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-rw-r--r--tools/objtool/builtin-check.c145
1 files changed, 100 insertions, 45 deletions
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index cdbdd7d9333a..cf1e48dbfa97 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -61,6 +61,7 @@ struct alternative {
struct objtool_file {
struct elf *elf;
struct list_head insn_list;
+ struct section *rodata;
};
const char *objname;
@@ -599,73 +600,125 @@ out:
return ret;
}
-/*
- * For some switch statements, gcc generates a jump table in the .rodata
- * section which contains a list of addresses within the function to jump to.
- * This finds these jump tables and adds them to the insn->alts lists.
- */
-static int add_switch_table_alts(struct objtool_file *file)
+static int add_switch_table(struct objtool_file *file, struct symbol *func,
+ struct instruction *insn, struct rela *table,
+ struct rela *next_table)
{
- struct instruction *insn, *alt_insn;
- struct rela *rodata_rela, *text_rela;
- struct section *rodata;
- struct symbol *func;
+ struct rela *rela = table;
+ struct instruction *alt_insn;
struct alternative *alt;
- for_each_insn(file, insn) {
+ list_for_each_entry_from(rela, &file->rodata->rela->rela_list, list) {
+ if (rela == next_table)
+ break;
+
+ if (rela->sym->sec != insn->sec ||
+ rela->addend <= func->offset ||
+ rela->addend >= func->offset + func->len)
+ break;
+
+ alt_insn = find_insn(file, insn->sec, rela->addend);
+ if (!alt_insn) {
+ WARN("%s: can't find instruction at %s+0x%x",
+ file->rodata->rela->name, insn->sec->name,
+ rela->addend);
+ return -1;
+ }
+
+ alt = malloc(sizeof(*alt));
+ if (!alt) {
+ WARN("malloc failed");
+ return -1;
+ }
+
+ alt->insn = alt_insn;
+ list_add_tail(&alt->list, &insn->alts);
+ }
+
+ return 0;
+}
+
+static int add_func_switch_tables(struct objtool_file *file,
+ struct symbol *func)
+{
+ struct instruction *insn, *prev_jump;
+ struct rela *text_rela, *rodata_rela, *prev_rela;
+ int ret;
+
+ prev_jump = NULL;
+
+ func_for_each_insn(file, func, insn) {
if (insn->type != INSN_JUMP_DYNAMIC)
continue;
text_rela = find_rela_by_dest_range(insn->sec, insn->offset,
insn->len);
- if (!text_rela || strcmp(text_rela->sym->name, ".rodata"))
- continue;
-
- rodata = find_section_by_name(file->elf, ".rodata");
- if (!rodata || !rodata->rela)
+ if (!text_rela || text_rela->sym != file->rodata->sym)
continue;
/* common case: jmpq *[addr](,%rax,8) */
- rodata_rela = find_rela_by_dest(rodata, text_rela->addend);
+ rodata_rela = find_rela_by_dest(file->rodata,
+ text_rela->addend);
- /* rare case: jmpq *[addr](%rip) */
+ /*
+ * TODO: Document where this is needed, or get rid of it.
+ *
+ * rare case: jmpq *[addr](%rip)
+ */
if (!rodata_rela)
- rodata_rela = find_rela_by_dest(rodata,
+ rodata_rela = find_rela_by_dest(file->rodata,
text_rela->addend + 4);
+
if (!rodata_rela)
continue;
- func = find_containing_func(insn->sec, insn->offset);
- if (!func) {
- WARN_FUNC("can't find containing func",
- insn->sec, insn->offset);
- return -1;
+ /*
+ * We found a switch table, but we don't know yet how big it
+ * is. Don't add it until we reach the end of the function or
+ * the beginning of another switch table in the same function.
+ */
+ if (prev_jump) {
+ ret = add_switch_table(file, func, prev_jump, prev_rela,
+ rodata_rela);
+ if (ret)
+ return ret;
}
- list_for_each_entry_from(rodata_rela, &rodata->rela->rela_list,
- list) {
- if (rodata_rela->sym->sec != insn->sec ||
- rodata_rela->addend <= func->offset ||
- rodata_rela->addend >= func->offset + func->len)
- break;
+ prev_jump = insn;
+ prev_rela = rodata_rela;
+ }
- alt_insn = find_insn(file, insn->sec,
- rodata_rela->addend);
- if (!alt_insn) {
- WARN("%s: can't find instruction at %s+0x%x",
- rodata->rela->name, insn->sec->name,
- rodata_rela->addend);
- return -1;
- }
+ if (prev_jump) {
+ ret = add_switch_table(file, func, prev_jump, prev_rela, NULL);
+ if (ret)
+ return ret;
+ }
- alt = malloc(sizeof(*alt));
- if (!alt) {
- WARN("malloc failed");
- return -1;
- }
+ return 0;
+}
- alt->insn = alt_insn;
- list_add_tail(&alt->list, &insn->alts);
+/*
+ * For some switch statements, gcc generates a jump table in the .rodata
+ * section which contains a list of addresses within the function to jump to.
+ * This finds these jump tables and adds them to the insn->alts lists.
+ */
+static int add_switch_table_alts(struct objtool_file *file)
+{
+ struct section *sec;
+ struct symbol *func;
+ int ret;
+
+ if (!file->rodata || !file->rodata->rela)
+ return 0;
+
+ list_for_each_entry(sec, &file->elf->sections, list) {
+ list_for_each_entry(func, &sec->symbol_list, list) {
+ if (func->type != STT_FUNC)
+ continue;
+
+ ret = add_func_switch_tables(file, func);
+ if (ret)
+ return ret;
}
}
@@ -676,6 +729,8 @@ static int decode_sections(struct objtool_file *file)
{
int ret;
+ file->rodata = find_section_by_name(file->elf, ".rodata");
+
ret = decode_instructions(file);
if (ret)
return ret;