From ae63126346744e20264934f01d7b4653bc366a30 Mon Sep 17 00:00:00 2001 From: "Ronald G. Minnich" Date: Wed, 1 Apr 2009 10:48:39 +0000 Subject: [PATCH] This code adds support for coreboot images that use ROMFS. It also removes the call to FILO from hardwaremain -- that has needed removal for a long time. abuild tested. Note that this code has been tested and works on both qemu and kontron. The changes to use it are coming next. Signed-off-by: Ronald G. Minnich Acked-by: Patrick Georgi git-svn-id: svn://svn.coreboot.org/coreboot/trunk@4039 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1 --- src/boot/Config.lb | 3 + src/boot/hardwaremain.c | 17 +- src/boot/selfboot.c | 497 ++++++++++++++++++++++++++++++++++++++++ src/lib/Config.lb | 4 + src/lib/romfs.c | 234 +++++++++++++++++++ 5 files changed, 752 insertions(+), 3 deletions(-) create mode 100644 src/boot/selfboot.c create mode 100644 src/lib/romfs.c diff --git a/src/boot/Config.lb b/src/boot/Config.lb index f6b82a3610..4c2f4d71f0 100644 --- a/src/boot/Config.lb +++ b/src/boot/Config.lb @@ -1,5 +1,8 @@ object elfboot.o object hardwaremain.o +if CONFIG_ROMFS + object selfboot.o +end if CONFIG_FS_PAYLOAD object filo.o end diff --git a/src/boot/hardwaremain.c b/src/boot/hardwaremain.c index cc3741f583..fdecc7d9ba 100644 --- a/src/boot/hardwaremain.c +++ b/src/boot/hardwaremain.c @@ -88,10 +88,21 @@ void hardwaremain(int boot_complete) */ lb_mem = write_tables(); -#if CONFIG_FS_PAYLOAD == 1 - filo(lb_mem); +#if CONFIG_ROMFS == 1 + printk_err("=================================================\n"); +#if USE_FALLBACK_IMAGE == 1 + void (*pl)(void) = romfs_load_payload(lb_mem, "fallback/payload"); #else - elfboot(lb_mem); + void (*pl)(void) = romfs_load_payload(lb_mem, "normal/payload"); #endif +#endif + +#warning elfboot will soon be deprecated + + printk_err("Trying elfboot, but that will be gone soon!\n"); + elfboot(lb_mem); + + printk_err("NO BOOT METHOD succeeded\n"); + } diff --git a/src/boot/selfboot.c b/src/boot/selfboot.c new file mode 100644 index 0000000000..6aae0d8f55 --- /dev/null +++ b/src/boot/selfboot.c @@ -0,0 +1,497 @@ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifndef CONFIG_BIG_ENDIAN +#define ntohl(x) ( ((x&0xff)<<24) | ((x&0xff00)<<8) | \ + ((x&0xff0000) >> 8) | ((x&0xff000000) >> 24) ) +#else +#define ntohl(x) (x) +#endif + +/* Maximum physical address we can use for the coreboot bounce buffer. + */ +#ifndef MAX_ADDR +#define MAX_ADDR -1UL +#endif + +extern unsigned char _ram_seg; +extern unsigned char _eram_seg; + +struct segment { + struct segment *next; + struct segment *prev; + struct segment *phdr_next; + struct segment *phdr_prev; + unsigned long s_dstaddr; + unsigned long s_srcaddr; + unsigned long s_memsz; + unsigned long s_filesz; +}; + +struct verify_callback { + struct verify_callback *next; + int (*callback)(struct verify_callback *vcb, + Elf_ehdr *ehdr, Elf_phdr *phdr, struct segment *head); + unsigned long desc_offset; + unsigned long desc_addr; +}; + +struct ip_checksum_vcb { + struct verify_callback data; + unsigned short ip_checksum; +}; + +int romfs_self_decompress(int algo, void *src,struct segment *new) +{ + u8 *dst; + + /* for uncompressed, it's easy: just point at the area in ROM */ + if (algo == ROMFS_COMPRESS_NONE) { + new->s_srcaddr = (u32) src; + new->s_filesz = new->s_memsz; + return 0; + } + + /* for compression, let's keep it simple. We'll malloc the destination + * area and decompress to there. The compression overhead far