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* [PATCH bpf-next 0/2] Modify BPF_JIT_ALWAYS_ON and BPF_JIT_DEFAULT_ON
@ 2022-02-11  8:57 Tiezhu Yang
  2022-02-11  8:57 ` [PATCH bpf-next 1/2] bpf: Add some description about BPF_JIT_ALWAYS_ON in Kconfig Tiezhu Yang
  2022-02-11  8:57 ` [PATCH bpf-next 2/2] bpf: Make BPF_JIT_DEFAULT_ON selectable " Tiezhu Yang
  0 siblings, 2 replies; 6+ messages in thread
From: Tiezhu Yang @ 2022-02-11  8:57 UTC (permalink / raw)
  To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
	Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
	KP Singh
  Cc: Xuefeng Li, netdev, bpf, linux-kernel

Tiezhu Yang (2):
  bpf: Add some description about BPF_JIT_ALWAYS_ON in Kconfig
  bpf: Make BPF_JIT_DEFAULT_ON selectable in Kconfig

 kernel/bpf/Kconfig | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

-- 
2.1.0


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH bpf-next 1/2] bpf: Add some description about BPF_JIT_ALWAYS_ON in Kconfig
  2022-02-11  8:57 [PATCH bpf-next 0/2] Modify BPF_JIT_ALWAYS_ON and BPF_JIT_DEFAULT_ON Tiezhu Yang
@ 2022-02-11  8:57 ` Tiezhu Yang
  2022-02-11 14:44   ` Daniel Borkmann
  2022-02-11  8:57 ` [PATCH bpf-next 2/2] bpf: Make BPF_JIT_DEFAULT_ON selectable " Tiezhu Yang
  1 sibling, 1 reply; 6+ messages in thread
From: Tiezhu Yang @ 2022-02-11  8:57 UTC (permalink / raw)
  To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
	Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
	KP Singh
  Cc: Xuefeng Li, netdev, bpf, linux-kernel

When CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently
set to 1 and setting any other value than that will return in failure.

Add the above description in the help text of BPF_JIT_ALWAYS_ON, and then
we can distinguish between BPF_JIT_ALWAYS_ON and BPF_JIT_DEFAULT_ON.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 kernel/bpf/Kconfig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
index d24d518..88409f8 100644
--- a/kernel/bpf/Kconfig
+++ b/kernel/bpf/Kconfig
@@ -58,6 +58,9 @@ config BPF_JIT_ALWAYS_ON
 	  Enables BPF JIT and removes BPF interpreter to avoid speculative
 	  execution of BPF instructions by the interpreter.
 
+	  When CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently
+	  set to 1 and setting any other value than that will return in failure.
+
 config BPF_JIT_DEFAULT_ON
 	def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
 	depends on HAVE_EBPF_JIT && BPF_JIT
-- 
2.1.0


^ permalink raw reply related	[flat|nested] 6+ messages in thread

* [PATCH bpf-next 2/2] bpf: Make BPF_JIT_DEFAULT_ON selectable in Kconfig
  2022-02-11  8:57 [PATCH bpf-next 0/2] Modify BPF_JIT_ALWAYS_ON and BPF_JIT_DEFAULT_ON Tiezhu Yang
  2022-02-11  8:57 ` [PATCH bpf-next 1/2] bpf: Add some description about BPF_JIT_ALWAYS_ON in Kconfig Tiezhu Yang
@ 2022-02-11  8:57 ` Tiezhu Yang
  2022-02-11 10:23   ` Daniel Borkmann
  1 sibling, 1 reply; 6+ messages in thread
From: Tiezhu Yang @ 2022-02-11  8:57 UTC (permalink / raw)
  To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
	Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
	KP Singh
  Cc: Xuefeng Li, netdev, bpf, linux-kernel

