vpe.c

LINUX 2.6.17.4的源码

	/*
	 * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
	 */
	val = v + vallo;
	insnlo = (insnlo & ~0xffff) | (val & 0xffff);
	*location = insnlo;

	return 0;
}

static int (*reloc_handlers[]) (struct module *me, uint32_t *location,
				Elf32_Addr v) = {
	[R_MIPS_NONE]	= apply_r_mips_none,
	[R_MIPS_32]	= apply_r_mips_32,
	[R_MIPS_26]	= apply_r_mips_26,
	[R_MIPS_HI16]	= apply_r_mips_hi16,
	[R_MIPS_LO16]	= apply_r_mips_lo16,
	[R_MIPS_GPREL16] = apply_r_mips_gprel16,
	[R_MIPS_PC16] = apply_r_mips_pc16
};

static char *rstrs[] = {
    	[R_MIPS_NONE]	= "MIPS_NONE",
	[R_MIPS_32]	= "MIPS_32",
	[R_MIPS_26]	= "MIPS_26",
	[R_MIPS_HI16]	= "MIPS_HI16",
	[R_MIPS_LO16]	= "MIPS_LO16",
	[R_MIPS_GPREL16] = "MIPS_GPREL16",
	[R_MIPS_PC16] = "MIPS_PC16"
};

int apply_relocations(Elf32_Shdr *sechdrs,
		      const char *strtab,
		      unsigned int symindex,
		      unsigned int relsec,
		      struct module *me)
{
	Elf32_Rel *rel = (void *) sechdrs[relsec].sh_addr;
	Elf32_Sym *sym;
	uint32_t *location;
	unsigned int i;
	Elf32_Addr v;
	int res;

	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
		Elf32_Word r_info = rel[i].r_info;

		/* This is where to make the change */
		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
			+ rel[i].r_offset;
		/* This is the symbol it is referring to */
		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
			+ ELF32_R_SYM(r_info);

		if (!sym->st_value) {
			printk(KERN_DEBUG "%s: undefined weak symbol %s\n",
			       me->name, strtab + sym->st_name);
			/* just print the warning, dont barf */
		}

		v = sym->st_value;

		res = reloc_handlers[ELF32_R_TYPE(r_info)](me, location, v);
		if( res ) {
			char *r = rstrs[ELF32_R_TYPE(r_info)];
		    	printk(KERN_WARNING "VPE loader: .text+0x%x "
			       "relocation type %s for symbol \"%s\" failed\n",
			       rel[i].r_offset, r ? r : "UNKNOWN",
			       strtab + sym->st_name);
			return res;
		}
	}

	return 0;
}

void save_gp_address(unsigned int secbase, unsigned int rel)
{
	gp_addr = secbase + rel;
	gp_offs = gp_addr - (secbase & 0xffff0000);
}
/* end module-elf32.c */



/* Change all symbols so that sh_value encodes the pointer directly. */
static void simplify_symbols(Elf_Shdr * sechdrs,
			    unsigned int symindex,
			    const char *strtab,
			    const char *secstrings,
			    unsigned int nsecs, struct module *mod)
{
	Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
	unsigned long secbase, bssbase = 0;
	unsigned int i, n = sechdrs[symindex].sh_size / sizeof(Elf_Sym);
	int size;

	/* find the .bss section for COMMON symbols */
	for (i = 0; i < nsecs; i++) {
		if (strncmp(secstrings + sechdrs[i].sh_name, ".bss", 4) == 0) {
			bssbase = sechdrs[i].sh_addr;
			break;
		}
	}

	for (i = 1; i < n; i++) {
		switch (sym[i].st_shndx) {
		case SHN_COMMON:
			/* Allocate space for the symbol in the .bss section.
			   st_value is currently size.
			   We want it to have the address of the symbol. */

			size = sym[i].st_value;
			sym[i].st_value = bssbase;

			bssbase += size;
			break;

		case SHN_ABS:
			/* Don't need to do anything */
			break;

		case SHN_UNDEF:
			/* ret = -ENOENT; */
			break;

		case SHN_MIPS_SCOMMON:
			printk(KERN_DEBUG "simplify_symbols: ignoring SHN_MIPS_SCOMMON"
			       "symbol <%s> st_shndx %d\n", strtab + sym[i].st_name,
			       sym[i].st_shndx);
			// .sbss section
			break;

		default:
			secbase = sechdrs[sym[i].st_shndx].sh_addr;

