From b0a0c2566f28e71e5e32121992ac8060cec75510 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 4 Aug 2017 14:20:54 +0200 Subject: [PATCH 1/2] bpf, s390: fix jit branch offset related to ldimm64 While testing some other work that required JIT modifications, I run into test_bpf causing a hang when JIT enabled on s390. The problematic test case was the one from ddc665a4bb4b (bpf, arm64: fix jit branch offset related to ldimm64), and turns out that we do have a similar issue on s390 as well. In bpf_jit_prog() we update next instruction address after returning from bpf_jit_insn() with an insn_count. bpf_jit_insn() returns either -1 in case of error (e.g. unsupported insn), 1 or 2. The latter is only the case for ldimm64 due to spanning 2 insns, however, next address is only set to i + 1 not taking actual insn_count into account, thus fix is to use insn_count instead of 1. bpf_jit_enable in mode 2 provides also disasm on s390: Before fix: 000003ff800349b6: a7f40003 brc 15,3ff800349bc ; target 000003ff800349ba: 0000 unknown 000003ff800349bc: e3b0f0700024 stg %r11,112(%r15) 000003ff800349c2: e3e0f0880024 stg %r14,136(%r15) 000003ff800349c8: 0db0 basr %r11,%r0 000003ff800349ca: c0ef00000000 llilf %r14,0 000003ff800349d0: e320b0360004 lg %r2,54(%r11) 000003ff800349d6: e330b03e0004 lg %r3,62(%r11) 000003ff800349dc: ec23ffeda065 clgrj %r2,%r3,10,3ff800349b6 ; jmp 000003ff800349e2: e3e0b0460004 lg %r14,70(%r11) 000003ff800349e8: e3e0b04e0004 lg %r14,78(%r11) 000003ff800349ee: b904002e lgr %r2,%r14 000003ff800349f2: e3b0f0700004 lg %r11,112(%r15) 000003ff800349f8: e3e0f0880004 lg %r14,136(%r15) 000003ff800349fe: 07fe bcr 15,%r14 After fix: 000003ff80ef3db4: a7f40003 brc 15,3ff80ef3dba 000003ff80ef3db8: 0000 unknown 000003ff80ef3dba: e3b0f0700024 stg %r11,112(%r15) 000003ff80ef3dc0: e3e0f0880024 stg %r14,136(%r15) 000003ff80ef3dc6: 0db0 basr %r11,%r0 000003ff80ef3dc8: c0ef00000000 llilf %r14,0 000003ff80ef3dce: e320b0360004 lg %r2,54(%r11) 000003ff80ef3dd4: e330b03e0004 lg %r3,62(%r11) 000003ff80ef3dda: ec230006a065 clgrj %r2,%r3,10,3ff80ef3de6 ; jmp 000003ff80ef3de0: e3e0b0460004 lg %r14,70(%r11) 000003ff80ef3de6: e3e0b04e0004 lg %r14,78(%r11) ; target 000003ff80ef3dec: b904002e lgr %r2,%r14 000003ff80ef3df0: e3b0f0700004 lg %r11,112(%r15) 000003ff80ef3df6: e3e0f0880004 lg %r14,136(%r15) 000003ff80ef3dfc: 07fe bcr 15,%r14 test_bpf.ko suite runs fine after the fix. Fixes: 054623105728 ("s390/bpf: Add s390x eBPF JIT compiler backend") Signed-off-by: Daniel Borkmann Tested-by: Michael Holzheu Signed-off-by: David S. Miller --- arch/s390/net/bpf_jit_comp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 01c6fbc3e85b..1803797fc885 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -1253,7 +1253,8 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp) insn_count = bpf_jit_insn(jit, fp, i); if (insn_count < 0) return -1; - jit->addrs[i + 1] = jit->prg; /* Next instruction address */ + /* Next instruction address */ + jit->addrs[i + insn_count] = jit->prg; } bpf_jit_epilogue(jit); From bad1926dd2f60bbb4af5223ace3a7b34a0219a66 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 4 Aug 2017 14:20:55 +0200 Subject: [PATCH 2/2] bpf, s390: fix build for libbpf and selftest suite The BPF feature test as well as libbpf is missing the __NR_bpf define for s390 and currently refuses to compile (selftest suite depends on libbpf as well). Similar issue was fixed some time ago via b0c47807d31d ("bpf: Add sparc support to tools and samples."), just do the same and add definitions. Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller --- tools/build/feature/test-bpf.c | 2 ++ tools/lib/bpf/bpf.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/tools/build/feature/test-bpf.c b/tools/build/feature/test-bpf.c index 7598361ef1f1..da2172ff9662 100644 --- a/tools/build/feature/test-bpf.c +++ b/tools/build/feature/test-bpf.c @@ -11,6 +11,8 @@ # define __NR_bpf 280 # elif defined(__sparc__) # define __NR_bpf 349 +# elif defined(__s390__) +# define __NR_bpf 351 # else # error __NR_bpf not defined. libbpf does not support your arch. # endif diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index 256f571f2ab5..e5bbb090bf88 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -39,6 +39,8 @@ # define __NR_bpf 280 # elif defined(__sparc__) # define __NR_bpf 349 +# elif defined(__s390__) +# define __NR_bpf 351 # else # error __NR_bpf not defined. libbpf does not support your arch. # endif