outweighs + * any overhead for an extra copy. + */ + dst = malloc(new->s_memsz); + if (! dst) + return -1; + + switch(algo) { +#ifdef CONFIG_COMPRESSION_LZMA + case ROMFS_COMPRESS_LZMA: { + unsigned long ulzma(unsigned char *src, unsigned char *dst); + ulzma(src, dst); + } +#endif + +#ifdef CONFIG_COMPRESSION_NRV2B + case ROMFS_COMPRESS_NRV2B: { + unsigned long unrv2b(u8 *src, u8 *dst, unsigned long *ilen_p); + unsigned long tmp; + unrv2b(src, dst, &tmp); + } +#endif + default: + printk_info( "ROMFS: Unknown compression type %d\n", + algo); + return -1; + } + + new->s_srcaddr = (u32) dst; + new->s_filesz = new->s_memsz; + return 0; + +} + +/* The problem: + * Static executables all want to share the same addresses + * in memory because only a few addresses are reliably present on + * a machine, and implementing general relocation is hard. + * + * The solution: + * - Allocate a buffer twice the size of the coreboot image. + * - Anything that would overwrite coreboot copy into the lower half of + * the buffer. + * - After loading an ELF image copy coreboot to the upper half of the + * buffer. + * - Then jump to the loaded image. + * + * Benefits: + * - Nearly arbitrary standalone executables can be loaded. + * - Coreboot is preserved, so it can be returned to. + * - The implementation is still relatively simple, + * and much simpler then the general case implemented in kexec. + * + */ + +static unsigned long get_bounce_buffer(struct lb_memory *mem) +{ + unsigned long lb_size; + unsigned long mem_entries; + unsigned long buffer; + int i; + lb_size = (unsigned long)(&_eram_seg - &_ram_seg); + /* Double coreboot size so I have somewhere to place a copy to return to */ + lb_size = lb_size + lb_size; + mem_entries = (mem->size - sizeof(*mem))/sizeof(mem->map[0]); + buffer = 0; + for(i = 0; i < mem_entries; i++) { + unsigned long mstart, mend; + unsigned long msize; + unsigned long tbuffer; + if (mem->map[i].type != LB_MEM_RAM) + continue; + if (unpack_lb64(mem->map[i].start) > MAX_ADDR) + continue; + if (unpack_lb64(mem->map[i].size) < lb_size) + continue; + mstart = unpack_lb64(mem->map[i].start); + msize = MAX_ADDR - mstart +1; + if (msize > unpack_lb64(mem->map[i].size)) + msize = unpack_lb64(mem->map[i].size); + mend = mstart + msize; + tbuffer = mend - lb_size; + if (tbuffer < buffer) + continue; + buffer = tbuffer; + } + return buffer; +} + +static int valid_area(struct lb_memory *mem, unsigned long buffer, + unsigned long start, unsigned long len) +{ + /* Check through all of the memory segments and ensure + * the segment that was passed in is completely contained + * in RAM. + */ + int i; + unsigned long end = start + len; + unsigned long mem_entries = (mem->size - sizeof(*mem))/sizeof(mem->map[0]); + + /* See if I conflict with the bounce buffer */ + if (end >= buffer) { + return 0; + } + + /* Walk through the table of valid memory ranges and see if I + * have a match. + */ + for(i = 0; i < mem_entries; i++) { + uint64_t mstart, mend; + uint32_t mtype; + mtype = mem->map[i].type; + mstart = unpack_lb64(mem->map[i].start); + mend = mstart + unpack_lb64(mem->map[i].size); + if ((mtype == LB_MEM_RAM) && (start < mend) && (end > mstart)) { + break; + } + if ((mtype == LB_MEM_TABLE) && (start < mend) && (end > mstart)) { + printk_err("Payload is overwriting Coreboot tables.