This is a note to let you know that I've just added the patch titled
s390: enable HAVE_IOREMAP_PROT
to the 5.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-enable-have_ioremap_prot.patch
and it can be found in the queue-5.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3a666411ed34b4014ecf3b9c681b787a14c134b2
Author: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
Date: Fri Feb 19 12:00:52 2021 +0100
s390: enable HAVE_IOREMAP_PROT
[ 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@xxxxxxxxxxxxx>
Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index b4c7c34069f8..d6582f57e0a1 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -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
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index b38f7b781564..adea53f69bfd 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -863,6 +863,25 @@ 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
*/
