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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187// 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/moduleloader.h>#include <linux/ftrace.h>#include <linux/sort.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];}
#define cmp_3way(a, b) ((a) < (b) ? -1 : (a) > (b))
static int compare_rela(const void *x, const void *y){ int ret; const Elf_Rela *rela_x = x, *rela_y = y;
ret = cmp_3way(rela_x->r_info, rela_y->r_info); if (ret == 0) ret = cmp_3way(rela_x->r_addend, rela_y->r_addend);
return ret;}
static void count_max_entries(Elf_Rela *relas, int num, unsigned int *plts, unsigned int *gots){ unsigned int i;
sort(relas, num, sizeof(Elf_Rela), compare_rela, NULL);
for (i = 0; i < num; i++) { if (i && !compare_rela(&relas[i-1], &relas[i])) continue;
switch (ELF_R_TYPE(relas[i].r_info)) { case R_LARCH_SOP_PUSH_PLT_PCREL: case R_LARCH_B26: (*plts)++; break; case R_LARCH_GOT_PC_HI20: case R_LARCH_GOT_PCADD_HI20: (*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;}