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| author | Michael Holzheu <holzheu@linux.vnet.ibm.com> | 2012-04-11 16:28:11 +0400 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2012-04-11 16:28:26 +0400 |
| commit | 37e37c20ab2dbccdc7a7fa5922e182a51adf50f6 (patch) | |
| tree | 920637cfbaecb8b999216d262ff8941f9fb5264c /arch/s390/include/asm/facility.h | |
| parent | af0ee94e541e366ee4b84c6d476c88fd633fe80a (diff) | |
| download | linux-37e37c20ab2dbccdc7a7fa5922e182a51adf50f6.tar.xz | |
[S390] Fix stfle() lowcore protection problem
The stfle() function writes into lowcore memory when stfl_fac_list
is initialized with "S390_lowcore.stfl_fac_list = 0". For older
compilers this triggers a lowcore exception. With newer compilers
and "-OXX" compile option the bug does not show up because
the "S390_lowcore.stfl_fac_list" initialization is removed by the
compiler. The reason for thatis the incorrect "=m"
(S390_lowcore.stfl_fac_list) constraint in the stfl inline assembly.
The following shows the disassembly of the stfle() optimized code
that is inlined in the lgr_info_get() function:
000000000011325c <lgr_info_get>:
11325c: eb 9f f0 60 00 24 stmg %r9,%r15,96(%r15)
113262: c0 d0 00 29 0e 47 larl %r13,634ef0 <servi..>
113268: a7 f1 3f c0 tml %r15,16320
11326c: b9 04 00 ef lgr %r14,%r15
113270: a7 84 00 01 je 113272 <lgr_info_g..>
113274: a7 fb ff c0 aghi %r15,-64
113278: b9 04 00 c2 lgr %r12,%r2
11327c: a7 29 00 01 lghi %r2,1
113280: e3 e0 f0 98 00 24 stg %r14,152(%r15)
113286: d7 97 c0 00 c0 00 xc 0(152,%r12),0(%r12)
11328c: c0 e5 00 28 db 4c brasl %r14,62e924 <add_e..>
113292: b2 b1 00 00 stfl 0
To fix the problem we now clear the S390_lowcore.stfl_fac_list at
startup in "head.S" for all machine types before lowcore protection
is enabled.
In addition to that the "=m" constraint is replaced by "+m".
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/facility.h')
| -rw-r--r-- | arch/s390/include/asm/facility.h | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/s390/include/asm/facility.h b/arch/s390/include/asm/facility.h index 1e5b27edc0c9..2ee66a65f2d4 100644 --- a/arch/s390/include/asm/facility.h +++ b/arch/s390/include/asm/facility.h @@ -38,12 +38,11 @@ static inline void stfle(u64 *stfle_fac_list, int size) unsigned long nr; preempt_disable(); - S390_lowcore.stfl_fac_list = 0; asm volatile( " .insn s,0xb2b10000,0(0)\n" /* stfl */ "0:\n" EX_TABLE(0b, 0b) - : "=m" (S390_lowcore.stfl_fac_list)); + : "+m" (S390_lowcore.stfl_fac_list)); nr = 4; /* bytes stored by stfl */ memcpy(stfle_fac_list, &S390_lowcore.stfl_fac_list, 4); if (S390_lowcore.stfl_fac_list & 0x01000000) { |