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/samples/bpf/asm_goto_workaround.h b/samples/bpf/asm_goto_workaround.h
> index 7409722727ca..7048bb3594d6 100644
> --- a/samples/bpf/asm_goto_workaround.h
> +++ b/samples/bpf/asm_goto_workaround.h
> @@ -3,7 +3,8 @@
> #ifndef __ASM_GOTO_WORKAROUND_H
> #define __ASM_GOTO_WORKAROUND_H
>
> -/* this will bring in asm_volatile_goto macro definition
> +/*
> + * This will bring in asm_volatile_goto and asm_inline macro definitions
> * if enabled by compiler and config options.
> */
> #include <linux/types.h>
> @@ -13,5 +14,15 @@
> #define asm_volatile_goto(x...) asm volatile("invalid use of asm_volatile_goto")
> #endif
>
> +/*
> + * asm_inline is defined as asm __inline in "include/linux/compiler_types.h"
> + * if supported by the kernel's CC (i.e CONFIG_CC_HAS_ASM_INLINE) which is not
> + * supported by CLANG.
> + */
> +#ifdef asm_inline
> +#undef asm_inline
> +#define asm_inline asm
> +#endif

Would it be better to just #undef CONFIG_CC_HAS_ASM_INLINE for BPF programs?

> +
> #define volatile(x...) volatile("")
> #endif
> --
> 2.20.1
>

2019-10-02 21:54:30

by Song Liu

Subject: Re: [PATCH v2] samples/bpf: Add a workaround for asm_inline

> On Oct 2, 2019, at 1:22 PM, Andrii Nakryiko <[email protected]> wrote:
>
> On Wed, Oct 2, 2019 at 12:17 PM KP Singh <[email protected]> wrote:
>>
>> From: KP Singh <[email protected]>
>>
>> This was added in:
>>
>> commit eb111869301e ("compiler-types.h: add asm_inline definition")
>>
>> and breaks samples/bpf as clang does not support asm __inline.
>>
>> Co-developed-by: Florent Revest <[email protected]>
>> Signed-off-by: Florent Revest <[email protected]>
>> Signed-off-by: KP Singh <[email protected]>
>> ---
>>
>> Changes since v1:
>>
>> - Dropped the rename from asm_workaround.h to asm_goto_workaround.h
>> - Dropped the fix for task_fd_query_user.c as it is updated in
>> https://lore.kernel.org/bpf/[email protected]/
>>
>> samples/bpf/asm_goto_workaround.h | 13 ++++++++++++-
>> 1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/samples/bpf/asm_goto_workaround.h b/samples/bpf/asm_goto_workaround.h
>> index 7409722727ca..7048bb3594d6 100644
>> --- a/samples/bpf/asm_goto_workaround.h
>> +++ b/samples/bpf/asm_goto_workaround.h
>> @@ -3,7 +3,8 @@
>> #ifndef __ASM_GOTO_WORKAROUND_H
>> #define __ASM_GOTO_WORKAROUND_H
>>
>> -/* this will bring in asm_volatile_goto macro definition
>> +/*
>> + * This will bring in asm_volatile_goto and asm_inline macro definitions
>> * if enabled by compiler and config options.
>> */
>> #include <linux/types.h>
>> @@ -13,5 +14,15 @@
>> #define asm_volatile_goto(x...) asm volatile("invalid use of asm_volatile_goto")
>> #endif
>>
>> +/*
>> + * asm_inline is defined as asm __inline in "include/linux/compiler_types.h"
>> + * if supported by the kernel's CC (i.e CONFIG_CC_HAS_ASM_INLINE) which is not
>> + * supported by CLANG.
>> + */
>> +#ifdef asm_inline
>> +#undef asm_inline
>> +#define asm_inline asm
>> +#endif
>
> Would it be better to just #undef CONFIG_CC_HAS_ASM_INLINE for BPF programs?

I guess that is still useful when gcc fully support BPF?