			if (strncmp(strtab + sym[i].st_name, "_gp", 3) == 0) {
				save_gp_address(secbase, sym[i].st_value);
			}

			sym[i].st_value += secbase;
			break;
		}
	}
}

#ifdef DEBUG_ELFLOADER
static void dump_elfsymbols(Elf_Shdr * sechdrs, unsigned int symindex,
			    const char *strtab, struct module *mod)
{
	Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
	unsigned int i, n = sechdrs[symindex].sh_size / sizeof(Elf_Sym);

	printk(KERN_DEBUG "dump_elfsymbols: n %d\n", n);
	for (i = 1; i < n; i++) {
		printk(KERN_DEBUG " i %d name <%s> 0x%x\n", i,
		       strtab + sym[i].st_name, sym[i].st_value);
	}
}
#endif

static void dump_tc(struct tc *t)
{
  	unsigned long val;

  	settc(t->index);
 	printk(KERN_DEBUG "VPE loader: TC index %d targtc %ld "
 	       "TCStatus 0x%lx halt 0x%lx\n",
  	       t->index, read_c0_vpecontrol() & VPECONTROL_TARGTC,
  	       read_tc_c0_tcstatus(), read_tc_c0_tchalt());

 	printk(KERN_DEBUG " tcrestart 0x%lx\n", read_tc_c0_tcrestart());
 	printk(KERN_DEBUG " tcbind 0x%lx\n", read_tc_c0_tcbind());

  	val = read_c0_vpeconf0();
 	printk(KERN_DEBUG " VPEConf0 0x%lx MVP %ld\n", val,
  	       (val & VPECONF0_MVP) >> VPECONF0_MVP_SHIFT);

 	printk(KERN_DEBUG " c0 status 0x%lx\n", read_vpe_c0_status());
 	printk(KERN_DEBUG " c0 cause 0x%lx\n", read_vpe_c0_cause());

 	printk(KERN_DEBUG " c0 badvaddr 0x%lx\n", read_vpe_c0_badvaddr());
 	printk(KERN_DEBUG " c0 epc 0x%lx\n", read_vpe_c0_epc());
}

static void dump_tclist(void)
{
	struct tc *t;

	list_for_each_entry(t, &vpecontrol.tc_list, list) {
		dump_tc(t);
	}
}

/* We are prepared so configure and start the VPE... */
int vpe_run(struct vpe * v)
{
	struct vpe_notifications *n;
	unsigned long val, dmt_flag;
	struct tc *t;

	/* check we are the Master VPE */
	val = read_c0_vpeconf0();
	if (!(val & VPECONF0_MVP)) {
		printk(KERN_WARNING
		       "VPE loader: only Master VPE's are allowed to configure MT\n");
		return -1;
	}

	/* disable MT (using dvpe) */
	dvpe();

	if (!list_empty(&v->tc)) {
                if ((t = list_entry(v->tc.next, struct tc, tc)) == NULL) {
                        printk(KERN_WARNING "VPE loader: TC %d is already in use.\n",
                               t->index);
                        return -ENOEXEC;
                }
        } else {
                printk(KERN_WARNING "VPE loader: No TC's associated with VPE %d\n",
                       v->minor);
                return -ENOEXEC;
        }

	/* Put MVPE's into 'configuration state' */
	set_c0_mvpcontrol(MVPCONTROL_VPC);

	settc(t->index);

	/* should check it is halted, and not activated */
	if ((read_tc_c0_tcstatus() & TCSTATUS_A) || !(read_tc_c0_tchalt() & TCHALT_H)) {
		printk(KERN_WARNING "VPE loader: TC %d is already doing something!\n",
		       t->index);
		dump_tclist();
		return -ENOEXEC;
	}

	/*
	 * Disable multi-threaded execution whilst we activate, clear the
	 * halt bit and bound the tc to the other VPE...
	 */
	dmt_flag = dmt();

	/* Write the address we want it to start running from in the TCPC register. */
	write_tc_c0_tcrestart((unsigned long)v->__start);
	write_tc_c0_tccontext((unsigned long)0);
	/*
	 * Mark the TC as activated, not interrupt exempt and not dynamically
	 * allocatable
	 */
	val = read_tc_c0_tcstatus();
	val = (val & ~(TCSTATUS_DA | TCSTATUS_IXMT)) | TCSTATUS_A;
	write_tc_c0_tcstatus(val);

	write_tc_c0_tchalt(read_tc_c0_tchalt() & ~TCHALT_H);

