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, 245 insertions, 0 deletions

diff --git a/src/lib/rmodule.c b/src/lib/rmodule.c
new file mode 100644
index 0000000000..56d7c6d646
--- /dev/null
+++ b/src/lib/rmodule.c
@@ -0,0 +1,245 @@
+/*
+ * 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
+ */
+#include <stdint.h>
+#include <string.h>
+#include <console/console.h>
+#include <rmodule.h>
+
+/* Change this define to get more verbose debugging for module loading. */
+#define PK_ADJ_LEVEL BIOS_NEVER
+
+#if CONFIG_ARCH_X86
+/*
+ * On X86, the only relocations currently allowed are R_386_RELATIVE which
+ * have '0' for the symbol info in the relocation metadata (in r_info).
+ * The reason is that the module is fully linked and just has the relocations'
+ * locations.
+ */
+typedef struct {
+	u32 r_offset;
+	u32 r_info;
+} Elf32_Rel;
+
+#define R_386_RELATIVE 8
+
+#define RELOCTION_ENTRY_SIZE sizeof(Elf32_Rel)
+static inline int rmodule_reloc_offset(const void *reloc)
+{
+	const Elf32_Rel *rel = reloc;
+	return rel->r_offset;
+}
+
+static inline int rmodule_reloc_valid(const void *reloc)
+{
+	const Elf32_Rel *rel = reloc;
+	return (rel->r_info == R_386_RELATIVE);
+}
+
+static inline void *remodule_next_reloc(const void *reloc)
+{
+	const Elf32_Rel *rel = reloc;
+	rel++;
+	return (void *)rel;
+}
+
+#else
+#error Arch needs to add relocation information support for RMODULE
+#endif
+
+static inline int rmodule_is_loaded(const struct rmodule *module)
+{
+	return module->location != NULL;
+}
+
+/* Calculate a loaded program address based on the blob address. */
+static inline void *rmodule_load_addr(const struct rmodule *module,
+                                      u32 blob_addr)
+{
+	char *loc = module->location;
+	return &loc[blob_addr - module->header->module_link_start_address];
+}
+
+/* Initialize a rmodule structure based on raw data. */
+int rmodule_parse(void *ptr, struct rmodule *module)
+{
+	char *base;
+	struct rmodule_header *rhdr;
+
+	base = ptr;
+	rhdr = ptr;
+
+	if (rhdr == NULL)
+		return -1;
+
+	/* Sanity check the raw data. */
+	if (rhdr->magic != RMODULE_MAGIC)
+		return -1;
+	if (rhdr->version != RMODULE_VERSION_1)
+		return -1;
+
+	/* Indicate the module hasn't been loaded yet. */
+	module->location = NULL;
+
+	/* The rmodule only needs a reference to the reloc_header. */
+	module->header = rhdr;
+
+	/* The payload lives after the header. */
+	module->payload = &base[rhdr->payload_begin_offset];
+	module->payload_size = rhdr->payload_end_offset -
+	                       rhdr->payload_begin_offset;
+	module->relocations = &base[rhdr->relocations_begin_offset];
+
+	return 0;
+}
+
+int rmodule_memory_size(const struct rmodule *module)
+{
+	return module->header->module_program_size;
+}
+
+void *rmodule_parameters(const struct rmodule *module)
+{
+	if (!rmodule_is_loaded(module))
+		return NULL;
+
+	/* Indicate if there are no parameters. */
+	if (module->header->parameters_begin == module->header->parameters_end)
+		return NULL;
+
+	return rmodule_load_addr(module, module->header->parameters_begin);
+}
+
+int rmodule_entry_offset(const struct rmodule *module)
+{
+	return module->header->module_entry_point -
+	       module->header->module_link_start_address;
+}
+
+void *rmodule_entry(const struct rmodule *module)
+{
+	if (!rmodule_is_loaded(module))
+		return NULL;
+
+	return rmodule_load_addr(module, module->header->module_entry_point);
+}
+
+static void rmodule_clear_bss(struct rmodule *module)
+{
+	char *begin;
+	int size;
+
+	begin = rmodule_load_addr(module, module->header->bss_begin);
+	size = module->header->bss_end - module->header->bss_begin;
+	memset(begin, 0, size);
+}
+
+static inline int rmodule_number_relocations(const struct rmodule *module)
+{
+	int r;
+
+	r = module->header->relocations_end_offset;
+	r -= module->header->relocations_begin_offset;
+	r /= RELOCTION_ENTRY_SIZE;
+	return r;
+}
+
+static void rmodule_copy_payload(const struct rmodule *module)
+{
+	printk(BIOS_DEBUG, "Loading module at %p with entry %p. "
+	       "filesize: 0x%x memsize: 0x%x\n",
+	       module->location, rmodule_entry(module),
+	       module->payload_size, rmodule_memory_size(module));
+	memcpy(module->location, module->payload, module->payload_size);
+}
+
+static inline u32 *rmodule_adjustment_location(const struct rmodule *module,
+                                               const void *reloc)
+{
+	int reloc_offset;
+
+	/* Don't relocate header field entries -- only program relocations. */
+	reloc_offset = rmodule_reloc_offset(reloc);
+	if (reloc_offset < module->header->module_link_start_address)
+		return NULL;
+
+	return rmodule_load_addr(module, reloc_offset);
+}
+
+static int rmodule_relocate(const struct rmodule *module)
+{
+	int num_relocations;
+	const void *reloc;
+	u32 adjustment;
+
+	/* Each relocation needs to be adjusted relative to the beginning of
+	 * the loaded program. */
+	adjustment = (u32)rmodule_load_addr(module, 0);
+
+	reloc = module->relocations;
+	num_relocations = rmodule_number_relocations(module);
+
+	printk(BIOS_DEBUG, "Processing %d relocs with adjust value of 0x%08x\n",
+	       num_relocations, adjustment);
+
+	while (num_relocations > 0) {
+		u32 *adjust_loc;
+
+		if (!rmodule_reloc_valid(reloc))
+			return -1;
+
+		/* If the adjustment location is non-NULL adjust it. */
+		adjust_loc = rmodule_adjustment_location(module, reloc);
+		if (adjust_loc != NULL) {
+			printk(PK_ADJ_LEVEL, "Adjusting %p: 0x%08x -> 0x%08x\n",
+			       adjust_loc, *adjust_loc,
+			       *adjust_loc + adjustment);
+			*adjust_loc += adjustment;
+		}
+
+		reloc = remodule_next_reloc(reloc);
+		num_relocations--;
+	}
+
+	return 0;
+}
+
+int rmodule_load_alignment(const struct rmodule *module)
+{
+	/* The load alignment is the start of the program's linked address.
+	 * The base address where the program is loaded needs to be a multiple
+	 * of the program's starting link address. That way all data alignment
+	 * in the program is presered. */
+	return module->header->module_link_start_address;
+}
+
+int rmodule_load(void *base, struct rmodule *module)
+{
+	/*
+	 * In order to load the module at a given address, the following steps
+	 * take place:
+	 *  1. Copy payload to base address.
+	 *  2. Clear the bss segment.
+	 *  3. Adjust relocations within the module to new base address.
+	 */
+	module->location = base;
+	rmodule_copy_payload(module);
+	rmodule_clear_bss(module);
+	return rmodule_relocate(module);
+}
+