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[PATCH 4.9 05/16] bpf, s390: fix jit branch offset related to ldimm64

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.9 05/16] bpf, s390: fix jit branch offset related to ldimm64
Date 2017-08-12 00:20 +0200
Message-ID <udqrF-Hs-49@gated-at.bofh.it> (permalink)
References <udqhX-E7-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel Borkmann <daniel@iogearbox.net>


[ 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@iogearbox.net>
Tested-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 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
@@ -1252,7 +1252,8 @@ 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);
 

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Thread

[PATCH 4.9 00/16] 4.9.43-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:10 +0200
  [PATCH 4.9 07/16] net: sched: set xt_tgchk_param par.nft_compat as 0 in ipt_init_target Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:10 +0200
  [PATCH 4.9 13/16] revert "ipv4: Should use consistent conditional judgement for ip fragment in __ip_append_data and ip_finish_output" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:10 +0200
  [PATCH 4.9 08/16] tcp: fastopen: tcp_connect() must refresh the route Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 16/16] KVM: arm/arm64: Handle hva aging while destroying the vm Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 11/16] packet: fix tp_reserve race in packet_set_ring Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 15/16] sparc64: Prevent perf from running during super critical sections Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 04/16] net: fix keepalive code vs TCP_FASTOPEN_CONNECT Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 12/16] revert "net: account for current skb length when deciding about UFO" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 03/16] tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 06/16] net/mlx4_en: dont set CHECKSUM_COMPLETE on SCTP packets Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 14/16] udp: consistently apply ufo or fragmentation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 05/16] bpf, s390: fix jit branch offset related to ldimm64 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 10/16] igmp: Fix regression caused by igmp sysctl namespace code. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 02/16] ppp: fix xmit recursion detection on ppp channels Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.9 01/16] ppp: Fix false xmit recursion detect with two ppp devices Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  Re: [PATCH 4.9 00/16] 4.9.43-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-08-12 04:00 +0200
  Re: [PATCH 4.9 00/16] 4.9.43-stable review Guenter Roeck <linux@roeck-us.net> - 2017-08-12 14:40 +0200
    Re: [PATCH 4.9 00/16] 4.9.43-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 18:10 +0200
      Re: [PATCH 4.9 00/16] 4.9.43-stable review Guenter Roeck <linux@roeck-us.net> - 2017-08-12 18:30 +0200

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