[PATCH bpf-next v3 05/12] bpf: sparc64: Fix jumping to the first insn

[Ilya Leoshkevich <iii@xxxxxxxxxxxxx>]

Jumping to the first insn causes emit_compare_and_branch() to access
ctx->offsets[-1]. Currently ctx->offsets[] stores instruction end
addresses; change it to store start addresses instead. We never need
the end address of the last instruction.

Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
 arch/sparc/net/bpf_jit_comp_64.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/sparc/net/bpf_jit_comp_64.c b/arch/sparc/net/bpf_jit_comp_64.c
index 59d2d9953aa7..0a3c18e39199 100644
--- a/arch/sparc/net/bpf_jit_comp_64.c
+++ b/arch/sparc/net/bpf_jit_comp_64.c
@@ -1168,7 +1168,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
 
 	/* JUMP off */
 	case BPF_JMP | BPF_JA:
-		emit_branch(BA, ctx->idx, ctx->offset[i + off], ctx);
+		emit_branch(BA, ctx->idx, ctx->offset[i + off + 1], ctx);
 		emit_nop(ctx);
 		break;
 	/* IF (dst COND src) JUMP off */
@@ -1185,7 +1185,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
 	case BPF_JMP | BPF_JSET | BPF_X: {
 		int err;
 
-		err = emit_compare_and_branch(code, dst, src, 0, false, i + off, ctx);
+		err = emit_compare_and_branch(code, dst, src, 0, false, i + off + 1, ctx);
 		if (err)
 			return err;
 		break;
@@ -1204,7 +1204,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
 	case BPF_JMP | BPF_JSET | BPF_K: {
 		int err;
 
-		err = emit_compare_and_branch(code, dst, 0, imm, true, i + off, ctx);
+		err = emit_compare_and_branch(code, dst, 0, imm, true, i + off + 1, ctx);
 		if (err)
 			return err;
 		break;
@@ -1453,16 +1453,12 @@ static int build_body(struct jit_ctx *ctx)
 		const struct bpf_insn *insn = &prog->insnsi[i];
 		int ret;
 
-		ret = build_insn(insn, ctx);
-
-		if (ret > 0) {
-			i++;
-			ctx->offset[i] = ctx->idx;
-			continue;
-		}
 		ctx->offset[i] = ctx->idx;
-		if (ret)
+		ret = build_insn(insn, ctx);
+		if (ret < 0)
 			return ret;
+
+		i += ret;
 	}
 	return 0;
 }
-- 
2.39.1