[linux-block.git] / arch / powerpc / kernel / module_32.c

// 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>

/* 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") != 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
			 * 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_FTRACE
int 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
Commit	Line	Data
1a59d1b8	1	// SPDX-License-Identifier: GPL-2.0-or-later
1da177e4 LT	2	/* Kernel module help for PPC.
	3	Copyright (C) 2001 Rusty Russell.
	4
1da177e4	5	*/
c7d1f6af AB	6
	7	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	8
1da177e4 LT	9	#include <linux/module.h>
	10	#include <linux/moduleloader.h>
	11	#include <linux/elf.h>
	12	#include <linux/vmalloc.h>
	13	#include <linux/fs.h>
	14	#include <linux/string.h>
	15	#include <linux/kernel.h>
7cc45e64	16	#include <linux/ftrace.h>
1da177e4	17	#include <linux/cache.h>
73c9ceab	18	#include <linux/bug.h>
eda09fbd	19	#include <linux/sort.h>
b88c4767	20	#include <asm/setup.h>
21c4ff80	21
1da177e4 LT	22	/* Count how many different relocations (different symbol, different
	23	addend) */
	24	static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
	25	{
eda09fbd EM	26	unsigned int i, r_info, r_addend, _count_relocs;
	27
	28	_count_relocs = 0;
	29	r_info = 0;
	30	r_addend = 0;
	31	for (i = 0; i < num; i++)
	32	/* Only count 24-bit relocs, others don't need stubs */
	33	if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
	34	(r_info != ELF32_R_SYM(rela[i].r_info) \|\|
	35	r_addend != rela[i].r_addend)) {
	36	_count_relocs++;
	37	r_info = ELF32_R_SYM(rela[i].r_info);
	38	r_addend = rela[i].r_addend;
1da177e4	39	}
eda09fbd	40
7cc45e64 SR	41	#ifdef CONFIG_DYNAMIC_FTRACE
	42	_count_relocs++; /* add one for ftrace_caller */
	43	#endif
eda09fbd EM	44	return _count_relocs;
	45	}
	46
	47	static int relacmp(const void _x, const void _y)
	48	{
	49	const Elf32_Rela x, y;
	50
	51	y = (Elf32_Rela *)_x;
	52	x = (Elf32_Rela *)_y;
	53
	54	/* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to
	55	* make the comparison cheaper/faster. It won't affect the sorting or
	56	* the counting algorithms' performance
	57	*/
	58	if (x->r_info < y->r_info)
	59	return -1;
	60	else if (x->r_info > y->r_info)
	61	return 1;
	62	else if (x->r_addend < y->r_addend)
	63	return -1;
	64	else if (x->r_addend > y->r_addend)
	65	return 1;
	66	else
	67	return 0;
	68	}
	69
	70	static void relaswap(void _x, void _y, int size)
	71	{
	72	uint32_t x, y, tmp;
	73	int i;
	74
	75	y = (uint32_t *)_x;
	76	x = (uint32_t *)_y;
	77
	78	for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) {
	79	tmp = x[i];
	80	x[i] = y[i];
	81	y[i] = tmp;
1da177e4	82	}
1da177e4 LT	83	}
	84
	85	/* Get the potential trampolines size required of the init and
	86	non-init sections */
	87	static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
	88	const Elf32_Shdr *sechdrs,
	89	const char *secstrings,
	90	int is_init)
	91	{
	92	unsigned long ret = 0;
	93	unsigned i;
	94
	95	/* Everything marked ALLOC (this includes the exported
	96	symbols) */
	97	for (i = 1; i < hdr->e_shnum; i++) {
	98	/* If it's called .init, and we're not init, we're
	99	not interested */
d8731527	100	if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != NULL)
1da177e4 LT	101	!= is_init)
	102	continue;
	103
