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linux/arch/arm/mm
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Vladimir Murzin 5c9d9a1b3a ARM: 8712/1: NOMMU: Use more MPU regions to cover memory 
PMSAv7 defines curious alignment requirements to the regions:
- size must be power of 2, and
- region start must be aligned to the region size

Because of that we currently adjust lowmem bounds plus we assign
only one MPU region to cover memory all these lead to significant amount of
memory could be wasted. As an example, consider 64Mb of memory at
0x70000000 - it fits alignment requirements nicely; now, imagine that
2Mb of memory is reserved for coherent DMA allocation, so now Linux is
expected to see 62Mb of memory... and here annoying thing happens -
memory gets truncated to 32Mb (we've lost 30Mb!), i.e. MPU layout
looks like:

0: base 0x70000000, size 0x2000000

This patch tries to allocate as much as possible MPU slots to minimise
amount of truncated memory. Moreover, with this patch MPU subregions
starting to get used. MPU subregions allow us reduce the number of MPU
slots used. For example given above, MPU layout looks like:

0: base 0x70000000, size 0x2000000
1: base 0x72000000, size 0x1000000
2: base 0x73000000, size 0x1000000, disable subreg 7 (0x73e00000 - 0x73ffffff)

Where without subregions we'd get:

0: base 0x70000000, size 0x2000000
1: base 0x72000000, size 0x1000000
2: base 0x73000000, size 0x800000
3: base 0x73800000, size 0x400000
4: base 0x73c00000, size 0x200000

To achieve better layout we fist try to cover specified memory as is
(maybe with help of subregions) and if we failed, we truncate memory
to fit alignment requirements (so it occupies one MPU slot) and
perform one more attempt with the reminder, and so on till we either
cover all memory or run out of MPU slots.

