[PATCH bpf] sparc: Correct ctx->saw_frame_pointer logic.

[David Miller]

We need to initialize the frame pointer register not just if it is
seen as a source operand, but also if it is seen as the destination
operand of a store or an atomic instruction (which effectively is a
source operand).

This is exercised by test_verifier's "non-invalid fp arithmetic"

Signed-off-by: David S. Miller <da...@davemloft.net>

diff --git a/arch/sparc/net/bpf_jit_comp_64.c b/arch/sparc/net/bpf_jit_comp_64.c
index 222785a..ec4da4d 100644
--- a/arch/sparc/net/bpf_jit_comp_64.c
+++ b/arch/sparc/net/bpf_jit_comp_64.c
@@ -1270,6 +1270,9 @@ static int build_insn(const struct bpf_insn *insn, struct 
jit_ctx *ctx)
                const u8 tmp2 = bpf2sparc[TMP_REG_2];
                u32 opcode = 0, rs2;
 
+               if (insn->dst_reg == BPF_REG_FP)
+                       ctx->saw_frame_pointer = true;
+
                ctx->tmp_2_used = true;
                emit_loadimm(imm, tmp2, ctx);
 
@@ -1308,6 +1311,9 @@ static int build_insn(const struct bpf_insn *insn, struct 
jit_ctx *ctx)
                const u8 tmp = bpf2sparc[TMP_REG_1];
                u32 opcode = 0, rs2;
 
+               if (insn->dst_reg == BPF_REG_FP)
+                       ctx->saw_frame_pointer = true;
+
                switch (BPF_SIZE(code)) {
                case BPF_W:
                        opcode = ST32;
@@ -1340,6 +1346,9 @@ static int build_insn(const struct bpf_insn *insn, struct 
jit_ctx *ctx)
                const u8 tmp2 = bpf2sparc[TMP_REG_2];
                const u8 tmp3 = bpf2sparc[TMP_REG_3];
 
+               if (insn->dst_reg == BPF_REG_FP)
+                       ctx->saw_frame_pointer = true;
+
                ctx->tmp_1_used = true;
                ctx->tmp_2_used = true;
                ctx->tmp_3_used = true;
@@ -1360,6 +1369,9 @@ static int build_insn(const struct bpf_insn *insn, struct 
jit_ctx *ctx)
                const u8 tmp2 = bpf2sparc[TMP_REG_2];
                const u8 tmp3 = bpf2sparc[TMP_REG_3];
 
+               if (insn->dst_reg == BPF_REG_FP)
+                       ctx->saw_frame_pointer = true;
+
                ctx->tmp_1_used = true;
                ctx->tmp_2_used = true;
                ctx->tmp_3_used = true;