lkml.org 
[lkml]   [2013]   [Jan]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Subject[PATCH 1/5] make DEBUG_VIRTUAL work earlier in boot
    From
    Date

    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>
    ---

    linux-2.6.git-dave/arch/x86/mm/numa.c | 2 +-
    linux-2.6.git-dave/arch/x86/mm/pat.c | 4 ++--
    linux-2.6.git-dave/arch/x86/mm/physaddr.c | 9 ++++++++-
    3 files changed, 11 insertions(+), 4 deletions(-)

    diff -puN arch/x86/mm/numa.c~make-DEBUG_VIRTUAL-work-earlier-in-boot arch/x86/mm/numa.c
    --- linux-2.6.git/arch/x86/mm/numa.c~make-DEBUG_VIRTUAL-work-earlier-in-boot 2013-01-17 10:22:25.614425502 -0800
    +++ linux-2.6.git-dave/arch/x86/mm/numa.c 2013-01-17 10:22:25.622425572 -0800
    @@ -219,7 +219,7 @@ static void __init setup_node_data(int n
    */
    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);
    diff -puN arch/x86/mm/pat.c~make-DEBUG_VIRTUAL-work-earlier-in-boot arch/x86/mm/pat.c
    --- linux-2.6.git/arch/x86/mm/pat.c~make-DEBUG_VIRTUAL-work-earlier-in-boot 2013-01-17 10:22:25.614425502 -0800
    +++ linux-2.6.git-dave/arch/x86/mm/pat.c 2013-01-17 10:22:25.622425572 -0800
    @@ -560,10 +560,10 @@ int kernel_map_sync_memtype(u64 base, un
    {
    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;

    diff -puN arch/x86/mm/physaddr.c~make-DEBUG_VIRTUAL-work-earlier-in-boot arch/x86/mm/physaddr.c
    --- linux-2.6.git/arch/x86/mm/physaddr.c~make-DEBUG_VIRTUAL-work-earlier-in-boot 2013-01-17 10:22:25.618425536 -0800
    +++ linux-2.6.git-dave/arch/x86/mm/physaddr.c 2013-01-17 10:22:25.622425572 -0800
    @@ -1,3 +1,4 @@
    +#include <linux/bootmem.h>
    #include <linux/mmdebug.h>
    #include <linux/module.h>
    #include <linux/mm.h>
    @@ -47,10 +48,16 @@ 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
    _


    \
     
     \ /
      Last update: 2013-01-21 19:21    [W:4.878 / U:0.580 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site