s390/bpf: Remove unused SEEN_RET0, SEEN_REG_AX and ret0_ip

We don't need them since commit e1cf4befa297 ("bpf, s390x: remove
ld_abs/ld_ind") and commit a3212b8f15d8 ("bpf, s390x: remove obsolete
exception handling from div/mod").

Also, use BIT(n) instead of 1 << n, because checkpatch says so.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191107114033.90505-1-iii@linux.ibm.com

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 35661c2..1115071 100644 (file)
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -42,7 +42,6 @@ struct bpf_jit {
        int lit_start;          /* Start of literal pool */
        int lit;                /* Current position in literal pool */
        int base_ip;            /* Base address for literal pool */
-       int ret0_ip;            /* Address of return 0 */
        int exit_ip;            /* Address of exit */
        int r1_thunk_ip;        /* Address of expoline thunk for 'br %r1' */
        int r14_thunk_ip;       /* Address of expoline thunk for 'br %r14' */
@@ -52,12 +51,10 @@ struct bpf_jit {
 
 #define BPF_SIZE_MAX   0xffff  /* Max size for program (16 bit branches) */
 
-#define SEEN_MEM       (1 << 0)        /* use mem[] for temporary storage */
-#define SEEN_RET0      (1 << 1)        /* ret0_ip points to a valid return 0 */
-#define SEEN_LITERAL   (1 << 2)        /* code uses literals */
-#define SEEN_FUNC      (1 << 3)        /* calls C functions */
-#define SEEN_TAIL_CALL (1 << 4)        /* code uses tail calls */
-#define SEEN_REG_AX    (1 << 5)        /* code uses constant blinding */
+#define SEEN_MEM       BIT(0)          /* use mem[] for temporary storage */
+#define SEEN_LITERAL   BIT(1)          /* code uses literals */
+#define SEEN_FUNC      BIT(2)          /* calls C functions */
+#define SEEN_TAIL_CALL BIT(3)          /* code uses tail calls */
 #define SEEN_STACK     (SEEN_FUNC | SEEN_MEM)
 
 /*
@@ -447,12 +444,6 @@ static void bpf_jit_prologue(struct bpf_jit *jit, u32 stack_depth)
  */
 static void bpf_jit_epilogue(struct bpf_jit *jit, u32 stack_depth)
 {
-       /* Return 0 */
-       if (jit->seen & SEEN_RET0) {
-               jit->ret0_ip = jit->prg;
-               /* lghi %b0,0 */
-               EMIT4_IMM(0xa7090000, BPF_REG_0, 0);
-       }
        jit->exit_ip = jit->prg;
        /* Load exit code: lgr %r2,%b0 */
        EMIT4(0xb9040000, REG_2, BPF_REG_0);
@@ -515,8 +506,6 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
        s16 off = insn->off;
        unsigned int mask;
 
-       if (dst_reg == BPF_REG_AX || src_reg == BPF_REG_AX)
-               jit->seen |= SEEN_REG_AX;
        switch (insn->code) {
        /*
         * BPF_MOV
@@ -1111,7 +1100,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
                break;
        case BPF_JMP | BPF_EXIT: /* return b0 */
                last = (i == fp->len - 1) ? 1 : 0;
-               if (last && !(jit->seen & SEEN_RET0))
+               if (last)
                        break;
                /* j <exit> */
                EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);