arch/alpha/kernel/module.c - third_party/linux - Git at Google

 /*  Kernel module help for Alpha.
     Copyright (C) 2002 Richard Henderson.

     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
 */
 #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/slab.h>

 #if 0
 #define DEBUGP printk
 #else
 #define DEBUGP(fmt...)
 #endif

 /* Allocate the GOT at the end of the core sections.  */

 struct got_entry {
 	struct got_entry *next;
 	Elf64_Sxword r_addend;
 	int got_offset;
 };

 static inline void
 process_reloc_for_got(Elf64_Rela *rela,
 		      struct got_entry *chains, Elf64_Xword *poffset)
 {
 	unsigned long r_sym = ELF64_R_SYM (rela->r_info);
 	unsigned long r_type = ELF64_R_TYPE (rela->r_info);
 	Elf64_Sxword r_addend = rela->r_addend;
 	struct got_entry *g;

 	if (r_type != R_ALPHA_LITERAL)
 		return;

 	for (g = chains + r_sym; g ; g = g->next)
 		if (g->r_addend == r_addend) {
 			if (g->got_offset == 0) {
 				g->got_offset = *poffset;
 				*poffset += 8;
 			}
 			goto found_entry;
 		}

 	g = kmalloc (sizeof (*g), GFP_KERNEL);
 	g->next = chains[r_sym].next;
 	g->r_addend = r_addend;
 	g->got_offset = *poffset;
 	*poffset += 8;
 	chains[r_sym].next = g;

  found_entry:
 	/* Trick: most of the ELF64_R_TYPE field is unused.  There are
 	   42 valid relocation types, and a 32-bit field.  Co-opt the
 	   bits above 256 to store the got offset for this reloc.  */
 	rela->r_info |= g->got_offset << 8;
 }

 int
 module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs,
 			  char *secstrings, struct module *me)
 {
 	struct got_entry *chains;
 	Elf64_Rela *rela;
 	Elf64_Shdr *esechdrs, *symtab, *s, *got;
 	unsigned long nsyms, nrela, i;

 	esechdrs = sechdrs + hdr->e_shnum;
 	symtab = got = NULL;

 	/* Find out how large the symbol table is.  Allocate one got_entry
 	   head per symbol.  Normally this will be enough, but not always.
 	   We'll chain different offsets for the symbol down each head.  */
 	for (s = sechdrs; s < esechdrs; ++s)
 		if (s->sh_type == SHT_SYMTAB)
 			symtab = s;
 		else if (!strcmp(".got", secstrings + s->sh_name)) {
 			got = s;
 			me->arch.gotsecindex = s - sechdrs;
 		}

 	if (!symtab) {
 		printk(KERN_ERR "module %s: no symbol table\n", me->name);
 		return -ENOEXEC;
 	}
 	if (!got) {
 		printk(KERN_ERR "module %s: no got section\n", me->name);
 		return -ENOEXEC;
 	}

 	nsyms = symtab->sh_size / sizeof(Elf64_Sym);
 	chains = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL);
 	if (!chains) {
 		printk(KERN_ERR
 		       "module %s: no memory for symbol chain buffer\n",
 		       me->name);
 		return -ENOMEM;
 	}

 	got->sh_size = 0;
 	got->sh_addralign = 8;
 	got->sh_type = SHT_NOBITS;

 	/* Examine all LITERAL relocations to find out what GOT entries
 	   are required.  This sizes the GOT section as well.  */
 	for (s = sechdrs; s < esechdrs; ++s)
 		if (s->sh_type == SHT_RELA) {
 			nrela = s->sh_size / sizeof(Elf64_Rela);
 			rela = (void *)hdr + s->sh_offset;
 			for (i = 0; i < nrela; ++i)
 				process_reloc_for_got(rela+i, chains,
 						      &got->sh_size);
 		}

 	/* Free the memory we allocated.  */
 	for (i = 0; i < nsyms; ++i) {
 		struct got_entry *g, *n;
 		for (g = chains[i].next; g ; g = n) {
 			n = g->next;
 			kfree(g);
 		}
 	}
 	kfree(chains);

 	return 0;
 }

 int
 apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab,
 		   unsigned int symindex, unsigned int relsec,
 		   struct module *me)
 {
 	Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
 	unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela);
 	Elf64_Sym *symtab, *sym;
 	void *base, *location;
 	unsigned long got, gp;

