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The KVM code has some repeated bugs in it around use of __pa() on
per-cpu data. Those data are not in an area on which using
__pa() is valid. However, they are also called early enough in
boot that __vmalloc_start_set is not set, and thus the
CONFIG_DEBUG_VIRTUAL debugging does not catch them.
This adds a check to also verify __pa() calls against max_low_pfn,
which we can use earler in boot than is_vmalloc_addr(). However,
if we are super-early in boot, max_low_pfn=0 and this will trip
on every call, so also make sure that max_low_pfn is set before
we try to use it.
With this patch applied, CONFIG_DEBUG_VIRTUAL will actually
catch the bug I was chasing (and fix later in this series).
I'd love to find a generic way so that any __pa() call on percpu
areas could do a BUG_ON(), but there don't appear to be any nice
and easy ways to check if an address is a percpu one. Anybody
have ideas on a way to do this?
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20130122212430.F46F8159@kernel.stglabs.ibm.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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I submitted an earlier patch that make __phys_addr an inline. This obviously
results in an increase in the code size. One step I can take to reduce that
is to make it so that the __pa_symbol call does a direct translation for
kernel addresses instead of covering all of virtual memory.
On my system this reduced the size for __pa_symbol from 5 instructions
totalling 30 bytes to 3 instructions totalling 16 bytes.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Link: http://lkml.kernel.org/r/20121116215356.8521.92472.stgit@ahduyck-cp1.jf.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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This patch is meant to improve overall system performance when making use of
the __phys_addr call. To do this I have implemented several changes.
First if CONFIG_DEBUG_VIRTUAL is not defined __phys_addr is made an inline,
similar to how this is currently handled in 32 bit. However in order to do
this it is required to export phys_base so that it is available if __phys_addr
is used in kernel modules.
The second change was to streamline the code by making use of the carry flag
on an add operation instead of performing a compare on a 64 bit value. The
advantage to this is that it allows us to significantly reduce the overall
size of the call. On my Xeon E5 system the entire __phys_addr inline call
consumes a little less than 32 bytes and 5 instructions. I also applied
similar logic to the debug version of the function. My testing shows that the
debug version of the function with this patch applied is slightly faster than
the non-debug version without the patch.
Finally I also applied the same logic changes to __virt_addr_valid since it
used the same general code flow as __phys_addr and could achieve similar gains
though these changes.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Link: http://lkml.kernel.org/r/20121116215315.8521.46270.stgit@ahduyck-cp1.jf.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Split __phys_addr out into its own file so we can disable
-fstack-protector in a fine-grained fashion. Also it doesn't
have terribly much to do with the rest of ioremap.c.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
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