cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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module.c (11190B)


      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 *
      4 *  Copyright (C) 2001 Rusty Russell.
      5 *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
      6 *  Copyright (C) 2005 Thiemo Seufer
      7 */
      8
      9#undef DEBUG
     10
     11#include <linux/extable.h>
     12#include <linux/moduleloader.h>
     13#include <linux/elf.h>
     14#include <linux/mm.h>
     15#include <linux/numa.h>
     16#include <linux/vmalloc.h>
     17#include <linux/slab.h>
     18#include <linux/fs.h>
     19#include <linux/string.h>
     20#include <linux/kernel.h>
     21#include <linux/spinlock.h>
     22#include <linux/jump_label.h>
     23
     24
     25struct mips_hi16 {
     26	struct mips_hi16 *next;
     27	Elf_Addr *addr;
     28	Elf_Addr value;
     29};
     30
     31static LIST_HEAD(dbe_list);
     32static DEFINE_SPINLOCK(dbe_lock);
     33
     34#ifdef MODULE_START
     35void *module_alloc(unsigned long size)
     36{
     37	return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END,
     38				GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE,
     39				__builtin_return_address(0));
     40}
     41#endif
     42
     43static void apply_r_mips_32(u32 *location, u32 base, Elf_Addr v)
     44{
     45	*location = base + v;
     46}
     47
     48static int apply_r_mips_26(struct module *me, u32 *location, u32 base,
     49			   Elf_Addr v)
     50{
     51	if (v % 4) {
     52		pr_err("module %s: dangerous R_MIPS_26 relocation\n",
     53		       me->name);
     54		return -ENOEXEC;
     55	}
     56
     57	if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
     58		pr_err("module %s: relocation overflow\n",
     59		       me->name);
     60		return -ENOEXEC;
     61	}
     62
     63	*location = (*location & ~0x03ffffff) |
     64		    ((base + (v >> 2)) & 0x03ffffff);
     65
     66	return 0;
     67}
     68
     69static int apply_r_mips_hi16(struct module *me, u32 *location, Elf_Addr v,
     70			     bool rela)
     71{
     72	struct mips_hi16 *n;
     73
     74	if (rela) {
     75		*location = (*location & 0xffff0000) |
     76			    ((((long long) v + 0x8000LL) >> 16) & 0xffff);
     77		return 0;
     78	}
     79
     80	/*
     81	 * We cannot relocate this one now because we don't know the value of
     82	 * the carry we need to add.  Save the information, and let LO16 do the
     83	 * actual relocation.
     84	 */
     85	n = kmalloc(sizeof *n, GFP_KERNEL);
     86	if (!n)
     87		return -ENOMEM;
     88
     89	n->addr = (Elf_Addr *)location;
     90	n->value = v;
     91	n->next = me->arch.r_mips_hi16_list;
     92	me->arch.r_mips_hi16_list = n;
     93
     94	return 0;
     95}
     96
     97static void free_relocation_chain(struct mips_hi16 *l)
     98{
     99	struct mips_hi16 *next;
    100
    101	while (l) {
    102		next = l->next;
    103		kfree(l);
    104		l = next;
    105	}
    106}
    107
    108static int apply_r_mips_lo16(struct module *me, u32 *location,
    109			     u32 base, Elf_Addr v, bool rela)
    110{
    111	unsigned long insnlo = base;
    112	struct mips_hi16 *l;
    113	Elf_Addr val, vallo;
    114
    115	if (rela) {
    116		*location = (*location & 0xffff0000) | (v & 0xffff);
    117		return 0;
    118	}
    119
    120	/* Sign extend the addend we extract from the lo insn.	*/
    121	vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
    122
    123	if (me->arch.r_mips_hi16_list != NULL) {
    124		l = me->arch.r_mips_hi16_list;
    125		while (l != NULL) {
    126			struct mips_hi16 *next;
    127			unsigned long insn;
    128
    129			/*
    130			 * The value for the HI16 had best be the same.
