2017-03-10 22:14:20

by David Daney

[permalink] [raw]

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

---

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 <[email protected]>
---
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
@@ -1111,6 +1111,7 @@ 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 */
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);
+ }
break;
case BPF_ANC | SKF_AD_MARK:
ctx->flags |= SEEN_SKB | SEEN_A;
--
2.9.3

2017-03-13 10:57:12

by James Hogan

[permalink] [raw]

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

---

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 <[email protected]>

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
> @@ -1111,6 +1111,7 @@ 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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2017-03-13 16:46:04

by David Daney

[permalink] [raw]

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

---

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 <[email protected]>
>
> 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
>> @@ -1111,6 +1111,7 @@ 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
>