s390/bpf: Use lgrl instead of lg where possible

lg and lgrl have the same performance characteristics, but the former
requires a base register and is subject to long displacement range
limits, while the latter does not. Therefore, lgrl is totally superior
to lg and should be used instead whenever possible.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191118180340.68373-5-iii@linux.ibm.com

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 964a09f..6b3f85e 100644 (file)
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -287,28 +287,38 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
        REG_SET_SEEN(b1);                                       \
 })
 
-#define EMIT_CONST_U32(val)                                    \
+#define _EMIT_CONST_U32(val)                                   \
 ({                                                             \
        unsigned int ret;                                       \
-       ret = jit->lit32 - jit->base_ip;                        \
-       jit->seen |= SEEN_LITERAL;                              \
+       ret = jit->lit32;                                       \
        if (jit->prg_buf)                                       \
                *(u32 *)(jit->prg_buf + jit->lit32) = (u32)(val);\
        jit->lit32 += 4;                                        \
        ret;                                                    \
 })
 
-#define EMIT_CONST_U64(val)                                    \
+#define EMIT_CONST_U32(val)                                    \
 ({                                                             \
-       unsigned int ret;                                       \
-       ret = jit->lit64 - jit->base_ip;                        \
        jit->seen |= SEEN_LITERAL;                              \
+       _EMIT_CONST_U32(val) - jit->base_ip;                    \
+})
+
+#define _EMIT_CONST_U64(val)                                   \
+({                                                             \
+       unsigned int ret;                                       \
+       ret = jit->lit64;                                       \
        if (jit->prg_buf)                                       \
                *(u64 *)(jit->prg_buf + jit->lit64) = (u64)(val);\
        jit->lit64 += 8;                                        \
        ret;                                                    \
 })
 
+#define EMIT_CONST_U64(val)                                    \
+({                                                             \
+       jit->seen |= SEEN_LITERAL;                              \
+       _EMIT_CONST_U64(val) - jit->base_ip;                    \
+})
+
 #define EMIT_ZERO(b1)                                          \
 ({                                                             \
        if (!fp->aux->verifier_zext) {                          \
@@ -612,9 +622,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
                u64 imm64;
 
                imm64 = (u64)(u32) insn[0].imm | ((u64)(u32) insn[1].imm) << 32;
-               /* lg %dst,<d(imm)>(%l) */
-               EMIT6_DISP_LH(0xe3000000, 0x0004, dst_reg, REG_0, REG_L,
-                             EMIT_CONST_U64(imm64));
+               /* lgrl %dst,imm */
+               EMIT6_PCREL_RILB(0xc4080000, dst_reg, _EMIT_CONST_U64(imm64));
                insn_count = 2;
                break;
        }
@@ -1086,9 +1095,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
 
                REG_SET_SEEN(BPF_REG_5);
                jit->seen |= SEEN_FUNC;
-               /* lg %w1,<d(imm)>(%l) */
-               EMIT6_DISP_LH(0xe3000000, 0x0004, REG_W1, REG_0, REG_L,
-                             EMIT_CONST_U64(func));
+               /* lgrl %w1,func */
+               EMIT6_PCREL_RILB(0xc4080000, REG_W1, _EMIT_CONST_U64(func));
                if (__is_defined(CC_USING_EXPOLINE) && !nospec_disable) {
                        /* brasl %r14,__s390_indirect_jump_r1 */
                        EMIT6_PCREL_RILB(0xc0050000, REG_14, jit->r1_thunk_ip);