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

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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
This commit is contained in:
Linus Torvalds 2018-01-29 18:58:16 -08:00
commit 942633523c
2 changed files with 46 additions and 2 deletions
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46
arch/x86/kernel/aperture_64.c
View file

@ -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;

2
arch/x86/xen/mmu_hvm.c
View file

@ -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
}