Initial commit: functional for newer bzImage kernels

1 files changed, 187 insertions, 0 deletions

diff --git a/reloc/reloc_linux.c b/reloc/reloc_linux.c
new file mode 100644
index 0000000..5849c54
--- /dev/null
+++ b/reloc/reloc_linux.c
@@ -0,0 +1,187 @@
+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 2008 H. Peter Anvin - All Rights Reserved
+ *
+ *   Permission is hereby granted, free of charge, to any person
+ *   obtaining a copy of this software and associated documentation
+ *   files (the "Software"), to deal in the Software without
+ *   restriction, including without limitation the rights to use,
+ *   copy, modify, merge, publish, distribute, sublicense, and/or
+ *   sell copies of the Software, and to permit persons to whom
+ *   the Software is furnished to do so, subject to the following
+ *   conditions:
+ *   
+ *   The above copyright notice and this permission notice shall
+ *   be included in all copies or substantial portions of the Software.
+ *   
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ *   OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * reloc_linux.c
+ *
+ * This is the initial program run before the Linux kernel.
+ * It serves to hoist the initrd as high as permitted.
+ *
+ * This runs in protected mode, but in low memory, and should be kept
+ * as small as possible.
+ */
+
+#include "reloc.h"
+#include "setup.h"
+#include "conio.h"
+
+static uint32_t initrd_len, initrd_addr;
+static uint64_t max_addr;
+
+static int initrd_fit(uint32_t base, uint32_t end)
+{
+	uint64_t ibase;
+
+	printf("Fit: base = %08x, end = %08x\n", base, end);
+
+	if (end <= base)
+		return -1;	/* Invalid */
+
+	if (base > max_addr)
+		return -1;	/* Not accessible */
+
+	if (end > max_addr)
+		end = max_addr;
+
+	if (end < initrd_len)
+		return -1;
+
+	ibase = (end - initrd_len) & ~0xfff;
+	if (ibase < base)
+		return -1;
+
+	if (initrd_addr < ibase) {
+		initrd_addr = ibase; /* This is a better one... */
+		printf("Best: initrd_addr = %08x\n", initrd_addr);
+	}
+
+	return 0;
+}
+
+static int probe_memory_e820(void)
+{
+	com32sys_t regs;
+	struct e820_info {
+		uint64_t base;
+		uint64_t len;
+		uint32_t type;
+	} buf;
+	uint64_t base, end;
+	int rv = -1;
+	uint32_t copied;
+
+	memset(&regs, 0, sizeof regs);
+
+	do {
+		regs.eax.l = 0x0000e820;
+		regs.ecx.l = sizeof buf;
+		regs.edx.l = 0x534d4150;
+		regs.edi.w[0] = OFFS(&buf);
+		regs.es = SEG(&buf);
+
+		intcall(0x15, &regs, &regs);
+		copied = (regs.eflags.l & EFLAGS_CF)
+			? 0 : regs.ecx.l;
+		
+		if ( regs.eax.l != 0x534d4150 || copied < 20 )
+			break;
+
+		if (buf.type != 1)
+			continue; /* Not memory */
+
+		rv &= initrd_fit(buf.base, buf.base+buf.len);
+	} while (regs.ebx.l);
+
+	return rv;
+}
+
+static int probe_memory_e801(void)
+{
+	com32sys_t regs;
+	uint64_t base, end;
+
+	memset(&regs, 0, sizeof regs);
+	regs.eax.w[0] = 0xe801;
+	intcall(0x15, &regs, &regs);
+
+	if (regs.eflags.l & EFLAGS_CF)
+		return -1;	/* No e801 */
+
+	if (regs.eax.w[0] < 15*1024)
+		end = (uint64_t)(regs.eax.w[0] << 10) + 0x100000;
+	else
+		end = (uint64_t)(regs.ebx.w[0] << 16) + 0x1000000;
+
+	return initrd_fit(0x100000, end);
+}
+
+static int probe_memory_88(void)
+{
+	com32sys_t regs;
+
+	memset(&regs, 0, sizeof regs);
+	regs.eax.b[1] = 0x88;
+	intcall(0x15, &regs, &regs);
+
+	if (regs.eflags.l & EFLAGS_CF)
+		return -1;
+
+	return initrd_fit(0x100000, (regs.eax.w[0] << 10)+0x100000);
+}
+
+static int place_initrd(void)
+{
+	int rv;
+
+	rv = probe_memory_e820();
+	if (!rv)
+		return 0;
+
+	rv = probe_memory_e801();
+	if (!rv)
+		return 0;
+
+	return probe_memory_88();
+}
+
+int main(void)
+{
+	extern struct startup_info _start[]; /* Cute hack, eh? */
+	struct startup_info *info = _start - 1;
+	struct setup_header *hdr = (void *)(info->setup_addr + 0x1f1);
+
+	if (info->rd_len) {
+		initrd_len = info->rd_len;
+		max_addr   = info->rd_maxaddr;
+
+		if (place_initrd())
+			return -1;
+
+		/* Move the initrd into place */
+		printf("Moving initrd: 0x%08x -> 0x%08x (0x%08x bytes)\n",
+		       info->rd_addr, initrd_addr, info->rd_len);
+
+		memmove((void *)initrd_addr, (void *)info->rd_addr,
+			info->rd_len);
+		
+		hdr->ramdisk_image = initrd_addr;
+	}
+
+	jump_to_kernel(info->setup_addr >> 4,
+		       info->cmdline_addr - info->setup_addr);
+	return -1;		/* Shouldn't return... */
+}