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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/kernel/pgm_check.S | |
| parent | 45f7a0da600d3c409b5ad8d5ddddacd98ddc8840 (diff) | |
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/kernel/pgm_check.S')
| -rw-r--r-- | arch/s390/kernel/pgm_check.S | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/s390/kernel/pgm_check.S b/arch/s390/kernel/pgm_check.S index 59dee9d3bebf..eee3a482195a 100644 --- a/arch/s390/kernel/pgm_check.S +++ b/arch/s390/kernel/pgm_check.S @@ -81,7 +81,7 @@ PGM_CHECK_DEFAULT /* 3c */ PGM_CHECK_DEFAULT /* 3d */ PGM_CHECK_DEFAULT /* 3e */ PGM_CHECK_DEFAULT /* 3f */ -PGM_CHECK_DEFAULT /* 40 */ +PGM_CHECK(monitor_event_exception) /* 40 */ PGM_CHECK_DEFAULT /* 41 */ PGM_CHECK_DEFAULT /* 42 */ PGM_CHECK_DEFAULT /* 43 */ |