/*  Kernel module help for PPC.    Copyright (C) 2001 Rusty Russell.     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; either version 2 of the License, or    (at your option) any later version.     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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA*/ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h>#include <linux/moduleloader.h>#include <linux/elf.h>#include <linux/vmalloc.h>#include <linux/fs.h>#include <linux/string.h>#include <linux/kernel.h>#include <linux/ftrace.h>#include <linux/cache.h>#include <linux/bug.h>#include <linux/sort.h>#include <asm/setup.h> /* Count how many different relocations (different symbol, different   addend) */static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num){	unsigned int i, r_info, r_addend, _count_relocs; 	_count_relocs = 0;	r_info = 0;	r_addend = 0;	for (i = 0; i < num; i++)		/* Only count 24-bit relocs, others don't need stubs */		if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&		    (r_info != ELF32_R_SYM(rela[i].r_info) ||		     r_addend != rela[i].r_addend)) {			_count_relocs++;			r_info = ELF32_R_SYM(rela[i].r_info);			r_addend = rela[i].r_addend;		} #ifdef CONFIG_DYNAMIC_FTRACE	_count_relocs++;	/* add one for ftrace_caller */#endif	return _count_relocs;} static int relacmp(const void *_x, const void *_y){	const Elf32_Rela *x, *y; 	y = (Elf32_Rela *)_x;	x = (Elf32_Rela *)_y; 	/* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to	 * make the comparison cheaper/faster. It won't affect the sorting or	 * the counting algorithms' performance	 */	if (x->r_info < y->r_info)		return -1;	else if (x->r_info > y->r_info)		return 1;	else if (x->r_addend < y->r_addend)		return -1;	else if (x->r_addend > y->r_addend)		return 1;	else		return 0;} static void relaswap(void *_x, void *_y, int size){	uint32_t *x, *y, tmp;	int i; 	y = (uint32_t *)_x;	x = (uint32_t *)_y; 	for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) {		tmp = x[i];		x[i] = y[i];		y[i] = tmp;	}} /* Get the potential trampolines size required of the init and   non-init sections */static unsigned long get_plt_size(const Elf32_Ehdr *hdr,				  const Elf32_Shdr *sechdrs,				  const char *secstrings,				  int is_init){	unsigned long ret = 0;	unsigned i; 	/* Everything marked ALLOC (this includes the exported           symbols) */	for (i = 1; i < hdr->e_shnum; i++) {		/* If it's called *.init*, and we're not init, we're                   not interested */		if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0)		    != is_init)			continue; 		/* We don't want to look at debug sections. */		if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0)			continue; 		if (sechdrs[i].sh_type == SHT_RELA) {			pr_debug("Found relocations in section %u\n", i);			pr_debug("Ptr: %p.  Number: %u\n",			       (void *)hdr + sechdrs[i].sh_offset,			       sechdrs[i].sh_size / sizeof(Elf32_Rela)); 			/* Sort the relocation information based on a symbol and			 * addend key. This is a stable O(n*log n) complexity			 * alogrithm but it will reduce the complexity of			 * count_relocs() to linear complexity O(n)			 */			sort((void *)hdr + sechdrs[i].sh_offset,			     sechdrs[i].sh_size / sizeof(Elf32_Rela),			     sizeof(Elf32_Rela), relacmp, relaswap); 			ret += count_relocs((void *)hdr					     + sechdrs[i].sh_offset,					     sechdrs[i].sh_size					     / sizeof(Elf32_Rela))				* sizeof(struct ppc_plt_entry);		}	} 	return ret;} int module_frob_arch_sections(Elf32_Ehdr *hdr,			      Elf32_Shdr *sechdrs,			      char *secstrings,			      struct module *me){	unsigned int i; 	/* Find .plt and .init.plt sections */	for (i = 0; i < hdr->e_shnum; i++) {		if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)			me->arch.init_plt_section = i;		else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)			me->arch.core_plt_section = i;	}	if (!me->arch.core_plt_section || !me->arch.init_plt_section) {		pr_err("Module doesn't contain .plt or .init.plt sections.