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>
This commit is contained in:
Vladimir Murzin
Russell King
parent
9fcb01a9f5
commit
5c9d9a1b3a
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@ -15,6 +15,11 @@
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/* MPU D/I Size Register fields */
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#define MPU_RSR_SZ 1
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#define MPU_RSR_EN 0
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#define MPU_RSR_SD 8
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/* Number of subregions (SD) */
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#define MPU_NR_SUBREGS 8
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#define MPU_MIN_SUBREG_SIZE 256
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/* The D/I RSR value for an enabled region spanning the whole of memory */
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#define MPU_RSR_ALL_MEM 63
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@ -4,6 +4,7 @@
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* ARM PMSAv7 supporting functions.
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*/
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#include <linux/bitops.h>
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#include <linux/memblock.h>
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#include <asm/cp15.h>
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@ -12,9 +13,20 @@
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#include "mm.h"
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struct region {
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phys_addr_t base;
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phys_addr_t size;
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unsigned long subreg;
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};
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static struct region __initdata mem[MPU_MAX_REGIONS];
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static unsigned int __initdata mpu_min_region_order;
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static unsigned int __initdata mpu_max_regions;
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static int __init __mpu_min_region_order(void);
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static int __init __mpu_max_regions(void);
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#ifndef CONFIG_CPU_V7M
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#define DRBAR __ACCESS_CP15(c6, 0, c1, 0)
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@ -130,19 +142,120 @@ static int __init mpu_present(void)
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return ((read_cpuid_ext(CPUID_EXT_MMFR0) & MMFR0_PMSA) == MMFR0_PMSAv7);
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}
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static bool __init try_split_region(phys_addr_t base, phys_addr_t size, struct region *region)
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{
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unsigned long subreg, bslots, sslots;
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phys_addr_t abase = base & ~(size - 1);
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phys_addr_t asize = base + size - abase;
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phys_addr_t p2size = 1 << __fls(asize);
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phys_addr_t bdiff, sdiff;
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if (p2size != asize)
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p2size *= 2;
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bdiff = base - abase;
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sdiff = p2size - asize;
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subreg = p2size / MPU_NR_SUBREGS;
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if ((bdiff % subreg) || (sdiff % subreg))
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return false;
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bslots = bdiff / subreg;
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sslots = sdiff / subreg;
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if (bslots || sslots) {
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int i;
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if (subreg < MPU_MIN_SUBREG_SIZE)
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return false;
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if (bslots + sslots > MPU_NR_SUBREGS)
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return false;
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for (i = 0; i < bslots; i++)
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_set_bit(i, ®ion->subreg);
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for (i = 1; i <= sslots; i++)
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_set_bit(MPU_NR_SUBREGS - i, ®ion->subreg);
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}
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region->base = abase;
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region->size = p2size;
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return true;
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}
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static int __init allocate_region(phys_addr_t base, phys_addr_t size,
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unsigned int limit, struct region *regions)
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{
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int count = 0;
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phys_addr_t diff = size;
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int attempts = MPU_MAX_REGIONS;
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while (diff) {
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/* Try cover region as is (maybe with help of subregions) */
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if (try_split_region(base, size, ®ions[count])) {
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count++;
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base += size;
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diff -= size;
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size = diff;
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} else {
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/*
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* Maximum aligned region might overflow phys_addr_t
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* if "base" is 0. Hence we keep everything below 4G
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* until we take the smaller of the aligned region
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* size ("asize") and rounded region size ("p2size"),
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* one of which is guaranteed to be smaller than the
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* maximum physical address.
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*/
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phys_addr_t asize = (base - 1) ^ base;
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phys_addr_t p2size = (1 << __fls(diff)) - 1;
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size = asize < p2size ? asize + 1 : p2size + 1;
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}
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if (count > limit)
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break;
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if (!attempts)
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break;
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attempts--;
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}
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return count;
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}
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/* MPU initialisation functions */
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void __init adjust_lowmem_bounds_mpu(void)
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{
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phys_addr_t phys_offset = PHYS_OFFSET;
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phys_addr_t aligned_region_size, specified_mem_size, rounded_mem_size;
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phys_addr_t specified_mem_size, total_mem_size = 0;
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struct memblock_region *reg;
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bool first = true;
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phys_addr_t mem_start;
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phys_addr_t mem_end;
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unsigned int mem_max_regions;
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int num, i;
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if (!mpu_present())
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return;
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/* Free-up MPU_PROBE_REGION */
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mpu_min_region_order = __mpu_min_region_order();
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/* How many regions are supported */
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mpu_max_regions = __mpu_max_regions();
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mem_max_regions = min((unsigned int)MPU_MAX_REGIONS, mpu_max_regions);
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/* We need to keep one slot for background region */
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mem_max_regions--;
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#ifndef CONFIG_CPU_V7M
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/* ... and one for vectors */
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mem_max_regions--;
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#endif
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for_each_memblock(memory, reg) {
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if (first) {
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/*
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@ -168,40 +281,23 @@ void __init adjust_lowmem_bounds_mpu(void)
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}
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}
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/*
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* MPU has curious alignment requirements: Size must be power of 2, and
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* region start must be aligned to the region size
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*/
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if (phys_offset != 0)
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pr_info("PHYS_OFFSET != 0 => MPU Region size constrained by alignment requirements\n");
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num = allocate_region(mem_start, specified_mem_size, mem_max_regions, mem);
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/*
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* Maximum aligned region might overflow phys_addr_t if phys_offset is
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* 0. Hence we keep everything below 4G until we take the smaller of
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* the aligned_region_size and rounded_mem_size, one of which is
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* guaranteed to be smaller than the maximum physical address.