\n"); + break; + } + } + if (i == mem_entries) { + printk_err("No matching ram area found for range:\n"); + printk_err(" [0x%016lx, 0x%016lx)\n", start, end); + printk_err("Ram areas\n"); + for(i = 0; i < mem_entries; i++) { + uint64_t mstart, mend; + uint32_t mtype; + mtype = mem->map[i].type; + mstart = unpack_lb64(mem->map[i].start); + mend = mstart + unpack_lb64(mem->map[i].size); + printk_err(" [0x%016lx, 0x%016lx) %s\n", + (unsigned long)mstart, + (unsigned long)mend, + (mtype == LB_MEM_RAM)?"RAM":"Reserved"); + + } + return 0; + } + return 1; +} + +static void relocate_segment(unsigned long buffer, struct segment *seg) +{ + /* Modify all segments that want to load onto coreboot + * to load onto the bounce buffer instead. + */ + unsigned long lb_start = (unsigned long)&_ram_seg; + unsigned long lb_end = (unsigned long)&_eram_seg; + unsigned long start, middle, end; + + printk_spew("lb: [0x%016lx, 0x%016lx)\n", + lb_start, lb_end); + + start = seg->s_dstaddr; + middle = start + seg->s_filesz; + end = start + seg->s_memsz; + /* I don't conflict with coreboot so get out of here */ + if ((end <= lb_start) || (start >= lb_end)) + return; + + printk_spew("segment: [0x%016lx, 0x%016lx, 0x%016lx)\n", + start, middle, end); + + /* Slice off a piece at the beginning + * that doesn't conflict with coreboot. + */ + if (start < lb_start) { + struct segment *new; + unsigned long len = lb_start - start; + new = malloc(sizeof(*new)); + *new = *seg; + new->s_memsz = len; + seg->s_memsz -= len; + seg->s_dstaddr += len; + seg->s_srcaddr += len; + if (seg->s_filesz > len) { + new->s_filesz = len; + seg->s_filesz -= len; + } else { + seg->s_filesz = 0; + } + + /* Order by stream offset */ + new->next = seg; + new->prev = seg->prev; + seg->prev->next = new; + seg->prev = new; + /* Order by original program header order */ + new->phdr_next = seg; + new->phdr_prev = seg->phdr_prev; + seg->phdr_prev->phdr_next = new; + seg->phdr_prev = new; + + /* compute the new value of start */ + start = seg->s_dstaddr; + + printk_spew(" early: [0x%016lx, 0x%016lx, 0x%016lx)\n", + new->s_dstaddr, + new->s_dstaddr + new->s_filesz, + new->s_dstaddr + new->s_memsz); + } + + /* Slice off a piece at the end + * that doesn't conflict with coreboot + */ + if (end > lb_end) { + unsigned long len = lb_end - start; + struct segment *new; + new = malloc(sizeof(*new)); + *new = *seg; + seg->s_memsz = len; + new->s_memsz -= len; + new->s_dstaddr += len; + new->s_srcaddr += len; + if (seg->s_filesz > len) { + seg->s_filesz = len; + new->s_filesz -= len; + } else { + new->s_filesz = 0; + } + /* Order by stream offset */ + new->next = seg->next; + new->prev = seg; + seg->next->prev = new; + seg->next = new; + /* Order by original program header order */ + new->phdr_next = seg->phdr_next; + new->phdr_prev = seg; + seg->phdr_next->phdr_prev = new; + seg->phdr_next = new; + + /* compute the new value of end */ + end = start + len; + + printk_spew(" late: [0x%016lx, 0x%016lx, 0x%016lx)\n", + new->s_dstaddr, + new->s_dstaddr + new->s_filesz, + new->s_dstaddr + new->s_memsz); + + } + /* Now retarget this segment onto the bounce buffer */ + /* sort of explanation: the buffer is a 1:1 mapping to coreboot. + * so you will make the dstaddr be this buffer, and it will get copied + * later to where coreboot lives. + */ + seg->s_dstaddr = buffer + (seg->s_dstaddr - lb_start); + + printk_spew(" bounce: [0x%016lx, 0x%016lx, 0x%016lx)\n", + seg->s_dstaddr, + seg->s_dstaddr + seg->s_filesz, + seg->s_dstaddr + seg->s_memsz); +} + + +static int build_self_segment_list( + struct segment *head, + unsigned long bounce_buffer, struct lb_memory *mem, + struct