Kazuo Moriwaka wrote:
> Hi Dave,
>
> > The problem is that the return vmalloc address of zero eventually
> > gets stored in vt->vmalloc_start, which, among a few other places,
> > is used here:
> >
> > #define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
> >
> > Can you verify that setting it to zero will not cause problems in
> > the macro above, and the other places that it's used directly?
>
> Thank you for your advice. I rushed..
>
> > Upon a quick examination, it does looks safe enough in the relevant
> > vtop routines, but for example, the search command's use of next_kpage()
> > looks like it might fail.
> >
> > Perhaps IS_VMALLOC_ADDRESS() itself should also verify
> > that vt->vmalloc_start is non-zero, and the other places that
> > use vt->vmalloc_start directly should be verified. (Of course
> > we don't need to do this kind of check for the processors
> > that have hardwired vmalloc addresses).
>
> I checked all places which use vt->vmalloc_start directory,
> and fixing IS_VMALLOC_ADDRESS looks enough.
>
> All places are:
> 1. IS_VMALLOC_ADDRESS
> 2. in memory.c: they looks work fine with zero.
> 3. each architectures .c: just check if(!vt->vmalloc_start). They'll work.
>
> thanks,
> --
> Kazuo Moriwaka <moriwaka@xxxxxxxxxxxxx>
>
OK, this looks reasonable. The only issue is that the vtop command
will not do the page-table translation on unity-mapped kernel addresses
at all. But this is such a rare situation that it's fine with me if it's fine
with you.
Queued for next release.
Thanks,
Dave
>
> diff -ru crash-4.0-2.31.orig/defs.h crash-4.0-2.31/defs.h
> --- crash-4.0-2.31.orig/defs.h 2006-06-27 23:15:32.000000000 +0900
> +++ crash-4.0-2.31/defs.h 2006-07-11 11:17:31.000000000 +0900
> @@ -1813,7 +1813,7 @@
> #define MACHINE_TYPE "X86"
> #define PTOV(X) ((unsigned long)(X)+(machdep->kvbase))
> #define VTOP(X) ((unsigned long)(X)-(machdep->kvbase))
> -#define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
> +#define IS_VMALLOC_ADDR(X) (vt->vmalloc_start && (ulong)(X) >= vt->vmalloc_start)
> #define KVBASE_MASK (0x7fffff)
>
> #define PGDIR_SHIFT_2LEVEL (22)
> @@ -2011,7 +2011,7 @@
>
> #define PTOV(X) ((unsigned long)(X)+(machdep->kvbase))
> #define VTOP(X) ((unsigned long)(X)-(machdep->kvbase))
> -#define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
> +#define IS_VMALLOC_ADDR(X) (vt->vmalloc_start && (ulong)(X) >= vt->vmalloc_start)
> #define KSEG_BASE_48_BIT (0xffff800000000000)
> #define KSEG_BASE (0xfffffc0000000000)
> #define _PFN_MASK (0xFFFFFFFF00000000)
> @@ -2056,7 +2056,7 @@
>
> #define PTOV(X) ((unsigned long)(X)+(machdep->kvbase))
> #define VTOP(X) ((unsigned long)(X)-(machdep->kvbase))
> -#define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
> +#define IS_VMALLOC_ADDR(X) (vt->vmalloc_start && (ulong)(X) >= vt->vmalloc_start)
>
> #define PGDIR_SHIFT (22)
> #define PTRS_PER_PTE (1024)
> @@ -2240,7 +2240,7 @@
>
> #define PTOV(X) ((unsigned long)(X)+(machdep->kvbase))
> #define VTOP(X) ((unsigned long)(X)-(machdep->kvbase))
> -#define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
> +#define IS_VMALLOC_ADDR(X) (vt->vmalloc_start && (ulong)(X) >= vt->vmalloc_start)
> #define KERNELBASE machdep->pageoffset
>
> #define PGDIR_SHIFT (machdep->pageshift + (machdep->pageshift -3) + (machdep->pageshift - 2))
> @@ -2343,7 +2343,7 @@
>
> #define PTOV(X) ((unsigned long)(X)+(machdep->kvbase))
> #define VTOP(X) ((unsigned long)(X)-(machdep->kvbase))
> -#define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
> +#define IS_VMALLOC_ADDR(X) (vt->vmalloc_start && (ulong)(X) >= vt->vmalloc_start)
> #define PTRS_PER_PTE 512
> #define PTRS_PER_PMD 1024
> #define PTRS_PER_PGD 2048
> diff -ru crash-4.0-2.31.orig/memory.c crash-4.0-2.31/memory.c
> --- crash-4.0-2.31.orig/memory.c 2006-06-27 23:15:32.000000000 +0900
> +++ crash-4.0-2.31/memory.c 2006-07-11 11:20:12.000000000 +0900
> @@ -11049,10 +11049,13 @@
> ulong vmlist, addr;
>
> get_symbol_data("vmlist", sizeof(void *), &vmlist);
> -
> - if (!readmem(vmlist+OFFSET(vm_struct_addr), KVADDR, &addr,
> - sizeof(void *), "first vmlist addr", RETURN_ON_ERROR))
> - non_matching_kernel();
> + if (vmlist != 0x0) {
> + if (!readmem(vmlist+OFFSET(vm_struct_addr), KVADDR, &addr,
> + sizeof(void *), "first vmlist addr", RETURN_ON_ERROR))
> + non_matching_kernel();
> + } else {
> + addr = 0;
> + }
>
> return addr;
> }
>
> --
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