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*/
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aligned_region_size = (phys_offset - 1) ^ (phys_offset);
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/* Find the max power-of-two sized region that fits inside our bank */
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rounded_mem_size = (1 << __fls(specified_mem_size)) - 1;
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for (i = 0; i < num; i++) {
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unsigned long subreg = mem[i].size / MPU_NR_SUBREGS;
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/* The actual region size is the smaller of the two */
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aligned_region_size = aligned_region_size < rounded_mem_size
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? aligned_region_size + 1
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: rounded_mem_size + 1;
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total_mem_size += mem[i].size - subreg * hweight_long(mem[i].subreg);
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if (aligned_region_size != specified_mem_size) {
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pr_warn("Truncating memory from %pa to %pa (MPU region constraints)",
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&specified_mem_size, &aligned_region_size);
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memblock_remove(mem_start + aligned_region_size,
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specified_mem_size - aligned_region_size);
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mem_end = mem_start + aligned_region_size;
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pr_debug("MPU: base %pa size %pa disable subregions: %*pbl\n",
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&mem[i].base, &mem[i].size, MPU_NR_SUBREGS, &mem[i].subreg);
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}
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pr_debug("MPU Region from %pa size %pa (end %pa))\n",
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&phys_offset, &aligned_region_size, &mem_end);
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if (total_mem_size != specified_mem_size) {
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pr_warn("Truncating memory from %pa to %pa (MPU region constraints)",
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&specified_mem_size, &total_mem_size);
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memblock_remove(mem_start + total_mem_size,
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specified_mem_size - total_mem_size);
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}
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}
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static int __init __mpu_max_regions(void)
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@ -258,7 +354,8 @@ static int __init __mpu_min_region_order(void)
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}
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static int __init mpu_setup_region(unsigned int number, phys_addr_t start,
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unsigned int size_order, unsigned int properties)
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unsigned int size_order, unsigned int properties,
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unsigned int subregions)
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{
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u32 size_data;
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@ -275,6 +372,7 @@ static int __init mpu_setup_region(unsigned int number, phys_addr_t start,
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/* Writing N to bits 5:1 (RSR_SZ) specifies region size 2^N+1 */
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size_data = ((size_order - 1) << MPU_RSR_SZ) | 1 << MPU_RSR_EN;
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size_data |= subregions << MPU_RSR_SD;
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dsb(); /* Ensure all previous data accesses occur with old mappings */
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rgnr_write(number);
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@ -308,33 +406,33 @@ static int __init mpu_setup_region(unsigned int number, phys_addr_t start,
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*/
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void __init mpu_setup(void)
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{
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int region = 0, err = 0;
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int i, region = 0, err = 0;
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if (!mpu_present())
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return;
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/* Free-up MPU_PROBE_REGION */
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mpu_min_region_order = __mpu_min_region_order();
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/* How many regions are supported */
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mpu_max_regions = __mpu_max_regions();
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/* Now setup MPU (order is important) */
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/* Setup MPU (order is important) */
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/* Background */
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err |= mpu_setup_region(region++, 0, 32,
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MPU_ACR_XN | MPU_RGN_STRONGLY_ORDERED | MPU_AP_PL1RW_PL0NA);
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MPU_ACR_XN | MPU_RGN_STRONGLY_ORDERED | MPU_AP_PL1RW_PL0NA,
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0);
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/* RAM */
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err |= mpu_setup_region(region++, PHYS_OFFSET,
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ilog2(memblock.memory.regions[0].size),
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MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL);
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for (i = 0; i < ARRAY_SIZE(mem); i++) {
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if (!mem[i].size)
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continue;
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err |= mpu_setup_region(region++, mem[i].base, ilog2(mem[i].size),
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MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL,
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mem[i].subreg);
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}
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/* Vectors */
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#ifndef CONFIG_CPU_V7M
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err |= mpu_setup_region(region++, vectors_base,
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ilog2(2 * PAGE_SIZE),
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MPU_AP_PL1RW_PL0NA | MPU_RGN_NORMAL);
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err |= mpu_setup_region(region++, vectors_base, ilog2(2 * PAGE_SIZE),
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MPU_AP_PL1RW_PL0NA | MPU_RGN_NORMAL,
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0);
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#endif
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if (err) {
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panic("MPU region initialization failure! %d", err);
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