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// SPDX-License-Identifier: GPL-2.0
#include <linux/ioport.h>
#include <linux/printk.h>
#include <asm/e820/api.h>
#include <asm/pci_x86.h>
static void resource_clip(struct resource *res, resource_size_t start,
resource_size_t end)
{
resource_size_t low = 0, high = 0;
if (res->end < start || res->start > end)
return; /* no conflict */
if (res->start < start)
low = start - res->start;
if (res->end > end)
high = res->end - end;
/* Keep the area above or below the conflict, whichever is larger */
if (low > high)
res->end = start - 1;
else
res->start = end + 1;
}
static void remove_e820_regions(struct resource *avail)
{
int i;
struct e820_entry *entry;
u64 e820_start, e820_end;
struct resource orig = *avail;
if (!pci_use_e820)
return;
for (i = 0; i < e820_table->nr_entries; i++) {
entry = &e820_table->entries[i];
e820_start = entry->addr;
e820_end = entry->addr + entry->size - 1;
resource_clip(avail, e820_start, e820_end);
if (orig.start != avail->start || orig.end != avail->end) {
pr_info("clipped %pR to %pR for e820 entry [mem %#010Lx-%#010Lx]\n",
&orig, avail, e820_start, e820_end);
orig = *avail;
}
}
}
void arch_remove_reservations(struct resource *avail)
{
/*
* Trim out BIOS area (high 2MB) and E820 regions. We do not remove
* the low 1MB unconditionally, as this area is needed for some ISA
* cards requiring a memory range, e.g. the i82365 PCMCIA controller.
*/
if (avail->flags & IORESOURCE_MEM) {
resource_clip(avail, BIOS_ROM_BASE, BIOS_ROM_END);
remove_e820_regions(avail);
}
}
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