This is a note to let you know that I've just added the patch titled
bpf, s390: fix jit branch offset related to ldimm64
to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-s390-fix-jit-branch-offset-related-to-ldimm64.patch
and it can be found in the queue-4.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Aug 11 09:09:38 PDT 2017
From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Date: Fri, 4 Aug 2017 14:20:54 +0200
Subject: bpf, s390: fix jit branch offset related to ldimm64
From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
[ Upstream commit b0a0c2566f28e71e5e32121992ac8060cec75510 ]
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 <daniel@xxxxxxxxxxxxx>
Tested-by: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/net/bpf_jit_comp.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- 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 *
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);
Patches currently in stable-queue which might be from daniel@xxxxxxxxxxxxx are
queue-4.12/bpf-s390-fix-jit-branch-offset-related-to-ldimm64.patch