 	DEBUGP("Applying relocate section %u to %u\n", relsec,
 	       sechdrs[relsec].sh_info);

 	base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr;
 	symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr;

 	/* The small sections were sorted to the end of the segment.
 	   The following should definitely cover them.  */
 	gp = (u64)me->core_layout.base + me->core_layout.size - 0x8000;
 	got = sechdrs[me->arch.gotsecindex].sh_addr;

 	for (i = 0; i < n; i++) {
 		unsigned long r_sym = ELF64_R_SYM (rela[i].r_info);
 		unsigned long r_type = ELF64_R_TYPE (rela[i].r_info);
 		unsigned long r_got_offset = r_type >> 8;
 		unsigned long value, hi, lo;
 		r_type &= 0xff;

 		/* This is where to make the change.  */
 		location = base + rela[i].r_offset;

 		/* This is the symbol it is referring to.  Note that all
 		   unresolved symbols have been resolved.  */
 		sym = symtab + r_sym;
 		value = sym->st_value + rela[i].r_addend;

 		switch (r_type) {
 		case R_ALPHA_NONE:
 			break;
 		case R_ALPHA_REFLONG:
 			*(u32 *)location = value;
 			break;
 		case R_ALPHA_REFQUAD:
 			/* BUG() can produce misaligned relocations. */
 			((u32 *)location)[0] = value;
 			((u32 *)location)[1] = value >> 32;
 			break;
 		case R_ALPHA_GPREL32:
 			value -= gp;
 			if ((int)value != value)
 				goto reloc_overflow;
 			*(u32 *)location = value;
 			break;
 		case R_ALPHA_LITERAL:
 			hi = got + r_got_offset;
 			lo = hi - gp;
 			if ((short)lo != lo)
 				goto reloc_overflow;
 			*(u16 *)location = lo;
 			*(u64 *)hi = value;
 			break;
 		case R_ALPHA_LITUSE:
 			break;
 		case R_ALPHA_GPDISP:
 			value = gp - (u64)location;
 			lo = (short)value;
 			hi = (int)(value - lo);
 			if (hi + lo != value)
 				goto reloc_overflow;
 			*(u16 *)location = hi >> 16;
 			*(u16 *)(location + rela[i].r_addend) = lo;
 			break;
 		case R_ALPHA_BRSGP:
 			/* BRSGP is only allowed to bind to local symbols.
 			   If the section is undef, this means that the
 			   value was resolved from somewhere else.  */
 			if (sym->st_shndx == SHN_UNDEF)
 				goto reloc_overflow;
 			if ((sym->st_other & STO_ALPHA_STD_GPLOAD) ==
 			    STO_ALPHA_STD_GPLOAD)
 				/* Omit the prologue. */
 				value += 8;
 			/* FALLTHRU */
 		case R_ALPHA_BRADDR:
 			value -= (u64)location + 4;
 			if (value & 3)
 				goto reloc_overflow;
 			value = (long)value >> 2;
 			if (value + (1<<21) >= 1<<22)
 				goto reloc_overflow;
 			value &= 0x1fffff;
 			value |= *(u32 *)location & ~0x1fffff;
 			*(u32 *)location = value;
 			break;
 		case R_ALPHA_HINT:
 			break;
 		case R_ALPHA_SREL32:
 			value -= (u64)location;
 			if ((int)value != value)
 				goto reloc_overflow;
 			*(u32 *)location = value;
 			break;
 		case R_ALPHA_SREL64:
 			value -= (u64)location;
 			*(u64 *)location = value;
 			break;
 		case R_ALPHA_GPRELHIGH:
 			value = (long)(value - gp + 0x8000) >> 16;
 			if ((short) value != value)
 				goto reloc_overflow;
 			*(u16 *)location = value;
 			break;
 		case R_ALPHA_GPRELLOW:
 			value -= gp;
 			*(u16 *)location = value;
 			break;
 		case R_ALPHA_GPREL16:
 			value -= gp;
 			if ((short) value != value)
 				goto reloc_overflow;
 			*(u16 *)location = value;
 			break;
 		default:
 			printk(KERN_ERR "module %s: Unknown relocation: %lu\n",
 			       me->name, r_type);
 			return -ENOEXEC;
 		reloc_overflow:
 			if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION)
 			  printk(KERN_ERR
 			         "module %s: Relocation (type %lu) overflow vs section %d\n",
 			         me->name, r_type, sym->st_shndx);
 			else
 			  printk(KERN_ERR
 			         "module %s: Relocation (type %lu) overflow vs %s\n",
 			         me->name, r_type, strtab + sym->st_name);
 			return -ENOEXEC;
 		}
 	}

 	return 0;
 }
	/* Kernel module help for Alpha.
	Copyright (C) 2002 Richard Henderson.

