nfp: bpf: add helpers for modifying branch addresses

In preparation for better handling of relocations move existing
helper for setting branch offset to nfp_asm.c and add two more.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

drivers/net/ethernet/netronome/nfp/bpf/jit.c

@@ -2110,18 +2110,6 @@ static const instr_cb_t instr_cb[256] = {
 	[BPF_JMP | BPF_EXIT] =		goto_out,
 };
 
-/* --- Misc code --- */
-static void br_set_offset(u64 *instr, u16 offset)
-{
-	u16 addr_lo, addr_hi;
-
-	addr_lo = offset & (OP_BR_ADDR_LO >> __bf_shf(OP_BR_ADDR_LO));
-	addr_hi = offset != addr_lo;
-	*instr &= ~(OP_BR_ADDR_HI | OP_BR_ADDR_LO);
-	*instr |= FIELD_PREP(OP_BR_ADDR_HI, addr_hi);
-	*instr |= FIELD_PREP(OP_BR_ADDR_LO, addr_lo);
-}
-
 /* --- Assembler logic --- */
 static int nfp_fixup_branches(struct nfp_prog *nfp_prog)
 {

drivers/net/ethernet/netronome/nfp/nfp_asm.c

@@ -50,6 +50,36 @@ const struct cmd_tgt_act cmd_tgt_act[__CMD_TGT_MAP_SIZE] = {
 	[CMD_TGT_READ_SWAP_LE] =	{ 0x03, 0x40 },
 };
 
+u16 br_get_offset(u64 instr)
+{
+	u16 addr_lo, addr_hi;
+
+	addr_lo = FIELD_GET(OP_BR_ADDR_LO, instr);
+	addr_hi = FIELD_GET(OP_BR_ADDR_HI, instr);
+
+	return (addr_hi * ((OP_BR_ADDR_LO >> __bf_shf(OP_BR_ADDR_LO)) + 1)) |
+		addr_lo;
+}
+
+void br_set_offset(u64 *instr, u16 offset)
+{
+	u16 addr_lo, addr_hi;
+
+	addr_lo = offset & (OP_BR_ADDR_LO >> __bf_shf(OP_BR_ADDR_LO));
+	addr_hi = offset != addr_lo;
+	*instr &= ~(OP_BR_ADDR_HI | OP_BR_ADDR_LO);
+	*instr |= FIELD_PREP(OP_BR_ADDR_HI, addr_hi);
+	*instr |= FIELD_PREP(OP_BR_ADDR_LO, addr_lo);
+}
+
+void br_add_offset(u64 *instr, u16 offset)
+{
+	u16 addr;
+
+	addr = br_get_offset(*instr);
+	br_set_offset(instr, addr + offset);
+}
+
 static u16 nfp_swreg_to_unreg(swreg reg, bool is_dst)
 {
 	bool lm_id, lm_dec = false;

drivers/net/ethernet/netronome/nfp/nfp_asm.h

@@ -93,6 +93,10 @@ enum br_ctx_signal_state {
 	BR_CSS_NONE = 2,
 };
 
+u16 br_get_offset(u64 instr);
+void br_set_offset(u64 *instr, u16 offset);
+void br_add_offset(u64 *instr, u16 offset);
+
 #define OP_BBYTE_BASE		0x0c800000000ULL
 #define OP_BB_A_SRC		0x000000000ffULL
 #define OP_BB_BYTE		0x00000000300ULL