	104	/* We don't want to look at debug sections. */
d8731527	105	if (strstr(secstrings + sechdrs[i].sh_name, ".debug"))
1da177e4 LT	106	continue;
	107
	108	if (sechdrs[i].sh_type == SHT_RELA) {
c7d1f6af AB	109	pr_debug("Found relocations in section %u\n", i);
c7d1f6af AB	110	pr_debug("Ptr: %p. Number: %u\n",
1da177e4 LT	111	(void *)hdr + sechdrs[i].sh_offset,
1da177e4 LT	112	sechdrs[i].sh_size / sizeof(Elf32_Rela));
eda09fbd EM	113
	114	/* Sort the relocation information based on a symbol and
	115	* addend key. This is a stable O(n*log n) complexity
	116	* alogrithm but it will reduce the complexity of
	117	* count_relocs() to linear complexity O(n)
	118	*/
	119	sort((void *)hdr + sechdrs[i].sh_offset,
	120	sechdrs[i].sh_size / sizeof(Elf32_Rela),
	121	sizeof(Elf32_Rela), relacmp, relaswap);
	122
1da177e4 LT	123	ret += count_relocs((void *)hdr
	124	+ sechdrs[i].sh_offset,
	125	sechdrs[i].sh_size
	126	/ sizeof(Elf32_Rela))
	127	* sizeof(struct ppc_plt_entry);
	128	}
	129	}
	130
	131	return ret;
	132	}
	133
	134	int module_frob_arch_sections(Elf32_Ehdr *hdr,
	135	Elf32_Shdr *sechdrs,
	136	char *secstrings,
	137	struct module *me)
	138	{
	139	unsigned int i;
	140
	141	/* Find .plt and .init.plt sections */
	142	for (i = 0; i < hdr->e_shnum; i++) {
	143	if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)
	144	me->arch.init_plt_section = i;
	145	else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
	146	me->arch.core_plt_section = i;
	147	}
	148	if (!me->arch.core_plt_section \|\| !me->arch.init_plt_section) {
c7d1f6af	149	pr_err("Module doesn't contain .plt or .init.plt sections.\n");
1da177e4 LT	150	return -ENOEXEC;
	151	}
	152
	153	/* Override their sizes */
	154	sechdrs[me->arch.core_plt_section].sh_size
	155	= get_plt_size(hdr, sechdrs, secstrings, 0);
	156	sechdrs[me->arch.init_plt_section].sh_size
	157	= get_plt_size(hdr, sechdrs, secstrings, 1);
	158	return 0;
	159	}
	160
1da177e4 LT	161	static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val)
1da177e4 LT	162	{
3c752965 SR	163	if (entry->jump[0] == 0x3d800000 + ((val + 0x8000) >> 16)
3c752965 SR	164	&& entry->jump[1] == 0x398c0000 + (val & 0xffff))
1da177e4 LT	165	return 1;
	166	return 0;
	167	}
	168
	169	/* Set up a trampoline in the PLT to bounce us to the distant function */
	170	static uint32_t do_plt_call(void *location,
	171	Elf32_Addr val,
136cd345	172	const Elf32_Shdr *sechdrs,
1da177e4 LT	173	struct module *mod)
	174	{
	175	struct ppc_plt_entry *entry;
	176
c7d1f6af	177	pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location);
1da177e4	178	/* Init, or core PLT? */
7523e4dc RR	179	if (location >= mod->core_layout.base
7523e4dc RR	180	&& location < mod->core_layout.base + mod->core_layout.size)
1da177e4 LT	181	entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
	182	else
	183	entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;
	184
	185	/* Find this entry, or if that fails, the next avail. entry */
	186	while (entry->jump[0]) {
	187	if (entry_matches(entry, val)) return (uint32_t)entry;
	188	entry++;
	189	}
	190
3c752965 SR	191	entry->jump[0] = 0x3d800000+((val+0x8000)>>16); /* lis r12,sym@ha */
	192	entry->jump[1] = 0x398c0000 + (val&0xffff); /* addi r12,r12,sym@l*/
	193	entry->jump[2] = 0x7d8903a6; /* mtctr r12 */
1da177e4 LT	194	entry->jump[3] = 0x4e800420; /* bctr */
