x86: flatten hierarchy

It never made sense to have bootblock_* in init, but
pirq_routing.c in boot, and some ld scripts on the main
level while others live in subdirectories.

This patch flattens the directory hierarchy and makes
x86 more similar to the other architectures.

Change-Id: I4056038fe7813e4d3d3042c441e7ab6076a36384
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/10901
Tested-by: build bot (Jenkins)
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/arch/x86/thread_switch.S

@@ -0,0 +1,58 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2013 Google, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc.
+ */
+.code32
+.text
+
+/*
+ * stack layout after pushad:
+ * +------------+
+ * | save stack | <-- esp + 0x28
+ * +------------+
+ * |  new stack | <-- esp + 0x24
+ * +------------+
+ * |  ret addr  | <-- esp + 0x20
+ * +------------+
+ * |    eax     | <-- esp + 0x1c
+ * +------------+
+ * |    ecx     | <-- esp + 0x18
+ * +------------+
+ * |    edx     | <-- esp + 0x14
+ * +------------+
+ * |    ebx     | <-- esp + 0x10
+ * +------------+
+ * |  orig esp  | <-- esp + 0x0c
+ * +------------+
+ * |    ebp     | <-- esp + 0x08
+ * +------------+
+ * |    esi     | <-- esp + 0x04
+ * +------------+
+ * |    edi     | <-- esp + 0x00
+ * +------------+
+ */
+.globl switch_to_thread
+switch_to_thread:
+	pusha
+	/* Save the current stack */
+	movl	0x28(%esp), %ebx
+	movl	%esp, (%ebx)
+	/* Switch to the new stack. */
+	movl	0x24(%esp), %eax
+	movl	%eax, %esp
+	popa
+	ret