romfs_payload *payload, u32 *entry) +{ + struct segment *new; + struct segment *ptr; + u8 *data; + int datasize; + struct romfs_payload_segment *segment, *first_segment; + memset(head, 0, sizeof(*head)); + head->phdr_next = head->phdr_prev = head; + head->next = head->prev = head; + first_segment = segment = &payload->segments; + + while(1) { + printk_debug("Segment %p\n", segment); + switch(segment->type) { + default: printk_emerg("Bad segment type %x\n", segment->type); + return -1; + case PAYLOAD_SEGMENT_PARAMS: + printk_info("found param section\n"); + segment++; + continue; + case PAYLOAD_SEGMENT_CODE: + case PAYLOAD_SEGMENT_DATA: + printk_info( "%s: ", segment->type == PAYLOAD_SEGMENT_CODE ? + "code" : "data"); + new = malloc(sizeof(*new)); + new->s_dstaddr = ntohl((u32) segment->load_addr); + new->s_memsz = ntohl(segment->mem_len); + + datasize = ntohl(segment->len); + /* figure out decompression, do it, get pointer to the area */ + if (romfs_self_decompress(ntohl(segment->compression), + ((unsigned char *) first_segment) + + ntohl(segment->offset), new)) { + printk_emerg("romfs_self_decompress failed\n"); + return; + } + printk_debug("New segment dstaddr 0x%lx memsize 0x%lx srcaddr 0x%lx filesize 0x%lx\n", + new->s_dstaddr, new->s_memsz, new->s_srcaddr, new->s_filesz); + /* Clean up the values */ + if (new->s_filesz > new->s_memsz) { + new->s_filesz = new->s_memsz; + } + printk_debug("(cleaned up) New segment addr 0x%lx size 0x%lx offset 0x%lx filesize 0x%lx\n", + new->s_dstaddr, new->s_memsz, new->s_srcaddr, new->s_filesz); + break; + case PAYLOAD_SEGMENT_BSS: + printk_info("BSS %p/%d\n", (void *) ntohl((u32) segment->load_addr), + ntohl(segment->mem_len)); + new = malloc(sizeof(*new)); + new->s_filesz = 0; + new->s_dstaddr = ntohl((u32) segment->load_addr); + new->s_memsz = ntohl(segment->mem_len); + + break; + + case PAYLOAD_SEGMENT_ENTRY: + printk_info("Entry %p\n", (void *) ntohl((u32) segment->load_addr)); + *entry = (void *) ntohl((u32) segment->load_addr); + return 1; + } + segment++; + for(ptr = head->next; ptr != head; ptr = ptr->next) { + if (new->s_srcaddr < ntohl((u32) segment->load_addr)) + break; + } + /* Order by stream offset */ + new->next = ptr; + new->prev = ptr->prev; + ptr->prev->next = new; + ptr->prev = new; + /* Order by original program header order */ + new->phdr_next = head; + new->phdr_prev = head->phdr_prev; + head->phdr_prev->phdr_next = new; + head->phdr_prev = new; + + /* Verify the memory addresses in the segment are valid */ + if (!valid_area(mem, bounce_buffer, new->s_dstaddr, new->s_memsz)) + goto out; + + /* Modify the segment to load onto the bounce_buffer if necessary. + */ + relocate_segment(bounce_buffer, new); + } + return 1; + out: + return 0; +} + +static int load_self_segments( + struct segment *head, struct romfs_payload *payload) +{ + unsigned long offset; + struct segment *ptr; + + offset = 0; + for(ptr = head->next; ptr != head; ptr = ptr->next) { + unsigned long skip_bytes, read_bytes; + unsigned char *dest, *middle, *end, *src; + byte_offset_t result; + printk_debug("Loading Segment: addr: 0x%016lx memsz: 0x%016lx filesz: 0x%016lx\n", + ptr->s_dstaddr, ptr->s_memsz, ptr->s_filesz); + + /* Compute the boundaries of the segment */ + dest = (unsigned char *)(ptr->s_dstaddr); + end = dest + ptr->s_memsz; + middle = dest + ptr->s_filesz; + src = ptr->s_srcaddr; + printk_spew("[ 0x%016lx, %016lx, 0x%016lx) <- %016lx\n", + (unsigned long)dest, + (unsigned long)middle, + (unsigned