Currently, it is not possible to set bpf_jit_enable to 1 by default
and the users can change it to 0 or 2, it seems bad for some users,
make BPF_JIT_DEFAULT_ON selectable to give them a chance.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 kernel/bpf/Kconfig | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
index 88409f8..28b7d71 100644
--- a/kernel/bpf/Kconfig
+++ b/kernel/bpf/Kconfig
@@ -54,6 +54,7 @@ config BPF_JIT
 config BPF_JIT_ALWAYS_ON
 	bool "Permanently enable BPF JIT and remove BPF interpreter"
 	depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
+	select BPF_JIT_DEFAULT_ON
 	help
 	  Enables BPF JIT and removes BPF interpreter to avoid speculative
 	  execution of BPF instructions by the interpreter.
@@ -62,8 +63,16 @@ config BPF_JIT_ALWAYS_ON
 	  set to 1 and setting any other value than that will return in failure.
 
 config BPF_JIT_DEFAULT_ON
-	def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
-	depends on HAVE_EBPF_JIT && BPF_JIT
+	bool "Defaultly enable BPF JIT and remove BPF interpreter"
+	default y if ARCH_WANT_DEFAULT_BPF_JIT
+	depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
+	help
+	  Enables BPF JIT and removes BPF interpreter to avoid speculative
+	  execution of BPF instructions by the interpreter.
+
+	  When CONFIG_BPF_JIT_DEFAULT_ON is enabled but CONFIG_BPF_JIT_ALWAYS_ON
+	  is disabled, bpf_jit_enable is set to 1 by default and can be changed
+	  to 0 or 2.
 
 config BPF_UNPRIV_DEFAULT_OFF
 	bool "Disable unprivileged BPF by default"
-- 
2.1.0


^ permalink raw reply related	[flat|nested] 6+ messages in thread

* Re: [PATCH bpf-next 2/2] bpf: Make BPF_JIT_DEFAULT_ON selectable in Kconfig
  2022-02-11  8:57 ` [PATCH bpf-next 2/2] bpf: Make BPF_JIT_DEFAULT_ON selectable " Tiezhu Yang
@ 2022-02-11 10:23   ` Daniel Borkmann
  2022-02-12  2:40     ` Tiezhu Yang
  0 siblings, 1 reply; 6+ messages in thread
From: Daniel Borkmann @ 2022-02-11 10:23 UTC (permalink / raw)
  To: Tiezhu Yang, Alexei Starovoitov, Andrii Nakryiko,
	Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
	KP Singh
  Cc: Xuefeng Li, netdev, bpf, linux-kernel

On 2/11/22 9:57 AM, Tiezhu Yang wrote:
> Currently, it is not possible to set bpf_jit_enable to 1 by default
> and the users can change it to 0 or 2, it seems bad for some users,
> make BPF_JIT_DEFAULT_ON selectable to give them a chance.

I'm not fully sure I follow the above, so you are saying that a kconfig of
!BPF_JIT_ALWAYS_ON and ARCH_WANT_DEFAULT_BPF_JIT, enables BPF_JIT_DEFAULT_ON
however in such setting you are not able to reset bpf_jit_enable back to 0 at
runtime?

Thanks,
Daniel

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH bpf-next 1/2] bpf: Add some description about BPF_JIT_ALWAYS_ON in Kconfig
  2022-02-11  8:57 ` [PATCH bpf-next 1/2] bpf: Add some description about BPF_JIT_ALWAYS_ON in Kconfig Tiezhu Yang
@ 2022-02-11 14:44   ` Daniel Borkmann
  0 siblings, 0 replies; 6+ messages in thread
From: Daniel Borkmann @ 2022-02-11 14:44 UTC (permalink / raw)
  To: Tiezhu Yang, Alexei Starovoitov, Andrii Nakryiko,
	Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
	KP Singh
  Cc: Xuefeng Li, netdev, bpf, linux-kernel

On 2/11/22 9:57 AM, Tiezhu Yang wrote:
> When CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently
> set to 1 and setting any other value than that will return in failure.
> 
> Add the above description in the help text of BPF_JIT_ALWAYS_ON, and then
> we can distinguish between BPF_JIT_ALWAYS_ON and BPF_JIT_DEFAULT_ON.
> 
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>   kernel/bpf/Kconfig | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
> index d24d518..88409f8 100644
> --- a/kernel/bpf/Kconfig
> +++ b/kernel/bpf/Kconfig
> @@ -58,6 +58,9 @@ config BPF_JIT_ALWAYS_ON
>   	  Enables BPF JIT and removes BPF interpreter to avoid speculative
>   	  execution of BPF instructions by the interpreter.
>   
> +	  When CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently
> +	  set to 1 and setting any other value than that will return in failure.

