3 files changed, 93 insertions, 44 deletions

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 264522d4e4af..14daf6a27d9f 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -59,6 +59,31 @@ static struct instruction *next_insn_same_sec(struct objtool_file *file,
         return next;
 }
 
+static struct instruction *next_insn_same_func(struct objtool_file *file,
+                                               struct instruction *insn)
+{
+        struct instruction *next = list_next_entry(insn, list);
+        struct symbol *func = insn->func;
+
+        if (!func)
+                return NULL;
+
+        if (&next->list != &file->insn_list && next->func == func)
+                return next;
+
+        /* Check if we're already in the subfunction: */
+        if (func == func->cfunc)
+                return NULL;
+
+        /* Move to the subfunction: */
+        return find_insn(file, func->cfunc->sec, func->cfunc->offset);
+}
+
+#define func_for_each_insn_all(file, func, insn)                        \
+        for (insn = find_insn(file, func->sec, func->offset);           \
+             insn;                                                      \
+             insn = next_insn_same_func(file, insn))
+
 #define func_for_each_insn(file, func, insn)                            \
         for (insn = find_insn(file, func->sec, func->offset);           \
              insn && &insn->list != &file->insn_list &&                 \
@@ -149,10 +174,14 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
                         if (!strcmp(func->name, global_noreturns[i]))
                                 return 1;
 
-        if (!func->sec)
+        if (!func->len)
                 return 0;
 
-        func_for_each_insn(file, func, insn) {
+        insn = find_insn(file, func->sec, func->offset);
+        if (!insn->func)
+                return 0;
+
+        func_for_each_insn_all(file, func, insn) {
                 empty = false;
 
                 if (insn->type == INSN_RETURN)
@@ -167,28 +196,17 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
          * case, the function's dead-end status depends on whether the target
          * of the sibling call returns.
          */
-        func_for_each_insn(file, func, insn) {
-                if (insn->sec != func->sec ||
-                    insn->offset >= func->offset + func->len)
-                        break;
-
+        func_for_each_insn_all(file, func, insn) {
                 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
                         struct instruction *dest = insn->jump_dest;
-                        struct symbol *dest_func;
 
                         if (!dest)
                                 /* sibling call to another file */
                                 return 0;
 
-                        if (dest->sec != func->sec ||
-                            dest->offset < func->offset ||
-                            dest->offset >= func->offset + func->len) {
-                                /* local sibling call */
-                                dest_func = find_symbol_by_offset(dest->sec,
-                                                                  dest->offset);
-                                if (!dest_func)
-                                        continue;
+                        if (dest->func && dest->func->pfunc != insn->func->pfunc) {
 
+                                /* local sibling call */
                                 if (recursion == 5) {
                                         /*
                                          * Infinite recursion: two functions
@@ -199,7 +217,7 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
                                         return 0;
                                 }
 
-                                return __dead_end_function(file, dest_func,
+                                return __dead_end_function(file, dest->func,
                                                            recursion + 1);
                         }
                 }
@@ -426,7 +444,7 @@ static void add_ignores(struct objtool_file *file)
                         if (!ignore_func(file, func))
                                 continue;
 
-                        func_for_each_insn(file, func, insn)
+                        func_for_each_insn_all(file, func, insn)
                                 insn->ignore = true;
                 }
         }
@@ -786,9 +804,8 @@ out:
         return ret;
 }
 
-static int add_switch_table(struct objtool_file *file, struct symbol *func,
-                            struct instruction *insn, struct rela *table,
-                            struct rela *next_table)
+static int add_switch_table(struct objtool_file *file, struct instruction *insn,
+                            struct rela *table, struct rela *next_table)
 {
         struct rela *rela = table;
         struct instruction *alt_insn;
@@ -798,18 +815,13 @@ static int add_switch_table(struct objtool_file *file, struct symbol *func,
                 if (rela == next_table)
                         break;
 
-                if (rela->sym->sec != insn->sec ||
-                    rela->addend <= func->offset ||
-                    rela->addend >= func->offset + func->len)
+                alt_insn = find_insn(file, rela->sym->sec, rela->addend);
+                if (!alt_insn)
                         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;
-                }
+                /* Make sure the jmp dest is in the function or subfunction: */
+                if (alt_insn->func->pfunc != insn->func->pfunc)
+                        break;
 
                 alt = malloc(sizeof(*alt));
                 if (!alt) {
@@ -947,7 +959,7 @@ static int add_func_switch_tables(struct objtool_file *file,
         struct rela *rela, *prev_rela = NULL;
         int ret;
 
-        func_for_each_insn(file, func, insn) {
+        func_for_each_insn_all(file, func, insn) {
                 if (!last)
                         last = insn;
 