    131			 */
    132			if (v != l->value)
    133				goto out_danger;
    134
    135			/*
    136			 * Do the HI16 relocation.  Note that we actually don't
    137			 * need to know anything about the LO16 itself, except
    138			 * where to find the low 16 bits of the addend needed
    139			 * by the LO16.
    140			 */
    141			insn = *l->addr;
    142			val = ((insn & 0xffff) << 16) + vallo;
    143			val += v;
    144
    145			/*
    146			 * Account for the sign extension that will happen in
    147			 * the low bits.
    148			 */
    149			val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;
    150
    151			insn = (insn & ~0xffff) | val;
    152			*l->addr = insn;
    153
    154			next = l->next;
    155			kfree(l);
    156			l = next;
    157		}
    158
    159		me->arch.r_mips_hi16_list = NULL;
    160	}
    161
    162	/*
    163	 * Ok, we're done with the HI16 relocs.	 Now deal with the LO16.
    164	 */
    165	val = v + vallo;
    166	insnlo = (insnlo & ~0xffff) | (val & 0xffff);
    167	*location = insnlo;
    168
    169	return 0;
    170
    171out_danger:
    172	free_relocation_chain(l);
    173	me->arch.r_mips_hi16_list = NULL;
    174
    175	pr_err("module %s: dangerous R_MIPS_LO16 relocation\n", me->name);
    176
    177	return -ENOEXEC;
    178}
    179
    180static int apply_r_mips_pc(struct module *me, u32 *location, u32 base,
    181			   Elf_Addr v, unsigned int bits)
    182{
    183	unsigned long mask = GENMASK(bits - 1, 0);
    184	unsigned long se_bits;
    185	long offset;
    186
    187	if (v % 4) {
    188		pr_err("module %s: dangerous R_MIPS_PC%u relocation\n",
    189		       me->name, bits);
    190		return -ENOEXEC;
    191	}
    192
    193	/* retrieve & sign extend implicit addend if any */
    194	offset = base & mask;
    195	offset |= (offset & BIT(bits - 1)) ? ~mask : 0;
    196
    197	offset += ((long)v - (long)location) >> 2;
    198
    199	/* check the sign bit onwards are identical - ie. we didn't overflow */
    200	se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0;
    201	if ((offset & ~mask) != (se_bits & ~mask)) {
    202		pr_err("module %s: relocation overflow\n", me->name);
    203		return -ENOEXEC;
    204	}
    205
    206	*location = (*location & ~mask) | (offset & mask);
    207
    208	return 0;
    209}
    210
    211static int apply_r_mips_pc16(struct module *me, u32 *location, u32 base,
    212			     Elf_Addr v)
    213{
    214	return apply_r_mips_pc(me, location, base, v, 16);
    215}
    216
    217static int apply_r_mips_pc21(struct module *me, u32 *location, u32 base,
    218			     Elf_Addr v)
    219{
    220	return apply_r_mips_pc(me, location, base, v, 21);
    221}
    222
    223static int apply_r_mips_pc26(struct module *me, u32 *location, u32 base,
    224			     Elf_Addr v)
    225{
    226	return apply_r_mips_pc(me, location, base, v, 26);
    227}
    228
    229static int apply_r_mips_64(u32 *location, Elf_Addr v, bool rela)
    230{
    231	if (WARN_ON(!rela))
    232		return -EINVAL;
    233
    234	*(Elf_Addr *)location = v;
    235
    236	return 0;
    237}
    238
    239static int apply_r_mips_higher(u32 *location, Elf_Addr v, bool rela)
    240{
    241	if (WARN_ON(!rela))
    242		return -EINVAL;
    243
    244	*location = (*location & 0xffff0000) |
    245		    ((((long long)v + 0x80008000LL) >> 32) & 0xffff);
    246
    247	return 0;
    248}
    249
    250static int apply_r_mips_highest(u32 *location, Elf_Addr v, bool rela)
    251{
    252	if (WARN_ON(!rela))
    253		return -EINVAL;
    254
    255	*location = (*location & 0xffff0000) |
    256		    ((((long long)v + 0x800080008000LL) >> 48) & 0xffff);
    257
    258	return 0;
    259}
    260
    261/**
    262 * reloc_handler() - Apply a particular relocation to a module
    263 * @type: type of the relocation to apply
    264 * @me: the module to apply the reloc to
    265 * @location: the address at which the reloc is to be applied
    266 * @base: the existing value at location for REL-style; 0 for RELA-style
    267 * @v: the value of the reloc, with addend for RELA-style
    268 * @rela: indication of is this a RELA (true) or REL (false) relocation
    269 *
    270 * Each implemented relocation function applies a particular type of
    271 * relocation to the module @me. Relocs that may be found in either REL or RELA
    272 * variants can be handled by making use of the @base & @v parameters which are
    273 * set to values which abstract the difference away from the particular reloc
    274 * implementations.
