From: Niklas Schnelle schnelle@linux.ibm.com
[ Upstream commit d460bb6c6417588dd8b0907d34f69b237918812a ]
In commit b02002cc4c0f ("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: b02002cc4c0f ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/Kconfig | 1 + arch/s390/include/asm/pgtable.h | 19 +++++++++++++++++++ 2 files changed, 20 insertions(+)
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index dc5c3e6fd200..7105d44a335b 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -154,6 +154,7 @@ 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 diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index b5dbae78969b..2338345912a3 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -864,6 +864,25 @@ 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 */