1 files changed, 206 insertions, 83 deletions

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 93fa833a49a5..d08f5f3670f8 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -211,32 +211,6 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns
 	return find_reloc_by_dest_range(elf, sec, offset, 1);
 }
 
-void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,
-			      struct reloc *reloc)
-{
-	if (sec->sym) {
-		reloc->sym = sec->sym;
-		reloc->addend = offset;
-		return;
-	}
-
-	/*
-	 * The Clang assembler strips section symbols, so we have to reference
-	 * the function symbol instead:
-	 */
-	reloc->sym = find_symbol_containing(sec, offset);
-	if (!reloc->sym) {
-		/*
-		 * Hack alert.  This happens when we need to reference the NOP
-		 * pad insn immediately after the function.
-		 */
-		reloc->sym = find_symbol_containing(sec, offset - 1);
-	}
-
-	if (reloc->sym)
-		reloc->addend = offset - reloc->sym->offset;
-}
-
 static int read_sections(struct elf *elf)
 {
 	Elf_Scn *s = NULL;
@@ -316,12 +290,39 @@ static int read_sections(struct elf *elf)
 	return 0;
 }
 
+static void elf_add_symbol(struct elf *elf, struct symbol *sym)
+{
+	struct list_head *entry;
+	struct rb_node *pnode;
+
+	sym->type = GELF_ST_TYPE(sym->sym.st_info);
+	sym->bind = GELF_ST_BIND(sym->sym.st_info);
+
+	sym->offset = sym->sym.st_value;
+	sym->len = sym->sym.st_size;
+
+	rb_add(&sym->node, &sym->sec->symbol_tree, symbol_to_offset);
+	pnode = rb_prev(&sym->node);
+	if (pnode)
+		entry = &rb_entry(pnode, struct symbol, node)->list;
+	else
+		entry = &sym->sec->symbol_list;
+	list_add(&sym->list, entry);
+	elf_hash_add(elf->symbol_hash, &sym->hash, sym->idx);
+	elf_hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name));
+
+	/*
+	 * Don't store empty STT_NOTYPE symbols in the rbtree.  They
+	 * can exist within a function, confusing the sorting.
+	 */
+	if (!sym->len)
+		rb_erase(&sym->node, &sym->sec->symbol_tree);
+}
+
 static int read_symbols(struct elf *elf)
 {
 	struct section *symtab, *symtab_shndx, *sec;
 	struct symbol *sym, *pfunc;
-	struct list_head *entry;
-	struct rb_node *pnode;
 	int symbols_nr, i;
 	char *coldstr;
 	Elf_Data *shndx_data = NULL;
@@ -366,9 +367,6 @@ static int read_symbols(struct elf *elf)
 			goto err;
 		}
 
-		sym->type = GELF_ST_TYPE(sym->sym.st_info);
-		sym->bind = GELF_ST_BIND(sym->sym.st_info);
-
 		if ((sym->sym.st_shndx > SHN_UNDEF &&
 		     sym->sym.st_shndx < SHN_LORESERVE) ||
 		    (shndx_data && sym->sym.st_shndx == SHN_XINDEX)) {
@@ -381,32 +379,14 @@ static int read_symbols(struct elf *elf)
 				     sym->name);
 				goto err;
 			}
-			if (sym->type == STT_SECTION) {
+			if (GELF_ST_TYPE(sym->sym.st_info) == STT_SECTION) {
 				sym->name = sym->sec->name;
 				sym->sec->sym = sym;
 			}
 		} else
 			sym->sec = find_section_by_index(elf, 0);
 
-		sym->offset = sym->sym.st_value;
-		sym->len = sym->sym.st_size;
-
-		rb_add(&sym->node, &sym->sec->symbol_tree, symbol_to_offset);
-		pnode = rb_prev(&sym->node);
-		if (pnode)
-			entry = &rb_entry(pnode, struct symbol, node)->list;
-		else
-			entry = &sym->sec->symbol_list;
-		list_add(&sym->list, entry);
-		elf_hash_add(elf->symbol_hash, &sym->hash, sym->idx);
-		elf_hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name));
-
-		/*
-		 * Don't store empty STT_NOTYPE symbols in the rbtree.  They
-		 * can exist within a function, confusing the sorting.
-		 */
-		if (!sym->len)
-			rb_erase(&sym->node, &sym->sec->symbol_tree);
+		elf_add_symbol(elf, sym);
 	}
 
