v4.19.13 snapshot.
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
new file mode 100644
index 0000000..84f001d
--- /dev/null
+++ b/tools/objtool/special.c
@@ -0,0 +1,193 @@
+/*
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * This file reads all the special sections which have alternate instructions
+ * which can be patched in or redirected to at runtime.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#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->d_buf + offset +
+ entry->orig_len);
+ alt->new_len = *(unsigned char *)(sec->data->d_buf + offset +
+ entry->new_len);
+ }
+
+ if (entry->feature) {
+ unsigned short feature;
+
+ feature = *(unsigned short *)(sec->data->d_buf + 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;
+}