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| author |   Sven Schnelle <svens@linux.ibm.com> | 2020-01-15 13:42:27 +0100 |
|---|---|---|
| committer |   Vasily Gorbik <gor@linux.ibm.com> | 2020-01-22 13:05:35 +0100 |
| commit | 17248ea0367465f4aaef728f6af661ed38e38cf1 (patch) | |
| tree | eca8f398e38ffb1e1557cf131ab2afa0ca2eda78 /arch/s390/boot | |
| parent | s390/ftrace: generate traced function stack frame (diff) | |
| download | linux-dev-17248ea0367465f4aaef728f6af661ed38e38cf1.tar.xz linux-dev-17248ea0367465f4aaef728f6af661ed38e38cf1.zip | |
s390: fix __EMIT_BUG() macro
Setting a kprobe on getname_flags() failed:
$ echo 'p:tmr1 getname_flags +0(%r2):ustring' > kprobe_events
-bash: echo: write error: Invalid argument
Debugging the kprobes code showed that the address of
getname_flags() is contained in the __bug_table. Kprobes
doesn't allow to set probes at BUG() locations.
$ objdump -j __bug_table -x build/fs/namei.o
[..]
0000000000000108 R_390_PC32 .text+0x00000000000075a8
000000000000010c R_390_PC32 .L223+0x0000000000000004
I was expecting getname_flags() to start with a BUG(), but:
7598: e3 20 10 00 00 04 lg %r2,0(%r1)
759e: c0 f4 00 00 00 00 jg 759e <putname+0x7e>
75a0: R_390_PLT32DBL kmem_cache_free+0x2
75a4: a7 f4 00 01 j 75a6 <putname+0x86>
00000000000075a8 <getname_flags>:
75a8: c0 04 00 00 00 00 brcl 0,75a8 <getname_flags>
75ae: eb 6f f0 48 00 24 stmg %r6,%r15,72(%r15)
75b4: b9 04 00 ef lgr %r14,%r15
75b8: e3 f0 ff a8 ff 71 lay %r15,-88(%r15)
So the BUG() is actually the last opcode of the previous function.
Fix this by switching to using the MONITOR CALL (MC) instruction,
and set the entry in __bug_table to the beginning of that MC.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/boot')
| -rw-r--r-- | arch/s390/boot/head.S | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/s390/boot/head.S b/arch/s390/boot/head.S index 4b86a8d3c121..dae10961d072 100644 --- a/arch/s390/boot/head.S +++ b/arch/s390/boot/head.S @@ -329,7 +329,7 @@ ENTRY(startup_kdump) .quad .Lduct # cr5: primary-aste origin .quad 0 # cr6: I/O interrupts .quad 0 # cr7: secondary space segment table - .quad 0 # cr8: access registers translation + .quad 0x0000000000008000 # cr8: access registers translation .quad 0 # cr9: tracing off .quad 0 # cr10: tracing off .quad 0 # cr11: tracing off |