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authorSven Schnelle <svens@linux.ibm.com>2020-01-15 13:42:27 +0100
committerVasily Gorbik <gor@linux.ibm.com>2020-01-22 13:05:35 +0100
commit17248ea0367465f4aaef728f6af661ed38e38cf1 (patch)
treeeca8f398e38ffb1e1557cf131ab2afa0ca2eda78 /arch/s390/boot
parent45f7a0da600d3c409b5ad8d5ddddacd98ddc8840 (diff)
downloadlinux-17248ea0367465f4aaef728f6af661ed38e38cf1.tar.bz2
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.S2
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