objtool: Fix segfault in .cold detection with -ffunction-sections

[GitHub/moto-9609/android_kernel_motorola_exynos9610.git] / tools / objtool / elf.c

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 24460155c82c9b2305a2484d037be9017a00becb..dd4ed7c3c062608cbd87a44592996a7578cc8772 100644 (file)
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -26,10 +26,13 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <errno.h>
 
 #include "elf.h"
 #include "warn.h"
 
+#define MAX_NAME_LEN 128
+
 struct section *find_section_by_name(struct elf *elf, const char *name)
 {
        struct section *sec;
@@ -78,6 +81,19 @@ 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;
@@ -202,10 +218,11 @@ 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) {
@@ -280,6 +297,54 @@ 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) {
+                       char pname[MAX_NAME_LEN + 1];
+                       size_t pnamelen;
+                       if (sym->type != STT_FUNC)
+                               continue;
+                       sym->pfunc = sym->cfunc = sym;
+                       coldstr = strstr(sym->name, ".cold.");
+                       if (!coldstr)
+                               continue;
+
+                       pnamelen = coldstr - sym->name;
+                       if (pnamelen > MAX_NAME_LEN) {
+                               WARN("%s(): parent function name exceeds maximum length of %d characters",
+                                    sym->name, MAX_NAME_LEN);
+                               return -1;
+                       }
+
+                       strncpy(pname, sym->name, pnamelen);
+                       pname[pnamelen] = '\0';
+                       pfunc = find_symbol_by_name(elf, pname);
+
+                       if (!pfunc) {
+                               WARN("%s(): can't find parent function",
+                                    sym->name);
+                               return -1;
+                       }
+
+                       sym->pfunc = pfunc;
+                       pfunc->cfunc = sym;
+
+                       /*
+                        * Unfortunately, -fnoreorder-functions puts the child
+                        * inside the parent.  Remove the overlap so we can
+                        * have sane assumptions.
+                        *
+                        * Note that pfunc->len now no longer matches
+                        * pfunc->sym.st_size.
+                        */
+                       if (sym->sec == pfunc->sec &&
+                           sym->offset >= pfunc->offset &&
+                           sym->offset + sym->len == pfunc->offset + pfunc->len) {
+                               pfunc->len -= sym->len;
+                       }
+               }
+       }
+
        return 0;
 
 err:
@@ -358,7 +423,8 @@ struct elf *elf_open(const char *name, int flags)
 
        elf->fd = open(name, flags);
        if (elf->fd == -1) {
-               perror("open");
+               fprintf(stderr, "objtool: Can't open '%s': %s\n",
+                       name, strerror(errno));
                goto err;
        }