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| author |   Alexander Gordeev <agordeev@linux.ibm.com> | 2021-08-24 15:30:21 +0200 |
|---|---|---|
| committer |   Heiko Carstens <hca@linux.ibm.com> | 2021-08-26 20:22:12 +0200 |
| commit | 915fea04f9320d0f4ab6ecbb6bf759eebcd2c41d (patch) | |
| tree | ef9a9405858ddd3efe76aa2b5346bbcb447f4a30 /arch/s390/kernel/entry.S | |
| parent | s390: update defconfigs (diff) | |
| download | linux-dev-915fea04f9320d0f4ab6ecbb6bf759eebcd2c41d.tar.xz linux-dev-915fea04f9320d0f4ab6ecbb6bf759eebcd2c41d.zip | |
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/kernel/entry.S')
| -rw-r--r-- | arch/s390/kernel/entry.S | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 5a2f70cbd3a9..b9716a7e326d 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -624,12 +624,15 @@ ENTRY(mcck_int_handler) 4: j 4b ENDPROC(mcck_int_handler) -# -# PSW restart interrupt handler -# ENTRY(restart_int_handler) ALTERNATIVE "", ".insn s,0xb2800000,_LPP_OFFSET", 40 stg %r15,__LC_SAVE_AREA_RESTART + TSTMSK __LC_RESTART_FLAGS,RESTART_FLAG_CTLREGS,4 + jz 0f + la %r15,4095 + lctlg %c0,%c15,__LC_CREGS_SAVE_AREA-4095(%r15) +0: larl %r15,.Lstosm_tmp + stosm 0(%r15),0x04 # turn dat on, keep irqs off lg %r15,__LC_RESTART_STACK xc STACK_FRAME_OVERHEAD(__PT_SIZE,%r15),STACK_FRAME_OVERHEAD(%r15) stmg %r0,%r14,STACK_FRAME_OVERHEAD+__PT_R0(%r15) @@ -638,7 +641,7 @@ ENTRY(restart_int_handler) xc 0(STACK_FRAME_OVERHEAD,%r15),0(%r15) lg %r1,__LC_RESTART_FN # load fn, parm & source cpu lg %r2,__LC_RESTART_DATA - lg %r3,__LC_RESTART_SOURCE + lgf %r3,__LC_RESTART_SOURCE ltgr %r3,%r3 # test source cpu address jm 1f # negative -> skip source stop 0: sigp %r4,%r3,SIGP_SENSE # sigp sense to source cpu |