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Commit a25b9316 authored by Dave Hansen's avatar Dave Hansen Committed by H. Peter Anvin
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x86, mm: Make DEBUG_VIRTUAL work earlier in boot 



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: default avatarDave Hansen <dave@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20130122212430.F46F8159@kernel.stglabs.ibm.com


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 7b5c4a65

arch/x86/mm/numa.c

+1 −1
Original line number Diff line number Diff line
@@ -219,7 +219,7 @@ static void __init setup_node_data(int nid, u64 start, u64 end) 
	 */

	nd = alloc_remap(nid, nd_size);

	if (nd) {

		nd_pa = __pa(nd);

		nd_pa = __phys_addr_nodebug(nd);

		remapped = true;

	} else {

		nd_pa = memblock_alloc_nid(nd_size, SMP_CACHE_BYTES, nid);

arch/x86/mm/pat.c

+2 −2
Original line number Diff line number Diff line
@@ -560,10 +560,10 @@ int kernel_map_sync_memtype(u64 base, unsigned long size, unsigned long flags) 
{

	unsigned long id_sz;



	if (base >= __pa(high_memory))

	if (base > __pa(high_memory-1))

		return 0;



	id_sz = (__pa(high_memory) < base + size) ?

	id_sz = (__pa(high_memory-1) <= base + size) ?

				__pa(high_memory) - base :

				size;

arch/x86/mm/physaddr.c

+8 −1
Original line number Diff line number Diff line 
#include <linux/bootmem.h>

#include <linux/mmdebug.h>

#include <linux/module.h>

#include <linux/mm.h>
@@ -68,10 +69,16 @@ EXPORT_SYMBOL(__virt_addr_valid); 
#ifdef CONFIG_DEBUG_VIRTUAL

unsigned long __phys_addr(unsigned long x)

{

	unsigned long phys_addr = x - PAGE_OFFSET;

	/* VMALLOC_* aren't constants  */

	VIRTUAL_BUG_ON(x < PAGE_OFFSET);

	VIRTUAL_BUG_ON(__vmalloc_start_set && is_vmalloc_addr((void *) x));

	return x - PAGE_OFFSET;

	/* max_low_pfn is set early, but not _that_ early */

	if (max_low_pfn) {

		VIRTUAL_BUG_ON((phys_addr >> PAGE_SHIFT) > max_low_pfn);

		BUG_ON(slow_virt_to_phys((void *)x) != phys_addr);

	}

	return phys_addr;

}

EXPORT_SYMBOL(__phys_addr);

#endif