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Commit 94263352 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 mm update from Thomas Gleixner:
 "A single patch which excludes the GART aperture from vmcore as
  accessing that area from a dump kernel can crash the kernel.

  Not necessarily the nicest way to fix this, but curing this from
  ground up requires a more thorough rewrite of the whole kexec/kdump
  magic"

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/gart: Exclude GART aperture from vmcore
parents 36c289e7 2a3e83c6

arch/x86/kernel/aperture_64.c

+45 −1
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <asm/dma.h>

#include <asm/amd_nb.h>

#include <asm/x86_init.h>

#include <linux/crash_dump.h>



/*

 * Using 512M as goal, in case kexec will load kernel_big
@@ -56,6 +57,33 @@ int fallback_aper_force __initdata; 


int fix_aperture __initdata = 1;



#ifdef CONFIG_PROC_VMCORE

/*

 * If the first kernel maps the aperture over e820 RAM, the kdump kernel will

 * use the same range because it will remain configured in the northbridge.

 * Trying to dump this area via /proc/vmcore may crash the machine, so exclude

 * it from vmcore.

 */

static unsigned long aperture_pfn_start, aperture_page_count;



static int gart_oldmem_pfn_is_ram(unsigned long pfn)

{

	return likely((pfn < aperture_pfn_start) ||

		      (pfn >= aperture_pfn_start + aperture_page_count));

}



static void exclude_from_vmcore(u64 aper_base, u32 aper_order)

{

	aperture_pfn_start = aper_base >> PAGE_SHIFT;

	aperture_page_count = (32 * 1024 * 1024) << aper_order >> PAGE_SHIFT;

	WARN_ON(register_oldmem_pfn_is_ram(&gart_oldmem_pfn_is_ram));

}

#else

static void exclude_from_vmcore(u64 aper_base, u32 aper_order)

{

}

#endif



/* This code runs before the PCI subsystem is initialized, so just

   access the northbridge directly. */
@@ -435,8 +463,16 @@ int __init gart_iommu_hole_init(void) 


out:

	if (!fix && !fallback_aper_force) {

		if (last_aper_base)

		if (last_aper_base) {

			/*

			 * If this is the kdump kernel, the first kernel

			 * may have allocated the range over its e820 RAM

			 * and fixed up the northbridge

			 */

			exclude_from_vmcore(last_aper_base, last_aper_order);



			return 1;

		}

		return 0;

	}
@@ -473,6 +509,14 @@ int __init gart_iommu_hole_init(void) 
		return 0;

	}



	/*

	 * If this is the kdump kernel _and_ the first kernel did not

	 * configure the aperture in the northbridge, this range may

	 * overlap with the first kernel's memory. We can't access the

	 * range through vmcore even though it should be part of the dump.

	 */

	exclude_from_vmcore(aper_alloc, aper_order);



	/* Fix up the north bridges */

	for (i = 0; i < amd_nb_bus_dev_ranges[i].dev_limit; i++) {

		int bus, dev_base, dev_limit;

arch/x86/xen/mmu_hvm.c

+1 −1
Original line number Diff line number Diff line
@@ -75,6 +75,6 @@ void __init xen_hvm_init_mmu_ops(void) 
	if (is_pagetable_dying_supported())

		pv_mmu_ops.exit_mmap = xen_hvm_exit_mmap;

#ifdef CONFIG_PROC_VMCORE

	register_oldmem_pfn_is_ram(&xen_oldmem_pfn_is_ram);

	WARN_ON(register_oldmem_pfn_is_ram(&xen_oldmem_pfn_is_ram));

#endif

}