Tested-by: Szemző András <sza@esh.hu>
Tested-by: Alexandre TORGUE <alexandre.torgue@st.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2017-10-23 16:59:23 +01:00
..
abort-ev4.S ARM: entry: provide uaccess assembly macro hooks 2015-08-26 20:27:02 +01:00
abort-ev4t.S
abort-ev5t.S ARM: entry: provide uaccess assembly macro hooks 2015-08-26 20:27:02 +01:00
abort-ev5tj.S ARM: entry: provide uaccess assembly macro hooks 2015-08-26 20:27:02 +01:00
abort-ev6.S ARM: entry: provide uaccess assembly macro hooks 2015-08-26 20:27:02 +01:00
abort-ev7.S ARM: entry: provide uaccess assembly macro hooks 2015-08-26 20:27:02 +01:00
abort-lv4t.S ARM: fix oops when using older ARMv4T CPUs 2016-10-19 10:18:43 +01:00
abort-macro.S ARM: entry: provide uaccess assembly macro hooks 2015-08-26 20:27:02 +01:00
abort-nommu.S
alignment.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
cache-aurora-l2.h
cache-fa.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
cache-feroceon-l2.c ARM: 8416/1: Feroceon: use of_iomap() to map register base 2015-08-18 14:00:30 +01:00
cache-l2x0-pmu.c cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
cache-l2x0.c ARM: 8659/1: l2c: allow CA9 optimizations to be disabled 2017-03-17 10:01:26 +00:00
cache-nop.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
cache-tauros2.c ARM: l2c: tauros2: use descriptive definitions for register bits 2015-11-26 22:12:26 +00:00
cache-tauros3.h
cache-uniphier.c ARM: 8652/1: cache-uniphier: clean up active way setup code 2017-02-28 11:06:17 +00:00
cache-v4.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
cache-v4wb.S ARM: align .data section 2017-08-14 16:22:55 +01:00
cache-v4wt.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
cache-v6.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
cache-v7.S scripts/spelling.txt: add "swith" pattern and fix typo instances 2017-02-27 18:43:46 -08:00
cache-v7m.S scripts/spelling.txt: add "swith" pattern and fix typo instances 2017-02-27 18:43:46 -08:00
cache-xsc3l2.c
context.c ARM: 8465/1: mm: keep reserved ASIDs in sync with mm after multiple rollovers 2015-12-02 23:57:54 +00:00
copypage-fa.c
copypage-feroceon.c
copypage-v4mc.c
copypage-v4wb.c
copypage-v4wt.c
copypage-v6.c ARM: 8236/1: mm: fix discard_old_kernel_data 2014-12-03 16:00:04 +00:00
copypage-xsc3.c
copypage-xscale.c
dma-mapping-nommu.c ARM: NOMMU: Wire-up default DMA interface 2017-07-20 16:09:27 +02:00
dma-mapping.c dma-coherent: introduce interface for default DMA pool 2017-07-20 16:09:10 +02:00
dma.h ARM: reduce visibility of dmac_* functions 2015-08-01 22:25:04 +01:00
dump.c ARM: 8666/1: mm: dump: Add domain to output 2017-03-29 17:39:17 +01:00
extable.c arm: migrate exception table users off module.h and onto extable.h 2017-01-24 12:41:46 -05:00
fault-armv.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
fault.c ARM: 8692/1: mm: abort uaccess retries upon fatal signal 2017-08-29 13:09:14 +01:00
fault.h ARM: 8642/1: LPAE: catch pending imprecise abort on unmask 2017-01-30 12:04:12 +00:00
flush.c ARM: 8627/1: avoid cache flushing in flush_dcache_page() 2017-01-10 23:31:30 +00:00
fsr-2level.c
fsr-3level.c
highmem.c kmap_atomic_to_page() has no users, remove it 2015-11-09 15:11:24 -08:00
hugetlbpage.c mm/hugetlb: reduce arch dependent code about huge_pmd_unshare 2015-06-24 17:49:41 -07:00
idmap.c sched/headers: Prepare to remove the <linux/mm_types.h> dependency from <linux/sched.h> 2017-03-02 08:42:37 +01:00
init.c ARM: 8672/1: mm: remove tasklist locking from update_sections_early() 2017-04-26 10:59:36 +01:00
iomap.c
ioremap.c ARM: Implement pci_remap_cfgspace() interface 2017-04-24 13:53:13 -05:00
Kconfig Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-07-08 12:17:25 -07:00
l2c-common.c ARM: outer cache: add WARN_ON() to outer_disable() 2014-05-30 00:47:23 +01:00
l2c-l2x0-resume.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
Makefile ARM: 8706/1: NOMMU: Move out MPU setup in separate module 2017-10-23 16:58:31 +01:00
mm.h ARM: provide common method to clear bits in CPU control register 2014-06-02 09:20:11 +01:00
mmap.c mm: larger stack guard gap, between vmas 2017-06-19 21:50:20 +08:00
mmu.c ARM: 8685/1: ensure memblock-limit is pmd-aligned 2017-06-29 23:10:12 +01:00
nommu.c ARM: 8706/1: NOMMU: Move out MPU setup in separate module 2017-10-23 16:58:31 +01:00
pabort-legacy.S
pabort-v6.S
pabort-v7.S
pageattr.c arm: use set_memory.h header 2017-05-08 17:15:13 -07:00
pgd.c arm: get rid of superfluous __GFP_REPEAT 2016-07-26 16:19:19 -07:00
physaddr.c ARM: 8640/1: Add support for CONFIG_DEBUG_VIRTUAL 2017-02-28 11:06:09 +00:00
pmsa-v7.c ARM: 8712/1: NOMMU: Use more MPU regions to cover memory 2017-10-23 16:59:23 +01:00
proc-arm7tdmi.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-arm9tdmi.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-arm720.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-arm740.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-arm920.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-arm922.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-arm925.S ARM: 8349/1: arch/arm/mm/proc-arm925.S: remove dead #ifdef block 2015-05-03 23:22:27 +01:00
proc-arm926.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-arm940.S Merge branches 'misc', 'vdso' and 'fixes' into for-next 2015-04-14 22:28:25 +01:00
proc-arm946.S Merge branches 'misc', 'vdso' and 'fixes' into for-next 2015-04-14 22:28:25 +01:00
proc-arm1020.S ARM: 8348/1: remove comments on CPU_ARM1020_CPU_IDLE 2015-05-03 23:22:09 +01:00
proc-arm1020e.S ARM: 8348/1: remove comments on CPU_ARM1020_CPU_IDLE 2015-05-03 23:22:09 +01:00
proc-arm1022.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-arm1026.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-fa526.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-feroceon.S ARM: 8350/1: proc-feroceon: Fix feroceon_proc_info macro 2015-05-03 23:23:09 +01:00
proc-macros.S ARM: Prepare for randomized task_struct 2017-06-30 12:00:50 -07:00
proc-mohawk.S ARM: mohawk: allow building with MMU disabled 2015-12-01 21:44:25 +01:00
proc-sa110.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-sa1100.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-syms.c
proc-v6.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-v7-2level.S Merge branches 'arnd-fixes', 'clk', 'misc', 'v7' and 'fixes' into for-next 2015-06-12 21:18:08 +01:00
proc-v7-3level.S ARM: 8690/1: lpae: build TTB control register value from scratch in v7_ttb_setup 2017-08-29 13:09:12 +01:00
proc-v7.S ARM: Update cpu_v7_reset documentation 2017-04-09 07:49:25 -07:00
proc-v7m.S Merge branches 'fixes' and 'misc' into for-next 2017-04-26 10:59:49 +01:00
proc-xsc3.S ARM: 8314/1: replace PROCINFO embedded branch with relative offset 2015-03-28 15:46:14 +00:00
proc-xscale.S ARM: align .data section 2017-08-14 16:22:55 +01:00
pv-fixup-asm.S ARM: re-implement physical address space switching 2015-06-01 23:46:33 +01:00
tcm.h
tlb-fa.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
tlb-v4.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
tlb-v4wb.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
tlb-v4wbi.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
tlb-v6.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00
tlb-v7.S ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ 2014-07-18 12:29:04 +01:00