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.
Additionally, 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.
Signed-off-by: Tiezhu Yang <[email protected]>
---
kernel/bpf/Kconfig | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
index cbf3f65..461ac60 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.
@@ -63,8 +64,16 @@ config BPF_JIT_ALWAYS_ON
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, /proc/sys/net/core/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
On Fri, Feb 18, 2022 at 7:15 PM Tiezhu Yang <[email protected]> wrote:
>
> 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.
>
> Additionally, 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.
>
> Signed-off-by: Tiezhu Yang <[email protected]>
> ---
> kernel/bpf/Kconfig | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
> index cbf3f65..461ac60 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.
> @@ -63,8 +64,16 @@ config BPF_JIT_ALWAYS_ON
> 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"
I think "remove BPF interpreter" is not accurate. I guess we can just say
"Enable BPF JIT by default". (also "defaultly" sounds weird to me).
> + 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, /proc/sys/net/core/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
>