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authorDave Hansen <dave@linux.vnet.ibm.com>2013-01-22 13:24:30 -0800
committerH. Peter Anvin <hpa@linux.intel.com>2013-01-25 16:33:22 -0800
commita25b9316841c5afa226f8f70a457861b35276a92 (patch)
treee1fb6722bcb783329de3c09d7a9df1a6b0f25d58 /arch/x86/mm/physaddr.c
parent7b5c4a65cc27f017c170b025f8d6d75dabb11c6f (diff)
downloadop-kernel-dev-a25b9316841c5afa226f8f70a457861b35276a92.zip
op-kernel-dev-a25b9316841c5afa226f8f70a457861b35276a92.tar.gz
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: 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>
Diffstat (limited to 'arch/x86/mm/physaddr.c')
-rw-r--r--arch/x86/mm/physaddr.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/mm/physaddr.c b/arch/x86/mm/physaddr.c
index c73fedd..e666cbb 100644
--- a/arch/x86/mm/physaddr.c
+++ b/arch/x86/mm/physaddr.c
@@ -1,3 +1,4 @@
+#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
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