Commit 430d0b88 authored by Paul Burton's avatar Paul Burton Committed by Ralf Baechle
Browse files

MIPS: module: Unify rel & rela reloc handling 



The module load code has previously had entirely separate
implementations for rel & rela style relocs, which unnecessarily
duplicates a whole lot of code. Unify the implementations of both types
of reloc, sharing the bulk of the code.

Signed-off-by: default avatarPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15832/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 351b0940

arch/mips/include/asm/module.h

+4 −4
Original line number Diff line number Diff line
@@ -47,8 +47,8 @@ typedef struct { 
#define Elf_Mips_Rel	Elf32_Rel

#define Elf_Mips_Rela	Elf32_Rela



#define ELF_MIPS_R_SYM(rel) ELF32_R_SYM(rel.r_info)

#define ELF_MIPS_R_TYPE(rel) ELF32_R_TYPE(rel.r_info)

#define ELF_MIPS_R_SYM(rel) ELF32_R_SYM((rel).r_info)

#define ELF_MIPS_R_TYPE(rel) ELF32_R_TYPE((rel).r_info)



#endif
@@ -65,8 +65,8 @@ typedef struct { 
#define Elf_Mips_Rel	Elf64_Mips_Rel

#define Elf_Mips_Rela	Elf64_Mips_Rela



#define ELF_MIPS_R_SYM(rel) (rel.r_sym)

#define ELF_MIPS_R_TYPE(rel) (rel.r_type)

#define ELF_MIPS_R_SYM(rel) ((rel).r_sym)

#define ELF_MIPS_R_TYPE(rel) ((rel).r_type)



#endif

arch/mips/kernel/Makefile

+0 −1
Original line number Diff line number Diff line
@@ -31,7 +31,6 @@ obj-$(CONFIG_SYNC_R4K) += sync-r4k.o 
obj-$(CONFIG_DEBUG_FS)		+= segment.o

obj-$(CONFIG_STACKTRACE)	+= stacktrace.o

obj-$(CONFIG_MODULES)		+= module.o

obj-$(CONFIG_MODULES_USE_ELF_RELA) += module-rela.o



obj-$(CONFIG_FTRACE_SYSCALLS)	+= ftrace.o

obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o ftrace.o

arch/mips/kernel/module-rela.c

deleted100644 → 0
+0 −202
Original line number Diff line number Diff line 
/*

 *  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

 *

 *  Copyright (C) 2001 Rusty Russell.

 *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)

 *  Copyright (C) 2005 Thiemo Seufer

 *  Copyright (C) 2015 Imagination Technologies Ltd.

 */



#include <linux/elf.h>

#include <linux/err.h>

#include <linux/errno.h>

#include <linux/moduleloader.h>



extern int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v);



static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)

{

	*location = v;



	return 0;

}



static int apply_r_mips_26_rela(struct module *me, u32 *location, Elf_Addr v)

{

	if (v % 4) {

		pr_err("module %s: dangerous R_MIPS_26 RELA relocation\n",

		       me->name);

		return -ENOEXEC;

	}



	if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {

		pr_err("module %s: relocation overflow\n", me->name);

		return -ENOEXEC;

	}



	*location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);



	return 0;

}



static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)

{

	*location = (*location & 0xffff0000) |

		    ((((long long) v + 0x8000LL) >> 16) & 0xffff);



	return 0;

}



static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)

{

	*location = (*location & 0xffff0000) | (v & 0xffff);



	return 0;

}



static int apply_r_mips_pc_rela(struct module *me, u32 *location, Elf_Addr v,

				unsigned bits)

{

	unsigned long mask = GENMASK(bits - 1, 0);

	unsigned long se_bits;

	long offset;



	if (v % 4) {

		pr_err("module %s: dangerous R_MIPS_PC%u RELA relocation\n",

		       me->name, bits);

		return -ENOEXEC;

	}



	offset = ((long)v - (long)location) >> 2;



	/* check the sign bit onwards are identical - ie. we didn't overflow */

	se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0;

	if ((offset & ~mask) != (se_bits & ~mask)) {

		pr_err("module %s: relocation overflow\n", me->name);

		return -ENOEXEC;

	}



	*location = (*location & ~mask) | (offset & mask);



	return 0;

}



static int apply_r_mips_pc16_rela(struct module *me, u32 *location, Elf_Addr v)

{

	return apply_r_mips_pc_rela(me, location, v, 16);

}



static int apply_r_mips_pc21_rela(struct module *me, u32 *location, Elf_Addr v)

