From a571d4eb55d83ff538d98870fa8a8497b24d39bc Mon Sep 17 00:00:00 2001 From: Dennis Chen Date: Thu, 28 Jul 2016 15:48:26 -0700 Subject: mm/memblock.c: add new infrastructure to address the mem limit issue In some cases, memblock is queried by kernel to determine whether a specified address is RAM or not. For example, the ACPI core needs this information to determine which attributes to use when mapping ACPI regions(acpi_os_ioremap). Use of incorrect memory types can result in faults, data corruption, or other issues. Removing memory with memblock_enforce_memory_limit() throws away this information, and so a kernel booted with 'mem=' may suffer from the issues described above. To avoid this, we need to keep those NOMAP regions instead of removing all above the limit, which preserves the information we need while preventing other use of those regions. This patch adds new infrastructure to retain all NOMAP memblock regions while removing others, to cater for this. Link: http://lkml.kernel.org/r/1468475036-5852-2-git-send-email-dennis.chen@arm.com Signed-off-by: Dennis Chen Acked-by: Steve Capper Cc: Catalin Marinas Cc: Ard Biesheuvel Cc: Pekka Enberg Cc: Mel Gorman Cc: Tang Chen Cc: Tony Luck Cc: Ingo Molnar Cc: Rafael J. Wysocki Cc: Will Deacon Cc: Mark Rutland Cc: Matt Fleming Cc: Kaly Xin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memblock.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 52 insertions(+), 5 deletions(-) (limited to 'mm') diff --git a/mm/memblock.c b/mm/memblock.c index d8a79dfbf891..4884a162e3ad 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1465,15 +1465,16 @@ phys_addr_t __init_memblock memblock_end_of_DRAM(void) return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size); } -void __init memblock_enforce_memory_limit(phys_addr_t limit) +static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit) { phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX; struct memblock_region *r; - if (!limit) - return; - - /* find out max address */ + /* + * translate the memory @limit size into the max address within one of + * the memory memblock regions, if the @limit exceeds the total size + * of those regions, max_addr will keep original value ULLONG_MAX + */ for_each_memblock(memory, r) { if (limit <= r->size) { max_addr = r->base + limit; @@ -1482,6 +1483,22 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit) limit -= r->size; } + return max_addr; +} + +void __init memblock_enforce_memory_limit(phys_addr_t limit) +{ + phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX; + + if (!limit) + return; + + max_addr = __find_max_addr(limit); + + /* @limit exceeds the total size of the memory, do nothing */ + if (max_addr == (phys_addr_t)ULLONG_MAX) + return; + /* truncate both memory and reserved regions */ memblock_remove_range(&memblock.memory, max_addr, (phys_addr_t)ULLONG_MAX); @@ -1489,6 +1506,36 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit) (phys_addr_t)ULLONG_MAX); } +void __init memblock_mem_limit_remove_map(phys_addr_t limit) +{ + struct memblock_type *type = &memblock.memory; + phys_addr_t max_addr; + int i, ret, start_rgn, end_rgn; + + if (!limit) + return; + + max_addr = __find_max_addr(limit); + + /* @limit exceeds the total size of the memory, do nothing */ + if (max_addr == (phys_addr_t)ULLONG_MAX) + return; + + ret = memblock_isolate_range(type, max_addr, (phys_addr_t)ULLONG_MAX, + &start_rgn, &end_rgn); + if (ret) + return; + + /* remove all the MAP regions above the limit */ + for (i = end_rgn - 1; i >= start_rgn; i--) { + if (!memblock_is_nomap(&type->regions[i])) + memblock_remove_region(type, i); + } + /* truncate the reserved regions */ + memblock_remove_range(&memblock.reserved, max_addr, + (phys_addr_t)ULLONG_MAX); +} + static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr) { unsigned int left = 0, right = type->cnt; -- cgit v1.2.3