Thanks,
Song

2019-10-02 21:54:53

by Song Liu

Subject: Re: [PATCH v2] samples/bpf: Add a workaround for asm_inline

On Wed, Oct 2, 2019 at 12:17 PM KP Singh <[email protected]> wrote:
>
> From: KP Singh <[email protected]>
>
> This was added in:
>
> commit eb111869301e ("compiler-types.h: add asm_inline definition")
>
> and breaks samples/bpf as clang does not support asm __inline.
>
> Co-developed-by: Florent Revest <[email protected]>
> Signed-off-by: Florent Revest <[email protected]>
> Signed-off-by: KP Singh <[email protected]>

Acked-by: Song Liu <[email protected]>

2019-10-02 21:57:43

by Andrii Nakryiko

Subject: Re: [PATCH v2] samples/bpf: Add a workaround for asm_inline

On Wed, Oct 2, 2019 at 2:05 PM Song Liu <[email protected]> wrote:
>
>
>
> > On Oct 2, 2019, at 1:22 PM, Andrii Nakryiko <[email protected]> wrote:
> >
> > On Wed, Oct 2, 2019 at 12:17 PM KP Singh <[email protected]> wrote:
> >>
> >> From: KP Singh <[email protected]>
> >>
> >> This was added in:
> >>
> >> commit eb111869301e ("compiler-types.h: add asm_inline definition")
> >>
> >> and breaks samples/bpf as clang does not support asm __inline.
> >>
> >> Co-developed-by: Florent Revest <[email protected]>
> >> Signed-off-by: Florent Revest <[email protected]>
> >> Signed-off-by: KP Singh <[email protected]>
> >> ---
> >>
> >> Changes since v1:
> >>
> >> - Dropped the rename from asm_workaround.h to asm_goto_workaround.h
> >> - Dropped the fix for task_fd_query_user.c as it is updated in
> >> https://lore.kernel.org/bpf/[email protected]/
> >>
> >> samples/bpf/asm_goto_workaround.h | 13 ++++++++++++-
> >> 1 file changed, 12 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/samples/bpf/asm_goto_workaround.h b/samples/bpf/asm_goto_workaround.h
> >> index 7409722727ca..7048bb3594d6 100644
> >> --- a/samples/bpf/asm_goto_workaround.h
> >> +++ b/samples/bpf/asm_goto_workaround.h
> >> @@ -3,7 +3,8 @@
> >> #ifndef __ASM_GOTO_WORKAROUND_H
> >> #define __ASM_GOTO_WORKAROUND_H
> >>
> >> -/* this will bring in asm_volatile_goto macro definition
> >> +/*
> >> + * This will bring in asm_volatile_goto and asm_inline macro definitions
> >> * if enabled by compiler and config options.
> >> */
> >> #include <linux/types.h>
> >> @@ -13,5 +14,15 @@
> >> #define asm_volatile_goto(x...) asm volatile("invalid use of asm_volatile_goto")
> >> #endif
> >>
> >> +/*
> >> + * asm_inline is defined as asm __inline in "include/linux/compiler_types.h"
> >> + * if supported by the kernel's CC (i.e CONFIG_CC_HAS_ASM_INLINE) which is not
> >> + * supported by CLANG.
> >> + */
> >> +#ifdef asm_inline
> >> +#undef asm_inline
> >> +#define asm_inline asm
> >> +#endif
> >
> > Would it be better to just #undef CONFIG_CC_HAS_ASM_INLINE for BPF programs?
>
> I guess that is still useful when gcc fully support BPF?

Ah, I missed that it's Clang-specific, not BPF target-specific thing.
Yeah, then it makes sense.

Acked-by: Andrii Nakryiko <[email protected]>

>
> Thanks,
> Song
>

2019-10-03 16:01:20

by Daniel Borkmann

Subject: Re: [PATCH v2] samples/bpf: Add a workaround for asm_inline

On Wed, Oct 02, 2019 at 09:16:52PM +0200, KP Singh wrote:
> From: KP Singh <[email protected]>
>
> This was added in:
>
> commit eb111869301e ("compiler-types.h: add asm_inline definition")
>
> and breaks samples/bpf as clang does not support asm __inline.
>
> Co-developed-by: Florent Revest <[email protected]>
> Signed-off-by: Florent Revest <[email protected]>
> Signed-off-by: KP Singh <[email protected]>

Applied, thanks!