x86: avoid low BIOS area when allocating address space

This implements arch_remove_reservations() so allocate_resource() can
avoid any arch-specific reserved areas.  This currently just avoids the
BIOS area (the first 1MB), but could be used for E820 reserved areas if
that turns out to be necessary.

We previously avoided this area in pcibios_align_resource().  This patch
moves the test from that PCI-specific path to a generic path, so *all*
resource allocations will avoid this area.

Acked-by: H. Peter Anvin <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Signed-off-by: Jesse Barnes <[email protected]>

Author: Bjorn Helgaas

arch/x86/kernel/Makefile

@@ -45,6 +45,7 @@ obj-y			+= pci-dma.o quirks.o i8237.o topology.o kdebugfs.o
 obj-y			+= alternative.o i8253.o pci-nommu.o hw_breakpoint.o
 obj-y			+= tsc.o io_delay.o rtc.o
 obj-y			+= pci-iommu_table.o
+obj-y			+= resource.o
 
 obj-$(CONFIG_X86_TRAMPOLINE)	+= trampoline.o
 obj-y				+= process.o

arch/x86/kernel/resource.c

@@ -0,0 +1,11 @@
+#include <linux/ioport.h>
+#include <asm/e820.h>
+
+void arch_remove_reservations(struct resource *avail)
+{
+	/* Trim out BIOS area (low 1MB) */
+	if (avail->flags & IORESOURCE_MEM) {
+		if (avail->start < BIOS_END)
+			avail->start = BIOS_END;
+	}
+}

arch/x86/pci/i386.c

@@ -72,9 +72,6 @@ pcibios_align_resource(void *data, const struct resource *res,
 			return start;
 		if (start & 0x300)
 			start = (start + 0x3ff) & ~0x3ff;
-	} else if (res->flags & IORESOURCE_MEM) {
-		if (start < BIOS_END)
-			start = BIOS_END;
 	}
 	return start;
 }