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s390/smp: reallocate IPL CPU lowcore

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The lowcore for IPL CPU is special. It is allocated early
in the boot process using memblock and never freed since.
The reason is pcpu_alloc_lowcore() and pcpu_free_lowcore()
routines use page allocator which is not available when
the IPL CPU is getting initialized.

Similar problem is already addressed for stacks - once the
virtual memory is available the early boot stacks get re-
allocated. Doing the same for lowcore will allow freeing
the IPL CPU lowcore and make no difference between the
boot and secondary CPUs.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Alexander Gordeev 2021-05-06 16:26:52 +02:00 • committed by Vasily Gorbik
parent bdb8c9353e
commit 5789284710
2 changed files with 52 additions and 21 deletions
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21
arch/s390/kernel/setup.c
View file

@ -341,27 +341,6 @@ int __init arch_early_irq_init(void)
return 0;
}
static int __init stack_realloc(void)
{
unsigned long old, new;
old = S390_lowcore.async_stack - STACK_INIT_OFFSET;
new = stack_alloc();
if (!new)
panic("Couldn't allocate async stack");
WRITE_ONCE(S390_lowcore.async_stack, new + STACK_INIT_OFFSET);
free_pages(old, THREAD_SIZE_ORDER);
old = S390_lowcore.mcck_stack - STACK_INIT_OFFSET;
new = stack_alloc();
if (!new)
panic("Couldn't allocate machine check stack");
WRITE_ONCE(S390_lowcore.mcck_stack, new + STACK_INIT_OFFSET);
memblock_free_late(old, THREAD_SIZE);
return 0;
}
early_initcall(stack_realloc);
void __init arch_call_rest_init(void)
{
unsigned long stack;

52
arch/s390/kernel/smp.c
View file

@ -1234,3 +1234,55 @@ out:
return rc;
}
subsys_initcall(s390_smp_init);
static __always_inline void set_new_lowcore(struct lowcore *lc)
{
struct lowcore *old_lc = &S390_lowcore;
struct lowcore *new_lc = lc;
u32 pfx;
register struct lowcore *reg2 asm ("2") = new_lc;
register unsigned long reg3 asm ("3") = sizeof(*reg2);
register struct lowcore *reg4 asm ("4") = old_lc;
register unsigned long reg5 asm ("5") = sizeof(*reg4);
asm volatile(
" st 2,%[pfx]\n"
" mvcl 2,4\n"
" spx %[pfx]\n"
: "+&d" (reg2), "+&d" (reg3),
"+&d" (reg4), "+&d" (reg5), [pfx] "=Q" (pfx)
: : "memory", "cc");
}
static int __init smp_reinit_ipl_cpu(void)
{
unsigned long async_stack, nodat_stack, mcck_stack;
struct lowcore *lc, *lc_ipl;
unsigned long flags;
lc_ipl = lowcore_ptr[0];
lc = (struct lowcore *) __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
nodat_stack = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER);
async_stack = stack_alloc();
mcck_stack = stack_alloc();
if (!lc || !nodat_stack || !async_stack || !mcck_stack)
panic("Couldn't allocate memory");
local_irq_save(flags);
local_mcck_disable();
set_new_lowcore(lc);
S390_lowcore.nodat_stack = nodat_stack + STACK_INIT_OFFSET;
S390_lowcore.async_stack = async_stack + STACK_INIT_OFFSET;
S390_lowcore.mcck_stack = mcck_stack + STACK_INIT_OFFSET;
lowcore_ptr[0] = lc;
pcpu_devices[0].lowcore = lc;
local_mcck_enable();
local_irq_restore(flags);
free_pages(lc_ipl->async_stack - STACK_INIT_OFFSET, THREAD_SIZE_ORDER);
memblock_free_late(lc_ipl->mcck_stack - STACK_INIT_OFFSET, THREAD_SIZE);
memblock_free_late((unsigned long) lc_ipl, sizeof(*lc_ipl));
return 0;
}
early_initcall(smp_reinit_ipl_cpu);