Re: [PATCH] MIPS: BPF: Add support for SKF_AD_HATYPE

[David Daney]

On 03/13/2017 03:56 AM, James Hogan wrote:

On Fri, Mar 10, 2017 at 02:14:05PM -0800, David Daney wrote:

This let's us pass some additional "modprobe test-bpf" tests.

Reuse the code for SKF_AD_IFINDEX, but substitute the offset and size
of the "type" field.

Signed-off-by: David Daney 


I think the BPF maintainers should probably be Cc'd on this patch.
Cc'ing now.



Good point.

Since there are some corrections needed, I will send another version and 
CC the proper people.




---
 arch/mips/net/bpf_jit.c | 14 ++
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
index 49a2e22..f613708 100644
--- a/arch/mips/net/bpf_jit.c
+++ b/arch/mips/net/bpf_jit.c
@@ -,6 +,7 @@ static int build_body(struct jit_ctx *ctx)
emit_load(r_A, 28, off, ctx);
break;
case BPF_ANC | SKF_AD_IFINDEX:
+   case BPF_ANC | SKF_AD_HATYPE:
/* A = skb->dev->ifindex */


this comment should probably be updated.


Right.




ctx->flags |= SEEN_SKB | SEEN_A;
off = offsetof(struct sk_buff, dev);
@@ -1120,10 +1121,15 @@ static int build_body(struct jit_ctx *ctx)
emit_bcond(MIPS_COND_EQ, r_s0, r_zero,
   b_imm(prog->len, ctx), ctx);
emit_reg_move(r_ret, r_zero, ctx);
-   BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
- ifindex) != 4);
-   off = offsetof(struct net_device, ifindex);
-   emit_load(r_A, r_s0, off, ctx);
+   if (code == (BPF_ANC | SKF_AD_IFINDEX)) {
+   BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, 
ifindex) != 4);
+   off = offsetof(struct net_device, ifindex);
+   emit_load(r_A, r_s0, off, ctx);
+   } else { /* (code == (BPF_ANC | SKF_AD_HATYPE) */
+   BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, 
type) != 2);
+   off = offsetof(struct net_device, type);
+   emit_half_load(r_A, r_s0, off, ctx);


Technically net_device::type is unsigned, and emit_half_load uses LH
which sign extends. Does that matter in practice.


The next version will use LHU.




Cheers
James

Re: [PATCH] MIPS: BPF: Add support for SKF_AD_HATYPE

[James Hogan]

On Fri, Mar 10, 2017 at 02:14:05PM -0800, David Daney wrote:
> This let's us pass some additional "modprobe test-bpf" tests.
> 
> Reuse the code for SKF_AD_IFINDEX, but substitute the offset and size
> of the "type" field.
> 
> Signed-off-by: David Daney 

I think the BPF maintainers should probably be Cc'd on this patch.
Cc'ing now.

> ---
>  arch/mips/net/bpf_jit.c | 14 ++
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
> index 49a2e22..f613708 100644
> --- a/arch/mips/net/bpf_jit.c
> +++ b/arch/mips/net/bpf_jit.c
> @@ -,6 +,7 @@ static int build_body(struct jit_ctx *ctx)
>   emit_load(r_A, 28, off, ctx);
>   break;
>   case BPF_ANC | SKF_AD_IFINDEX:
> + case BPF_ANC | SKF_AD_HATYPE:
>   /* A = skb->dev->ifindex */

this comment should probably be updated.

>   ctx->flags |= SEEN_SKB | SEEN_A;
>   off = offsetof(struct sk_buff, dev);
> @@ -1120,10 +1121,15 @@ static int build_body(struct jit_ctx *ctx)
>   emit_bcond(MIPS_COND_EQ, r_s0, r_zero,
>  b_imm(prog->len, ctx), ctx);
>   emit_reg_move(r_ret, r_zero, ctx);
> - BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
> -   ifindex) != 4);
> - off = offsetof(struct net_device, ifindex);
> - emit_load(r_A, r_s0, off, ctx);
> + if (code == (BPF_ANC | SKF_AD_IFINDEX)) {
> + BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, 
> ifindex) != 4);
> + off = offsetof(struct net_device, ifindex);
> + emit_load(r_A, r_s0, off, ctx);
> + } else { /* (code == (BPF_ANC | SKF_AD_HATYPE) */
> + BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, 
> type) != 2);
> + off = offsetof(struct net_device, type);
> + emit_half_load(r_A, r_s0, off, ctx);

Technically net_device::type is unsigned, and emit_half_load uses LH
which sign extends. Does that matter in practice.

Cheers
James


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