[linux-2.6-block.git] / arch / loongarch / kernel / module-sections.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
 */

#include <linux/elf.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/ftrace.h>

Elf_Addr module_emit_got_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
{
	struct mod_section *got_sec = &mod->arch.got;
	int i = got_sec->num_entries;
	struct got_entry *got = get_got_entry(val, sechdrs, got_sec);

	if (got)
		return (Elf_Addr)got;

	/* There is no GOT entry for val yet, create a new one. */
	got = (struct got_entry *)sechdrs[got_sec->shndx].sh_addr;
	got[i] = emit_got_entry(val);

	got_sec->num_entries++;
	if (got_sec->num_entries > got_sec->max_entries) {
		/*
		 * This may happen when the module contains a GOT_HI20 without
		 * a paired GOT_LO12. Such a module is broken, reject it.
		 */
		pr_err("%s: module contains bad GOT relocation\n", mod->name);
		return 0;
	}

	return (Elf_Addr)&got[i];
}

Elf_Addr module_emit_plt_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
{
	int nr;
	struct mod_section *plt_sec = &mod->arch.plt;
	struct mod_section *plt_idx_sec = &mod->arch.plt_idx;
	struct plt_entry *plt = get_plt_entry(val, sechdrs, plt_sec, plt_idx_sec);
	struct plt_idx_entry *plt_idx;

	if (plt)
		return (Elf_Addr)plt;

	nr = plt_sec->num_entries;

	/* There is no duplicate entry, create a new one */
	plt = (struct plt_entry *)sechdrs[plt_sec->shndx].sh_addr;
	plt[nr] = emit_plt_entry(val);
	plt_idx = (struct plt_idx_entry *)sechdrs[plt_idx_sec->shndx].sh_addr;
	plt_idx[nr] = emit_plt_idx_entry(val);

	plt_sec->num_entries++;
	plt_idx_sec->num_entries++;
	BUG_ON(plt_sec->num_entries > plt_sec->max_entries);

	return (Elf_Addr)&plt[nr];
}

static int is_rela_equal(const Elf_Rela *x, const Elf_Rela *y)
{
	return x->r_info == y->r_info && x->r_addend == y->r_addend;
}

static bool duplicate_rela(const Elf_Rela *rela, int idx)
{
	int i;

	for (i = 0; i < idx; i++) {
		if (is_rela_equal(&rela[i], &rela[idx]))
			return true;
	}

	return false;
}

static void count_max_entries(Elf_Rela *relas, int num,
			      unsigned int *plts, unsigned int *gots)
{
	unsigned int i, type;

	for (i = 0; i < num; i++) {
		type = ELF_R_TYPE(relas[i].r_info);
		switch (type) {
		case R_LARCH_SOP_PUSH_PLT_PCREL:
		case R_LARCH_B26:
			if (!duplicate_rela(relas, i))
				(*plts)++;
			break;
		case R_LARCH_GOT_PC_HI20:
			if (!duplicate_rela(relas, i))
				(*gots)++;
			break;
		default:
			break; /* Do nothing. */
		}
	}
}

int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
			      char *secstrings, struct module *mod)
{
	unsigned int i, num_plts = 0, num_gots = 0;
	Elf_Shdr *got_sec, *plt_sec, *plt_idx_sec, *tramp = NULL;

	/*
	 * Find the empty .plt sections.
	 */
	for (i = 0; i < ehdr->e_shnum; i++) {
		if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
			mod->arch.got.shndx = i;
		else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
			mod->arch.plt.shndx = i;
		else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx"))
			mod->arch.plt_idx.shndx = i;
		else if (!strcmp(secstrings + sechdrs[i].sh_name, ".ftrace_trampoline"))
			tramp = sechdrs + i;
	}

	if (!mod->arch.got.shndx) {
		pr_err("%s: module GOT section(s) missing\n", mod->name);
		return -ENOEXEC;
	}
	if (!mod->arch.plt.shndx) {
		pr_err("%s: module PLT section(s) missing\n", mod->name);
		return -ENOEXEC;
	}
	if (!mod->arch.plt_idx.shndx) {
		pr_err("%s: module PLT.IDX section(s) missing\n", mod->name);
		return -ENOEXEC;
	}

	/* Calculate the maxinum number of entries */
	for (i = 0; i < ehdr->e_shnum; i++) {
		int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela);
		Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset;
		Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info;

		if (sechdrs[i].sh_type != SHT_RELA)
			continue;

