The bpf_jit_alloc_exec function serves as the core mechanism for BPF
memory allocation, invoking execmem_alloc(EXECMEM_BPF, size) to
allocate memory. This change explicitly designates the allocation space
for EXECMEM_BPF.

Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
---
 arch/loongarch/mm/init.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
index c3e4586a7..07cedd9ee 100644
--- a/arch/loongarch/mm/init.c
+++ b/arch/loongarch/mm/init.c
@@ -239,6 +239,12 @@ struct execmem_info __init *execmem_arch_setup(void)
 				.pgprot	= PAGE_KERNEL,
 				.alignment = 1,
 			},
+			[EXECMEM_BPF] = {
+				.start	= VMALLOC_START,
+				.end	= VMALLOC_END,
+				.pgprot	= PAGE_KERNEL,
+				.alignment = PAGE_SIZE,
+			},
 		},
 	};
 
-- 
2.43.0

Hi, Chenghao,

On Wed, Jul 9, 2025 at 1:50 PM Chenghao Duan <duanchenghao@kylinos.cn> wrote:
>
> The bpf_jit_alloc_exec function serves as the core mechanism for BPF
> memory allocation, invoking execmem_alloc(EXECMEM_BPF, size) to
> allocate memory. This change explicitly designates the allocation space
> for EXECMEM_BPF.
Without this patch, BPF JIT is allocated from MODULES region; with
this patch, BPF JIT will be allocated from VMALLOC region. However,
BPF JIT is similar to modules that the target of direct branch
instruction is limited, so it should also be allocated from the
MODULES region.

So, it is better to drop this patch.


Huacai

>
> Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
> ---
>  arch/loongarch/mm/init.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
> index c3e4586a7..07cedd9ee 100644
> --- a/arch/loongarch/mm/init.c
> +++ b/arch/loongarch/mm/init.c
> @@ -239,6 +239,12 @@ struct execmem_info __init *execmem_arch_setup(void)
>                                 .pgprot = PAGE_KERNEL,
>                                 .alignment = 1,
>                         },
> +                       [EXECMEM_BPF] = {
> +                               .start  = VMALLOC_START,
> +                               .end    = VMALLOC_END,
> +                               .pgprot = PAGE_KERNEL,
> +                               .alignment = PAGE_SIZE,
> +                       },
>                 },
>         };
>
> --
> 2.43.0
>
>

On Wed, Jul 09, 2025 at 11:23:12PM +0800, Huacai Chen wrote:
> Hi, Chenghao,
> 
> On Wed, Jul 9, 2025 at 1:50 PM Chenghao Duan <duanchenghao@kylinos.cn> wrote:
> >
> > The bpf_jit_alloc_exec function serves as the core mechanism for BPF
> > memory allocation, invoking execmem_alloc(EXECMEM_BPF, size) to
> > allocate memory. This change explicitly designates the allocation space
> > for EXECMEM_BPF.
> Without this patch, BPF JIT is allocated from MODULES region; with
> this patch, BPF JIT will be allocated from VMALLOC region. However,
> BPF JIT is similar to modules that the target of direct branch
> instruction is limited, so it should also be allocated from the
> MODULES region.
> 
> So, it is better to drop this patch.
> 
> 
> Huacai

Dear Chen,

I understand your technical considerations. Whether to keep or remove
the current patch has no impact on trampoline, so we can drop this
patch.

Chenghao

> 
> >
> > Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
> > ---
> >  arch/loongarch/mm/init.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
> > index c3e4586a7..07cedd9ee 100644
> > --- a/arch/loongarch/mm/init.c
> > +++ b/arch/loongarch/mm/init.c
> > @@ -239,6 +239,12 @@ struct execmem_info __init *execmem_arch_setup(void)
> >                                 .pgprot = PAGE_KERNEL,
> >                                 .alignment = 1,
> >                         },
> > +                       [EXECMEM_BPF] = {
> > +                               .start  = VMALLOC_START,
> > +                               .end    = VMALLOC_END,
> > +                               .pgprot = PAGE_KERNEL,
> > +                               .alignment = PAGE_SIZE,
> > +                       },
> >                 },
> >         };
> >
> > --
> > 2.43.0
> >
> >