	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
	*/
	#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/slab.h>

	#if 0
	#define DEBUGP printk
	#else
	#define DEBUGP(fmt...)
	#endif

	/* Allocate the GOT at the end of the core sections. */

	struct got_entry {
	struct got_entry *next;
	Elf64_Sxword r_addend;
	int got_offset;
	};

	static inline void
	process_reloc_for_got(Elf64_Rela *rela,
	struct got_entry chains, Elf64_Xword poffset)
	{
	unsigned long r_sym = ELF64_R_SYM (rela->r_info);
	unsigned long r_type = ELF64_R_TYPE (rela->r_info);
	Elf64_Sxword r_addend = rela->r_addend;
	struct got_entry *g;

	if (r_type != R_ALPHA_LITERAL)
	return;

	for (g = chains + r_sym; g ; g = g->next)
	if (g->r_addend == r_addend) {
	if (g->got_offset == 0) {
	g->got_offset = *poffset;
	*poffset += 8;
	}
	goto found_entry;
	}

	g = kmalloc (sizeof (*g), GFP_KERNEL);
	g->next = chains[r_sym].next;
	g->r_addend = r_addend;
	g->got_offset = *poffset;
	*poffset += 8;
	chains[r_sym].next = g;

	found_entry:
	/* Trick: most of the ELF64_R_TYPE field is unused. There are
	42 valid relocation types, and a 32-bit field. Co-opt the
	bits above 256 to store the got offset for this reloc. */
	rela->r_info \|= g->got_offset << 8;
	}

	int
	module_frob_arch_sections(Elf64_Ehdr hdr, Elf64_Shdr sechdrs,
	char secstrings, struct module me)
	{
	struct got_entry *chains;
	Elf64_Rela *rela;
	Elf64_Shdr esechdrs, symtab, s, got;
	unsigned long nsyms, nrela, i;

	esechdrs = sechdrs + hdr->e_shnum;
	symtab = got = NULL;

	/* Find out how large the symbol table is. Allocate one got_entry
	head per symbol. Normally this will be enough, but not always.
	We'll chain different offsets for the symbol down each head. */
	for (s = sechdrs; s < esechdrs; ++s)
	if (s->sh_type == SHT_SYMTAB)
	symtab = s;
	else if (!strcmp(".got", secstrings + s->sh_name)) {
	got = s;
	me->arch.gotsecindex = s - sechdrs;
	}

	if (!symtab) {
	printk(KERN_ERR "module %s: no symbol table\n", me->name);
	return -ENOEXEC;
	}
	if (!got) {
	printk(KERN_ERR "module %s: no got section\n", me->name);
	return -ENOEXEC;
	}

	nsyms = symtab->sh_size / sizeof(Elf64_Sym);
	chains = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL);
	if (!chains) {
	printk(KERN_ERR
	"module %s: no memory for symbol chain buffer\n",
	me->name);
	return -ENOMEM;
	}

	got->sh_size = 0;
	got->sh_addralign = 8;
	got->sh_type = SHT_NOBITS;

	/* Examine all LITERAL relocations to find out what GOT entries
	are required. This sizes the GOT section as well. */
	for (s = sechdrs; s < esechdrs; ++s)
	if (s->sh_type == SHT_RELA) {
	nrela = s->sh_size / sizeof(Elf64_Rela);
	rela = (void *)hdr + s->sh_offset;
	for (i = 0; i < nrela; ++i)
	process_reloc_for_got(rela+i, chains,
	&got->sh_size);
	}

	/* Free the memory we allocated. */
	for (i = 0; i < nsyms; ++i) {
	struct got_entry g, n;
	for (g = chains[i].next; g ; g = n) {
	n = g->next;
	kfree(g);
	}
	}
	kfree(chains);

	return 0;
	}

	int
	apply_relocate_add(Elf64_Shdr sechdrs, const char strtab,
	unsigned int symindex, unsigned int relsec,
	struct module *me)
	{
	Elf64_Rela rela = (void )sechdrs[relsec].sh_addr;
	unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela);
	Elf64_Sym symtab, sym;
	void base, location;
	unsigned long got, gp;

