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authorIlya Leoshkevich <iii@linux.ibm.com>2019-11-18 21:03:39 +0300
committerAlexei Starovoitov <ast@kernel.org>2019-11-19 06:51:16 +0300
commitb25c57b6b7dda3799aaebc5f463776e4a0555927 (patch)
treeb81a1acaf090da5f1608e91ba957f85b9bc6dfc7 /arch/s390/net
parent451e448ff4bb137da3d4b8b26a8260a2ff66869a (diff)
downloadlinux-b25c57b6b7dda3799aaebc5f463776e4a0555927.tar.xz
s390/bpf: Use lg(f)rl when long displacement cannot be used
If literal pool grows past 524287 mark, it's no longer possible to use long displacement to reference literal pool entries. In JIT setting maintaining multiple literal pool registers is next to impossible, since we operate on one instruction at a time. Therefore, fall back to loading literal pool entry using PC-relative addressing, and then using a register-register form of the following machine instruction. Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191118180340.68373-6-iii@linux.ibm.com
Diffstat (limited to 'arch/s390/net')
-rw-r--r--arch/s390/net/bpf_jit_comp.c96
1 files changed, 81 insertions, 15 deletions
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 6b3f85e4c5b0..3398cd939496 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -372,6 +372,24 @@ static bool is_valid_ldisp(int disp)
}
/*
+ * Return whether the next 32-bit literal pool entry can be referenced using
+ * Long-Displacement Facility
+ */
+static bool can_use_ldisp_for_lit32(struct bpf_jit *jit)
+{
+ return is_valid_ldisp(jit->lit32 - jit->base_ip);
+}
+
+/*
+ * Return whether the next 64-bit literal pool entry can be referenced using
+ * Long-Displacement Facility
+ */
+static bool can_use_ldisp_for_lit64(struct bpf_jit *jit)
+{
+ return is_valid_ldisp(jit->lit64 - jit->base_ip);
+}
+
+/*
* Fill whole space with illegal instructions
*/
static void jit_fill_hole(void *area, unsigned int size)
@@ -752,9 +770,18 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT4_IMM(0xa7080000, REG_W0, 0);
/* lr %w1,%dst */
EMIT2(0x1800, REG_W1, dst_reg);
- /* dl %w0,<d(imm)>(%l) */
- EMIT6_DISP_LH(0xe3000000, 0x0097, REG_W0, REG_0, REG_L,
- EMIT_CONST_U32(imm));
+ if (!is_first_pass(jit) && can_use_ldisp_for_lit32(jit)) {
+ /* dl %w0,<d(imm)>(%l) */
+ EMIT6_DISP_LH(0xe3000000, 0x0097, REG_W0, REG_0, REG_L,
+ EMIT_CONST_U32(imm));
+ } else {
+ /* lgfrl %dst,imm */
+ EMIT6_PCREL_RILB(0xc40c0000, dst_reg,
+ _EMIT_CONST_U32(imm));
+ jit->seen |= SEEN_LITERAL;
+ /* dlr %w0,%dst */
+ EMIT4(0xb9970000, REG_W0, dst_reg);
+ }
/* llgfr %dst,%rc */
EMIT4(0xb9160000, dst_reg, rc_reg);
if (insn_is_zext(&insn[1]))
@@ -776,9 +803,18 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT4_IMM(0xa7090000, REG_W0, 0);
/* lgr %w1,%dst */
EMIT4(0xb9040000, REG_W1, dst_reg);
- /* dlg %w0,<d(imm)>(%l) */
- EMIT6_DISP_LH(0xe3000000, 0x0087, REG_W0, REG_0, REG_L,
- EMIT_CONST_U64(imm));
+ if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
+ /* dlg %w0,<d(imm)>(%l) */
+ EMIT6_DISP_LH(0xe3000000, 0x0087, REG_W0, REG_0, REG_L,
+ EMIT_CONST_U64(imm));
+ } else {
+ /* lgrl %dst,imm */
+ EMIT6_PCREL_RILB(0xc4080000, dst_reg,
+ _EMIT_CONST_U64(imm));
+ jit->seen |= SEEN_LITERAL;
+ /* dlgr %w0,%dst */
+ EMIT4(0xb9870000, REG_W0, dst_reg);
+ }
/* lgr %dst,%rc */
EMIT4(0xb9040000, dst_reg, rc_reg);
break;
@@ -801,9 +837,19 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT_ZERO(dst_reg);
break;
case BPF_ALU64 | BPF_AND | BPF_K: /* dst = dst & imm */
- /* ng %dst,<d(imm)>(%l) */
- EMIT6_DISP_LH(0xe3000000, 0x0080, dst_reg, REG_0, REG_L,
- EMIT_CONST_U64(imm));
+ if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
+ /* ng %dst,<d(imm)>(%l) */
+ EMIT6_DISP_LH(0xe3000000, 0x0080,
+ dst_reg, REG_0, REG_L,
+ EMIT_CONST_U64(imm));
+ } else {
+ /* lgrl %w0,imm */
+ EMIT6_PCREL_RILB(0xc4080000, REG_W0,
+ _EMIT_CONST_U64(imm));
+ jit->seen |= SEEN_LITERAL;
+ /* ngr %dst,%w0 */
+ EMIT4(0xb9800000, dst_reg, REG_W0);
+ }
break;
/*
* BPF_OR
@@ -823,9 +869,19 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT_ZERO(dst_reg);
break;
case BPF_ALU64 | BPF_OR | BPF_K: /* dst = dst | imm */
- /* og %dst,<d(imm)>(%l) */
- EMIT6_DISP_LH(0xe3000000, 0x0081, dst_reg, REG_0, REG_L,
- EMIT_CONST_U64(imm));
+ if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
+ /* og %dst,<d(imm)>(%l) */
+ EMIT6_DISP_LH(0xe3000000, 0x0081,
+ dst_reg, REG_0, REG_L,
+ EMIT_CONST_U64(imm));
+ } else {
+ /* lgrl %w0,imm */
+ EMIT6_PCREL_RILB(0xc4080000, REG_W0,
+ _EMIT_CONST_U64(imm));
+ jit->seen |= SEEN_LITERAL;
+ /* ogr %dst,%w0 */
+ EMIT4(0xb9810000, dst_reg, REG_W0);
+ }
break;
/*
* BPF_XOR
@@ -847,9 +903,19 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT_ZERO(dst_reg);
break;
case BPF_ALU64 | BPF_XOR | BPF_K: /* dst = dst ^ imm */
- /* xg %dst,<d(imm)>(%l) */
- EMIT6_DISP_LH(0xe3000000, 0x0082, dst_reg, REG_0, REG_L,
- EMIT_CONST_U64(imm));
+ if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
+ /* xg %dst,<d(imm)>(%l) */
+ EMIT6_DISP_LH(0xe3000000, 0x0082,
+ dst_reg, REG_0, REG_L,
+ EMIT_CONST_U64(imm));
+ } else {
+ /* lgrl %w0,imm */
+ EMIT6_PCREL_RILB(0xc4080000, REG_W0,
+ _EMIT_CONST_U64(imm));
+ jit->seen |= SEEN_LITERAL;
+ /* xgr %dst,%w0 */
+ EMIT4(0xb9820000, dst_reg, REG_W0);
+ }
break;
/*
* BPF_LSH