 	if (stats)
@@ -473,12 +453,73 @@ err:
 	return -1;
 }
 
-void elf_add_reloc(struct elf *elf, struct reloc *reloc)
+static struct section *elf_create_reloc_section(struct elf *elf,
+						struct section *base,
+						int reltype);
+
+int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
+		  unsigned int type, struct symbol *sym, int addend)
 {
-	struct section *sec = reloc->sec;
+	struct reloc *reloc;
 
-	list_add_tail(&reloc->list, &sec->reloc_list);
+	if (!sec->reloc && !elf_create_reloc_section(elf, sec, SHT_RELA))
+		return -1;
+
+	reloc = malloc(sizeof(*reloc));
+	if (!reloc) {
+		perror("malloc");
+		return -1;
+	}
+	memset(reloc, 0, sizeof(*reloc));
+
+	reloc->sec = sec->reloc;
+	reloc->offset = offset;
+	reloc->type = type;
+	reloc->sym = sym;
+	reloc->addend = addend;
+
+	list_add_tail(&reloc->list, &sec->reloc->reloc_list);
 	elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
+
+	sec->reloc->changed = true;
+
+	return 0;
+}
+
+int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
+			  unsigned long offset, unsigned int type,
+			  struct section *insn_sec, unsigned long insn_off)
+{
+	struct symbol *sym;
+	int addend;
+
+	if (insn_sec->sym) {
+		sym = insn_sec->sym;
+		addend = insn_off;
+
+	} else {
+		/*
+		 * The Clang assembler strips section symbols, so we have to
+		 * reference the function symbol instead:
+		 */
+		sym = find_symbol_containing(insn_sec, insn_off);
+		if (!sym) {
+			/*
+			 * Hack alert.  This happens when we need to reference
+			 * the NOP pad insn immediately after the function.
+			 */
+			sym = find_symbol_containing(insn_sec, insn_off - 1);
+		}
+
+		if (!sym) {
+			WARN("can't find symbol containing %s+0x%lx", insn_sec->name, insn_off);
+			return -1;
+		}
+
+		addend = insn_off - sym->offset;
+	}
+
+	return elf_add_reloc(elf, sec, offset, type, sym, addend);
 }
 
 static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
@@ -558,7 +599,9 @@ static int read_relocs(struct elf *elf)
 				return -1;
 			}
 
-			elf_add_reloc(elf, reloc);
+			list_add_tail(&reloc->list, &sec->reloc_list);
+			elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
+
 			nr_reloc++;
 		}
 		max_reloc = max(max_reloc, nr_reloc);
@@ -636,13 +679,108 @@ err:
 	return NULL;
 }
 
+static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
+{
+	Elf_Data *data;
+	Elf_Scn *s;
+	int len;
+
+	if (!strtab)
+		strtab = find_section_by_name(elf, ".strtab");
+	if (!strtab) {
+		WARN("can't find .strtab section");
+		return -1;
+	}
+
+	s = elf_getscn(elf->elf, strtab->idx);
+	if (!s) {
+		WARN_ELF("elf_getscn");
+		return -1;
+	}
+
+	data = elf_newdata(s);
+	if (!data) {
+		WARN_ELF("elf_newdata");
+		return -1;
+	}
+
+	data->d_buf = str;
+	data->d_size = strlen(str) + 1;
+	data->d_align = 1;
+
+	len = strtab->len;
+	strtab->len += data->d_size;
+	strtab->changed = true;
+
+	return len;
+}
+
+struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name)
+{
+	struct section *symtab;
+	struct symbol *sym;
+	Elf_Data *data;
+	Elf_Scn *s;
+
+	sym = malloc(sizeof(*sym));
+	if (!sym) {
+		perror("malloc");
+		return NULL;
+	}
+	memset(sym, 0, sizeof(*sym));
+
+	sym->name = strdup(name);
+
+	sym->sym.st_name = elf_add_string(elf, NULL, sym->name);
+	if (sym->sym.st_name == -1)
+		return NULL;
+
+	sym->sym.st_info = GELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
+	// st_other 0
+	// st_shndx 0
+	// st_value 0
+	// st_size 0
+
+	symtab = find_section_by_name(elf, ".symtab");
+	if (!symtab) {
+		WARN("can't find .symtab");
+		return NULL;
+	}
+
+	s = elf_getscn(elf->elf, symtab->idx);
+	if (!s) {
+		WARN_ELF("elf_getscn");
+		return NULL;
+	}
+
+	data = elf_newdata(s);
+	if (!data) {
+		WARN_ELF("elf_newdata");
+		return NULL;
+	}
+
+	data->d_buf = &sym->sym;
+	data->d_size = sizeof(sym->sym);
+	data->d_align = 1;
+
+	sym->idx = symtab->len / sizeof(sym->sym);
+
+	symtab->len += data->d_size;
+	symtab->changed = true;
+
+	sym->sec = find_section_by_index(elf, 0);
+
+	elf_add_symbol(elf, sym);
+
+	return sym;
+}
+
 struct section *elf_create_section(struct elf *elf, const char *name,
 				   unsigned int sh_flags, size_t entsize, int nr)
 {
 	struct section *sec, *shstrtab;
 	size_t size = entsize * nr;
 	Elf_Scn *s;
-	Elf_Data *data;
 
