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| author | Dave Hansen <dave@linux.vnet.ibm.com> | 2013-01-22 13:24:30 -0800 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2013-01-25 16:33:22 -0800 |
| commit | a25b9316841c5afa226f8f70a457861b35276a92 (patch) | |
| tree | e1fb6722bcb783329de3c09d7a9df1a6b0f25d58 /arch/x86/mm/physaddr.c | |
| parent | 7b5c4a65cc27f017c170b025f8d6d75dabb11c6f (diff) | |
| download | lwn-a25b9316841c5afa226f8f70a457861b35276a92.tar.gz lwn-a25b9316841c5afa226f8f70a457861b35276a92.zip | |
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.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/mm/physaddr.c b/arch/x86/mm/physaddr.c index c73feddd518d..e666cbbb9261 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 |