    275 *
    276 * Return: 0 upon success, else -ERRNO
    277 */
    278static int reloc_handler(u32 type, struct module *me, u32 *location, u32 base,
    279			 Elf_Addr v, bool rela)
    280{
    281	switch (type) {
    282	case R_MIPS_NONE:
    283		break;
    284	case R_MIPS_32:
    285		apply_r_mips_32(location, base, v);
    286		break;
    287	case R_MIPS_26:
    288		return apply_r_mips_26(me, location, base, v);
    289	case R_MIPS_HI16:
    290		return apply_r_mips_hi16(me, location, v, rela);
    291	case R_MIPS_LO16:
    292		return apply_r_mips_lo16(me, location, base, v, rela);
    293	case R_MIPS_PC16:
    294		return apply_r_mips_pc16(me, location, base, v);
    295	case R_MIPS_PC21_S2:
    296		return apply_r_mips_pc21(me, location, base, v);
    297	case R_MIPS_PC26_S2:
    298		return apply_r_mips_pc26(me, location, base, v);
    299	case R_MIPS_64:
    300		return apply_r_mips_64(location, v, rela);
    301	case R_MIPS_HIGHER:
    302		return apply_r_mips_higher(location, v, rela);
    303	case R_MIPS_HIGHEST:
    304		return apply_r_mips_highest(location, v, rela);
    305	default:
    306		pr_err("%s: Unknown relocation type %u\n", me->name, type);
    307		return -EINVAL;
    308	}
    309
    310	return 0;
    311}
    312
    313static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
    314			    unsigned int symindex, unsigned int relsec,
    315			    struct module *me, bool rela)
    316{
    317	union {
    318		Elf_Mips_Rel *rel;
    319		Elf_Mips_Rela *rela;
    320	} r;
    321	Elf_Sym *sym;
    322	u32 *location, base;
    323	unsigned int i, type;
    324	Elf_Addr v;
    325	int err = 0;
    326	size_t reloc_sz;
    327
    328	pr_debug("Applying relocate section %u to %u\n", relsec,
    329	       sechdrs[relsec].sh_info);
    330
    331	r.rel = (void *)sechdrs[relsec].sh_addr;
    332	reloc_sz = rela ? sizeof(*r.rela) : sizeof(*r.rel);
    333	me->arch.r_mips_hi16_list = NULL;
    334	for (i = 0; i < sechdrs[relsec].sh_size / reloc_sz; i++) {
    335		/* This is where to make the change */
    336		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
    337			+ r.rel->r_offset;
    338		/* This is the symbol it is referring to */
    339		sym = (Elf_Sym *)sechdrs[symindex].sh_addr
    340			+ ELF_MIPS_R_SYM(*r.rel);
    341		if (sym->st_value >= -MAX_ERRNO) {
    342			/* Ignore unresolved weak symbol */
    343			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
    344				continue;
    345			pr_warn("%s: Unknown symbol %s\n",
    346				me->name, strtab + sym->st_name);
    347			err = -ENOENT;
    348			goto out;
    349		}
    350
    351		type = ELF_MIPS_R_TYPE(*r.rel);
    352
    353		if (rela) {
    354			v = sym->st_value + r.rela->r_addend;
    355			base = 0;
    356			r.rela = &r.rela[1];
    357		} else {
    358			v = sym->st_value;
    359			base = *location;
    360			r.rel = &r.rel[1];
    361		}
    362
    363		err = reloc_handler(type, me, location, base, v, rela);
    364		if (err)
    365			goto out;
    366	}
    367
    368out:
    369	/*
    370	 * Normally the hi16 list should be deallocated at this point. A
    371	 * malformed binary however could contain a series of R_MIPS_HI16
    372	 * relocations not followed by a R_MIPS_LO16 relocation, or if we hit
    373	 * an error processing a reloc we might have gotten here before
    374	 * reaching the R_MIPS_LO16. In either case, free up the list and
    375	 * return an error.
