qiurui
/
linux-kernelorg-stable
mirror of https://kernel.googlesource.com/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

s390/nmi: consistently enable machine checks in trap_init() 

The kernel starts with machine checks disabled (machine check mask bit in
the PSW is zero), and machine checks are enabled when trap_init() is
called. The rationale is that this allows to assume that the system is
initialized up to a certain point before the machine check handler may be
invoked.

However the implementation is incomplete: all new PSW masks in lowcore have
the machine check mask bit. This means that e.g. for any early program
check machine checks are enabled within the program check handler. This
contradicts the whole point of enabling machine checks at a single place.

Change this and initialize all new PSWs in lowcore so they have the machine
check mask bit not set. Set the bit in all masks in trap_init(). This way
machine check enabling is consistent.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2023-12-01 14:09:30 +01:00 committed by Alexander Gordeev
parent f88d368453
commit 84e599e3ad
2 changed files with 15 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/s390/kernel/setup.c
View File

@ -408,15 +408,15 @@ static void __init setup_lowcore(void)
lc->restart_psw.mask = PSW_KERNEL_BITS & ~PSW_MASK_DAT;
lc->restart_psw.addr = __pa(restart_int_handler);
lc->external_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
lc->external_new_psw.mask = PSW_KERNEL_BITS;
lc->external_new_psw.addr = (unsigned long) ext_int_handler;
lc->svc_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
lc->svc_new_psw.mask = PSW_KERNEL_BITS;
lc->svc_new_psw.addr = (unsigned long) system_call;
lc->program_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
lc->program_new_psw.mask = PSW_KERNEL_BITS;
lc->program_new_psw.addr = (unsigned long) pgm_check_handler;
lc->mcck_new_psw.mask = PSW_KERNEL_BITS;
lc->mcck_new_psw.addr = (unsigned long) mcck_int_handler;
lc->io_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
lc->io_new_psw.mask = PSW_KERNEL_BITS;
lc->io_new_psw.addr = (unsigned long) io_int_handler;
lc->clock_comparator = clock_comparator_max;
lc->current_task = (unsigned long)&init_task;

11
arch/s390/kernel/traps.c
View File

@ -286,6 +286,17 @@ static void __init test_monitor_call(void)
void __init trap_init(void)
{
unsigned long flags;
struct ctlreg cr0;
local_irq_save(flags);
cr0 = local_ctl_clear_bit(0, CR0_LOW_ADDRESS_PROTECTION_BIT);
psw_bits(S390_lowcore.external_new_psw).mcheck = 1;
psw_bits(S390_lowcore.program_new_psw).mcheck = 1;
psw_bits(S390_lowcore.svc_new_psw).mcheck = 1;
psw_bits(S390_lowcore.io_new_psw).mcheck = 1;
local_ctl_load(0, &cr0);
local_irq_restore(flags);
local_mcck_enable();
test_monitor_call();
}