lib: add rmodule support

A rmodule is short for relocation module. Relocaiton modules are
standalone programs. These programs are linked at address 0 as a shared
object with a special linker script that maintains the relocation
entries for the object. These modules can then be embedded as a raw
binary (objcopy -O binary) to be loaded at any location desired.

Initially, the only arch support is for x86. All comments below apply to
x86 specific properties.

The intial user of this support would be for SMM handlers since those
handlers sometimes need to be located at a dynamic address (e.g. TSEG
region).

The relocation entries are currently Elf32_Rel. They are 8 bytes large,
and the entries are not necessarily in sorted order. An future
optimization would be to have a tool convert the unsorted relocations
into just sorted offsets. This would reduce the size of the blob
produced after being processed. Essentialy, 8 bytes per relocation meta
entry would reduce to 4 bytes.

Change-Id: I2236dcb66e9d2b494ce2d1ae40777c62429057ef
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2692
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

1 files changed, 126 insertions, 0 deletions

diff --git a/src/include/rmodule.h b/src/include/rmodule.h
new file mode 100644
index 0000000000..b51700cc3a
--- /dev/null
+++ b/src/include/rmodule.h
@@ -0,0 +1,126 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2012 ChromeOS Authors
+ *
+ * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+#ifndef RMODULE_H
+#define RMODULE_H
+
+#include <stdint.h>
+
+#define RMODULE_MAGIC 0xf8fe
+#define RMODULE_VERSION_1 1
+
+enum {
+	RMODULE_TYPE_SMM,
+};
+
+struct rmodule;
+
+/* Public API for loading rmdoules. */
+int rmodule_parse(void *ptr, struct rmodule *m);
+void *rmodule_parameters(const struct rmodule *m);
+void *rmodule_entry(const struct rmodule *m);
+int rmodule_entry_offset(const struct rmodule *m);
+int rmodule_memory_size(const struct rmodule *m);
+int rmodule_load(void *loc, struct rmodule *m);
+int rmodule_load_alignment(const struct rmodule *m);
+
+#define FIELD_ENTRY(x_) ((u32)&x_)
+#define RMODULE_HEADER(entry_, type_)					\
+{									\
+	.magic = RMODULE_MAGIC,						\
+	.version = RMODULE_VERSION_1,					\
+	.type = type_,							\
+	.payload_begin_offset = FIELD_ENTRY(_payload_begin_offset),	\
+	.payload_end_offset = FIELD_ENTRY(_payload_end_offset),		\
+	.relocations_begin_offset  =					\
+		FIELD_ENTRY(_relocations_begin_offset),			\
+	.relocations_end_offset =					\
+		FIELD_ENTRY(_relocations_end_offset),			\
+	.module_link_start_address =					\
+		FIELD_ENTRY(_module_link_start_addr),			\
+	.module_program_size = FIELD_ENTRY(_module_program_size),	\
+	.module_entry_point = FIELD_ENTRY(entry_),			\
+	.parameters_begin = FIELD_ENTRY(_module_params_begin),		\
+	.parameters_end = FIELD_ENTRY(_module_params_end),		\
+	.bss_begin = FIELD_ENTRY(_bss_begin),				\
+	.bss_end = FIELD_ENTRY(_bss_end),				\
+}
+
+#define DEFINE_RMODULE_HEADER(name_, entry_, type_) \
+	struct rmodule_header name_ \
+	__attribute__ ((section (".module_header"))) = \
+	RMODULE_HEADER(entry_, type_)
+
+
+/* Private data structures below should not be used directly. */
+
+/* All fields with '_offset' in the name are byte offsets into the flat blob.
+ * The linker and the linker script takes are of assigning the values.  */
+struct rmodule_header {
+	u16 magic;
+	u8  version;
+	u8  type;
+	/* The payload represents the program's loadable code and data. */
+	u32 payload_begin_offset;
+	u32 payload_end_offset;
+	/* Begin and of relocation information about the program module. */
+	u32 relocations_begin_offset;
+	u32 relocations_end_offset;
+	/* The starting address of the linked program. This address is vital
+	 * for determining relocation offsets as the reloction info and other
+	 * symbols (bss, entry point) need this value as a basis to calculate
+	 * the offsets.
+	 */
+	u32 module_link_start_address;
+	/* The module_program_size is the size of memory used while running
+	 * the program. The program is assumed to consume a contiguos amount
+	 * of memory. */
+	u32 module_program_size;
+	/* This is program's execution entry point. */
+	u32 module_entry_point;
+	/* Optional paramter structure that can be used to pass data into
+	 * the module. */
+	u32 parameters_begin;
+	u32 parameters_end;
+	/* BSS section information so the loader can clear the bss. */
+	u32 bss_begin;
+	u32 bss_end;
+} __attribute__ ((packed));
+
+struct rmodule {
+	void *location;
+	struct rmodule_header *header;
+	const void *payload;
+	int payload_size;
+	void *relocations;
+};
+
+/* These are the symbols assumed that every module contains. The linker script
+ * provides these symbols. */
+extern char _relocations_begin_offset[];
+extern char _relocations_end_offset[];
+extern char _payload_end_offset[];
+extern char _payload_begin_offset[];
+extern char _bss_begin[];
+extern char _bss_end[];
+extern char _module_program_size[];
+extern char _module_link_start_addr[];
+extern char _module_params_begin[];
+extern char _module_params_end[];
+
+#endif /* RMODULE_H */