1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/ioport.h> 3 #include <linux/printk.h> 4 #include <asm/e820/api.h> 5 6 static void resource_clip(struct resource *res, resource_size_t start, 7 resource_size_t end) 8 { 9 resource_size_t low = 0, high = 0; 10 11 if (res->end < start || res->start > end) 12 return; /* no conflict */ 13 14 if (res->start < start) 15 low = start - res->start; 16 17 if (res->end > end) 18 high = res->end - end; 19 20 /* Keep the area above or below the conflict, whichever is larger */ 21 if (low > high) 22 res->end = start - 1; 23 else 24 res->start = end + 1; 25 } 26 27 static void remove_e820_regions(struct resource *avail) 28 { 29 int i; 30 struct e820_entry *entry; 31 u64 e820_start, e820_end; 32 struct resource orig = *avail; 33 34 for (i = 0; i < e820_table->nr_entries; i++) { 35 entry = &e820_table->entries[i]; 36 e820_start = entry->addr; 37 e820_end = entry->addr + entry->size - 1; 38 39 resource_clip(avail, e820_start, e820_end); 40 if (orig.start != avail->start || orig.end != avail->end) { 41 pr_info("clipped %pR to %pR for e820 entry [mem %#010Lx-%#010Lx]\n", 42 &orig, avail, e820_start, e820_end); 43 orig = *avail; 44 } 45 } 46 } 47 48 void arch_remove_reservations(struct resource *avail) 49 { 50 /* 51 * Trim out BIOS area (high 2MB) and E820 regions. We do not remove 52 * the low 1MB unconditionally, as this area is needed for some ISA 53 * cards requiring a memory range, e.g. the i82365 PCMCIA controller. 54 */ 55 if (avail->flags & IORESOURCE_MEM) { 56 resource_clip(avail, BIOS_ROM_BASE, BIOS_ROM_END); 57 58 remove_e820_regions(avail); 59 } 60 } 61