From bb2d267c448f4bc3a3389d97c56391cb779178ae Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Mon, 12 Aug 2019 17:03:32 +0200 Subject: s390/bpf: fix lcgr instruction encoding "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 Acked-by: Vasily Gorbik Signed-off-by: Daniel Borkmann --- arch/s390/net/bpf_jit_comp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index e636728ab452..6299156f9738 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -863,7 +863,7 @@ 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 -- cgit v1.2.3-59-g8ed1b From 91b4db5313a2c793aabc2143efb8ed0cf0fdd097 Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Mon, 12 Aug 2019 18:18:07 +0200 Subject: s390/bpf: use 32-bit index for tail calls "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 Acked-by: Vasily Gorbik Signed-off-by: Ilya Leoshkevich Signed-off-by: Daniel Borkmann --- arch/s390/net/bpf_jit_comp.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 6299156f9738..955eb355c2fd 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -1049,8 +1049,8 @@ 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); /* @@ -1076,8 +1076,10 @@ 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)); -- cgit v1.2.3-59-g8ed1b