1da177e4 LT	195
c7d1f6af	196	pr_debug("Initialized plt for 0x%x at %p\n", val, entry);
1da177e4 LT	197	return (uint32_t)entry;
	198	}
	199
	200	int apply_relocate_add(Elf32_Shdr *sechdrs,
	201	const char *strtab,
	202	unsigned int symindex,
	203	unsigned int relsec,
	204	struct module *module)
	205	{
	206	unsigned int i;
	207	Elf32_Rela rela = (void )sechdrs[relsec].sh_addr;
	208	Elf32_Sym *sym;
	209	uint32_t *location;
	210	uint32_t value;
	211
c7d1f6af	212	pr_debug("Applying ADD relocate section %u to %u\n", relsec,
1da177e4 LT	213	sechdrs[relsec].sh_info);
	214	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
	215	/* This is where to make the change */
	216	location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
	217	+ rela[i].r_offset;
	218	/* This is the symbol it is referring to. Note that all
	219	undefined symbols have been resolved. */
	220	sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
	221	+ ELF32_R_SYM(rela[i].r_info);
	222	/* `Everything is relative'. */
	223	value = sym->st_value + rela[i].r_addend;
	224
	225	switch (ELF32_R_TYPE(rela[i].r_info)) {
	226	case R_PPC_ADDR32:
	227	/* Simply set it */
	228	(uint32_t )location = value;
	229	break;
	230
	231	case R_PPC_ADDR16_LO:
	232	/* Low half of the symbol */
	233	(uint16_t )location = value;
	234	break;
9a3d6458 SV	235
	236	case R_PPC_ADDR16_HI:
	237	/* Higher half of the symbol */
	238	(uint16_t )location = (value >> 16);
	239	break;
	240
1da177e4 LT	241	case R_PPC_ADDR16_HA:
	242	/* Sign-adjusted lower 16 bits: PPC ELF ABI says:
	243	(((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF.
	244	This is the same, only sane.
	245	*/
	246	(uint16_t )location = (value + 0x8000) >> 16;
	247	break;
	248
	249	case R_PPC_REL24:
	250	if ((int)(value - (uint32_t)location) < -0x02000000
	251	\|\| (int)(value - (uint32_t)location) >= 0x02000000)
	252	value = do_plt_call(location, value,
	253	sechdrs, module);
	254
	255	/* Only replace bits 2 through 26 */
c7d1f6af	256	pr_debug("REL24 value = %08X. location = %08X\n",
1da177e4	257	value, (uint32_t)location);
c7d1f6af	258	pr_debug("Location before: %08X.\n",
1da177e4 LT	259	(uint32_t )location);
	260	(uint32_t )location
	261	= ((uint32_t )location & ~0x03fffffc)
	262	\| ((value - (uint32_t)location)
	263	& 0x03fffffc);
c7d1f6af	264	pr_debug("Location after: %08X.\n",
1da177e4	265	(uint32_t )location);
c7d1f6af	266	pr_debug("ie. jump to %08X+%08X = %08X\n",
1da177e4 LT	267	(uint32_t )location & 0x03fffffc,
	268	(uint32_t)location,
	269	((uint32_t )location & 0x03fffffc)
	270	+ (uint32_t)location);
	271	break;
	272
	273	case R_PPC_REL32:
	274	/* 32-bit relative jump. */
	275	(uint32_t )location = value - (uint32_t)location;
	276	break;
	277
	278	default:
c7d1f6af	279	pr_err("%s: unknown ADD relocation: %u\n",
1da177e4 LT	280	module->name,
	281	ELF32_R_TYPE(rela[i].r_info));
	282	return -ENOEXEC;
	283	}
	284	}
136cd345 ME	285
	286	return 0;
	287	}
	288
7cc45e64	289	#ifdef CONFIG_DYNAMIC_FTRACE
136cd345 ME	290	int module_finalize_ftrace(struct module module, const Elf_Shdr sechdrs)
	291	{
	292	module->arch.tramp = do_plt_call(module->core_layout.base,
	293	(unsigned long)ftrace_caller,
	294	sechdrs, module);
	295	if (!module->arch.tramp)
	296	return -ENOENT;
	297
1da177e4 LT	298	return 0;
1da177e4 LT	299	}
136cd345	300	#endif