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s390: enable HAVE_IOREMAP_PROT 

In commit b02002cc4c ("s390/pci: Implement ioremap_wc/prot() with
MIO") we implemented both ioremap_wc() and ioremap_prot() however until
now we had not set HAVE_IOREMAP_PROT in Kconfig, do so now.

This also requires implementing pte_pgprot() as this is used in the
generic_access_phys() code enabled by CONFIG_HAVE_IOREMAP_PROT. As with
ioremap_wc() we need to take the MMIO Write Back bit index into account.

Moreover since the pgprot value returned from pte_pgprot() is to be used
for mappings into kernel address space we must make sure that it uses
appropriate kernel page table protection bits. In particular a pgprot
value originally coming from userspace could have the _PAGE_PROTECT
bit set to enable fault based dirty bit accounting which would then make
the mapping inaccessible when used in kernel address space.

Fixes: b02002cc4c ("s390/pci: Implement ioremap_wc/prot() with MIO")
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Niklas Schnelle 2021-02-19 12:00:52 +01:00 committed by Vasily Gorbik
parent 15e5b53ff4
commit d460bb6c64
2 changed files with 20 additions and 0 deletions
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1
arch/s390/Kconfig
View File

@ -164,6 +164,7 @@ config S390
select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_GCC_PLUGINS
select HAVE_GENERIC_VDSO
select HAVE_IOREMAP_PROT if PCI
select HAVE_IRQ_EXIT_ON_IRQ_STACK
select HAVE_KERNEL_BZIP2
select HAVE_KERNEL_GZIP

19
arch/s390/include/asm/pgtable.h
View File

@ -865,6 +865,25 @@ static inline int pte_unused(pte_t pte)
return pte_val(pte) & _PAGE_UNUSED;
}
/*
* Extract the pgprot value from the given pte while at the same time making it
* usable for kernel address space mappings where fault driven dirty and
* young/old accounting is not supported, i.e _PAGE_PROTECT and _PAGE_INVALID
* must not be set.
*/
static inline pgprot_t pte_pgprot(pte_t pte)
{
unsigned long pte_flags = pte_val(pte) & _PAGE_CHG_MASK;
if (pte_write(pte))
pte_flags |= pgprot_val(PAGE_KERNEL);
else
pte_flags |= pgprot_val(PAGE_KERNEL_RO);
pte_flags |= pte_val(pte) & mio_wb_bit_mask;
return __pgprot(pte_flags);
}
/*
* pgd/pmd/pte modification functions
*/