netdev - [PATCH bpf-next 05/12] nfp: bpf: account for BPF-to-BPF calls when preparing nfp JIT

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Message-Id: <1538913418-16039-6-git-send-email-quentin.monnet@netronome.com>
Date:   Sun,  7 Oct 2018 12:56:51 +0100
From:   Quentin Monnet <quentin.monnet@...ronome.com>
To:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com,
        Quentin Monnet <quentin.monnet@...ronome.com>
Subject: [PATCH bpf-next 05/12] nfp: bpf: account for BPF-to-BPF calls when preparing nfp JIT

Similarly to "exit" or "helper call" instructions, BPF-to-BPF calls will
require additional processing before translation starts, in order to
record and mark jump destinations.

We also mark the instructions where each subprogram begins. This will be
used in a following commit to determine where to add prologues for
subprograms.

Signed-off-by: Quentin Monnet <quentin.monnet@...ronome.com>
Reviewed-by: Jiong Wang <jiong.wang@...ronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
---
 drivers/net/ethernet/netronome/nfp/bpf/jit.c  | 35 +++++++++++++++++++--------
 drivers/net/ethernet/netronome/nfp/bpf/main.h |  3 ++-
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
index 98a94ca36bfa..ccb80a5ac828 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -4018,20 +4018,35 @@ void nfp_bpf_jit_prepare(struct nfp_prog *nfp_prog, unsigned int cnt)
 
 	/* Another pass to record jump information. */
 	list_for_each_entry(meta, &nfp_prog->insns, l) {
+		struct nfp_insn_meta *dst_meta;
 		u64 code = meta->insn.code;
+		unsigned int dst_idx;
+		bool pseudo_call;
 
-		if (BPF_CLASS(code) == BPF_JMP && BPF_OP(code) != BPF_EXIT &&
-		    BPF_OP(code) != BPF_CALL) {
-			struct nfp_insn_meta *dst_meta;
-			unsigned short dst_indx;
+		if (BPF_CLASS(code) != BPF_JMP)
+			continue;
+		if (BPF_OP(code) == BPF_EXIT)
+			continue;
+		if (is_mbpf_helper_call(meta))
+			continue;
 
-			dst_indx = meta->n + 1 + meta->insn.off;
-			dst_meta = nfp_bpf_goto_meta(nfp_prog, meta, dst_indx,
-						     cnt);
+		/* If opcode is BPF_CALL at this point, this can only be a
+		 * BPF-to-BPF call (a.k.a pseudo call).
+		 */
+		pseudo_call = BPF_OP(code) == BPF_CALL;
 
-			meta->jmp_dst = dst_meta;
-			dst_meta->flags |= FLAG_INSN_IS_JUMP_DST;
-		}
+		if (pseudo_call)
+			dst_idx = meta->n + 1 + meta->insn.imm;
+		else
+			dst_idx = meta->n + 1 + meta->insn.off;
+
+		dst_meta = nfp_bpf_goto_meta(nfp_prog, meta, dst_idx, cnt);
+
+		if (pseudo_call)
+			dst_meta->flags |= FLAG_INSN_IS_SUBPROG_START;
+
+		dst_meta->flags |= FLAG_INSN_IS_JUMP_DST;
+		meta->jmp_dst = dst_meta;
 	}
 }
 
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h
index 853a5346378c..20a98ce4b345 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h
@@ -262,7 +262,8 @@ struct nfp_bpf_reg_state {
 	bool var_off;
 };
 
-#define FLAG_INSN_IS_JUMP_DST	BIT(0)
+#define FLAG_INSN_IS_JUMP_DST			BIT(0)
+#define FLAG_INSN_IS_SUBPROG_START		BIT(1)
 
 /**
  * struct nfp_insn_meta - BPF instruction wrapper
-- 
2.7.4