* [Bug bpf/23860] New: unknown opcode 0x8f in string manipulation code
@ 2018-11-04 18:38 fche at redhat dot com
2018-11-04 21:16 ` [Bug bpf/23860] " mark at klomp dot org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: fche at redhat dot com @ 2018-11-04 18:38 UTC (permalink / raw)
To: systemtap
https://sourceware.org/bugzilla/show_bug.cgi?id=23860
Bug ID: 23860
Summary: unknown opcode 0x8f in string manipulation code
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: bpf
Assignee: systemtap at sourceware dot org
Reporter: fche at redhat dot com
Target Milestone: ---
% stap -p4 --bpf -e 'global e probe kernel.function("vfs_read") { e[execname()]
= 0 }'
% eu-objdump -d stap_FOOBAR.bo
[...]
d0: 57 00 00 00 ff 00 00 00 r0 &= 255
d8: bf 01 00 00 00 00 00 00 r1 = r0
e0: 8f 01 00 00 00 00 00 00 invalid class alu64
e8: 4f 01 00 00 00 00 00 00 r1 |= r0
f0: bf 13 00 00 00 00 00 00 r3 = r1
f8: bf 20 00 00 00 00 00 00 r0 = r2
100: 77 00 00 00 08 00 00 00 r0 >>= 8
108: 57 00 00 00 ff 00 00 00 r0 &= 255
110: bf 01 00 00 00 00 00 00 r1 = r0
118: 8f 01 00 00 00 00 00 00 invalid class alu64
120: 4f 01 00 00 00 00 00 00 r1 |= r0
128: 5f 13 00 00 00 00 00 00 r3 &= r1
130: bf 20 00 00 00 00 00 00 r0 = r2
% stapbpf stap_FOOBAR.bo
(fails with unknown opcode 0x8f)
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^ permalink raw reply [flat|nested] 4+ messages in thread* [Bug bpf/23860] unknown opcode 0x8f in string manipulation code 2018-11-04 18:38 [Bug bpf/23860] New: unknown opcode 0x8f in string manipulation code fche at redhat dot com @ 2018-11-04 21:16 ` mark at klomp dot org 2018-11-05 22:01 ` me at serhei dot io 2018-11-05 22:03 ` me at serhei dot io 2 siblings, 0 replies; 4+ messages in thread From: mark at klomp dot org @ 2018-11-04 21:16 UTC (permalink / raw) To: systemtap https://sourceware.org/bugzilla/show_bug.cgi?id=23860 Mark Wielaard <mark at klomp dot org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |mark at klomp dot org --- Comment #1 from Mark Wielaard <mark at klomp dot org> --- If I am decoding this correctly this would be BPF_ALU64 | BPF_NEG | BPF_X. I am not sure that combination makes sense. I don't believe you can negate a source operand. You seem to only be able to negate the dest operand (register). -- You are receiving this mail because: You are the assignee for the bug. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug bpf/23860] unknown opcode 0x8f in string manipulation code 2018-11-04 18:38 [Bug bpf/23860] New: unknown opcode 0x8f in string manipulation code fche at redhat dot com 2018-11-04 21:16 ` [Bug bpf/23860] " mark at klomp dot org @ 2018-11-05 22:01 ` me at serhei dot io 2018-11-05 22:03 ` me at serhei dot io 2 siblings, 0 replies; 4+ messages in thread From: me at serhei dot io @ 2018-11-05 22:01 UTC (permalink / raw) To: systemtap https://sourceware.org/bugzilla/show_bug.cgi?id=23860 Serhei Makarov <me at serhei dot io> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |me at serhei dot io --- Comment #2 from Serhei Makarov <me at serhei dot io> --- This was a minor bug in program::mk_unary(). BPF_NEG indeed doesn't fit the pattern for eBPF opcodes: there is no src and BPF_X is not used even though the disassembly says 'negx'. Incorrect opcode should be fixed in commit 72ef87bba, but there's another underlying issue preventing the example from working ('invalid memory access' according to verifier). Not closing yet. -- You are receiving this mail because: You are the assignee for the bug. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug bpf/23860] unknown opcode 0x8f in string manipulation code 2018-11-04 18:38 [Bug bpf/23860] New: unknown opcode 0x8f in string manipulation code fche at redhat dot com 2018-11-04 21:16 ` [Bug bpf/23860] " mark at klomp dot org 2018-11-05 22:01 ` me at serhei dot io @ 2018-11-05 22:03 ` me at serhei dot io 2 siblings, 0 replies; 4+ messages in thread From: me at serhei dot io @ 2018-11-05 22:03 UTC (permalink / raw) To: systemtap https://sourceware.org/bugzilla/show_bug.cgi?id=23860 Serhei Makarov <me at serhei dot io> changed: What |Removed |Added ---------------------------------------------------------------------------- Assignee|systemtap at sourceware dot org |me at serhei dot io -- You are receiving this mail because: You are the assignee for the bug. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-11-05 22:03 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2018-11-04 18:38 [Bug bpf/23860] New: unknown opcode 0x8f in string manipulation code fche at redhat dot com 2018-11-04 21:16 ` [Bug bpf/23860] " mark at klomp dot org 2018-11-05 22:01 ` me at serhei dot io 2018-11-05 22:03 ` me at serhei dot io
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