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s390/entry: rework entering DAT-on mode on CPU restart

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Instead of enforcing PSW_MASK_DAT bit on previously stored
in lowcore restart_psw.mask use the PSW_KERNEL_BITS mask
(which contains PSW_MASK_DAT) directly.

As result, the PSW mask stored in lowcore is only used to
enter the CPU restart routine, while PSW_KERNEL_BITS is
used to enter the kernel code - similarily to commit
64ea2977add2 ("s390/mm: start kernel with DAT enabled").

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Alexander Gordeev 2023-04-18 17:40:37 +02:00
parent b492425c70
commit edbe289898
1 changed files with 8 additions and 3 deletions
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11
arch/s390/kernel/entry.S
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@ -598,8 +598,9 @@ SYM_CODE_START(restart_int_handler)
TSTMSK __LC_RESTART_FLAGS,RESTART_FLAG_CTLREGS,4
jz 0f
lctlg %c0,%c15,__LC_CREGS_SAVE_AREA
0: larl %r15,stosm_tmp
stosm 0(%r15),0x04 # turn dat on, keep irqs off
0: larl %r15,daton_psw
lpswe 0(%r15) # turn dat on, keep irqs off
.Ldaton:
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)
@ -646,7 +647,11 @@ SYM_CODE_END(stack_overflow)
.balign 4
SYM_DATA_LOCAL(stop_lock, .long 0)
SYM_DATA_LOCAL(this_cpu, .short 0)
SYM_DATA_LOCAL(stosm_tmp, .byte 0)
.balign 8
SYM_DATA_START_LOCAL(daton_psw)
.quad PSW_KERNEL_BITS
.quad .Ldaton
SYM_DATA_END(daton_psw)
.section .rodata, "a"
#define SYSCALL(esame,emu) .quad __s390x_ ## esame