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
resource_clip(struct resource * res,resource_size_t start,resource_size_t end)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
remove_e820_regions(struct resource * avail)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
arch_remove_reservations(struct resource * avail)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
