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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212/* SPDX-License-Identifier: GPL-2.0 * * Copyright (C) 2014-2017 Linaro Ltd. <ard.biesheuvel@linaro.org> * * Copyright (C) 2018 Andes Technology Corporation <zong@andestech.com> */
#include <linux/elf.h>#include <linux/kernel.h>#include <linux/module.h>#include <linux/moduleloader.h>#include <linux/sort.h>
unsigned long module_emit_got_entry(struct module *mod, unsigned long val){ struct mod_section *got_sec = &mod->arch.got; int i = got_sec->num_entries; struct got_entry *got = get_got_entry(val, got_sec);
if (got) return (unsigned long)got;
/* There is no duplicate entry, create a new one */ got = (struct got_entry *)got_sec->shdr->sh_addr; got[i] = emit_got_entry(val);
got_sec->num_entries++; BUG_ON(got_sec->num_entries > got_sec->max_entries);
return (unsigned long)&got[i];}
unsigned long module_emit_plt_entry(struct module *mod, unsigned long val){ struct mod_section *got_plt_sec = &mod->arch.got_plt; struct got_entry *got_plt; struct mod_section *plt_sec = &mod->arch.plt; struct plt_entry *plt = get_plt_entry(val, plt_sec, got_plt_sec); int i = plt_sec->num_entries;
if (plt) return (unsigned long)plt;
/* There is no duplicate entry, create a new one */ got_plt = (struct got_entry *)got_plt_sec->shdr->sh_addr; got_plt[i] = emit_got_entry(val); plt = (struct plt_entry *)plt_sec->shdr->sh_addr; plt[i] = emit_plt_entry(val, (unsigned long)&plt[i], (unsigned long)&got_plt[i]);
plt_sec->num_entries++; got_plt_sec->num_entries++; BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
return (unsigned long)&plt[i];}
static int cmp_rela(const void *a, const void *b){ const Elf_Rela *x = a, *y = b; int i;
/* sort by type, symbol index and addend */ i = cmp_int(x->r_info, y->r_info); if (i == 0) i = cmp_int(x->r_addend, y->r_addend); return i;}
static bool duplicate_rela(const Elf_Rela *rela, int idx){ /* * Entries are sorted by type, symbol index and addend. That means * that, if a duplicate entry exists, it must be in the preceding slot. */ return idx > 0 && cmp_rela(rela + idx, rela + idx - 1) == 0;}
static void count_max_entries(const Elf_Rela *relas, size_t num, unsigned int *plts, unsigned int *gots){ for (size_t i = 0; i < num; i++) { if (duplicate_rela(relas, i)) continue;
switch (ELF_R_TYPE(relas[i].r_info)) { case R_RISCV_CALL_PLT: case R_RISCV_PLT32: (*plts)++; break; case R_RISCV_GOT_HI20: (*gots)++; break; default: unreachable(); } }}
static bool rela_needs_plt_got_entry(const Elf_Rela *rela){ switch (ELF_R_TYPE(rela->r_info)) { case R_RISCV_CALL_PLT: case R_RISCV_GOT_HI20: case R_RISCV_PLT32: return true; default: return false; }}
int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, char *secstrings, struct module *mod){ size_t num_scratch_relas = 0; unsigned int num_plts = 0; unsigned int num_gots = 0; Elf_Rela *scratch = NULL; Elf_Rela *new_scratch; size_t scratch_size = 0; int i;
/* * Find the empty .got and .plt sections. */ for (i = 0; i < ehdr->e_shnum; i++) { if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt")) mod->arch.plt.shdr = sechdrs + i; else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got")) mod->arch.got.shdr = sechdrs + i; else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got.plt")) mod->arch.got_plt.shdr = sechdrs + i; }
if (!mod->arch.plt.shdr) { pr_err("%s: module PLT section(s) missing\n", mod->name); return -ENOEXEC; } if (!mod->arch.got.shdr) { pr_err("%s: module GOT section(s) missing\n", mod->name); return -ENOEXEC; } if (!mod->arch.got_plt.shdr) { pr_err("%s: module GOT.PLT section(s) missing\n", mod->name); return -ENOEXEC; }
/* Calculate the maximum number of entries */ for (i = 0; i < ehdr->e_shnum; i++) { size_t num_relas = 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; size_t scratch_size_needed;
if (sechdrs[i].sh_type != SHT_RELA) continue;
/* ignore relocations that operate on non-exec sections */ if (!(dst_sec->sh_flags & SHF_EXECINSTR)) continue;
/* * apply_relocate_add() relies on HI20 and LO12 relocation pairs being * close together, so sort a copy of the section to avoid interfering. */ scratch_size_needed = (num_scratch_relas + num_relas) * sizeof(*scratch); if (scratch_size_needed > scratch_size) { scratch_size = scratch_size_needed; new_scratch = kvrealloc(scratch, scratch_size, GFP_KERNEL); if (!new_scratch) { kvfree(scratch); return -ENOMEM; } scratch = new_scratch; }
for (size_t j = 0; j < num_relas; j++) if (rela_needs_plt_got_entry(&relas[j])) scratch[num_scratch_relas++] = relas[j]; }
if (scratch) { /* sort the accumulated PLT/GOT relocations so duplicates are adjacent */ sort(scratch, num_scratch_relas, sizeof(*scratch), cmp_rela, NULL); count_max_entries(scratch, num_scratch_relas, &num_plts, &num_gots); kvfree(scratch); }
mod->arch.plt.shdr->sh_type = SHT_NOBITS; mod->arch.plt.shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC; mod->arch.plt.shdr->sh_addralign = L1_CACHE_BYTES; mod->arch.plt.shdr->sh_size = (num_plts + 1) * sizeof(struct plt_entry); mod->arch.plt.num_entries = 0; mod->arch.plt.max_entries = num_plts;
mod->arch.got.shdr->sh_type = SHT_NOBITS; mod->arch.got.shdr->sh_flags = SHF_ALLOC; mod->arch.got.shdr->sh_addralign = L1_CACHE_BYTES; mod->arch.got.shdr->sh_size = (num_gots + 1) * sizeof(struct got_entry); mod->arch.got.num_entries = 0; mod->arch.got.max_entries = num_gots;
mod->arch.got_plt.shdr->sh_type = SHT_NOBITS; mod->arch.got_plt.shdr->sh_flags = SHF_ALLOC; mod->arch.got_plt.shdr->sh_addralign = L1_CACHE_BYTES; mod->arch.got_plt.shdr->sh_size = (num_plts + 1) * sizeof(struct got_entry); mod->arch.got_plt.num_entries = 0; mod->arch.got_plt.max_entries = num_plts; return 0;}