	/*
	 * The sde-kit passes 'memsize' to __start in $a3, so set something
	 * here...  Or set $a3 to zero and define DFLT_STACK_SIZE and
	 * DFLT_HEAP_SIZE when you compile your program
	 */
 	mttgpr(7, physical_memsize);


	/* set up VPE1 */
	/*
	 * bind the TC to VPE 1 as late as possible so we only have the final
	 * VPE registers to set up, and so an EJTAG probe can trigger on it
	 */
 	write_tc_c0_tcbind((read_tc_c0_tcbind() & ~TCBIND_CURVPE) | v->minor);

        /* Set up the XTC bit in vpeconf0 to point at our tc */
        write_vpe_c0_vpeconf0( (read_vpe_c0_vpeconf0() & ~(VPECONF0_XTC))
                               | (t->index << VPECONF0_XTC_SHIFT));

        /* enable this VPE */
        write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() | VPECONF0_VPA);

	/* clear out any left overs from a previous program */
	write_vpe_c0_status(0);
	write_vpe_c0_cause(0);

	/* take system out of configuration state */
	clear_c0_mvpcontrol(MVPCONTROL_VPC);

	/* now safe to re-enable multi-threading */
	emt(dmt_flag);

	/* set it running */
	evpe(EVPE_ENABLE);

	list_for_each_entry(n, &v->notify, list) {
		n->start(v->minor);
	}

	return 0;
}

static int find_vpe_symbols(struct vpe * v, Elf_Shdr * sechdrs,
				      unsigned int symindex, const char *strtab,
				      struct module *mod)
{
	Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
	unsigned int i, n = sechdrs[symindex].sh_size / sizeof(Elf_Sym);

	for (i = 1; i < n; i++) {
		if (strcmp(strtab + sym[i].st_name, "__start") == 0) {
			v->__start = sym[i].st_value;
		}

		if (strcmp(strtab + sym[i].st_name, "vpe_shared") == 0) {
			v->shared_ptr = (void *)sym[i].st_value;
		}
	}

	if ( (v->__start == 0) || (v->shared_ptr == NULL))
		return -1;

	return 0;
}

/*
 * Allocates a VPE with some program code space(the load address), copies the
 * contents of the program (p)buffer performing relocatations/etc, free's it
 * when finished.
 */
int vpe_elfload(struct vpe * v)
{
	Elf_Ehdr *hdr;
	Elf_Shdr *sechdrs;
	long err = 0;
	char *secstrings, *strtab = NULL;
	unsigned int len, i, symindex = 0, strindex = 0, relocate = 0;
	struct module mod;	// so we can re-use the relocations code

	memset(&mod, 0, sizeof(struct module));
	strcpy(mod.name, "VPE loader");

	hdr = (Elf_Ehdr *) v->pbuffer;
	len = v->plen;

	/* Sanity checks against insmoding binaries or wrong arch,
	   weird elf version */
	if (memcmp(hdr->e_ident, ELFMAG, 4) != 0
	    || (hdr->e_type != ET_REL && hdr->e_type != ET_EXEC)
	    || !elf_check_arch(hdr)
	    || hdr->e_shentsize != sizeof(*sechdrs)) {
		printk(KERN_WARNING
		       "VPE loader: program wrong arch or weird elf version\n");

		return -ENOEXEC;
	}

	if (hdr->e_type == ET_REL)
		relocate = 1;

	if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr)) {
		printk(KERN_ERR "VPE loader: program length %u truncated\n",
		       len);

		return -ENOEXEC;
	}

	/* Convenience variables */
	sechdrs = (void *)hdr + hdr->e_shoff;
	secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
	sechdrs[0].sh_addr = 0;

	/* And these should exist, but gcc whinges if we don't init them */
	symindex = strindex = 0;

	if (relocate) {
		for (i = 1; i < hdr->e_shnum; i++) {
			if (sechdrs[i].sh_type != SHT_NOBITS
			    && len < sechdrs[i].sh_offset + sechdrs[i].sh_size) {
				printk(KERN_ERR "VPE program length %u truncated\n",
				       len);
				return -ENOEXEC;
			}

			/* Mark all sections sh_addr with their address in the
			   temporary image. */
			sechdrs[i].sh_addr = (size_t) hdr + sechdrs[i].sh_offset;

