bpf: free up BPF_JMP | BPF_CALL | BPF_X opcode

free up BPF_JMP | BPF_CALL | BPF_X opcode to be used by actual
indirect call by register and use kernel internal opcode to
mark call instruction into bpf_tail_call() helper.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 71f9305..b1d38ee 100644 (file)
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -586,7 +586,7 @@ emit_cond_jmp:
                break;
        }
        /* tail call */
-       case BPF_JMP | BPF_CALL | BPF_X:
+       case BPF_JMP | BPF_TAIL_CALL:
                if (emit_bpf_tail_call(ctx))
                        return -EFAULT;
                break;

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index aee2bb8..a013665 100644 (file)
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -938,7 +938,7 @@ common_load:
                /*
                 * Tail call
                 */
-               case BPF_JMP | BPF_CALL | BPF_X:
+               case BPF_JMP | BPF_TAIL_CALL:
                        ctx->seen |= SEEN_TAILCALL;
                        bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]);
                        break;

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 6e97a2e..42ad383 100644 (file)
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -991,7 +991,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
                }
                break;
        }
-       case BPF_JMP | BPF_CALL | BPF_X:
+       case BPF_JMP | BPF_TAIL_CALL:
                /*
                 * Implicit input:
                 *  B1: pointer to ctx

diff --git a/arch/sparc/net/bpf_jit_comp_64.c b/arch/sparc/net/bpf_jit_comp_64.c
index 21de774..4a52d34 100644 (file)
--- a/arch/sparc/net/bpf_jit_comp_64.c
+++ b/arch/sparc/net/bpf_jit_comp_64.c
@@ -1217,7 +1217,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
        }
 
        /* tail call */
-       case BPF_JMP | BPF_CALL |BPF_X:
+       case BPF_JMP | BPF_TAIL_CALL:
                emit_tail_call(ctx);
                break;
 

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index f589393..fec12ea 100644 (file)
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -877,7 +877,7 @@ xadd:                       if (is_imm8(insn->off))
                        }
                        break;
 
-               case BPF_JMP | BPF_CALL | BPF_X:
+               case BPF_JMP | BPF_TAIL_CALL:
                        emit_bpf_tail_call(&prog);
                        break;
 

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 62d948f..a20ba40 100644 (file)
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -57,6 +57,9 @@ struct bpf_prog_aux;
 #define BPF_REG_AX             MAX_BPF_REG
 #define MAX_BPF_JIT_REG                (MAX_BPF_REG + 1)
 
+/* unused opcode to mark special call to bpf_tail_call() helper */
+#define BPF_TAIL_CALL  0xf0
+
 /* As per nm, we expose JITed images as text (code) section for
  * kallsyms. That way, tools like perf can find it to match
  * addresses.

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index dedf367..3392894 100644 (file)
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -824,7 +824,7 @@ static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
                [BPF_ALU64 | BPF_NEG] = &&ALU64_NEG,
                /* Call instruction */
                [BPF_JMP | BPF_CALL] = &&JMP_CALL,
-               [BPF_JMP | BPF_CALL | BPF_X] = &&JMP_TAIL_CALL,
+               [BPF_JMP | BPF_TAIL_CALL] = &&JMP_TAIL_CALL,
                /* Jumps */
                [BPF_JMP | BPF_JA] = &&JMP_JA,
                [BPF_JMP | BPF_JEQ | BPF_X] = &&JMP_JEQ_X,

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 339c8a1..28113d0 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3469,7 +3469,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
                         * that doesn't support bpf_tail_call yet
                         */
                        insn->imm = 0;
-                       insn->code |= BPF_X;
+                       insn->code = BPF_JMP | BPF_TAIL_CALL;
                        continue;
                }