diff options
Diffstat (limited to 'src/lib')
| -rw-r--r-- | src/lib/Makefile.inc | 18 | ||||
| -rw-r--r-- | src/lib/rmodule.c | 245 | ||||
| -rw-r--r-- | src/lib/rmodule.ld | 115 |
3 files changed, 378 insertions, 0 deletions
diff --git a/src/lib/Makefile.inc b/src/lib/Makefile.inc index be57f29411..160fce6714 100644 --- a/src/lib/Makefile.inc +++ b/src/lib/Makefile.inc @@ -107,3 +107,21 @@ endif $(obj)/lib/uart8250mem.smm.o : $(OPTION_TABLE_H) $(obj)/lib/uart8250.smm.o : $(OPTION_TABLE_H) +ifeq ($(CONFIG_RELOCATABLE_MODULES),y) +ramstage-y += rmodule.c + +RMODULE_LDSCRIPT := $(src)/lib/rmodule.ld +RMODULE_LDFLAGS := -nostartfiles -shared -z defs -nostdlib -Bsymbolic -T $(RMODULE_LDSCRIPT) + +# rmodule_link_rules is a function that should be called with: +# (1) the object name to link +# (2) the dependencies +# (3) heap size of the relocatable module +# It will create the necessary Make rules. +define rmodule_link +$(strip $(1)): $(strip $(2)) $$(RMODULE_LDSCRIPT) $$(obj)/ldoptions + $$(LD) $$(RMODULE_LDFLAGS) --defsym=__heap_size=$(strip $(3)) -o $$@ $(strip $(2)) + $$(NM) -n $$@ > $$(basename $$@).map +endef + +endif 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); +} + diff --git a/src/lib/rmodule.ld b/src/lib/rmodule.ld new file mode 100644 index 0000000000..4c13c84666 --- /dev/null +++ b/src/lib/rmodule.ld @@ -0,0 +1,115 @@ +OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386") +OUTPUT_ARCH(i386) + +/* + * This linker script is used to link rmodules (relocatable modules). It + * links at zero so that relocation fixups are easy when placing the binaries + * anywhere in the address space. + * + * NOTE: The program's loadable sections (text, module_params, and data) are + * packed into the flat blob using the AT directive. The rmodule loader assumes + * the entire program resides in one contiguous address space. Therefore, + * alignment for a given section (if required) needs to be done at the end of + * the preceeding section. e.g. if the data section should be aligned to an 8 + * byte address the text section should have ALIGN(8) at the end of its section. + * Otherwise there won't be a consistent mapping between the flat blob and the + * loaded program. + */ + +BASE_ADDRESS = 0x00000; + +SECTIONS +{ + . = BASE_ADDRESS; + + .header : AT (0) { + *(.module_header); + . = ALIGN(8); + } + + /* Align the start of the module program to a large enough alignment + * so that any data in the program with an alignement property is met. + * Essentially, this alignment is the maximum possible data alignment + * property a program can have. */ + . = ALIGN(4096); + _module_link_start_addr = .; + _payload_begin_offset = LOADADDR(.header) + SIZEOF(.header); + + .text : AT (_payload_begin_offset) { + /* C code of the module. */ + *(.text); + *(.text.*); + /* C read-only data. */ + . = ALIGN(16); + *(.rodata); + *(.rodata.*); + . = ALIGN(4); + } + + .module_params : AT (LOADADDR(.text) + SIZEOF(.text)) { + /* The parameters section can be used to pass parameters + * to a module, however there has to be an prior agreement + * on how to interpret the parameters. */ + _module_params_begin = .; + *(.module_parameters); + _module_params_end = .; + . = ALIGN(4); + } + + .data : AT (LOADADDR(.module_params) + SIZEOF(.module_params)) { + _sdata = .; + *(.data); + . = ALIGN(4); + _edata = .; + } + + /* _payload_end marks the end of the module's code and data. */ + _payload_end_offset = LOADADDR(.data) + SIZEOF(.data); + + .bss (NOLOAD) : { + /* C uninitialized data of the SMM handler */ + _bss_begin = .; + *(.bss); + *(.sbss); + *(COMMON); + . = ALIGN(8); + _bss_end = .; + } + + .heap (NOLOAD) : { + /* + * Place the heap after BSS. The heap size is passed in by + * by way of ld --defsym=__heap_size=<> + */ + _heap = .; + . = . + __heap_size; + _eheap = .; + } + + /* _module_program_size is the total memory used by the program. */ + _module_program_size = _eheap - _module_link_start_addr; + + /* The relocation information is linked on top of the BSS section + * because the BSS section takes no space on disk. The relocation data + * resides directly after the data section in the flat binary. */ + .relocations ADDR(.bss) : AT (_payload_end_offset) { + *(.rel.*); + } + _relocations_begin_offset = LOADADDR(.relocations); + _relocations_end_offset = _relocations_begin_offset + + SIZEOF(.relocations); + + /DISCARD/ : { + /* Drop unnecessary sections. Since these modules are linked + * as shared objects there are dynamic sections. These sections + * aren't needed so drop them. */ + *(.comment); + *(.note); + *(.note.*); + *(.dynamic); + *(.dynsym); + *(.dynstr); + *(.gnu.hash); + *(.eh_frame); + } +} |