[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] This patch fixes Bugzilla #169. (It should fix #187 too -- Keir).
# HG changeset patch # User kaf24@xxxxxxxxxxxxxxxxxxxx # Node ID b88c5350de57a1fc18943cbb33fa72c348004fc8 # Parent 85ccfd035658dfb33bd24815ad75bb24658d9d69 This patch fixes Bugzilla #169. (It should fix #187 too -- Keir). The root cause of bug 169 is, machine_to_phys_mapping, starting from 0xffff800000000000, is mapped using 2M pages. When the system has RAM no more than 2G, only one 2M page is allocated and only one PDE entry is created correspondingly, so calling mfn_to_pfn with mfn > 0x80000 will overflow this 2M page and cause a unable handled kernel paging request. The mfn > 0x80000 comes from PCI device I/O memory, here from AGP display card when booting X server. Jun suggested to use something like get_user() when accessing machine_to_phys_mapping. Signed-off-by: Xin Li <xin.b.li@xxxxxxxxx> diff -r 85ccfd035658 -r b88c5350de57 linux-2.6-xen-sparse/include/asm-xen/asm-i386/page.h --- a/linux-2.6-xen-sparse/include/asm-xen/asm-i386/page.h Thu Aug 25 15:53:03 2005 +++ b/linux-2.6-xen-sparse/include/asm-xen/asm-i386/page.h Thu Aug 25 16:21:19 2005 @@ -65,8 +65,26 @@ extern unsigned int *phys_to_machine_mapping; #define pfn_to_mfn(pfn) \ ((unsigned long)phys_to_machine_mapping[(unsigned int)(pfn)] & 0x7FFFFFFFUL) -#define mfn_to_pfn(mfn) \ -((unsigned long)machine_to_phys_mapping[(unsigned int)(mfn)]) +static inline unsigned long mfn_to_pfn(unsigned long mfn) +{ + unsigned int pfn; + + /* + * The array access can fail (e.g., device space beyond end of RAM). + * In such cases it doesn't matter what we return (we return garbage), + * but we must handle the fault without crashing! + */ + asm ( + "1: movl %1,%0\n" + "2:\n" + ".section __ex_table,\"a\"\n" + " .align 4\n" + " .long 1b,2b\n" + ".previous" + : "=r" (pfn) : "m" (machine_to_phys_mapping[mfn]) ); + + return (unsigned long)pfn; +} /* Definitions for machine and pseudophysical addresses. */ #ifdef CONFIG_X86_PAE diff -r 85ccfd035658 -r b88c5350de57 linux-2.6-xen-sparse/include/asm-xen/asm-x86_64/page.h --- a/linux-2.6-xen-sparse/include/asm-xen/asm-x86_64/page.h Thu Aug 25 15:53:03 2005 +++ b/linux-2.6-xen-sparse/include/asm-xen/asm-x86_64/page.h Thu Aug 25 16:21:19 2005 @@ -67,8 +67,26 @@ extern u32 *phys_to_machine_mapping; #define pfn_to_mfn(pfn) \ ((unsigned long)phys_to_machine_mapping[(unsigned int)(pfn)] & 0x7FFFFFFFUL) -#define mfn_to_pfn(mfn) \ -((unsigned long)machine_to_phys_mapping[(unsigned int)(mfn)]) +static inline unsigned long mfn_to_pfn(unsigned long mfn) +{ + unsigned int pfn; + + /* + * The array access can fail (e.g., device space beyond end of RAM). + * In such cases it doesn't matter what we return (we return garbage), + * but we must handle the fault without crashing! + */ + asm ( + "1: movl %1,%k0\n" + "2:\n" + ".section __ex_table,\"a\"\n" + " .align 8\n" + " .quad 1b,2b\n" + ".previous" + : "=r" (pfn) : "m" (machine_to_phys_mapping[mfn]) ); + + return (unsigned long)pfn; +} /* Definitions for machine and pseudophysical addresses. */ typedef unsigned long paddr_t; _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-changelog
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