[PATCH AUTOSEL 4.19 06/52] s390/bpf: fix lcgr instruction encoding

[PATCH AUTOSEL 4.19 06/52] s390/bpf: fix lcgr instruction encoding

[Sasha Levin]

From: Ilya Leoshkevich <iii@linux.ibm.com>

[ Upstream commit bb2d267c448f4bc3a3389d97c56391cb779178ae ]

"masking, test in bounds 3" fails on s390, because
BPF_ALU64_IMM(BPF_NEG, BPF_REG_2, 0) ignores the top 32 bits of
BPF_REG_2. The reason is that JIT emits lcgfr instead of lcgr.
The associated comment indicates that the code was intended to
emit lcgr in the first place, it's just that the wrong opcode
was used.

Fix by using the correct opcode.

Fixes: 054623105728 ("s390/bpf: Add s390x eBPF JIT compiler backend")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/s390/net/bpf_jit_comp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index d7052cbe984f8..a3ce1fdc3d802 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -841,7 +841,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 		break;
 	case BPF_ALU64 | BPF_NEG: /* dst = -dst */
 		/* lcgr %dst,%dst */
-		EMIT4(0xb9130000, dst_reg, dst_reg);
+		EMIT4(0xb9030000, dst_reg, dst_reg);
 		break;
 	/*
 	 * BPF_FROM_BE/LE
-- 
2.20.1

[PATCH AUTOSEL 4.19 11/52] s390/bpf: use 32-bit index for tail calls

[Sasha Levin]

From: Ilya Leoshkevich <iii@linux.ibm.com>

[ Upstream commit 91b4db5313a2c793aabc2143efb8ed0cf0fdd097 ]

"p runtime/jit: pass > 32bit index to tail_call" fails when
bpf_jit_enable=1, because the tail call is not executed.

This in turn is because the generated code assumes index is 64-bit,
while it must be 32-bit, and as a result prog array bounds check fails,
while it should pass. Even if bounds check would have passed, the code
that follows uses 64-bit index to compute prog array offset.

Fix by using clrj instead of clgrj for comparing index with array size,
and also by using llgfr for truncating index to 32 bits before using it
to compute prog array offset.

Fixes: 6651ee070b31 ("s390/bpf: implement bpf_tail_call() helper")
Reported-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/s390/net/bpf_jit_comp.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index a3ce1fdc3d802..2617e426c7926 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -1015,8 +1015,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 		/* llgf %w1,map.max_entries(%b2) */
 		EMIT6_DISP_LH(0xe3000000, 0x0016, REG_W1, REG_0, BPF_REG_2,
 			      offsetof(struct bpf_array, map.max_entries));
-		/* clgrj %b3,%w1,0xa,label0: if %b3 >= %w1 goto out */
-		EMIT6_PCREL_LABEL(0xec000000, 0x0065, BPF_REG_3,
+		/* clrj %b3,%w1,0xa,label0: if (u32)%b3 >= (u32)%w1 goto out */
+		EMIT6_PCREL_LABEL(0xec000000, 0x0077, BPF_REG_3,
 				  REG_W1, 0, 0xa);
 
 		/*
@@ -1042,8 +1042,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 		 *         goto out;
 		 */
 
-		/* sllg %r1,%b3,3: %r1 = index * 8 */
-		EMIT6_DISP_LH(0xeb000000, 0x000d, REG_1, BPF_REG_3, REG_0, 3);
+		/* llgfr %r1,%b3: %r1 = (u32) index */
+		EMIT4(0xb9160000, REG_1, BPF_REG_3);
+		/* sllg %r1,%r1,3: %r1 *= 8 */
+		EMIT6_DISP_LH(0xeb000000, 0x000d, REG_1, REG_1, REG_0, 3);
 		/* lg %r1,prog(%b2,%r1) */
 		EMIT6_DISP_LH(0xe3000000, 0x0004, REG_1, BPF_REG_2,
 			      REG_1, offsetof(struct bpf_array, ptrs));
-- 
2.20.1