long)end, + (unsigned long)src); + + /* Copy data from the initial buffer */ + if (ptr->s_filesz) { + size_t len; + len = ptr->s_filesz; + memcpy(dest, src, len); + dest += len; + } + + /* Zero the extra bytes between middle & end */ + if (middle < end) { + printk_debug("Clearing Segment: addr: 0x%016lx memsz: 0x%016lx\n", + (unsigned long)middle, (unsigned long)(end - middle)); + + /* Zero the extra bytes */ + memset(middle, 0, end - middle); + } + } + return 1; + out: + return 0; +} + +int selfboot(struct lb_memory *mem, struct romfs_payload *payload) +{ + void *entry; + struct segment head; + unsigned long bounce_buffer; + + /* Find a bounce buffer so I can load to coreboot's current location */ + bounce_buffer = get_bounce_buffer(mem); + if (!bounce_buffer) { + printk_err("Could not find a bounce buffer...\n"); + goto out; + } + + /* Preprocess the self segments */ + if (!build_self_segment_list(&head, bounce_buffer, mem, payload, &entry)) + goto out; + + /* Load the segments */ + if (!load_self_segments(&head, payload)) + goto out; + + printk_spew("Loaded segments\n"); + + /* Reset to booting from this image as late as possible */ + boot_successful(); + + printk_debug("Jumping to boot code at %p\n", entry); + post_code(0xfe); + + /* Jump to kernel */ + jmp_to_elf_entry(entry, bounce_buffer); + return 1; + + out: + return 0; +} + diff --git a/src/lib/Config.lb b/src/lib/Config.lb index 1906ec3a6a..4e6aa4d8d0 100644 --- a/src/lib/Config.lb +++ b/src/lib/Config.lb @@ -27,3 +27,7 @@ if CONFIG_USE_INIT initobject memcpy.o initobject memcmp.o end + +if CONFIG_ROMFS + object romfs.o +end diff --git a/src/lib/romfs.c b/src/lib/romfs.c new file mode 100644 index 0000000000..87095cfb07 --- /dev/null +++ b/src/lib/romfs.c @@ -0,0 +1,234 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 2008, Jordan Crouse + * + * 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 +#include +#include +#include +#include + +#ifndef CONFIG_BIG_ENDIAN +#define ntohl(x) ( ((x&0xff)<<24) | ((x&0xff00)<<8) | \ + ((x&0xff0000) >> 8) | ((x&0xff000000) >> 24) ) +#else +#define ntohl(x) (x) +#endif + +int run_address(void *f); + +int romfs_decompress(int algo, void *src, void *dst, int len) +{ + switch(algo) { + case ROMFS_COMPRESS_NONE: + memcpy(dst, src, len); + return 0; + +#ifdef CONFIG_COMPRESSION_LZMA + + case ROMFS_COMPRESS_LZMA: { + unsigned long ulzma(unsigned char *src, unsigned char *dst); + ulzma(src, dst); + } + return 0; +#endif + +#ifdef CONFIG_COMPRESSION_NRV2B + case ROMFS_COMPRESS_NRV2B: { + unsigned long unrv2b(u8 *src, u8 *dst, unsigned long *ilen_p); + unsigned long tmp; + + unrv2b(src, dst, &tmp); + } + return 0; +#endif + default: + printk_info( "ROMFS: Unknown compression type %d\n", + algo); + return -1; + } +} + +int romfs_check_magic(struct romfs_file *file) +{ + return !strcmp(file->magic, ROMFS_FILE_MAGIC) ? 1 : 0; +} + +struct romfs_header *romfs_master_header(void) +{ + struct romfs_header *header; + + unsigned long ptr = *((unsigned long *) ROMFS_HEADPTR_ADDR); + printk_debug("Check ROMFS header at %p\n", ptr); + header = (struct romfs_header *) ptr; + + printk_debug("magic is %08x\n", ntohl(header->magic)); + if (ntohl(header->magic) != ROMFS_HEADER_MAGIC) { + printk_err("NO ROMFS HEADER\n"); + return NULL; + } + + printk_debug("Found ROMFS header at %p\n", ptr); + return header; +} + +struct romfs_file *romfs_find(const char *name) +{ + struct romfs_header *header = romfs_master_header(); + unsigned long offset; + + if (header == NULL) + return NULL; + offset = 0 - ntohl(header->romsize) + ntohl(header->offset); + + while(1) { + struct romfs_file *file = (struct romfs_file *) offset; + if (romfs_check_magic(file)) printk_info("Check %s\n", ROMFS_NAME(file)); + if (romfs_check_magic(file) && + !strcmp(ROMFS_NAME(file), name)) + return file; + + offset += ntohl(header->align); + + if (offset < 0xFFFFFFFF - ntohl(header->romsize)) + return NULL; + } +} + +struct romfs_stage *romfs_find_file(const char *name, int type) +{ + struct romfs_file *file = romfs_find(name); + + if (file == NULL) { + printk_info( "ROMFS: Could not find file %s\n", + name); + return NULL; + } + + if (ntohl(file->type) != type) { + printk_info( "ROMFS: File %s is of type %x instead of" + "type %x\n", name, file->type, type); + + return NULL; + } + + return (void *) ROMFS_SUBHEADER(file); +} + +int romfs_load_optionrom(const char *name, u32 dest) +{ + struct romfs_optionrom *orom = (struct romfs_optionrom *) + romfs_find_file(name, ROMFS_TYPE_OPTIONROM); + + if (orom == NULL) + return -1; + + if (romfs_decompress(ntohl(orom->compression), + ((unsigned char *) orom) + + sizeof(struct romfs_optionrom), + (void *) dest, + ntohl(orom->len))) + return -1; + + return 0; +} + +void * romfs_load_payload(struct lb_memory *lb_mem, const char *name) +{ + int selfboot(struct lb_memory *mem, struct romfs_payload *payload); + struct romfs_payload *payload = (struct romfs_payload *) + romfs_find_file(name, ROMFS_TYPE_PAYLOAD); + + struct romfs_payload_segment *segment, *first_segment; + + if (payload == NULL) + return (void *) -1; + printk_debug("Got a payload\n"); + first_segment = segment = &payload->segments; + selfboot(lb_mem, payload); + printk_emerg("SELFBOOT RETURNED!\n"); + + return (void *) -1; +} + +void * romfs_load_stage(const char *name) +{ + struct romfs_stage *stage = (struct romfs_stage *) + romfs_find_file(name, ROMFS_TYPE_STAGE); + /* this is a mess. There is no ntohll. */ + /* for now, assume compatible byte order until we solve this. */ + u32 entry; + + if (stage == NULL) + return (void *) -1; + + printk_info("Stage: load @ %d/%d bytes, enter @ %llx\n", + ntohl((u32) stage->load), ntohl(stage->memlen), + stage->entry); + memset((void *) ntohl((u32) stage->load), 0, ntohl(stage->memlen)); + + if (romfs_decompress(ntohl(stage->compression), + ((unsigned char *) stage) + + sizeof(struct romfs_stage), + (void *) ntohl((u32) stage->load), + ntohl(stage->len))) + return (void *) -1; + + entry = stage->entry; +// return (void *) ntohl((u32) stage->entry); + return (void *) entry; +} + +void * romfs_get_file(const char *name) +{ + return romfs_find(name); +} + +int romfs_execute_stage(const char *name) +{ + struct romfs_stage *stage = (struct romfs_stage *) + romfs_find_file(name, ROMFS_TYPE_STAGE); + + if (stage == NULL) + return 1; + + if (ntohl(stage->compression) != ROMFS_COMPRESS_NONE) { + printk_info( "ROMFS: Unable to run %s: Compressed file" + "Not supported for in-place execution\n", name); + return 1; + } + + /* FIXME: This isn't right */ + printk_info( "ROMFS: run @ %p\n", (void *) ntohl((u32) stage->entry)); + return run_address((void *) ntohl((u32) stage->entry)); +} + +/** + * * run_address is passed the address of a function taking no parameters and + * * jumps to it, returning the result. + * * @param f the address to call as a function. + * * returns value returned by the function. + * */ + +int run_address(void *f) +{ + int (*v) (void); + v = f; + return v(); +} +