* Fwd: [Bug 205459] New: mips: bpf: test_bpf failures, eBPF JIT on mips32 outputs invalid 64-bit insns
[not found] <bug-205459-65011@https.bugzilla.kernel.org/>
@ 2019-11-08 23:42 ` Daniel Borkmann
0 siblings, 0 replies; only message in thread
From: Daniel Borkmann @ 2019-11-08 23:42 UTC (permalink / raw)
To: Paul Burton, linux-mips, Ralf Baechle, James Hogan,
Hassan Naveed, Matt Redfearn, David Daney
Cc: bpf, itugrok
[ Cc MIPS folks ]
Hassan, James, Paul, others, please take a look. Thanks!
-------- Forwarded Message --------
Subject: [Bug 205459] New: mips: bpf: test_bpf failures, eBPF JIT on mips32 outputs invalid 64-bit insns
Date: Thu, 07 Nov 2019 06:41:21 +0000
From: bugzilla-daemon@bugzilla.kernel.org
To: daniel@iogearbox.net
https://bugzilla.kernel.org/show_bug.cgi?id=205459
Bug ID: 205459
Summary: mips: bpf: test_bpf failures, eBPF JIT on mips32
outputs invalid 64-bit insns
Product: Networking
Version: 2.5
Kernel Version: 5.2.17
Hardware: Mips32
OS: Linux
Tree: Mainline
Status: NEW
Severity: high
Priority: P1
Component: Other
Assignee: stephen@networkplumber.org
Reporter: itugrok@yahoo.com
Regression: No
Created attachment 285809
--> https://bugzilla.kernel.org/attachment.cgi?id=285809&action=edit
EXCEPTION/failures: kernel 5.2.17/mips32 (Debian 10.1)
Summary:
========
Linux 5.2.x added an eBPF JIT for MIPS32 (yay!). Based on discussion of the
original submission (https://www.spinics.net/lists/mips/msg77008.html) I
expected that:
(1) all tests from module test_bpf.ko would pass, and
(2) any previously JITed tests (i.e. cBPF) would still be JITed.
However, I can't reproduce the above based on my testing as per the attached
log.
Point (2) doesn't stand since the first ~30 tests are not JITed, but were
previously cBPF JITed for the most part.
As for point (1), the full test set doesn't complete, but errors out early on
with a "Reserved instruction in kernel code[#1]" error. Manually hopping
through some of the tests yields the same error for many:
#68 ALU_MOV_K: 0x0000ffffffff0000 = 0x00000000ffffffff jited:1
#73 ALU_ADD_X: 1 + 2 = 3 jited:1
#74 ALU_ADD_X: 1 + 4294967294 = 4294967295 jited:1
#75 ALU_ADD_X: 2 + 4294967294 = 0 jited:1
#79 ALU_ADD_K: 1 + 2 = 3 jited:1
(.. and so on ...)
Disassembling the JITed code for test #68 shows incorrect MIPS64 instructions:
24 03 00 20 li v1,32
34 05 ff ff li a1,0xffff
00 05 2c 38 dsll a1,a1,0x10 <=== MIPS64 insn
34 a5 ff ff ori a1,a1,0xffff
00 05 2c 38 dsll a1,a1,0x10 <=== MIPS64 insn
34 06 ff ff li a2,0xffff
00 06 34 38 dsll a2,a2,0x10 <=== MIPS64 insn
34 c6 ff ff ori a2,a2,0xffff
Since this was tested in the past, I'm really hoping there's a simple solution
to these problems, or else a case of "operator error". A review by someone more
knowledgeable with the MIPS32 eBPF JIT would be appreciated.
Steps to Reproduce:
===================
# sysctl net.core.bpf_jit_enable=1
# modprobe test_bpf
<Kernel log with "Reserved instruction" exception>
Affected Systems Tested:
========================
Debian 10.1 on QEMU/malta(mips32_be) [distro kernel 5.2.17-1~bpo10+1
(2019-09-30)]
Kernel Logs:
============
Boot log with test results up to first failure is attached.
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