			/* Internal symbols and strings. */
			if (sechdrs[i].sh_type == SHT_SYMTAB) {
				symindex = i;
				strindex = sechdrs[i].sh_link;
				strtab = (char *)hdr + sechdrs[strindex].sh_offset;
			}
		}
		layout_sections(&mod, hdr, sechdrs, secstrings);
	}

	v->load_addr = alloc_progmem(mod.core_size);
	memset(v->load_addr, 0, mod.core_size);

	printk("VPE loader: loading to %p\n", v->load_addr);

	if (relocate) {
		for (i = 0; i < hdr->e_shnum; i++) {
			void *dest;

			if (!(sechdrs[i].sh_flags & SHF_ALLOC))
				continue;

			dest = v->load_addr + sechdrs[i].sh_entsize;

			if (sechdrs[i].sh_type != SHT_NOBITS)
				memcpy(dest, (void *)sechdrs[i].sh_addr,
				       sechdrs[i].sh_size);
			/* Update sh_addr to point to copy in image. */
			sechdrs[i].sh_addr = (unsigned long)dest;

			printk(KERN_DEBUG " section sh_name %s sh_addr 0x%x\n",
			       secstrings + sechdrs[i].sh_name, sechdrs[i].sh_addr);
		}

 		/* Fix up syms, so that st_value is a pointer to location. */
 		simplify_symbols(sechdrs, symindex, strtab, secstrings,
 				 hdr->e_shnum, &mod);

 		/* Now do relocations. */
 		for (i = 1; i < hdr->e_shnum; i++) {
 			const char *strtab = (char *)sechdrs[strindex].sh_addr;
 			unsigned int info = sechdrs[i].sh_info;

 			/* Not a valid relocation section? */
 			if (info >= hdr->e_shnum)
 				continue;

 			/* Don't bother with non-allocated sections */
 			if (!(sechdrs[info].sh_flags & SHF_ALLOC))
 				continue;

 			if (sechdrs[i].sh_type == SHT_REL)
 				err = apply_relocations(sechdrs, strtab, symindex, i,
 							&mod);
 			else if (sechdrs[i].sh_type == SHT_RELA)
 				err = apply_relocate_add(sechdrs, strtab, symindex, i,
 							 &mod);
 			if (err < 0)
 				return err;

  		}
  	} else {
  		for (i = 0; i < hdr->e_shnum; i++) {

 			/* Internal symbols and strings. */
 			if (sechdrs[i].sh_type == SHT_SYMTAB) {
 				symindex = i;
 				strindex = sechdrs[i].sh_link;
 				strtab = (char *)hdr + sechdrs[strindex].sh_offset;

 				/* mark the symtab's address for when we try to find the
 				   magic symbols */
 				sechdrs[i].sh_addr = (size_t) hdr + sechdrs[i].sh_offset;
 			}

 			/* filter sections we dont want in the final image */
 			if (!(sechdrs[i].sh_flags & SHF_ALLOC) ||
 			    (sechdrs[i].sh_type == SHT_MIPS_REGINFO)) {
 				printk( KERN_DEBUG " ignoring section, "
 					"name %s type %x address 0x%x \n",
 					secstrings + sechdrs[i].sh_name,
 					sechdrs[i].sh_type, sechdrs[i].sh_addr);
 				continue;
 			}

  			if (sechdrs[i].sh_addr < (unsigned int)v->load_addr) {
 				printk( KERN_WARNING "VPE loader: "
 					"fully linked image has invalid section, "
 					"name %s type %x address 0x%x, before load "
 					"address of 0x%x\n",
 					secstrings + sechdrs[i].sh_name,
 					sechdrs[i].sh_type, sechdrs[i].sh_addr,
 					(unsigned int)v->load_addr);
  				return -ENOEXEC;
  			}

 			printk(KERN_DEBUG " copying section sh_name %s, sh_addr 0x%x "
			       "size 0x%x0 from x%p\n",
			       secstrings + sechdrs[i].sh_name, sechdrs[i].sh_addr,
			       sechdrs[i].sh_size, hdr + sechdrs[i].sh_offset);

  			if (sechdrs[i].sh_type != SHT_NOBITS)
				memcpy((void *)sechdrs[i].sh_addr,
				       (char *)hdr + sechdrs[i].sh_offset,
 				       sechdrs[i].sh_size);
			else
				memset((void *)sechdrs[i].sh_addr, 0, sechdrs[i].sh_size);
		}
	}

	/* make sure it's physically written out */
	flush_icache_range((unsigned long)v->load_addr,
			   (unsigned long)v->load_addr + v->len);