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    Subject[PATCH 2/2] powerpc: kdump: Override crash_free_reserved_phys_range to avoid freeing RTAS

    The crashkernel region will almost always overlap RTAS. If we free the
    crashkernel region via "echo 0 > /sys/kernel/kexec_crash_size" then we will
    free RTAS and the machine will crash in confusing and exciting ways.

    Override crash_free_reserved_phys_range and check for overlap with RTAS.

    Signed-off-by: Anton Blanchard <anton@samba.org>
    ---

    Index: powerpc.git/arch/powerpc/kernel/crash_dump.c
    ===================================================================
    --- powerpc.git.orig/arch/powerpc/kernel/crash_dump.c 2010-08-24 09:24:32.219643256 +1000
    +++ powerpc.git/arch/powerpc/kernel/crash_dump.c 2010-08-24 09:46:22.826868330 +1000
    @@ -19,6 +19,7 @@
    #include <asm/prom.h>
    #include <asm/firmware.h>
    #include <asm/uaccess.h>
    +#include <asm/rtas.h>

    #ifdef DEBUG
    #include <asm/udbg.h>
    @@ -141,3 +142,35 @@ ssize_t copy_oldmem_page(unsigned long p

    return csize;
    }
    +
    +#ifdef CONFIG_PPC_RTAS
    +/*
    + * The crashkernel region will almost always overlap the RTAS region, so
    + * we have to be careful when shrinking the crashkernel region.
    + */
    +void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
    +{
    + unsigned long addr;
    + const u32 *basep, *sizep;
    + unsigned int rtas_start = 0, rtas_end = 0;
    +
    + basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
    + sizep = of_get_property(rtas.dev, "rtas-size", NULL);
    +
    + if (basep && sizep) {
    + rtas_start = *basep;
    + rtas_end = *basep + *sizep;
    + }
    +
    + for (addr = begin; addr < end; addr += PAGE_SIZE) {
    + /* Does this page overlap with the RTAS region? */
    + if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
    + continue;
    +
    + ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT));
    + init_page_count(pfn_to_page(addr >> PAGE_SHIFT));
    + free_page((unsigned long)__va(addr));
    + totalram_pages++;
    + }
    +}
    +#endif

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