@@ -978,8 +990,7 @@ static int add_func_switch_tables(struct objtool_file *file,
                  * the beginning of another switch table in the same function.
                  */
                 if (prev_jump) {
-                        ret = add_switch_table(file, func, prev_jump, prev_rela,
-                                               rela);
+                        ret = add_switch_table(file, prev_jump, prev_rela, rela);
                         if (ret)
                                 return ret;
                 }
@@ -989,7 +1000,7 @@ static int add_func_switch_tables(struct objtool_file *file,
         }
 
         if (prev_jump) {
-                ret = add_switch_table(file, func, prev_jump, prev_rela, NULL);
+                ret = add_switch_table(file, prev_jump, prev_rela, NULL);
                 if (ret)
                         return ret;
         }
@@ -1753,15 +1764,13 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
         while (1) {
                 next_insn = next_insn_same_sec(file, insn);
 
-
-                if (file->c_file && func && insn->func && func != insn->func) {
+                if (file->c_file && func && insn->func && func != insn->func->pfunc) {
                         WARN("%s() falls through to next function %s()",
                              func->name, insn->func->name);
                         return 1;
                 }
 
-                if (insn->func)
-                        func = insn->func;
+                func = insn->func ? insn->func->pfunc : NULL;
 
                 if (func && insn->ignore) {
                         WARN_FUNC("BUG: why am I validating an ignored function?",
@@ -1782,7 +1791,7 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
 
                                 i = insn;
                                 save_insn = NULL;
-                                func_for_each_insn_continue_reverse(file, func, i) {
+                                func_for_each_insn_continue_reverse(file, insn->func, i) {
                                         if (i->save) {
                                                 save_insn = i;
                                                 break;
@@ -1869,7 +1878,7 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
                 case INSN_JUMP_UNCONDITIONAL:
                         if (insn->jump_dest &&
                             (!func || !insn->jump_dest->func ||
-                             func == insn->jump_dest->func)) {
+                             insn->jump_dest->func->pfunc == func)) {
                                 ret = validate_branch(file, insn->jump_dest,
                                                       state);
                                 if (ret)
@@ -2064,7 +2073,7 @@ static int validate_functions(struct objtool_file *file)
 
         for_each_sec(file, sec) {
                 list_for_each_entry(func, &sec->symbol_list, list) {
-                        if (func->type != STT_FUNC)
+                        if (func->type != STT_FUNC || func->pfunc != func)
                                 continue;
 
                         insn = find_insn(file, sec, func->offset);
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index c1c338661699..4e60e105583e 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -79,6 +79,19 @@ struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
         return NULL;
 }
 
+struct symbol *find_symbol_by_name(struct elf *elf, const char *name)
+{
+        struct section *sec;
+        struct symbol *sym;
+
+        list_for_each_entry(sec, &elf->sections, list)
+                list_for_each_entry(sym, &sec->symbol_list, list)
+                        if (!strcmp(sym->name, name))
+                                return sym;
+
+        return NULL;
+}
+
 struct symbol *find_symbol_containing(struct section *sec, unsigned long offset)
 {
         struct symbol *sym;
@@ -203,10 +216,11 @@ static int read_sections(struct elf *elf)
 
 static int read_symbols(struct elf *elf)
 {
-        struct section *symtab;
-        struct symbol *sym;
+        struct section *symtab, *sec;
+        struct symbol *sym, *pfunc;
         struct list_head *entry, *tmp;
         int symbols_nr, i;
+        char *coldstr;
 
         symtab = find_section_by_name(elf, ".symtab");
         if (!symtab) {
@@ -281,6 +295,30 @@ static int read_symbols(struct elf *elf)
                 hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx);
         }
 
+        /* Create parent/child links for any cold subfunctions */
+        list_for_each_entry(sec, &elf->sections, list) {
+                list_for_each_entry(sym, &sec->symbol_list, list) {
+                        if (sym->type != STT_FUNC)
+                                continue;
+                        sym->pfunc = sym->cfunc = sym;
+                        coldstr = strstr(sym->name, ".cold.");
+                        if (coldstr) {
+                                coldstr[0] = '\0';
+                                pfunc = find_symbol_by_name(elf, sym->name);
+                                coldstr[0] = '.';
+
+                                if (!pfunc) {
+                                        WARN("%s(): can't find parent function",
+                                             sym->name);
+                                        goto err;
+                                }
+
+                                sym->pfunc = pfunc;
+                                pfunc->cfunc = sym;
+                        }
+                }
+        }
+
         return 0;
 
 err:
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index d86e2ff14466..de5cd2ddded9 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -61,6 +61,7 @@ struct symbol {
         unsigned char bind, type;
         unsigned long offset;
         unsigned int len;
+        struct symbol *pfunc, *cfunc;
 };
 
 struct rela {
@@ -86,6 +87,7 @@ struct elf {
 struct elf *elf_open(const char *name, int flags);
 struct section *find_section_by_name(struct elf *elf, const char *name);
 struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
+struct symbol *find_symbol_by_name(struct elf *elf, const char *name);
 struct symbol *find_symbol_containing(struct section *sec, unsigned long offset);
 struct rela *find_rela_by_dest(struct section *sec, unsigned long offset);
 struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset,