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| author | Alexander Gordeev <agordeev@linux.ibm.com> | 2021-08-24 16:30:21 +0300 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2021-08-26 21:22:12 +0300 |
| commit | 915fea04f9320d0f4ab6ecbb6bf759eebcd2c41d (patch) | |
| tree | ef9a9405858ddd3efe76aa2b5346bbcb447f4a30 /arch/s390/include/asm/lowcore.h | |
| parent | e7dc78d3d9ad1e70f2e955bdfef807a9f1dfcce7 (diff) | |
| download | linux-915fea04f9320d0f4ab6ecbb6bf759eebcd2c41d.tar.xz | |
s390/smp: enable DAT before CPU restart callback is called
The restart interrupt is triggered whenever a secondary CPU is
brought online, a remote function call dispatched from another
CPU or a manual PSW restart is initiated and causes the system
to kdump. The handling routine is always called with DAT turned
off. It then initializes the stack frame and invokes a callback.
The existing callbacks handle DAT as follows:
* __do_restart() and __machine_kexec() turn in on upon entry;
* __ipl_run(), __reipl_run() and __dump_run() do not turn it
right away, but all of them call diag308() - which turns DAT
on, but only if kasan is enabled;
In addition to the described complexity all callbacks (and the
functions they call) should avoid kasan instrumentation while
DAT is off.
This update enables DAT in the assembler restart handler and
relieves any callbacks (which are mostly C functions) from
dealing with DAT altogether.
There are four types of CPU restart that initialize control
registers in different ways:
1. Start of secondary CPU on boot - control registers are
inherited from the IPL CPU;
2. Restart of online CPU - control registers of the CPU being
restarted are kept;
3. Hotplug of offline CPU - control registers are inherited
from the starting CPU;
4. Start of offline CPU triggered by manual PSW restart -
the control registers are read from the absolute lowcore
and contain the boot time IPL CPU values updated with all
follow-up calls of smp_ctl_set_bit() and smp_ctl_clear_bit()
routines;
In first three cases contents of the control registers is the
most recent. In the latter case control registers are good
enough to facilitate successful completion of kdump operation.
Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/lowcore.h')
| -rw-r--r-- | arch/s390/include/asm/lowcore.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h index 47bde5a20a41..11213c8bfca5 100644 --- a/arch/s390/include/asm/lowcore.h +++ b/arch/s390/include/asm/lowcore.h @@ -124,7 +124,8 @@ struct lowcore { /* Restart function and parameter. */ __u64 restart_fn; /* 0x0370 */ __u64 restart_data; /* 0x0378 */ - __u64 restart_source; /* 0x0380 */ + __u32 restart_source; /* 0x0380 */ + __u32 restart_flags; /* 0x0384 */ /* Address space pointer. */ __u64 kernel_asce; /* 0x0388 */ |