In xdr_partial_copy_from_skb() there is that sequence:
kaddr = kmap_atomic(*ppage, KM_SKB_SUNRPC_DATA);
[...]
flush_dcache_page(*ppage);
kunmap_atomic(kaddr, KM_SKB_SUNRPC_DATA);
Mixing flush_dcache_page() and kmap_atomic() is a bit odd,
especially since kunmap_atomic() must deal with cache issues
already. OTOH the non-highmem case must use flush_dcache_page()
as kunmap_atomic() becomes a no op with no cache maintenance.
Problem is that with highmem the implementation of kmap_atomic()
doesn't set page->virtual, and page_address(page) returns 0 in
that case. Here flush_dcache_page() calls __flush_dcache_page()
which calls __cpuc_flush_dcache_page(page_address(page)) resulting
in a kernel oops.
None of the kmap_atomic() implementations uses set_page_address().
Hence we can assume page_address() is always expected to return 0 in
that case. Let's conditionally call __cpuc_flush_dcache_page() only
when the page address is non zero, and perform that test only when
highmem is configured.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch implements the recommended workaround for erratum 411920
(ARM1136, ARM1156, ARM1176).
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The kmap virtual area borrows a 2MB range at the top of the 16MB area
below PAGE_OFFSET currently reserved for kernel modules and/or the
XIP kernel. This 2MB corresponds to the range covered by 2 consecutive
second-level page tables, or a single pmd entry as seen by the Linux
page table abstraction. Because XIP kernels are unlikely to be seen
on systems needing highmem support, there shouldn't be any shortage of
VM space for modules (14 MB for modules is still way more than twice the
typical usage).
Because the virtual mapping of highmem pages can go away at any moment
after kunmap() is called on them, we need to bypass the delayed cache
flushing provided by flush_dcache_page() in that case.
The atomic kmap versions are based on fixmaps, and
__cpuc_flush_dcache_page() is used directly in that case.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Rather than pollute asm/cacheflush.h with the cache type definitions,
move them to asm/cachetype.h, and include this new header where
necessary.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch adds the I-cache invalidation in update_mmu_cache if the
corresponding vma is marked as executable. It also invalidates the
I-cache if a thread migrates to a CPU it never ran on.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
fuse does not work on ARM due to cache incoherency issues - fuse wants
to use get_user_pages() to copy data from the current process into
kernel space. However, since this accesses userspace via the kernel
mapping, the kernel mapping can be out of date wrt data written to
userspace.
This can lead to unpredictable behaviour (in the case of fuse) or data
corruption for direct-IO.
This resolves debian bug #402876
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
L_PTE_ASID is not really required to be stored in every PTE, since we
can identify it via the address passed to set_pte_at(). So, create
set_pte_ext() which takes the address of the PTE to set, the Linux
PTE value, and the additional CPU PTE bits which aren't encoded in
the Linux PTE value.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Fix thinko in the flush_ptrace_access() "if (expr)" for the ARM
VIPT non-aliasing cache case. We only need to flush cache when
VM_EXEC is set in vma->vm_flags but "if (expr) always evaluates
to true on UP systems for the ARM VIPT non-aliasing cache case.
Signed-off-by: George G. Davis <gdavis@mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Move top_pmd into arch/arm/mm/mm.h - nothing outside arch/arm/mm
references it.
Move the repeated definition of TOP_PTE into mm/mm.h, as well as
a few function prototypes.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from George G. Davis
Resolve ARM1136 VIPT non-aliasing cache coherency issues observed when
using ptrace to set breakpoints and cleanup copy_{to,from}_user_page()
while we're here as requested by Russell King because "it's also far
too heavy on non-v6 CPUs".
NOTES:
1. Only access_process_vm() calls copy_{to,from}_user_page().
2. access_process_vm() calls get_user_pages() to pin down the "page".
3. get_user_pages() calls flush_dcache_page(page) which ensures cache
coherency between kernel and userspace mappings of "page". However
flush_dcache_page(page) may not invalidate I-Cache over this range
for all cases, specifically, I-Cache is not invalidated for the VIPT
non-aliasing case. So memory is consistent between kernel and user
space mappings of "page" but I-Cache may still be hot over this
range. IOW, we don't have to worry about flush_cache_page() before
memcpy().
4. Now, for the copy_to_user_page() case, after memcpy(), we must flush
the caches so memory is consistent with kernel cache entries and
invalidate the I-Cache if this mm region is executable. We don't
need to do anything after memcpy() for the copy_from_user_page()
case since kernel cache entries will be invalidated via the same
process above if we access "page" again. The flush_ptrace_access()
function (borrowed from SPARC64 implementation) is added to handle
cache flushing after memcpy() for the copy_to_user_page() case.
Signed-off-by: George G. Davis <gdavis@mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Catalin Marinas
ARM1136 erratum 371025 (category 2) specifies that, under rare
conditions, an invalidate I-cache by MVA (line or range) operation can
fail to invalidate a cache line. The recommended workaround is to
either invalidate the entire I-cache or invalidate the range by
set/way rather than MVA.
Note that for a 16K cache size, invalidating a 4K page by set/way is
equivalent to invalidating the entire I-cache.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Lazy flush_dcache_page() causes userspace instability on SMP
platforms, so disable it for now.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Catalin Marinas
When CONFIG_CPU_CACHE_VIPT is defined, the flush_pfn_alias() function is
implicitely declared and it later conflicts with its actual definition.
This patch moves the function definition to the beginning of the file.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This adds the necessary changes to ensure that we flush the
caches correctly with aliasing VIPT caches.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
flush_dcache_page() did nothing for these caches, but since they
suffer from I/D cache coherency issues, we need to ensure that data
is written back to RAM.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
