Commit 02b30839 authored by Russell King's avatar Russell King Committed by Russell King
Browse files

[ARM] Fix some corner cases in new mm initialisation 



Document that the VMALLOC_END address must be aligned to 2MB since
it must align with a PGD boundary.

Allocate the vectors page early so that the flush_cache_all() later
will cause any dirty cache lines in the direct mapping will be safely
written back.

Move the flush_cache_all() to the second local_flush_cache_tlb() and
remove the now redundant first local_flush_cache_tlb().

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 67a1901f

Documentation/arm/memory.txt

+3 −1
Original line number Diff line number Diff line 
		Kernel Memory Layout on ARM Linux



		Russell King <rmk@arm.linux.org.uk>

			May 21, 2004 (2.6.6)

		     November 17, 2005 (2.6.15)



This document describes the virtual memory layout which the Linux

kernel uses for ARM processors.  It indicates which regions are
@@ -37,6 +37,8 @@ ff000000 ffbfffff Reserved for future expansion of DMA 
				mapping region.



VMALLOC_END	feffffff	Free for platform use, recommended.

				VMALLOC_END must be aligned to a 2MB

				boundary.



VMALLOC_START	VMALLOC_END-1	vmalloc() / ioremap() space.

				Memory returned by vmalloc/ioremap will

arch/arm/mm/init.c

+13 −11
Original line number Diff line number Diff line
@@ -420,7 +420,8 @@ static void __init bootmem_init(struct meminfo *mi) 
 * Set up device the mappings.  Since we clear out the page tables for all

 * mappings above VMALLOC_END, we will remove any debug device mappings.

 * This means you have to be careful how you debug this function, or any

 * called function.  (Do it by code inspection!)

 * called function.  This means you can't use any function or debugging

 * method which may touch any device, otherwise the kernel _will_ crash.

 */

static void __init devicemaps_init(struct machine_desc *mdesc)

{
@@ -428,6 +429,12 @@ static void __init devicemaps_init(struct machine_desc *mdesc) 
	unsigned long addr;

	void *vectors;



	/*

	 * Allocate the vector page early.

	 */

	vectors = alloc_bootmem_low_pages(PAGE_SIZE);

	BUG_ON(!vectors);



	for (addr = VMALLOC_END; addr; addr += PGDIR_SIZE)

		pmd_clear(pmd_off_k(addr));
@@ -461,12 +468,6 @@ static void __init devicemaps_init(struct machine_desc *mdesc) 
	create_mapping(&map);

#endif



	flush_cache_all();

	local_flush_tlb_all();



	vectors = alloc_bootmem_low_pages(PAGE_SIZE);

	BUG_ON(!vectors);



	/*

	 * Create a mapping for the machine vectors at the high-vectors

	 * location (0xffff0000).  If we aren't using high-vectors, also
@@ -491,12 +492,13 @@ static void __init devicemaps_init(struct machine_desc *mdesc) 
		mdesc->map_io();



	/*

	 * Finally flush the tlb again - this ensures that we're in a

	 * consistent state wrt the writebuffer if the writebuffer needs

	 * draining.  After this point, we can start to touch devices

	 * again.

	 * Finally flush the caches and tlb to ensure that we're in a

	 * consistent state wrt the writebuffer.  This also ensures that

	 * any write-allocated cache lines in the vector page are written

	 * back.  After this point, we can start to touch devices again.

	 */

	local_flush_tlb_all();

	flush_cache_all();

}



/*

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