arm64: bpf: add 'load 64-bit immediate' instruction

Commit 02ab695bb37e (net: filter: add "load 64-bit immediate" eBPF
instruction) introduced a new eBPF instruction. Let's add support
for this for arm64 as well.

Our arm64 eBPF JIT compiler now passes the new "load 64-bit
immediate" test case introduced in the same commit 02ab695bb37e.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 80cc76972798..618d2cdc2f1b 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -205,6 +205,12 @@ static void build_epilogue(struct jit_ctx *ctx)
         emit(A64_RET(A64_LR), ctx);
 }
 
+/* JITs an eBPF instruction.
+ * Returns:
+ * 0  - successfully JITed an 8-byte eBPF instruction.
+ * >0 - successfully JITed a 16-byte eBPF instruction.
+ * <0 - failed to JIT.
+ */
 static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
 {
         const u8 code = insn->code;
@@ -464,6 +470,27 @@ emit_cond_jmp:
                 emit(A64_B(jmp_offset), ctx);
                 break;
 
+        /* dst = imm64 */
+        case BPF_LD | BPF_IMM | BPF_DW:
+        {
+                const struct bpf_insn insn1 = insn[1];
+                u64 imm64;
+
+                if (insn1.code != 0 || insn1.src_reg != 0 ||
+                    insn1.dst_reg != 0 || insn1.off != 0) {
+                        /* Note: verifier in BPF core must catch invalid
+                         * instructions.
+                         */
+                        pr_err_once("Invalid BPF_LD_IMM64 instruction\n");
+                        return -EINVAL;
+                }
+
+                imm64 = (u64)insn1.imm << 32 | imm;
+                emit_a64_mov_i64(dst, imm64, ctx);
+
+                return 1;
+        }
+
         /* LDX: dst = *(size *)(src + off) */
         case BPF_LDX | BPF_MEM | BPF_W:
         case BPF_LDX | BPF_MEM | BPF_H:
@@ -615,6 +642,10 @@ static int build_body(struct jit_ctx *ctx)
                         ctx->offset[i] = ctx->idx;
 
                 ret = build_insn(insn, ctx);
+                if (ret > 0) {
+                        i++;
+                        continue;
+                }
                 if (ret)
                         return ret;
         }