	DEBUGP("Applying relocate section %u to %u\n", relsec,
	sechdrs[relsec].sh_info);

	base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr;
	symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr;

	/* The small sections were sorted to the end of the segment.
	The following should definitely cover them. */
	gp = (u64)me->core_layout.base + me->core_layout.size - 0x8000;
	got = sechdrs[me->arch.gotsecindex].sh_addr;

	for (i = 0; i < n; i++) {
	unsigned long r_sym = ELF64_R_SYM (rela[i].r_info);
	unsigned long r_type = ELF64_R_TYPE (rela[i].r_info);
	unsigned long r_got_offset = r_type >> 8;
	unsigned long value, hi, lo;
	r_type &= 0xff;

	/* This is where to make the change. */
	location = base + rela[i].r_offset;

	/* This is the symbol it is referring to. Note that all
	unresolved symbols have been resolved. */
	sym = symtab + r_sym;
	value = sym->st_value + rela[i].r_addend;

	switch (r_type) {
	case R_ALPHA_NONE:
	break;
	case R_ALPHA_REFLONG:
	(u32 )location = value;
	break;
	case R_ALPHA_REFQUAD:
	/* BUG() can produce misaligned relocations. */
	((u32 *)location)[0] = value;
	((u32 *)location)[1] = value >> 32;
	break;
	case R_ALPHA_GPREL32:
	value -= gp;
	if ((int)value != value)
	goto reloc_overflow;
	(u32 )location = value;
	break;
	case R_ALPHA_LITERAL:
	hi = got + r_got_offset;
	lo = hi - gp;
	if ((short)lo != lo)
	goto reloc_overflow;
	(u16 )location = lo;
	(u64 )hi = value;
	break;
	case R_ALPHA_LITUSE:
	break;
	case R_ALPHA_GPDISP:
	value = gp - (u64)location;
	lo = (short)value;
	hi = (int)(value - lo);
	if (hi + lo != value)
	goto reloc_overflow;
	(u16 )location = hi >> 16;
	(u16 )(location + rela[i].r_addend) = lo;
	break;
	case R_ALPHA_BRSGP:
	/* BRSGP is only allowed to bind to local symbols.
	If the section is undef, this means that the
	value was resolved from somewhere else. */
	if (sym->st_shndx == SHN_UNDEF)
	goto reloc_overflow;
	if ((sym->st_other & STO_ALPHA_STD_GPLOAD) ==
	STO_ALPHA_STD_GPLOAD)
	/* Omit the prologue. */
	value += 8;
	/* FALLTHRU */
	case R_ALPHA_BRADDR:
	value -= (u64)location + 4;
	if (value & 3)
	goto reloc_overflow;
	value = (long)value >> 2;
	if (value + (1<<21) >= 1<<22)
	goto reloc_overflow;
	value &= 0x1fffff;
	value \|= (u32 )location & ~0x1fffff;
	(u32 )location = value;
	break;
	case R_ALPHA_HINT:
	break;
	case R_ALPHA_SREL32:
	value -= (u64)location;
	if ((int)value != value)
	goto reloc_overflow;
	(u32 )location = value;
	break;
	case R_ALPHA_SREL64:
	value -= (u64)location;
	(u64 )location = value;
	break;
	case R_ALPHA_GPRELHIGH:
	value = (long)(value - gp + 0x8000) >> 16;
	if ((short) value != value)
	goto reloc_overflow;
	(u16 )location = value;
	break;
	case R_ALPHA_GPRELLOW:
	value -= gp;
	(u16 )location = value;
	break;
	case R_ALPHA_GPREL16:
	value -= gp;
	if ((short) value != value)
	goto reloc_overflow;
	(u16 )location = value;
	break;
	default:
	printk(KERN_ERR "module %s: Unknown relocation: %lu\n",
	me->name, r_type);
	return -ENOEXEC;
	reloc_overflow:
	if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION)
	printk(KERN_ERR
	"module %s: Relocation (type %lu) overflow vs section %d\n",
	me->name, r_type, sym->st_shndx);
	else
	printk(KERN_ERR
	"module %s: Relocation (type %lu) overflow vs %s\n",
	me->name, r_type, strtab + sym->st_name);
	return -ENOEXEC;
	}
	}

	return 0;
	}