/* * Copyright (C) 2015 Josh Poimboeuf * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see . */ /* * This file reads all the special sections which have alternate instructions * which can be patched in or redirected to at runtime. */ #include #include #include "special.h" #include "warn.h" #define EX_ENTRY_SIZE 12 #define EX_ORIG_OFFSET 0 #define EX_NEW_OFFSET 4 #define JUMP_ENTRY_SIZE 24 #define JUMP_ORIG_OFFSET 0 #define JUMP_NEW_OFFSET 8 #define ALT_ENTRY_SIZE 13 #define ALT_ORIG_OFFSET 0 #define ALT_NEW_OFFSET 4 #define ALT_FEATURE_OFFSET 8 #define ALT_ORIG_LEN_OFFSET 10 #define ALT_NEW_LEN_OFFSET 11 #define X86_FEATURE_POPCNT (4*32+23) struct special_entry { const char *sec; bool group, jump_or_nop; unsigned char size, orig, new; unsigned char orig_len, new_len; /* group only */ unsigned char feature; /* ALTERNATIVE macro CPU feature */ }; struct special_entry entries[] = { { .sec = ".altinstructions", .group = true, .size = ALT_ENTRY_SIZE, .orig = ALT_ORIG_OFFSET, .orig_len = ALT_ORIG_LEN_OFFSET, .new = ALT_NEW_OFFSET, .new_len = ALT_NEW_LEN_OFFSET, .feature = ALT_FEATURE_OFFSET, }, { .sec = "__jump_table", .jump_or_nop = true, .size = JUMP_ENTRY_SIZE, .orig = JUMP_ORIG_OFFSET, .new = JUMP_NEW_OFFSET, }, { .sec = "__ex_table", .size = EX_ENTRY_SIZE, .orig = EX_ORIG_OFFSET, .new = EX_NEW_OFFSET, }, {}, }; static int get_alt_entry(struct elf *elf, struct special_entry *entry, struct section *sec, int idx, struct special_alt *alt) { struct rela *orig_rela, *new_rela; unsigned long offset; offset = idx * entry->size; alt->group = entry->group; alt->jump_or_nop = entry->jump_or_nop; if (alt->group) { alt->orig_len = *(unsigned char *)(sec->data + offset + entry->orig_len); alt->new_len = *(unsigned char *)(sec->data + offset + entry->new_len); } if (entry->feature) { unsigned short feature; feature = *(unsigned short *)(sec->data + offset + entry->feature); /* * It has been requested that we don't validate the !POPCNT * feature path which is a "very very small percentage of * machines". */ if (feature == X86_FEATURE_POPCNT) alt->skip_orig = true; } orig_rela = find_rela_by_dest(sec, offset + entry->orig); if (!orig_rela) { WARN_FUNC("can't find orig rela", sec, offset + entry->orig); return -1; } if (orig_rela->sym->type != STT_SECTION) { WARN_FUNC("don't know how to handle non-section rela symbol %s", sec, offset + entry->orig, orig_rela->sym->name); return -1; } alt->orig_sec = orig_rela->sym->sec; alt->orig_off = orig_rela->addend; if (!entry->group || alt->new_len) { new_rela = find_rela_by_dest(sec, offset + entry->new); if (!new_rela) { WARN_FUNC("can't find new rela", sec, offset + entry->new); return -1; } alt->new_sec = new_rela->sym->sec; alt->new_off = (unsigned int)new_rela->addend; /* _ASM_EXTABLE_EX hack */ if (alt->new_off >= 0x7ffffff0) alt->new_off -= 0x7ffffff0; } return 0; } /* * Read all the special sections and create a list of special_alt structs which * describe all the alternate instructions which can be patched in or * redirected to at runtime. */ int special_get_alts(struct elf *elf, struct list_head *alts) { struct special_entry *entry; struct section *sec; unsigned int nr_entries; struct special_alt *alt; int idx, ret; INIT_LIST_HEAD(alts); for (entry = entries; entry->sec; entry++) { sec = find_section_by_name(elf, entry->sec); if (!sec) continue; if (sec->len % entry->size != 0) { WARN("%s size not a multiple of %d", sec->name, entry->size); return -1; } nr_entries = sec->len / entry->size; for (idx = 0; idx < nr_entries; idx++) { alt = malloc(sizeof(*alt)); if (!alt) { WARN("malloc failed"); return -1; } memset(alt, 0, sizeof(*alt)); ret = get_alt_entry(elf, entry, sec, idx, alt); if (ret) return ret; list_add_tail(&alt->list, alts); } } return 0; } ='ctrl'>
authorLinus Torvalds <torvalds@linux-foundation.org>2017-01-16 09:34:37 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-16 09:34:37 -0800
commit2eabb8b8d68bc9c7779ba8b04bec8d4f8baed0bc (patch)
tree4d8ea8e6ca52f1938269937834641205d8d888f0 /kernel/pid_namespace.c
parent49def1853334396f948dcb4cedb9347abb318df5 (diff)
parentce1ca7d2d140a1f4aaffd297ac487f246963dd2f (diff)
Merge tag 'nfsd-4.10-1' of git://linux-nfs.org/~bfields/linux
Pull nfsd fixes from Bruce Fields: "Miscellaneous nfsd bugfixes, one for a 4.10 regression, three for older bugs" * tag 'nfsd-4.10-1' of git://linux-nfs.org/~bfields/linux: svcrdma: avoid duplicate dma unmapping during error recovery sunrpc: don't call sleeping functions from the notifier block callbacks svcrpc: don't leak contexts on PROC_DESTROY nfsd: fix supported attributes for acl & labels
Diffstat (limited to 'kernel/pid_namespace.c')