\n");		return -ENOEXEC;	} 	/* Override their sizes */	sechdrs[me->arch.core_plt_section].sh_size		= get_plt_size(hdr, sechdrs, secstrings, 0);	sechdrs[me->arch.init_plt_section].sh_size		= get_plt_size(hdr, sechdrs, secstrings, 1);	return 0;} static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val){	if (entry->jump[0] == 0x3d800000 + ((val + 0x8000) >> 16)	    && entry->jump[1] == 0x398c0000 + (val & 0xffff))		return 1;	return 0;} /* Set up a trampoline in the PLT to bounce us to the distant function */static uint32_t do_plt_call(void *location,			    Elf32_Addr val,			    const Elf32_Shdr *sechdrs,			    struct module *mod){	struct ppc_plt_entry *entry; 	pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location);	/* Init, or core PLT? */	if (location >= mod->core_layout.base	    && location < mod->core_layout.base + mod->core_layout.size)		entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;	else		entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; 	/* Find this entry, or if that fails, the next avail. entry */	while (entry->jump[0]) {		if (entry_matches(entry, val)) return (uint32_t)entry;		entry++;	} 	entry->jump[0] = 0x3d800000+((val+0x8000)>>16); /* lis r12,sym@ha */	entry->jump[1] = 0x398c0000 + (val&0xffff);     /* addi r12,r12,sym@l*/	entry->jump[2] = 0x7d8903a6;                    /* mtctr r12 */	entry->jump[3] = 0x4e800420;			/* bctr */ 	pr_debug("Initialized plt for 0x%x at %p\n", val, entry);	return (uint32_t)entry;} int apply_relocate_add(Elf32_Shdr *sechdrs,		       const char *strtab,		       unsigned int symindex,		       unsigned int relsec,		       struct module *module){	unsigned int i;	Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;	Elf32_Sym *sym;	uint32_t *location;	uint32_t value; 	pr_debug("Applying ADD relocate section %u to %u\n", relsec,	       sechdrs[relsec].sh_info);	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {		/* This is where to make the change */		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr			+ rela[i].r_offset;		/* This is the symbol it is referring to.  Note that all		   undefined symbols have been resolved.  */		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr			+ ELF32_R_SYM(rela[i].r_info);		/* `Everything is relative'. */		value = sym->st_value + rela[i].r_addend; 		switch (ELF32_R_TYPE(rela[i].r_info)) {		case R_PPC_ADDR32:			/* Simply set it */			*(uint32_t *)location = value;			break; 		case R_PPC_ADDR16_LO:			/* Low half of the symbol */			*(uint16_t *)location = value;			break; 		case R_PPC_ADDR16_HI:			/* Higher half of the symbol */			*(uint16_t *)location = (value >> 16);			break; 		case R_PPC_ADDR16_HA:			/* Sign-adjusted lower 16 bits: PPC ELF ABI says:			   (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF.			   This is the same, only sane.			 */			*(uint16_t *)location = (value + 0x8000) >> 16;			break; 		case R_PPC_REL24:			if ((int)(value - (uint32_t)location) < -0x02000000			    || (int)(value - (uint32_t)location) >= 0x02000000)				value = do_plt_call(location, value,						    sechdrs, module); 			/* Only replace bits 2 through 26 */			pr_debug("REL24 value = %08X. location = %08X\n",			       value, (uint32_t)location);			pr_debug("Location before: %08X.\n",			       *(uint32_t *)location);			*(uint32_t *)location				= (*(uint32_t *)location & ~0x03fffffc)				| ((value - (uint32_t)location)				   & 0x03fffffc);			pr_debug("Location after: %08X.\n",			       *(uint32_t *)location);			pr_debug("ie. jump to %08X+%08X = %08X\n",			       *(uint32_t *)location & 0x03fffffc,			       (uint32_t)location,			       (*(uint32_t *)location & 0x03fffffc)			       + (uint32_t)location);			break; 		case R_PPC_REL32:			/* 32-bit relative jump. */			*(uint32_t *)location = value - (uint32_t)location;			break; 		default:			pr_err("%s: unknown ADD relocation: %u\n",			       module->name,			       ELF32_R_TYPE(rela[i].r_info));			return -ENOEXEC;		}	} 	return 0;} #ifdef CONFIG_DYNAMIC_FTRACEint module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs){	module->arch.tramp = do_plt_call(module->core_layout.base,					 (unsigned long)ftrace_caller,					 sechdrs, module);	if (!module->arch.tramp)		return -ENOENT; 	return 0;}#endif