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| author | Michael Holzheu <holzheu@linux.vnet.ibm.com> | 2011-05-10 19:13:39 +0400 |
|---|---|---|
| committer | Martin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com> | 2011-05-10 19:13:42 +0400 |
| commit | 8eb4bd666ffdca7171cd8118138a91842012b028 (patch) | |
| tree | c362b8e8ea64731854a2e894777252f315eca1dc | |
| parent | aade6c0dfb46ff7ce7df0ed7a2ef15d2d3c47f05 (diff) | |
| download | linux-8eb4bd666ffdca7171cd8118138a91842012b028.tar.xz | |
[S390] kernel: Initialize register 14 when starting new CPU
When starting a new CPU we currently jump to start_secondary() without
setting register 14 (the return address) correctly. Therefore on the stack
frame for start_secondary an invalid return address is stored. This leads
to wrong stack back traces in kernel dumps.
Example:
#00 [1f33fe48] cpu_idle at 10614a
#01 [1f33fe90] start_secondary at 54fa88
#02 [1f33feb8] (null) at 0 <--- invalid
To fix this start_secondary() is called now with basr/brasl that sets
register 14 correctly. The output of the stack backtrace looks then
like the following:
#00 [1f33fe48] cpu_idle at 10614a
#01 [1f33fe90] start_secondary at 54fa88
#02 [1f33feb8] restart_base at 54f41e <--- correct
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| -rw-r--r-- | arch/s390/kernel/entry.S | 2 | ||||
| -rw-r--r-- | arch/s390/kernel/entry64.S | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 648f64239a9d..1b67fc6ebdc2 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -836,7 +836,7 @@ restart_base: stosm __SF_EMPTY(%r15),0x04 # now we can turn dat on basr %r14,0 l %r14,restart_addr-.(%r14) - br %r14 # branch to start_secondary + basr %r14,%r14 # branch to start_secondary restart_addr: .long start_secondary .align 8 diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S index 9d3603d6c511..9fd864563499 100644 --- a/arch/s390/kernel/entry64.S +++ b/arch/s390/kernel/entry64.S @@ -841,7 +841,7 @@ restart_base: mvc __LC_SYSTEM_TIMER(8),__TI_system_timer(%r1) xc __LC_STEAL_TIMER(8),__LC_STEAL_TIMER stosm __SF_EMPTY(%r15),0x04 # now we can turn dat on - jg start_secondary + brasl %r14,start_secondary .align 8 restart_vtime: .long 0x7fffffff,0xffffffff |