Initial revision

1 files changed, 103 insertions, 0 deletions

diff --git a/src/core/relocate.c b/src/core/relocate.c
new file mode 100644
index 000000000..d20846a88
--- /dev/null
+++ b/src/core/relocate.c
@@ -0,0 +1,103 @@
+#ifndef	NORELOCATE
+
+#include "etherboot.h"
+
+/* by Eric Biederman */
+
+/* On some platforms etherboot is compiled as a shared library, and we use
+ * the ELF pic support to make it relocateable.  This works very nicely
+ * for code, but since no one has implemented PIC data yet pointer
+ * values in variables are a a problem.  Global variables are a
+ * pain but the return addresses on the stack are the worst.  On these
+ * platforms relocate_to will restart etherboot, to ensure the stack
+ * is reinitialize and hopefully get the global variables
+ * appropriately reinitialized as well.
+ * 
+ */
+
+void relocate(void)
+{
+	unsigned long addr, eaddr, size;
+	unsigned i;
+	/* Walk through the memory map and find the highest address
+	 * below 4GB that etherboot will fit into.  Ensure etherboot
+	 * lies entirely within a range with A20=0.  This means that
+	 * even if something screws up the state of the A20 line, the
+	 * etherboot code is still visible and we have a chance to
+	 * diagnose the problem.
+	 */
+	/* First find the size of etherboot */
+	addr = virt_to_phys(_text);
+	eaddr = virt_to_phys(_end);
+	size = (eaddr - addr + 0xf) & ~0xf;
+
+	/* If the current etherboot is beyond MAX_ADDR pretend it is
+	 * at the lowest possible address.
+	 */
+	if (eaddr > MAX_ADDR) {
+		eaddr = 0;
+	}
+
+	for(i = 0; i < meminfo.map_count; i++) {
+		unsigned long r_start, r_end;
+		if (meminfo.map[i].type != E820_RAM) {
+			continue;
+		}
+		if (meminfo.map[i].addr > MAX_ADDR) {
+			continue;
+		}
+		if (meminfo.map[i].size > MAX_ADDR) {
+			continue;
+		}
+		r_start = meminfo.map[i].addr;
+		r_end = r_start + meminfo.map[i].size;
+		/* Make the addresses 16 byte (128 bit) aligned */
+		r_start = (r_start + 15) & ~15;
+		r_end = r_end & ~15;
+		if (r_end < r_start) {
+			r_end = MAX_ADDR;
+		}
+		if (r_end < size) {
+			/* Avoid overflow weirdness when r_end - size < 0 */
+			continue;
+		}
+		/* Shrink the range down to use only even megabytes
+		 * (i.e. A20=0).
+		 */
+		if ( r_end & 0x100000 ) {
+			/* If r_end is in an odd megabyte, round down
+			 * r_end to the top of the next even megabyte.
+			 */
+			r_end = r_end & ~0xfffff;
+		} else if ( ( r_end - size ) & 0x100000 ) {
+			/* If r_end is in an even megabyte, but the
+			 * start of Etherboot would be in an odd
+			 * megabyte, round down to the top of the next
+			 * even megabyte.
+			*/
+			r_end = ( r_end - 0x100000 ) & ~0xfffff;
+		}
+		/* If we have rounded down r_end below r_ start, skip
+		 * this block.
+		 */
+		if ( r_end < r_start ) {
+			continue;
+		}
+		if (eaddr < r_end - size) {
+			addr = r_end - size;
+			eaddr = r_end;
+		}
+	}
+	if (addr != virt_to_phys(_text)) {
+		unsigned long old_addr = virt_to_phys(_text);
+		printf("Relocating _text from: [%lx,%lx) to [%lx,%lx)\n",
+			old_addr, virt_to_phys(_end),
+			addr, eaddr);
+		arch_relocate_to(addr);
+		cleanup();
+		relocate_to(addr);
+		arch_relocated_from(old_addr);
+	}
+}
+
+#endif /* NORELOCATE */