		/* ignore relocations that operate on non-exec sections */
		if (!(dst_sec->sh_flags & SHF_EXECINSTR))
			continue;

		count_max_entries(relas, num_rela, &num_plts, &num_gots);
	}

	got_sec = sechdrs + mod->arch.got.shndx;
	got_sec->sh_type = SHT_NOBITS;
	got_sec->sh_flags = SHF_ALLOC;
	got_sec->sh_addralign = L1_CACHE_BYTES;
	got_sec->sh_size = (num_gots + 1) * sizeof(struct got_entry);
	mod->arch.got.num_entries = 0;
	mod->arch.got.max_entries = num_gots;

	plt_sec = sechdrs + mod->arch.plt.shndx;
	plt_sec->sh_type = SHT_NOBITS;
	plt_sec->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
	plt_sec->sh_addralign = L1_CACHE_BYTES;
	plt_sec->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
	mod->arch.plt.num_entries = 0;
	mod->arch.plt.max_entries = num_plts;

	plt_idx_sec = sechdrs + mod->arch.plt_idx.shndx;
	plt_idx_sec->sh_type = SHT_NOBITS;
	plt_idx_sec->sh_flags = SHF_ALLOC;
	plt_idx_sec->sh_addralign = L1_CACHE_BYTES;
	plt_idx_sec->sh_size = (num_plts + 1) * sizeof(struct plt_idx_entry);
	mod->arch.plt_idx.num_entries = 0;
	mod->arch.plt_idx.max_entries = num_plts;

	if (tramp) {
		tramp->sh_type = SHT_NOBITS;
		tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
		tramp->sh_addralign = __alignof__(struct plt_entry);
		tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
	}

