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Date:   Thu, 24 Jan 2019 10:28:15 +0530
From:   Sandipan Das <sandipan@...ux.ibm.com>
To:     Jiong Wang <jiong.wang@...ronome.com>
Cc:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        oss-drivers@...ronome.com,
        "Naveen N . Rao" <naveen.n.rao@...ux.ibm.com>
Subject: Re: [PATCH bpf-next v2 13/16] ppc: bpf: implement jitting of JMP32

Hi Jiong,

On 21/01/19 6:45 PM, Jiong Wang wrote:
> This patch implements code-gen for new JMP32 instructions on ppc.
> 
> For JMP32 | JSET, instruction encoding for PPC_RLWINM_DOT is added to check
> the result of ANDing low 32-bit of operands.
> 
> Cc: Naveen N. Rao <naveen.n.rao@...ux.ibm.com>
> Cc: Sandipan Das <sandipan@...ux.ibm.com>
> Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
> ---
>  arch/powerpc/include/asm/ppc-opcode.h |  1 +
>  arch/powerpc/net/bpf_jit.h            |  4 ++
>  arch/powerpc/net/bpf_jit_comp64.c     | 98 ++++++++++++++++++++++++++++++-----
>  3 files changed, 89 insertions(+), 14 deletions(-)
> [...]

I ran the verifier selftests on a ppc64 test system and found that the jmp32 tests
were failing because the instructions were not being decoded by the JIT compiler.
The codegen logic looks good to me and the tests passed after I fixed the decoding
logic. Here are the changes that I had to make:

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 2e40c2b251ba..15bba765fa79 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -768,36 +768,58 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
                case BPF_JMP | BPF_JGT | BPF_X:
                case BPF_JMP | BPF_JSGT | BPF_K:
                case BPF_JMP | BPF_JSGT | BPF_X:
+               case BPF_JMP32 | BPF_JGT | BPF_K:
+               case BPF_JMP32 | BPF_JGT | BPF_X:
+               case BPF_JMP32 | BPF_JSGT | BPF_K:
+               case BPF_JMP32 | BPF_JSGT | BPF_X:
                        true_cond = COND_GT;
                        goto cond_branch;
                case BPF_JMP | BPF_JLT | BPF_K:
                case BPF_JMP | BPF_JLT | BPF_X:
                case BPF_JMP | BPF_JSLT | BPF_K:
                case BPF_JMP | BPF_JSLT | BPF_X:
+               case BPF_JMP32 | BPF_JLT | BPF_K:
+               case BPF_JMP32 | BPF_JLT | BPF_X:
+               case BPF_JMP32 | BPF_JSLT | BPF_K:
+               case BPF_JMP32 | BPF_JSLT | BPF_X:
                        true_cond = COND_LT;
                        goto cond_branch;
                case BPF_JMP | BPF_JGE | BPF_K:
                case BPF_JMP | BPF_JGE | BPF_X:
                case BPF_JMP | BPF_JSGE | BPF_K:
                case BPF_JMP | BPF_JSGE | BPF_X:
+               case BPF_JMP32 | BPF_JGE | BPF_K:
+               case BPF_JMP32 | BPF_JGE | BPF_X:
+               case BPF_JMP32 | BPF_JSGE | BPF_K:
+               case BPF_JMP32 | BPF_JSGE | BPF_X:
                        true_cond = COND_GE;
                        goto cond_branch;
                case BPF_JMP | BPF_JLE | BPF_K:
                case BPF_JMP | BPF_JLE | BPF_X:
                case BPF_JMP | BPF_JSLE | BPF_K:
                case BPF_JMP | BPF_JSLE | BPF_X:
+               case BPF_JMP32 | BPF_JLE | BPF_K:
+               case BPF_JMP32 | BPF_JLE | BPF_X:
+               case BPF_JMP32 | BPF_JSLE | BPF_K:
+               case BPF_JMP32 | BPF_JSLE | BPF_X:
                        true_cond = COND_LE;
                        goto cond_branch;
                case BPF_JMP | BPF_JEQ | BPF_K:
                case BPF_JMP | BPF_JEQ | BPF_X:
+               case BPF_JMP32 | BPF_JEQ | BPF_K:
+               case BPF_JMP32 | BPF_JEQ | BPF_X:
                        true_cond = COND_EQ;
                        goto cond_branch;
                case BPF_JMP | BPF_JNE | BPF_K:
                case BPF_JMP | BPF_JNE | BPF_X:
+               case BPF_JMP32 | BPF_JNE | BPF_K:
+               case BPF_JMP32 | BPF_JNE | BPF_X:
                        true_cond = COND_NE;
                        goto cond_branch;
                case BPF_JMP | BPF_JSET | BPF_K:
                case BPF_JMP | BPF_JSET | BPF_X:
+               case BPF_JMP32 | BPF_JSET | BPF_K:
+               case BPF_JMP32 | BPF_JSET | BPF_X:
                        true_cond = COND_NE;
                        /* Fall through */
 

--
With Regards,
Sandipan

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