{

	return apply_r_mips_pc_rela(me, location, v, 21);

}



static int apply_r_mips_pc26_rela(struct module *me, u32 *location, Elf_Addr v)

{

	return apply_r_mips_pc_rela(me, location, v, 26);

}



static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)

{

	*(Elf_Addr *)location = v;



	return 0;

}



static int apply_r_mips_higher_rela(struct module *me, u32 *location,

				    Elf_Addr v)

{

	*location = (*location & 0xffff0000) |

		    ((((long long) v + 0x80008000LL) >> 32) & 0xffff);



	return 0;

}



static int apply_r_mips_highest_rela(struct module *me, u32 *location,

				     Elf_Addr v)

{

	*location = (*location & 0xffff0000) |

		    ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);



	return 0;

}



static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,

				Elf_Addr v) = {

	[R_MIPS_NONE]		= apply_r_mips_none,

	[R_MIPS_32]		= apply_r_mips_32_rela,

	[R_MIPS_26]		= apply_r_mips_26_rela,

	[R_MIPS_HI16]		= apply_r_mips_hi16_rela,

	[R_MIPS_LO16]		= apply_r_mips_lo16_rela,

	[R_MIPS_PC16]		= apply_r_mips_pc16_rela,

	[R_MIPS_64]		= apply_r_mips_64_rela,

	[R_MIPS_HIGHER]		= apply_r_mips_higher_rela,

	[R_MIPS_HIGHEST]	= apply_r_mips_highest_rela,

	[R_MIPS_PC21_S2]	= apply_r_mips_pc21_rela,

	[R_MIPS_PC26_S2]	= apply_r_mips_pc26_rela,

};



int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,

		       unsigned int symindex, unsigned int relsec,

		       struct module *me)

{

	Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;

	int (*handler)(struct module *me, u32 *location, Elf_Addr v);

	Elf_Sym *sym;

	u32 *location;

	unsigned int i, type;

	Elf_Addr v;

	int res;



	pr_debug("Applying relocate section %u to %u\n", relsec,

	       sechdrs[relsec].sh_info);



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

		/* 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 = (Elf_Sym *)sechdrs[symindex].sh_addr

			+ ELF_MIPS_R_SYM(rel[i]);

		if (sym->st_value >= -MAX_ERRNO) {

			/* Ignore unresolved weak symbol */

			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)

				continue;

			pr_warn("%s: Unknown symbol %s\n",

			       me->name, strtab + sym->st_name);

			return -ENOENT;

		}



		type = ELF_MIPS_R_TYPE(rel[i]);



		if (type < ARRAY_SIZE(reloc_handlers_rela))

			handler = reloc_handlers_rela[type];

		else

			handler = NULL;



		if (!handler) {

			pr_err("%s: Unknown relocation type %u\n",

			       me->name, type);

			return -EINVAL;

		}



		v = sym->st_value + rel[i].r_addend;

		res = handler(me, location, v);

		if (res)

			return res;

	}



	return 0;

}

arch/mips/kernel/module.c

+150 −45
Original line number Diff line number Diff line
@@ -53,22 +53,25 @@ void *module_alloc(unsigned long size) 
}

#endif



int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v)

static int apply_r_mips_none(struct module *me, u32 *location,

			     u32 base, Elf_Addr v, bool rela)

{

	return 0;

}



static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v)

static int apply_r_mips_32(struct module *me, u32 *location,

			   u32 base, Elf_Addr v, bool rela)

{

	*location += v;

	*location = base + v;



	return 0;

}



static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v)

static int apply_r_mips_26(struct module *me, u32 *location,

			   u32 base, Elf_Addr v, bool rela)

{

	if (v % 4) {

		pr_err("module %s: dangerous R_MIPS_26 REL relocation\n",

		pr_err("module %s: dangerous R_MIPS_26 relocation\n",

		       me->name);

		return -ENOEXEC;

	}
@@ -80,15 +83,22 @@ static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v) 
	}



	*location = (*location & ~0x03ffffff) |

		    ((*location + (v >> 2)) & 0x03ffffff);

		    ((base + (v >> 2)) & 0x03ffffff);



	return 0;

}



static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_Addr v)

static int apply_r_mips_hi16(struct module *me, u32 *location,

			     u32 base, Elf_Addr v, bool rela)

{

	struct mips_hi16 *n;



	if (rela) {

		*location = (*location & 0xffff0000) |

			    ((((long long) v + 0x8000LL) >> 16) & 0xffff);

		return 0;