	return 0;
}
Commit	Line	Data
fcdfe9d2 HC	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
	4	*/
	5
	6	#include <linux/elf.h>
	7	#include <linux/kernel.h>
	8	#include <linux/module.h>
28ac0a9e	9	#include <linux/ftrace.h>
fcdfe9d2	10
9151dde4	11	Elf_Addr module_emit_got_entry(struct module mod, Elf_Shdr sechdrs, Elf_Addr val)
59b3d4a9 XR	12	{
	13	struct mod_section *got_sec = &mod->arch.got;
	14	int i = got_sec->num_entries;
9151dde4	15	struct got_entry *got = get_got_entry(val, sechdrs, got_sec);
59b3d4a9 XR	16
	17	if (got)
	18	return (Elf_Addr)got;
	19
	20	/* There is no GOT entry for val yet, create a new one. */
9151dde4	21	got = (struct got_entry *)sechdrs[got_sec->shndx].sh_addr;
59b3d4a9 XR	22	got[i] = emit_got_entry(val);
	23
	24	got_sec->num_entries++;
	25	if (got_sec->num_entries > got_sec->max_entries) {
	26	/*
	27	* This may happen when the module contains a GOT_HI20 without
	28	* a paired GOT_LO12. Such a module is broken, reject it.
	29	*/
	30	pr_err("%s: module contains bad GOT relocation\n", mod->name);
	31	return 0;
	32	}
	33
	34	return (Elf_Addr)&got[i];
	35	}
	36
9151dde4	37	Elf_Addr module_emit_plt_entry(struct module mod, Elf_Shdr sechdrs, Elf_Addr val)
fcdfe9d2 HC	38	{
	39	int nr;
	40	struct mod_section *plt_sec = &mod->arch.plt;
	41	struct mod_section *plt_idx_sec = &mod->arch.plt_idx;
9151dde4	42	struct plt_entry *plt = get_plt_entry(val, sechdrs, plt_sec, plt_idx_sec);
fcdfe9d2 HC	43	struct plt_idx_entry *plt_idx;
	44
	45	if (plt)
	46	return (Elf_Addr)plt;
	47
	48	nr = plt_sec->num_entries;
	49
	50	/* There is no duplicate entry, create a new one */
9151dde4	51	plt = (struct plt_entry *)sechdrs[plt_sec->shndx].sh_addr;
fcdfe9d2	52	plt[nr] = emit_plt_entry(val);
9151dde4	53	plt_idx = (struct plt_idx_entry *)sechdrs[plt_idx_sec->shndx].sh_addr;
fcdfe9d2 HC	54	plt_idx[nr] = emit_plt_idx_entry(val);
	55
	56	plt_sec->num_entries++;
	57	plt_idx_sec->num_entries++;
	58	BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
	59
	60	return (Elf_Addr)&plt[nr];
	61	}
	62
	63	static int is_rela_equal(const Elf_Rela x, const Elf_Rela y)
	64	{
	65	return x->r_info == y->r_info && x->r_addend == y->r_addend;
	66	}
	67
	68	static bool duplicate_rela(const Elf_Rela *rela, int idx)
	69	{
	70	int i;
	71
	72	for (i = 0; i < idx; i++) {
	73	if (is_rela_equal(&rela[i], &rela[idx]))
	74	return true;
	75	}
	76
	77	return false;
	78	}
	79
59b3d4a9 XR	80	static void count_max_entries(Elf_Rela *relas, int num,
59b3d4a9 XR	81	unsigned int plts, unsigned int gots)
fcdfe9d2 HC	82	{
	83	unsigned int i, type;
	84
	85	for (i = 0; i < num; i++) {
	86	type = ELF_R_TYPE(relas[i].r_info);
9bd1e380 XR	87	switch (type) {
	88	case R_LARCH_SOP_PUSH_PLT_PCREL:
	89	case R_LARCH_B26:
fcdfe9d2 HC	90	if (!duplicate_rela(relas, i))
fcdfe9d2 HC	91	(*plts)++;
9bd1e380	92	break;
59b3d4a9 XR	93	case R_LARCH_GOT_PC_HI20:
	94	if (!duplicate_rela(relas, i))
	95	(*gots)++;
	96	break;
9bd1e380 XR	97	default:
9bd1e380 XR	98	break; /* Do nothing. */
fcdfe9d2 HC	99	}
	100	}
	101	}
	102
	103	int module_frob_arch_sections(Elf_Ehdr ehdr, Elf_Shdr sechdrs,
	104	char secstrings, struct module mod)
	105	{
59b3d4a9	106	unsigned int i, num_plts = 0, num_gots = 0;
28ac0a9e	107	Elf_Shdr got_sec, plt_sec, plt_idx_sec, tramp = NULL;
fcdfe9d2 HC	108
	109	/*
	110	* Find the empty .plt sections.
	111	*/
	112	for (i = 0; i < ehdr->e_shnum; i++) {
59b3d4a9	113	if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
9151dde4	114	mod->arch.got.shndx = i;
59b3d4a9	115	else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
9151dde4	116	mod->arch.plt.shndx = i;
fcdfe9d2	117	else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx"))
9151dde4	118	mod->arch.plt_idx.shndx = i;
28ac0a9e QZ	119	else if (!strcmp(secstrings + sechdrs[i].sh_name, ".ftrace_trampoline"))
28ac0a9e QZ	120	tramp = sechdrs + i;
fcdfe9d2 HC	121	}
fcdfe9d2 HC	122
9151dde4	123	if (!mod->arch.got.shndx) {
59b3d4a9 XR	124	pr_err("%s: module GOT section(s) missing\n", mod->name);
	125	return -ENOEXEC;
	126	}
9151dde4	127	if (!mod->arch.plt.shndx) {
fcdfe9d2 HC	128	pr_err("%s: module PLT section(s) missing\n", mod->name);
	129	return -ENOEXEC;
	130	}
9151dde4	131	if (!mod->arch.plt_idx.shndx) {
fcdfe9d2 HC	132	pr_err("%s: module PLT.IDX section(s) missing\n", mod->name);
	133	return -ENOEXEC;
	134	}
	135
	136	/* Calculate the maxinum number of entries */
	137	for (i = 0; i < ehdr->e_shnum; i++) {
	138	int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela);
	139	Elf_Rela relas = (void )ehdr + sechdrs[i].sh_offset;
	140	Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info;
	141
	142	if (sechdrs[i].sh_type != SHT_RELA)
	143	continue;
	144
	145	/* ignore relocations that operate on non-exec sections */
	146	if (!(dst_sec->sh_flags & SHF_EXECINSTR))
	147	continue;
	148
59b3d4a9	149	count_max_entries(relas, num_rela, &num_plts, &num_gots);
fcdfe9d2 HC	150	}
fcdfe9d2 HC	151
9151dde4 HC	152	got_sec = sechdrs + mod->arch.got.shndx;
	153	got_sec->sh_type = SHT_NOBITS;
	154	got_sec->sh_flags = SHF_ALLOC;
	155	got_sec->sh_addralign = L1_CACHE_BYTES;
	156	got_sec->sh_size = (num_gots + 1) * sizeof(struct got_entry);
59b3d4a9 XR	157	mod->arch.got.num_entries = 0;
	158	mod->arch.got.max_entries = num_gots;
	159
9151dde4 HC	160	plt_sec = sechdrs + mod->arch.plt.shndx;
	161	plt_sec->sh_type = SHT_NOBITS;
	162	plt_sec->sh_flags = SHF_EXECINSTR \| SHF_ALLOC;
	163	plt_sec->sh_addralign = L1_CACHE_BYTES;
	164	plt_sec->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
fcdfe9d2 HC	165	mod->arch.plt.num_entries = 0;
	166	mod->arch.plt.max_entries = num_plts;
	167
9151dde4 HC	168	plt_idx_sec = sechdrs + mod->arch.plt_idx.shndx;
	169	plt_idx_sec->sh_type = SHT_NOBITS;
	170	plt_idx_sec->sh_flags = SHF_ALLOC;
	171	plt_idx_sec->sh_addralign = L1_CACHE_BYTES;
	172	plt_idx_sec->sh_size = (num_plts + 1) * sizeof(struct plt_idx_entry);
fcdfe9d2 HC	173	mod->arch.plt_idx.num_entries = 0;
	174	mod->arch.plt_idx.max_entries = num_plts;
	175
28ac0a9e QZ	176	if (tramp) {
	177	tramp->sh_type = SHT_NOBITS;
	178	tramp->sh_flags = SHF_EXECINSTR \| SHF_ALLOC;
	179	tramp->sh_addralign = __alignof__(struct plt_entry);
	180	tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
	181	}
	182
fcdfe9d2 HC	183	return 0;
fcdfe9d2 HC	184	}