1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/ioport.h> 3 #include <linux/printk.h> 4 #include <asm/e820/api.h> 5 #include <asm/pci_x86.h> 6 7 static void resource_clip(struct resource *res, resource_size_t start, 8 resource_size_t end) 9 { 10 resource_size_t low = 0, high = 0; 11 12 if (res->end < start || res->start > end) 13 return; /* no conflict */ 14 15 if (res->start < start) 16 low = start - res->start; 17 18 if (res->end > end) 19 high = res->end - end; 20 21 /* Keep the area above or below the conflict, whichever is larger */ 22 if (low > high) 23 res->end = start - 1; 24 else 25 res->start = end + 1; 26 } 27 28 static void remove_e820_regions(struct resource *avail) 29 { 30 int i; 31 struct e820_entry *entry; 32 u64 e820_start, e820_end; 33 struct resource orig = *avail; 34 35 if (!pci_use_e820) 36 return; 37 38 for (i = 0; i < e820_table->nr_entries; i++) { 39 entry = &e820_table->entries[i]; 40 e820_start = entry->addr; 41 e820_end = entry->addr + entry->size - 1; 42 43 resource_clip(avail, e820_start, e820_end); 44 if (orig.start != avail->start || orig.end != avail->end) { 45 pr_info("clipped %pR to %pR for e820 entry [mem %#010Lx-%#010Lx]\n", 46 &orig, avail, e820_start, e820_end); 47 orig = *avail; 48 } 49 } 50 } 51 52 void arch_remove_reservations(struct resource *avail) 53 { 54 /* 55 * Trim out BIOS area (high 2MB) and E820 regions. We do not remove 56 * the low 1MB unconditionally, as this area is needed for some ISA 57 * cards requiring a memory range, e.g. the i82365 PCMCIA controller. 58 */ 59 if (avail->flags & IORESOURCE_MEM) { 60 resource_clip(avail, BIOS_ROM_BASE, BIOS_ROM_END); 61 62 remove_e820_regions(avail); 63 } 64 } 65