netdev - [PATCH bpf-next v2 10/14] nfp: bpf: use a large constant in unresolved branches

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Message-Id: <1515587167-1959-11-git-send-email-quentin.monnet@netronome.com>
Date:   Wed, 10 Jan 2018 12:26:03 +0000
From:   Quentin Monnet <quentin.monnet@...ronome.com>
To:     daniel@...earbox.net, alexei.starovoitov@...il.com,
        netdev@...r.kernel.org
Cc:     oss-drivers@...ronome.com, jakub.kicinski@...ronome.com
Subject: [PATCH bpf-next v2 10/14] nfp: bpf: use a large constant in unresolved branches

From: Jakub Kicinski <jakub.kicinski@...ronome.com>

To make absolute relocated branches (branches which will be completely
rewritten with br_set_offset()) distinguishable in user space dumps
from normal jumps add a large offset to them.

Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Jiong Wang <jiong.wang@...ronome.com>
---
 drivers/net/ethernet/netronome/nfp/bpf/jit.c  | 14 +++++++-------
 drivers/net/ethernet/netronome/nfp/bpf/main.h |  6 ++++++
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
index 5deebbc18cfd..b4ed6bca4ea9 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -739,7 +739,7 @@ construct_data_ind_ld(struct nfp_prog *nfp_prog, u16 offset, u16 src, u8 size)
 		 imm_a(nfp_prog), ALU_OP_ADD, reg_imm(size));
 	emit_alu(nfp_prog, reg_none(),
 		 plen_reg(nfp_prog), ALU_OP_SUB, imm_a(nfp_prog));
-	emit_br_relo(nfp_prog, BR_BLO, 0, 0, RELO_BR_GO_ABORT);
+	emit_br_relo(nfp_prog, BR_BLO, BR_OFF_RELO, 0, RELO_BR_GO_ABORT);
 
 	/* Load data */
 	return data_ld(nfp_prog, imm_b(nfp_prog), 0, size);
@@ -752,7 +752,7 @@ static int construct_data_ld(struct nfp_prog *nfp_prog, u16 offset, u8 size)
 	/* Check packet length */
 	tmp_reg = ur_load_imm_any(nfp_prog, offset + size, imm_a(nfp_prog));
 	emit_alu(nfp_prog, reg_none(), plen_reg(nfp_prog), ALU_OP_SUB, tmp_reg);
-	emit_br_relo(nfp_prog, BR_BLO, 0, 0, RELO_BR_GO_ABORT);
+	emit_br_relo(nfp_prog, BR_BLO, BR_OFF_RELO, 0, RELO_BR_GO_ABORT);
 
 	/* Load data */
 	tmp_reg = re_load_imm_any(nfp_prog, offset, imm_b(nfp_prog));
@@ -2026,7 +2026,7 @@ static int call(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 
 static int goto_out(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
-	emit_br_relo(nfp_prog, BR_UNC, 0, 0, RELO_BR_GO_OUT);
+	emit_br_relo(nfp_prog, BR_UNC, BR_OFF_RELO, 0, RELO_BR_GO_OUT);
 
 	return 0;
 }
@@ -2175,7 +2175,7 @@ static void nfp_outro_tc_da(struct nfp_prog *nfp_prog)
 	/* Target for aborts */
 	nfp_prog->tgt_abort = nfp_prog_current_offset(nfp_prog);
 
-	emit_br_relo(nfp_prog, BR_UNC, 0, 2, RELO_BR_NEXT_PKT);
+	emit_br_relo(nfp_prog, BR_UNC, BR_OFF_RELO, 2, RELO_BR_NEXT_PKT);
 
 	wrp_mov(nfp_prog, reg_a(0), NFP_BPF_ABI_FLAGS);
 	emit_ld_field(nfp_prog, reg_a(0), 0xc, reg_imm(0x11), SHF_SC_L_SHF, 16);
@@ -2202,7 +2202,7 @@ static void nfp_outro_tc_da(struct nfp_prog *nfp_prog)
 	emit_shf(nfp_prog, reg_b(2),
 		 reg_imm(0xf), SHF_OP_AND, reg_b(3), SHF_SC_R_SHF, 0);
 
-	emit_br_relo(nfp_prog, BR_UNC, 0, 2, RELO_BR_NEXT_PKT);
+	emit_br_relo(nfp_prog, BR_UNC, BR_OFF_RELO, 2, RELO_BR_NEXT_PKT);
 
 	emit_shf(nfp_prog, reg_b(2),
 		 reg_a(2), SHF_OP_OR, reg_b(2), SHF_SC_L_SHF, 4);
@@ -2221,7 +2221,7 @@ static void nfp_outro_xdp(struct nfp_prog *nfp_prog)
 	/* Target for aborts */
 	nfp_prog->tgt_abort = nfp_prog_current_offset(nfp_prog);
 
-	emit_br_relo(nfp_prog, BR_UNC, 0, 2, RELO_BR_NEXT_PKT);
+	emit_br_relo(nfp_prog, BR_UNC, BR_OFF_RELO, 2, RELO_BR_NEXT_PKT);
 
 	wrp_mov(nfp_prog, reg_a(0), NFP_BPF_ABI_FLAGS);
 	emit_ld_field(nfp_prog, reg_a(0), 0xc, reg_imm(0x82), SHF_SC_L_SHF, 16);
@@ -2242,7 +2242,7 @@ static void nfp_outro_xdp(struct nfp_prog *nfp_prog)
 	emit_shf(nfp_prog, reg_b(2),
 		 reg_imm(0xff), SHF_OP_AND, reg_b(2), SHF_SC_R_SHF, 0);
 
-	emit_br_relo(nfp_prog, BR_UNC, 0, 2, RELO_BR_NEXT_PKT);
+	emit_br_relo(nfp_prog, BR_UNC, BR_OFF_RELO, 2, RELO_BR_NEXT_PKT);
 
 	wrp_mov(nfp_prog, reg_a(0), NFP_BPF_ABI_FLAGS);
 	emit_ld_field(nfp_prog, reg_a(0), 0xc, reg_b(2), SHF_SC_L_SHF, 16);
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h
index 5deba5099618..8d02c39b9b10 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h
@@ -58,6 +58,12 @@ enum nfp_relo_type {
 	RELO_BR_NEXT_PKT,
 };
 
+/* To make absolute relocated branches (branches other than RELO_BR_REL)
+ * distinguishable in user space dumps from normal jumps, add a large offset
+ * to them.
+ */
+#define BR_OFF_RELO		15000
+
 enum static_regs {
 	STATIC_REG_IMM		= 21, /* Bank AB */
 	STATIC_REG_STACK	= 22, /* Bank A */
-- 
2.7.4