	}



	/*

	 * We cannot relocate this one now because we don't know the value of

	 * the carry we need to add.  Save the information, and let LO16 do the
@@ -117,12 +127,18 @@ static void free_relocation_chain(struct mips_hi16 *l) 
	}

}



static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)

static int apply_r_mips_lo16(struct module *me, u32 *location,

			     u32 base, Elf_Addr v, bool rela)

{

	unsigned long insnlo = *location;

	unsigned long insnlo = base;

	struct mips_hi16 *l;

	Elf_Addr val, vallo;



	if (rela) {

		*location = (*location & 0xffff0000) | (v & 0xffff);

		return 0;

	}



	/* Sign extend the addend we extract from the lo insn.	*/

	vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
@@ -178,26 +194,26 @@ out_danger: 
	free_relocation_chain(l);

	me->arch.r_mips_hi16_list = NULL;



	pr_err("module %s: dangerous R_MIPS_LO16 REL relocation\n", me->name);

	pr_err("module %s: dangerous R_MIPS_LO16 relocation\n", me->name);



	return -ENOEXEC;

}



static int apply_r_mips_pc_rel(struct module *me, u32 *location, Elf_Addr v,

			       unsigned bits)

static int apply_r_mips_pc(struct module *me, u32 *location, u32 base,

			   Elf_Addr v, unsigned int bits)

{

	unsigned long mask = GENMASK(bits - 1, 0);

	unsigned long se_bits;

	long offset;



	if (v % 4) {

		pr_err("module %s: dangerous R_MIPS_PC%u REL relocation\n",

		pr_err("module %s: dangerous R_MIPS_PC%u relocation\n",

		       me->name, bits);

		return -ENOEXEC;

	}



	/* retrieve & sign extend implicit addend */

	offset = *location & mask;

	/* retrieve & sign extend implicit addend if any */

	offset = base & mask;

	offset |= (offset & BIT(bits - 1)) ? ~mask : 0;



	offset += ((long)v - (long)location) >> 2;
@@ -214,56 +230,121 @@ static int apply_r_mips_pc_rel(struct module *me, u32 *location, Elf_Addr v, 
	return 0;

}



static int apply_r_mips_pc16_rel(struct module *me, u32 *location, Elf_Addr v)

static int apply_r_mips_pc16(struct module *me, u32 *location,

			     u32 base, Elf_Addr v, bool rela)

{

	return apply_r_mips_pc(me, location, base, v, 16);

}



static int apply_r_mips_pc21(struct module *me, u32 *location,

			     u32 base, Elf_Addr v, bool rela)

{

	return apply_r_mips_pc(me, location, base, v, 21);

}



static int apply_r_mips_pc26(struct module *me, u32 *location,

			     u32 base, Elf_Addr v, bool rela)

{

	return apply_r_mips_pc_rel(me, location, v, 16);

	return apply_r_mips_pc(me, location, base, v, 26);

}



static int apply_r_mips_pc21_rel(struct module *me, u32 *location, Elf_Addr v)

static int apply_r_mips_64(struct module *me, u32 *location,

			   u32 base, Elf_Addr v, bool rela)

{

	return apply_r_mips_pc_rel(me, location, v, 21);

	if (WARN_ON(!rela))

		return -EINVAL;



	*(Elf_Addr *)location = v;



	return 0;

}



static int apply_r_mips_pc26_rel(struct module *me, u32 *location, Elf_Addr v)

static int apply_r_mips_higher(struct module *me, u32 *location,

			       u32 base, Elf_Addr v, bool rela)

{

	return apply_r_mips_pc_rel(me, location, v, 26);

	if (WARN_ON(!rela))

		return -EINVAL;



	*location = (*location & 0xffff0000) |

		    ((((long long)v + 0x80008000LL) >> 32) & 0xffff);



	return 0;

}



static int apply_r_mips_highest(struct module *me, u32 *location,

				u32 base, Elf_Addr v, bool rela)

{

	if (WARN_ON(!rela))

		return -EINVAL;



	*location = (*location & 0xffff0000) |

		    ((((long long)v + 0x800080008000LL) >> 48) & 0xffff);



	return 0;

}



static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,

				Elf_Addr v) = {

/**

 * reloc_handler() - Apply a particular relocation to a module

 * @me: the module to apply the reloc to

 * @location: the address at which the reloc is to be applied

 * @base: the existing value at location for REL-style; 0 for RELA-style

 * @v: the value of the reloc, with addend for RELA-style

 *

 * Each implemented reloc_handler function applies a particular type of

 * relocation to the module @me. Relocs that may be found in either REL or RELA

 * variants can be handled by making use of the @base & @v parameters which are

 * set to values which abstract the difference away from the particular reloc

 * implementations.

