// SPDX-License-Identifier: GPL-2.0-or-later/*  Kernel module help for PPC.    Copyright (C) 2001 Rusty Russell. */ #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>#include <asm/text-patching.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;} /* 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") != NULL)		    != is_init)			continue; 		/* We don't want to look at debug sections. */		if (strstr(secstrings + sechdrs[i].sh_name, ".debug"))			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			 * algorithm 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, NULL); 			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] != PPC_RAW_LIS(_R12, PPC_HA(val)))		return 0;	if (entry->jump[1] != PPC_RAW_ADDI(_R12, _R12, PPC_LO(val)))		return 0;	return 1;} /* 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 (within_module_core((unsigned long)location, mod))		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++;	} 	if (patch_instruction(&entry->jump[0], ppc_inst(PPC_RAW_LIS(_R12, PPC_HA(val)))))		return 0;	if (patch_instruction(&entry->jump[1], ppc_inst(PPC_RAW_ADDI(_R12, _R12, PPC_LO(val)))))		return 0;	if (patch_instruction(&entry->jump[2], ppc_inst(PPC_RAW_MTCTR(_R12))))		return 0;	if (patch_instruction(&entry->jump[3], ppc_inst(PPC_RAW_BCTR())))		return 0; 	pr_debug("Initialized plt for 0x%x at %p\n", val, entry);	return (uint32_t)entry;} static int patch_location_16(uint32_t *loc, u16 value){	loc = PTR_ALIGN_DOWN(loc, sizeof(u32));	return patch_instruction(loc, ppc_inst((*loc & 0xffff0000) | value));} 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 */			if (patch_location_16(location, PPC_LO(value)))				return -EFAULT;			break; 		case R_PPC_ADDR16_HI:			/* Higher half of the symbol */			if (patch_location_16(location, PPC_HI(value)))				return -EFAULT;			break; 		case R_PPC_ADDR16_HA:			if (patch_location_16(location, PPC_HA(value)))				return -EFAULT;			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);				if (!value)					return -EFAULT;			} 			/* 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);			value = (*(uint32_t *)location & ~PPC_LI_MASK) |				PPC_LI(value - (uint32_t)location); 			if (patch_instruction(location, ppc_inst(value)))				return -EFAULT; 			pr_debug("Location after: %08X.\n",			       *(uint32_t *)location);			pr_debug("ie. jump to %08X+%08X = %08X\n",				 *(uint32_t *)PPC_LI((uint32_t)location), (uint32_t)location,				 (*(uint32_t *)PPC_LI((uint32_t)location)) + (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_FTRACEnotrace int module_trampoline_target(struct module *mod, unsigned long addr,				     unsigned long *target){	ppc_inst_t jmp[4]; 	/* Find where the trampoline jumps to */	if (copy_inst_from_kernel_nofault(jmp, (void *)addr))		return -EFAULT;	if (__copy_inst_from_kernel_nofault(jmp + 1, (void *)addr + 4))		return -EFAULT;	if (__copy_inst_from_kernel_nofault(jmp + 2, (void *)addr + 8))		return -EFAULT;	if (__copy_inst_from_kernel_nofault(jmp + 3, (void *)addr + 12))		return -EFAULT; 	/* verify that this is what we expect it to be */	if ((ppc_inst_val(jmp[0]) & 0xffff0000) != PPC_RAW_LIS(_R12, 0))		return -EINVAL;	if ((ppc_inst_val(jmp[1]) & 0xffff0000) != PPC_RAW_ADDI(_R12, _R12, 0))		return -EINVAL;	if (ppc_inst_val(jmp[2]) != PPC_RAW_MTCTR(_R12))		return -EINVAL;	if (ppc_inst_val(jmp[3]) != PPC_RAW_BCTR())		return -EINVAL; 	addr = (ppc_inst_val(jmp[1]) & 0xffff) | ((ppc_inst_val(jmp[0]) & 0xffff) << 16);	if (addr & 0x8000)		addr -= 0x10000; 	*target = addr; 	return 0;} int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs){	module->arch.tramp = do_plt_call(module->mem[MOD_TEXT].base,					 (unsigned long)ftrace_caller,					 sechdrs, module);	if (!module->arch.tramp)		return -ENOENT; #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS	module->arch.tramp_regs = do_plt_call(module->mem[MOD_TEXT].base,					      (unsigned long)ftrace_regs_caller,					      sechdrs, module);	if (!module->arch.tramp_regs)		return -ENOENT;#endif 	return 0;}#endif