x86_64 Sanitize user specified e820 memmap values From: Vladimir Berezniker Sanitize user specified e820 memory ranges, using the same logic that is applied to the values returned by the BIOS. This ensures consistent handling regardless of the source of the memory mappings. Allows overriding portions of the memory map without specifying one in it's entirety (memmap=exactmap). E.g. marking a range of bad RAM as reserved with memmap=48M$528M BIOS supplied range BIOS-e820: 0000000000100000 - 000000007fe80000 (usable) becomes user: 0000000000100000 - 0000000021000000 (usable) user: 0000000021000000 - 0000000024000000 (reserved) user: 0000000024000000 - 000000007fe80000 (usable) Previously this did not work, as the original BIOS range was left untouched while the user defined range was appended to the end of the memory map. Signed-off-by: Vladimir Berezniker Signed-off-by: Andi Kleen --- arch/x86_64/kernel/e820.c | 7 +++++++ 1 file changed, 7 insertions(+) Index: linux/arch/x86_64/kernel/e820.c =================================================================== --- linux.orig/arch/x86_64/kernel/e820.c +++ linux/arch/x86_64/kernel/e820.c @@ -639,6 +639,8 @@ static int __init parse_memmap_opt(char mem_size = memparse(p, &p); if (p == oldp) return -EINVAL; + + userdef = 1; if (*p == '@') { start_at = memparse(p+1, &p); add_memory_region(start_at, mem_size, E820_RAM); @@ -658,6 +660,11 @@ early_param("memmap", parse_memmap_opt); void __init finish_e820_parsing(void) { if (userdef) { + char nr = e820.nr_map; + if (sanitize_e820_map(e820.map, &nr) < 0) + early_panic("Invalid user supplied memory map"); + e820.nr_map = nr; + printk(KERN_INFO "user-defined physical RAM map:\n"); e820_print_map("user"); }