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Commit ecc15f11 authored by Heiko Carstens's avatar Heiko Carstens Committed by Alexei Starovoitov
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s390: bpf: fix JMP32 code-gen 



Commit 626a5f66 ("s390: bpf: implement jitting of JMP32") added
JMP32 code-gen support for s390. However it triggers the warning below
due to some unusual gotos in the original s390 bpf jit code.

Add a couple of additional "is_jmp32" initializations to fix this.
Also fix the wrong opcode for the "llilf" instruction that was
introduced with the same commit.

arch/s390/net/bpf_jit_comp.c: In function 'bpf_jit_insn':
arch/s390/net/bpf_jit_comp.c:248:55: warning: 'is_jmp32' may be used uninitialized in this function [-Wmaybe-uninitialized]
  _EMIT6(op1 | reg(b1, b2) << 16 | (rel & 0xffff), op2 | mask); \
                                                       ^
arch/s390/net/bpf_jit_comp.c:1211:8: note: 'is_jmp32' was declared here
   bool is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;

Fixes: 626a5f66 ("s390: bpf: implement jitting of JMP32")
Cc: Jiong Wang <jiong.wang@netronome.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: default avatarJiong Wang <jiong.wang@netronome.com>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 9fa3b473

arch/s390/net/bpf_jit_comp.c

+5 −1
Original line number Diff line number Diff line
@@ -1154,7 +1154,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 
		mask = 0x7000; /* jnz */

		if (BPF_CLASS(insn->code) == BPF_JMP32) {

			/* llilf %w1,imm (load zero extend imm) */

			EMIT6_IMM(0xc0010000, REG_W1, imm);

			EMIT6_IMM(0xc00f0000, REG_W1, imm);

			/* nr %w1,%dst */

			EMIT2(0x1400, REG_W1, dst_reg);

		} else {
@@ -1216,6 +1216,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 
			  REG_W1, dst_reg, src_reg);

		goto branch_oc;

branch_ks:

		is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;

		/* lgfi %w1,imm (load sign extend imm) */

		EMIT6_IMM(0xc0010000, REG_W1, imm);

		/* crj or cgrj %dst,%w1,mask,off */
@@ -1223,6 +1224,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 
			    dst_reg, REG_W1, i, off, mask);

		break;

branch_ku:

		is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;

		/* lgfi %w1,imm (load sign extend imm) */

		EMIT6_IMM(0xc0010000, REG_W1, imm);

		/* clrj or clgrj %dst,%w1,mask,off */
@@ -1230,11 +1232,13 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 
			    dst_reg, REG_W1, i, off, mask);

		break;

branch_xs:

		is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;

		/* crj or cgrj %dst,%src,mask,off */

		EMIT6_PCREL(0xec000000, (is_jmp32 ? 0x0076 : 0x0064),

			    dst_reg, src_reg, i, off, mask);

		break;

branch_xu:

		is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;

		/* clrj or clgrj %dst,%src,mask,off */

		EMIT6_PCREL(0xec000000, (is_jmp32 ? 0x0077 : 0x0065),

			    dst_reg, src_reg, i, off, mask);