diff options
| author | Sven Schnelle <svens@linux.ibm.com> | 2020-01-15 15:42:27 +0300 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2020-01-22 15:05:35 +0300 |
| commit | 17248ea0367465f4aaef728f6af661ed38e38cf1 (patch) | |
| tree | eca8f398e38ffb1e1557cf131ab2afa0ca2eda78 /arch/s390/include/asm/bug.h | |
| parent | 45f7a0da600d3c409b5ad8d5ddddacd98ddc8840 (diff) | |
| download | linux-17248ea0367465f4aaef728f6af661ed38e38cf1.tar.xz | |
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/include/asm/bug.h')
| -rw-r--r-- | arch/s390/include/asm/bug.h | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/arch/s390/include/asm/bug.h b/arch/s390/include/asm/bug.h index a2b11ac00f60..7725f8006fdf 100644 --- a/arch/s390/include/asm/bug.h +++ b/arch/s390/include/asm/bug.h @@ -10,15 +10,14 @@ #define __EMIT_BUG(x) do { \ asm_inline volatile( \ - "0: j 0b+2\n" \ - "1:\n" \ + "0: mc 0,0\n" \ ".section .rodata.str,\"aMS\",@progbits,1\n" \ - "2: .asciz \""__FILE__"\"\n" \ + "1: .asciz \""__FILE__"\"\n" \ ".previous\n" \ ".section __bug_table,\"awM\",@progbits,%2\n" \ - "3: .long 1b-3b,2b-3b\n" \ + "2: .long 0b-2b,1b-2b\n" \ " .short %0,%1\n" \ - " .org 3b+%2\n" \ + " .org 2b+%2\n" \ ".previous\n" \ : : "i" (__LINE__), \ "i" (x), \ @@ -29,12 +28,11 @@ #define __EMIT_BUG(x) do { \ asm_inline volatile( \ - "0: j 0b+2\n" \ - "1:\n" \ + "0: mc 0,0\n" \ ".section __bug_table,\"awM\",@progbits,%1\n" \ - "2: .long 1b-2b\n" \ + "1: .long 0b-1b\n" \ " .short %0\n" \ - " .org 2b+%1\n" \ + " .org 1b+%1\n" \ ".previous\n" \ : : "i" (x), \ "i" (sizeof(struct bug_entry))); \ |