Small nit here: lets use the full path (/proc/sys/net/core/bpf_jit_enable) in order
to be consistent with the other descriptions in this Kconfig.

>   config BPF_JIT_DEFAULT_ON
>   	def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
>   	depends on HAVE_EBPF_JIT && BPF_JIT
> 


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH bpf-next 2/2] bpf: Make BPF_JIT_DEFAULT_ON selectable in Kconfig
  2022-02-11 10:23   ` Daniel Borkmann
@ 2022-02-12  2:40     ` Tiezhu Yang
  0 siblings, 0 replies; 6+ messages in thread
From: Tiezhu Yang @ 2022-02-12  2:40 UTC (permalink / raw)
  To: Daniel Borkmann, Alexei Starovoitov, Andrii Nakryiko,
	Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
	KP Singh
  Cc: Xuefeng Li, netdev, bpf, linux-kernel



On 02/11/2022 06:23 PM, Daniel Borkmann wrote:
> On 2/11/22 9:57 AM, Tiezhu Yang wrote:
>> Currently, it is not possible to set bpf_jit_enable to 1 by default
>> and the users can change it to 0 or 2, it seems bad for some users,
>> make BPF_JIT_DEFAULT_ON selectable to give them a chance.
>
> I'm not fully sure I follow the above, so you are saying that a kconfig of
> !BPF_JIT_ALWAYS_ON and ARCH_WANT_DEFAULT_BPF_JIT, enables
> BPF_JIT_DEFAULT_ON
> however in such setting you are not able to reset bpf_jit_enable back to
> 0 at
> runtime?

Oh, no. Sorry for the unclear description.

currently, only x86, arm64 and s390 select ARCH_WANT_DEFAULT_BPF_JIT,
the other archs do not select ARCH_WANT_DEFAULT_BPF_JIT. On the archs
without ARCH_WANT_DEFAULT_BPF_JIT, if we want to set bpf_jit_enable to
1 by default, the only way is to enable CONFIG_BPF_JIT_ALWAYS_ON, then
the users can not change it to 0 or 2, it seems bad for some users, we
can select ARCH_WANT_DEFAULT_BPF_JIT for those archs if it is proper,
but at least for now, make BPF_JIT_DEFAULT_ON selectable can give them
a chance.

Additionaly, with this patch, under !BPF_JIT_ALWAYS_ON, we can disable
BPF_JIT_DEFAULT_ON on the archs with ARCH_WANT_DEFAULT_BPF_JIT when
make menuconfig, it seems flexible for some developers.

If you are OK, I will update the commit message and then send v2.

Thanks,
Tiezhu

>
> Thanks,
> Daniel


^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2022-02-12  2:40 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-02-11  8:57 [PATCH bpf-next 0/2] Modify BPF_JIT_ALWAYS_ON and BPF_JIT_DEFAULT_ON Tiezhu Yang
2022-02-11  8:57 ` [PATCH bpf-next 1/2] bpf: Add some description about BPF_JIT_ALWAYS_ON in Kconfig Tiezhu Yang
2022-02-11 14:44   ` Daniel Borkmann
2022-02-11  8:57 ` [PATCH bpf-next 2/2] bpf: Make BPF_JIT_DEFAULT_ON selectable " Tiezhu Yang
2022-02-11 10:23   ` Daniel Borkmann
2022-02-12  2:40     ` Tiezhu Yang

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