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Daniel Borkmann b0a0c2566f 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 ddc665a4bb (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: 0546231057 ("s390/bpf: Add s390x eBPF JIT compiler backend")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-04 11:18:01 -07:00
..
appldata sched/headers: Move task statistics APIs from <linux/sched.h> to <linux/sched/stat.h> 2017-03-03 01:43:43 +01:00
boot s390/decompressor: fix initrd corruption caused by bss clear 2017-03-22 08:21:20 +01:00
configs s390: update defconfig 2017-06-08 15:53:48 +02:00
crypto s390/crypto: fix aes/paes Kconfig dependeny 2017-06-12 16:25:58 +02:00
hypfs s390: hypfs: make inode explicitly non-modular 2016-10-31 17:55:40 +01:00
include Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-21 10:41:19 -07:00
kernel Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2017-07-25 08:44:27 -07:00
kvm KVM: s390: take srcu lock when getting/setting storage keys 2017-07-25 14:59:52 +02:00
lib s390/uaccess: use sane length for __strncpy_from_user() 2017-05-09 10:43:24 +02:00
mm s390/mm: set change and reference bit on lazy key enablement 2017-07-13 11:28:29 +02:00
net bpf, s390: fix jit branch offset related to ldimm64 2017-08-04 11:18:01 -07:00
numa s390/numa: pin all possible cpus to nodes early 2016-12-07 07:23:33 +01:00
oprofile s390/dumpstack: restore reliable indicator for call traces 2016-10-17 14:44:30 +02:00
pci This is the first pull request for the new dma-mapping subsystem 2017-07-06 19:20:54 -07:00
tools s390/facilities: remove stfle requirement 2017-06-12 16:25:59 +02:00
defconfig s390: update defconfig 2017-06-08 15:53:48 +02:00
Kbuild s390/crypto: Provide s390 specific arch random functionality. 2017-04-26 13:41:35 +02:00
Kconfig mm/hugetlb: clean up ARCH_HAS_GIGANTIC_PAGE 2017-07-06 16:24:33 -07:00
Kconfig.debug Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2017-02-22 10:20:04 -08:00
Makefile s390: add assembler include path for vx-insn.h 2016-09-06 11:00:04 +02:00