An Athlon 64 X2 test system showed hard hangs shortly after marking
the kernel text read-only, if we tried to preserve largepages and
changed the PSE entry from RW to RO. The pagetable code itself is
correct, it's the CPU that locked up hard (and not even the NMI
watchdog could punch through that hard hang).
So be conservative and always do splitups - like we did in the past.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When CPA is called on a range which fits into a large page mapping,
avoid to split the page when:
1) There is no change of attributes
2) The range to change is a complete large mapping
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The number of arguments which need to be transported is increasing
and we want to add flush optimizations and large page preserving.
Create struct cpa data and pass a pointer instead of increasing the
number of arguments further.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We only need to flush the caches in cpa() if the the caching attributes
have changed. Otherwise only flush the TLBs.
This checks the PAT bits too although they are currently not used by
the kernel.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Mask out the not supported bits (e.g. NX). If the clr/set masks
are empty after the mask return without changing anything.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When splitting large pages, we ge the pfn from the existing entry
instead of calculating it ourself.
This removes the last remaining range restriction of the cpa code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When changing the attributes of a pte, we should use the PFN from the
existing PTE rather than going through hoops calculating what we think
it might have been; this is both fragile and totally unneeded. It also
makes it more hairy to call any of these functions on non-direct maps
for no good reason whatsover.
With this change, __change_page_attr() no longer takes a pfn as argument,
which simplifies all the callers.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@tglx.de>
Right now, enforcing that the high mapping of the kernel text doesn't
get the NX bit is done deep in the guts of CPA, rather than in the
static_protection() function that enforces all other per-arch sanity
checks.
This patch moves this sanity check into the central static_protection()
function instead, and makes it apply ONLY to the kernel text, not to all
other areas in the high mapping.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In split_large_page we clear the NX bit for the new split ptes, but we
need to preserve the original setting of it for the split ptes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch replaces __change_page_attr_set_clr() with
change_page_attr_set_clr() in change_page_attr_clear() to flush the
TLB/cache properly.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use a standard list threaded through page->lru for maintaining the pgd
list on PAE. This is the same as 64-bit, and seems saner than using a
non-standard list via page->index.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cleanup the address calculations, which are necessary to identify the
high/low alias mappings of the kernel on 64 bit machines. Instead of
calling __pa/__va back and forth, calculate the physical address once
and base the other calculations on it. Add understandable constants so
we can use the already available within() helper. Also add comments,
which help mere mortals to understand what this code does.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
clflush is sufficient to be issued on one CPU. The invalidation is
broadcast throughout the coherence domain.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
clflush is an unordered operation with respect to other memory
traffic, including other CLFLUSH instructions. This needs proper
fencing with mfence.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The function name global_flush_tlb() suggests something different from
what the function really does. Rename it to cpa_flush_all(), which is an
understandable counterpart to cpa_flush_range().
no global visibility of the old API anymore.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use clflush on CPUs which support this.
clflush is only used when the page attribute operation has been
successful. On CPUs which do not support clflush and in the case of
error the old fashioned global_flush_tlb() is called.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Convert cpa_set and cpa_clear to call the new set_clr function.
Seperate out the debug helpers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Create a set_and_clr function to avoid the duplicate loops. Allows
also to do combined operations for optimization.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
To avoid the modification of the flush code for the clflush
implementation, move the flush into the set and clear functions and
provide helper functions for the debugging code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In Ingo's testing, he found a bug in the CPA selftest code. What would
happen is that the test would call change_page_attr_addr on a range of
memory, part of which was read only, part of which was writable. The
only thing the test wanted to change was the global bit...
What actually happened was that the selftest would take the permissions
of the first page, and then the change_page_attr_addr call would then
set the permissions of the entire range to this first page. In the
rodata section case, this resulted in pages after the .rodata becoming
read only... which made the kernel rather unhappy in many interesting
ways.
This is just another example of how dangerous the cpa API is (was); this
patch changes the test to use the incremental clear/set APIs
instead, and it changes the clear/set implementation to work on a 1 page
at a time basis.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The set_memory_* and set_pages_* family of API's currently requires the
callers to do a global tlb flush after the function call; forgetting this is
a very nasty deathtrap. This patch moves the global tlb flush into
each of the callers
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
change_page_attr_add is only used in pageattr.c now, so we can
make this function static.
change_page_attr() isn't used anywere at all anymore; this function
is a really bad API anyway so just remove the bloat entirely.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
page_is_ram has a FIXME since ages, which reminds to sanity check the
BIOS area between 640k and 1M, which is sometimes falsely reported as
RAM in the e820 tables.
Implement the sanity check. Move the BIOS range defines from
pageattr.c into e820.h to avoid duplicate defines.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
With the introduction of the new API, no driver or non-archcore code needs
to use c-p-a anymore, so this patch also deprecates the EXPORT_SYMBOL of CPA
(it's a horrible API after all).
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Right now, if drivers or other code want to change, say, a cache attribute of a
page, the only API they have is change_page_attr(). c-p-a is a really bad API
for this, because it forces the caller to know *ALL* the attributes he wants
for the page, not just the 1 thing he wants to change. So code that wants to
set a page uncachable, needs to be aware of the NX status as well etc etc etc.
This patch introduces a set of new APIs for this, set_pages_<attr> and
set_memory_<attr>, that offer a logical change to the user, and leave all
attributes not implied by the requested logical change alone.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
What the check_exec() function really is trying to do is enforce certain
bits in the pgprot that are required by the x86 architecture, but that
callers might not be aware of (such as NX bit exclusion of the BIOS
area for BIOS based PCI access; it's not uncommon to ioremap the BIOS
region for various purposes and normally ioremap() memory has the NX bit
set).
This patch turns the check_exec() function into static_protections()
which also is now used to make sure the kernel text area remains non-NX
and that the .rodata section remains read-only. If the architecture
ends up requiring more such mandatory prot settings for specific areas,
this is now a reasonable place to add these.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch fixes a bug of change_page_attr/change_page_attr_addr on
Intel i386/x86_64 CPUs. After changing page attribute to be
executable with these functions, the page remains un-executable on
Intel i386/x86_64 CPU. Because on Intel i386/x86_64 CPU, only if the
"NX" bits of all three level page tables are cleared (PAE is enabled),
the corresponding page is executable (refer to section 4.13.2 of Intel
64 and IA-32 Architectures Software Developer's Manual). So, the bug
is fixed through clearing the "NX" bit of PMD when splitting the huge
PMD.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
do some leftover cleanups in the now unified arch/x86/mm/pageattr.c
file.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
unify the now perfectly identical pageattr_32/64.c files - no code changed.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Ingo Molnar