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xen/mmu: Remove from __ka space PMD entries for pagetables.

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Please first read the description in "xen/mmu: Copy and revector the
P2M tree."

At this stage, the __ka address space (which is what the old
P2M tree was using) is partially disassembled. The cleanup_highmap
has removed the PMD entries from 0-16MB and anything past _brk_end
up to the max_pfn_mapped (which is the end of the ramdisk).

The xen_remove_p2m_tree and code around has ripped out the __ka for
the old P2M array.

Here we continue on doing it to where the Xen page-tables were.
It is safe to do it, as the page-tables are addressed using __va.
For good measure we delete anything that is within MODULES_VADDR
and up to the end of the PMD.

At this point the __ka only contains PMD entries for the start
of the kernel up to __brk.

[v1: Per Stefano's suggestion wrapped the MODULES_VADDR in debug]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Konrad Rzeszutek Wilk 2012-08-14 14:34:00 -04:00
parent 7f9140626c
commit 3aca7fbc8e
1 changed files with 19 additions and 0 deletions
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19
arch/x86/xen/mmu.c
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@ -1240,6 +1240,25 @@ static void __init xen_pagetable_setup_done(pgd_t *base)
xen_start_info->mfn_list = new_mfn_list; xen_start_info->mfn_list = new_mfn_list;
} }
} }
/* At this stage, cleanup_highmap has already cleaned __ka space
* from _brk_limit way up to the max_pfn_mapped (which is the end of
* the ramdisk). We continue on, erasing PMD entries that point to page
* tables - do note that they are accessible at this stage via __va.
* For good measure we also round up to the PMD - which means that if
* anybody is using __ka address to the initial boot-stack - and try
* to use it - they are going to crash. The xen_start_info has been
* taken care of already in xen_setup_kernel_pagetable. */
addr = xen_start_info->pt_base;
size = roundup(xen_start_info->nr_pt_frames * PAGE_SIZE, PMD_SIZE);
xen_cleanhighmap(addr, addr + size);
xen_start_info->pt_base = (unsigned long)__va(__pa(xen_start_info->pt_base));
#ifdef DEBUG
/* This is superflous and is not neccessary, but you know what
* lets do it. The MODULES_VADDR -> MODULES_END should be clear of
* anything at this stage. */
xen_cleanhighmap(MODULES_VADDR, roundup(MODULES_VADDR, PUD_SIZE) - 1);
#endif
#endif #endif
xen_post_allocator_init(); xen_post_allocator_init();
} }