 	sec = malloc(sizeof(*sec));
 	if (!sec) {
@@ -699,7 +837,6 @@ struct section *elf_create_section(struct elf *elf, const char *name,
 	sec->sh.sh_addralign = 1;
 	sec->sh.sh_flags = SHF_ALLOC | sh_flags;
 
-
 	/* Add section name to .shstrtab (or .strtab for Clang) */
 	shstrtab = find_section_by_name(elf, ".shstrtab");
 	if (!shstrtab)
@@ -708,27 +845,9 @@ struct section *elf_create_section(struct elf *elf, const char *name,
 		WARN("can't find .shstrtab or .strtab section");
 		return NULL;
 	}
-
-	s = elf_getscn(elf->elf, shstrtab->idx);
-	if (!s) {
-		WARN_ELF("elf_getscn");
-		return NULL;
-	}
-
-	data = elf_newdata(s);
-	if (!data) {
-		WARN_ELF("elf_newdata");
+	sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);
+	if (sec->sh.sh_name == -1)
 		return NULL;
-	}
-
-	data->d_buf = sec->name;
-	data->d_size = strlen(name) + 1;
-	data->d_align = 1;
-
-	sec->sh.sh_name = shstrtab->len;
-
-	shstrtab->len += strlen(name) + 1;
-	shstrtab->changed = true;
 
 	list_add_tail(&sec->list, &elf->sections);
 	elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
@@ -799,7 +918,7 @@ static struct section *elf_create_rela_reloc_section(struct elf *elf, struct sec
 	return sec;
 }
 
-struct section *elf_create_reloc_section(struct elf *elf,
+static struct section *elf_create_reloc_section(struct elf *elf,
 					 struct section *base,
 					 int reltype)
 {
@@ -873,14 +992,11 @@ static int elf_rebuild_rela_reloc_section(struct section *sec, int nr)
 	return 0;
 }
 
-int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
+static int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
 {
 	struct reloc *reloc;
 	int nr;
 
-	sec->changed = true;
-	elf->changed = true;
-
 	nr = 0;
 	list_for_each_entry(reloc, &sec->reloc_list, list)
 		nr++;
@@ -944,9 +1060,15 @@ int elf_write(struct elf *elf)
 	struct section *sec;
 	Elf_Scn *s;
 
-	/* Update section headers for changed sections: */
+	/* Update changed relocation sections and section headers: */
 	list_for_each_entry(sec, &elf->sections, list) {
 		if (sec->changed) {
+			if (sec->base &&
+			    elf_rebuild_reloc_section(elf, sec)) {
+				WARN("elf_rebuild_reloc_section");
+				return -1;
+			}
+
 			s = elf_getscn(elf->elf, sec->idx);
 			if (!s) {
 				WARN_ELF("elf_getscn");
@@ -958,6 +1080,7 @@ int elf_write(struct elf *elf)
 			}
 
 			sec->changed = false;
+			elf->changed = true;
 		}
 	}