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arm64: Ignore any DMA offsets in the max_zone_phys() calculation

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Currently, the kernel assumes that if RAM starts above 32-bit (or
zone_bits), there is still a ZONE_DMA/DMA32 at the bottom of the RAM and
such constrained devices have a hardwired DMA offset. In practice, we
haven't noticed any such hardware so let's assume that we can expand
ZONE_DMA32 to the available memory if no RAM below 4GB. Similarly,
ZONE_DMA is expanded to the 4GB limit if no RAM addressable by
zone_bits.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20201118185809.1078362-1-catalin.marinas@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Catalin Marinas 2020-11-18 18:58:09 +00:00
parent f8394f232b
commit 791ab8b2e3
1 changed files with 12 additions and 5 deletions
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17
arch/arm64/mm/init.c
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@ -175,14 +175,21 @@ static void __init reserve_elfcorehdr(void)
#endif /* CONFIG_CRASH_DUMP */ #endif /* CONFIG_CRASH_DUMP */
/* /*
* Return the maximum physical address for a zone with a given address size * Return the maximum physical address for a zone accessible by the given bits
* limit. It currently assumes that for memory starting above 4G, 32-bit * limit. If DRAM starts above 32-bit, expand the zone to the maximum
* devices will use a DMA offset. * available memory, otherwise cap it at 32-bit.
*/ */
static phys_addr_t __init max_zone_phys(unsigned int zone_bits) static phys_addr_t __init max_zone_phys(unsigned int zone_bits)
{ {
phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, zone_bits); phys_addr_t zone_mask = DMA_BIT_MASK(zone_bits);
return min(offset + (1ULL << zone_bits), memblock_end_of_DRAM()); phys_addr_t phys_start = memblock_start_of_DRAM();
if (phys_start > U32_MAX)
zone_mask = PHYS_ADDR_MAX;
else if (phys_start > zone_mask)
zone_mask = U32_MAX;
return min(zone_mask, memblock_end_of_DRAM() - 1) + 1;
} }
static void __init zone_sizes_init(unsigned long min, unsigned long max) static void __init zone_sizes_init(unsigned long min, unsigned long max)