    376	 */
    377	if (me->arch.r_mips_hi16_list) {
    378		free_relocation_chain(me->arch.r_mips_hi16_list);
    379		me->arch.r_mips_hi16_list = NULL;
    380		err = err ?: -ENOEXEC;
    381	}
    382
    383	return err;
    384}
    385
    386int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
    387		   unsigned int symindex, unsigned int relsec,
    388		   struct module *me)
    389{
    390	return __apply_relocate(sechdrs, strtab, symindex, relsec, me, false);
    391}
    392
    393#ifdef CONFIG_MODULES_USE_ELF_RELA
    394int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
    395		       unsigned int symindex, unsigned int relsec,
    396		       struct module *me)
    397{
    398	return __apply_relocate(sechdrs, strtab, symindex, relsec, me, true);
    399}
    400#endif /* CONFIG_MODULES_USE_ELF_RELA */
    401
    402/* Given an address, look for it in the module exception tables. */
    403const struct exception_table_entry *search_module_dbetables(unsigned long addr)
    404{
    405	unsigned long flags;
    406	const struct exception_table_entry *e = NULL;
    407	struct mod_arch_specific *dbe;
    408
    409	spin_lock_irqsave(&dbe_lock, flags);
    410	list_for_each_entry(dbe, &dbe_list, dbe_list) {
    411		e = search_extable(dbe->dbe_start,
    412				   dbe->dbe_end - dbe->dbe_start, addr);
    413		if (e)
    414			break;
    415	}
    416	spin_unlock_irqrestore(&dbe_lock, flags);
    417
    418	/* Now, if we found one, we are running inside it now, hence
    419	   we cannot unload the module, hence no refcnt needed. */
    420	return e;
    421}
    422
    423/* Put in dbe list if necessary. */
    424int module_finalize(const Elf_Ehdr *hdr,
    425		    const Elf_Shdr *sechdrs,
    426		    struct module *me)
    427{
    428	const Elf_Shdr *s;
    429	char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
    430
    431	/* Make jump label nops. */
    432	jump_label_apply_nops(me);
    433
    434	INIT_LIST_HEAD(&me->arch.dbe_list);
    435	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
    436		if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
    437			continue;
    438		me->arch.dbe_start = (void *)s->sh_addr;
    439		me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
    440		spin_lock_irq(&dbe_lock);
    441		list_add(&me->arch.dbe_list, &dbe_list);
    442		spin_unlock_irq(&dbe_lock);
    443	}
    444	return 0;
    445}
    446
    447void module_arch_cleanup(struct module *mod)
    448{
    449	spin_lock_irq(&dbe_lock);
    450	list_del(&mod->arch.dbe_list);
    451	spin_unlock_irq(&dbe_lock);
    452}