"Sachin P. Sant" wrote:> Hi Dave
> Recently there were changes made to kexec tools to support 64K page size.
> With those changes vmcore file obtained from a kernel which supports 64K
> page size cannot be analyzed using crash on a machine running with kernel
> supporting 4K page size.
>
> The following changes in crash tool resolves the problem.
> Look if the symbol __hash_page_64k exists. This symbol is defined only
> for kernels with 64K PAGE SIZE support. If yes then the dump was taken
> with a kernel supporting 64k page size. So use the vmcore page size[64K]
> instead of getpagesize().
>
> Thanks
> -Sachin
>
> ------------------------------------------------------------------------------------------------------------------------
> * Recently there were changes made to kexec tools to support 64K page size.
> With those changes vmcore file obtained from a kernel which supports 64K
> page size cannot be analyzed using crash on a machine running with kernel
> supporting 4K page size.
> The following change were made in crash tool to solve the problem.
> Look if the symbol __hash_page_64k exists. If yes then the dump was taken
> with a kernel supporting 64k page size. So change the page size accordingly.
>
> Signed-Off-By: Sachin Sant <sachinp@xxxxxxxxxx>
> --
>
> diff -Naurp crash-4.0/defs.h crash-4.0-new/defs.h
> --- crash-4.0/defs.h 2006-09-14 21:41:50.000000000 -0400
> +++ crash-4.0-new/defs.h 2006-09-14 21:48:37.000000000 -0400
> @@ -2297,6 +2297,7 @@ struct efi_memory_desc_t {
> #define _64BIT_
> #define MACHINE_TYPE "PPC64"
>
> +#define PPC64_64K_PAGE_SIZE 65536
> #define PAGEBASE(X) (((ulong)(X)) & (ulong)machdep->pagemask)
>
> #define PTOV(X) ((unsigned long)(X)+(machdep->kvbase))
> diff -Naurp crash-4.0/ppc64.c crash-4.0-new/ppc64.c
> --- crash-4.0/ppc64.c 2006-09-14 21:41:50.000000000 -0400
> +++ crash-4.0-new/ppc64.c 2006-09-14 21:50:26.000000000 -0400
> @@ -67,19 +67,6 @@ ppc64_init(int when)
> machdep->verify_symbol = ppc64_verify_symbol;
> if (pc->flags & KERNEL_DEBUG_QUERY)
> return;
> - machdep->pagesize = memory_page_size();
> - machdep->pageshift = ffs(machdep->pagesize) - 1;
> - machdep->pageoffset = machdep->pagesize - 1;
> - machdep->pagemask = ~((ulonglong)machdep->pageoffset);
> - machdep->stacksize = 4 * machdep->pagesize;
> - if ((machdep->pgd = (char *)malloc(PAGESIZE())) == NULL)
> - error(FATAL, "cannot malloc pgd space.");
> - if ((machdep->pmd = (char *)malloc(PAGESIZE())) == NULL)
> - error(FATAL, "cannot malloc pmd space.");
> - if ((machdep->ptbl = (char *)malloc(PAGESIZE())) == NULL)
> - error(FATAL, "cannot malloc ptbl space.");
> - if ((machdep->machspec->level4 = (char *)malloc(PAGESIZE())) == NULL)
> - error(FATAL, "cannot malloc level4 space.");
> machdep->last_pgd_read = 0;
> machdep->last_pmd_read = 0;
> machdep->last_ptbl_read = 0;
> @@ -93,6 +80,40 @@ ppc64_init(int when)
> break;
>
> case PRE_GDB:
> + /*
> + * Recently there were changes made to kexec tools
> + * to support 64K page size. With those changes
> + * vmcore file obtained from a kernel which supports
> + * 64K page size cannot be analyzed using crash on a
> + * machine running with kernel supporting 4K page size
> + *
> + * The following modifications are required in crash
> + * tool to be in sync with kexec tools.
> + *
> + * Look if the following symbol exists. If yes then
> + * the dump was taken with a kernel supporting 64k
> + * page size. So change the page size accordingly.
> + *
> + * Also moved the following code block from
> + * PRE_SYMTAB case here.
> + */
> + if (symbol_exists("__hash_page_64K"))
> + machdep->pagesize = PPC64_64K_PAGE_SIZE;
> + else
> + machdep->pagesize = memory_page_size();
> + machdep->pageshift = ffs(machdep->pagesize) - 1;
> + machdep->pageoffset = machdep->pagesize - 1;
> + machdep->pagemask = ~((ulonglong)machdep->pageoffset);
> + machdep->stacksize = 4 * machdep->pagesize;
> + if ((machdep->pgd = (char *)malloc(PAGESIZE())) == NULL)
> + error(FATAL, "cannot malloc pgd space.");
> + if ((machdep->pmd = (char *)malloc(PAGESIZE())) == NULL)
> + error(FATAL, "cannot malloc pmd space.");
> + if ((machdep->ptbl = (char *)malloc(PAGESIZE())) == NULL)
> + error(FATAL, "cannot malloc ptbl space.");
> + if ((machdep->machspec->level4 = (char *)malloc(PAGESIZE())) == NULL)
> + error(FATAL, "cannot malloc level4 space.");
> +
> machdep->kvbase = symbol_value("_stext");
> machdep->identity_map_base = machdep->kvbase;
> machdep->is_kvaddr = generic_is_kvaddr;The patch looks safe enough.
A couple things I just noticed though...
Is it true that the process stack size will be 256K? And the
ppc64 hardware interrupt stack would be 512K? Based upon
the machdep->pagesize value, these inititializations get done
later:machdep->stacksize = 4 * machdep->pagesize;
machdep->machspec->hwstacksize = 8 * machdep->pagesize;
If they have not increased, won't the backtrace code get confused?
Thanks,
Dave
The kernel's asm-powerpc/thread_info.h file doesn't
show any change in stack size, which I didn't expect
it would anyway:
#ifdef __KERNEL__
/* We have 8k stacks on ppc32 and 16k on ppc64 */
#ifdef CONFIG_PPC64
#define THREAD_SHIFT
14
#else
#define THREAD_SHIFT
13
#endif
#define THREAD_SIZE (1 << THREAD_SHIFT)
and the hardware interrupt stack seems to only be in
the paca_struct in 2.4 kernels.
I think we can safely hardwire those two values anyway,
right?
Dave
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