 *

 * Return: 0 upon success, else -ERRNO

 */

typedef int (*reloc_handler)(struct module *me, u32 *location,

			     u32 base, Elf_Addr v, bool rela);



/* The handlers for known reloc types */

static reloc_handler reloc_handlers[] = {

	[R_MIPS_NONE]		= apply_r_mips_none,

	[R_MIPS_32]		= apply_r_mips_32_rel,

	[R_MIPS_26]		= apply_r_mips_26_rel,

	[R_MIPS_HI16]		= apply_r_mips_hi16_rel,

	[R_MIPS_LO16]		= apply_r_mips_lo16_rel,

	[R_MIPS_PC16]		= apply_r_mips_pc16_rel,

	[R_MIPS_PC21_S2]	= apply_r_mips_pc21_rel,

	[R_MIPS_PC26_S2]	= apply_r_mips_pc26_rel,

	[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_PC16]		= apply_r_mips_pc16,

	[R_MIPS_64]		= apply_r_mips_64,

	[R_MIPS_HIGHER]		= apply_r_mips_higher,

	[R_MIPS_HIGHEST]	= apply_r_mips_highest,

	[R_MIPS_PC21_S2]	= apply_r_mips_pc21,

	[R_MIPS_PC26_S2]	= apply_r_mips_pc26,

};



int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,

static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab,

			    unsigned int symindex, unsigned int relsec,

		   struct module *me)

			    struct module *me, bool rela)

{

	Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr;

	int (*handler)(struct module *me, u32 *location, Elf_Addr v);

	union {

		Elf_Mips_Rel *rel;

		Elf_Mips_Rela *rela;

	} r;

	reloc_handler handler;

	Elf_Sym *sym;

	u32 *location;

	u32 *location, base;

	unsigned int i, type;

	Elf_Addr v;

	int err = 0;

	size_t reloc_sz;



	pr_debug("Applying relocate section %u to %u\n", relsec,

	       sechdrs[relsec].sh_info);



	r.rel = (void *)sechdrs[relsec].sh_addr;

	reloc_sz = rela ? sizeof(*r.rela) : sizeof(*r.rel);

	me->arch.r_mips_hi16_list = NULL;

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

	for (i = 0; i < sechdrs[relsec].sh_size / reloc_sz; i++) {

		/* This is where to make the change */

		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr

			+ rel[i].r_offset;

			+ r.rel->r_offset;

		/* This is the symbol it is referring to */

		sym = (Elf_Sym *)sechdrs[symindex].sh_addr

			+ ELF_MIPS_R_SYM(rel[i]);

			+ ELF_MIPS_R_SYM(*r.rel);

		if (sym->st_value >= -MAX_ERRNO) {

			/* Ignore unresolved weak symbol */

			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
@@ -274,10 +355,9 @@ int apply_relocate(Elf_Shdr *sechdrs, const char *strtab, 
			goto out;

		}



		type = ELF_MIPS_R_TYPE(rel[i]);



		if (type < ARRAY_SIZE(reloc_handlers_rel))

			handler = reloc_handlers_rel[type];

		type = ELF_MIPS_R_TYPE(*r.rel);

		if (type < ARRAY_SIZE(reloc_handlers))

			handler = reloc_handlers[type];

		else

			handler = NULL;
@@ -288,8 +368,17 @@ int apply_relocate(Elf_Shdr *sechdrs, const char *strtab, 
			goto out;

		}



		if (rela) {

			v = sym->st_value + r.rela->r_addend;

			base = 0;

			r.rela = &r.rela[1];

		} else {

			v = sym->st_value;

		err = handler(me, location, v);

			base = *location;

			r.rel = &r.rel[1];

		}



		err = handler(me, location, base, v, rela);

		if (err)

			goto out;

	}
@@ -312,6 +401,22 @@ out: 
	return err;

}



int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,

		   unsigned int symindex, unsigned int relsec,

		   struct module *me)

{

	return __apply_relocate(sechdrs, strtab, symindex, relsec, me, false);

}



#ifdef CONFIG_MODULES_USE_ELF_RELA

int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,

		       unsigned int symindex, unsigned int relsec,

		       struct module *me)

{

	return __apply_relocate(sechdrs, strtab, symindex, relsec, me, true);

}

#endif /* CONFIG_MODULES_USE_ELF_RELA */



/* Given an address, look for it in the module exception tables. */

const struct exception_table_entry *search_module_dbetables(unsigned long addr)

{

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