objtool: sync up with the 4.14.47 version of objtool

There are pros and cons of dealing with tools in the kernel directory.
The pros are the fact that development happens fast, and new features
can be added to the kernel and the tools at the same times.  The cons
are when dealing with backported kernel patches, it can be necessary to
backport parts of the tool changes as well.

For 4.9.y so far, we have backported individual patches.  That quickly
breaks down when there are minor differences between how backports were
handled, so grabbing 40+ patch long series can be difficult, not
impossible, but really frustrating to attempt.

To help mitigate this mess, here's a single big patch to sync up the
objtool logic to the 4.14.47 version of the tool.  From this point
forward (after some other minor header file patches are applied), the
tool should be in sync and much easier to maintain over time.

This has survivied my limited testing, and as the codebase is identical
to 4.14.47, I'm pretty comfortable dropping this big change in here in
4.9.y.  Hopefully all goes well...

Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 237 insertions, 47 deletions

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index faacf0c89976..c1c338661699 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -31,13 +31,6 @@
 #include "elf.h"
 #include "warn.h"
 
-/*
- * Fallback for systems without this "read, mmaping if possible" cmd.
- */
-#ifndef ELF_C_READ_MMAP
-#define ELF_C_READ_MMAP ELF_C_READ
-#endif
-
 struct section *find_section_by_name(struct elf *elf, const char *name)
 {
 	struct section *sec;
@@ -140,12 +133,12 @@ static int read_sections(struct elf *elf)
 	int i;
 
 	if (elf_getshdrnum(elf->elf, &sections_nr)) {
-		perror("elf_getshdrnum");
+		WARN_ELF("elf_getshdrnum");
 		return -1;
 	}
 
 	if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
-		perror("elf_getshdrstrndx");
+		WARN_ELF("elf_getshdrstrndx");
 		return -1;
 	}
 
@@ -166,37 +159,37 @@ static int read_sections(struct elf *elf)
 
 		s = elf_getscn(elf->elf, i);
 		if (!s) {
-			perror("elf_getscn");
+			WARN_ELF("elf_getscn");
 			return -1;
 		}
 
 		sec->idx = elf_ndxscn(s);
 
 		if (!gelf_getshdr(s, &sec->sh)) {
-			perror("gelf_getshdr");
+			WARN_ELF("gelf_getshdr");
 			return -1;
 		}
 
 		sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
 		if (!sec->name) {
-			perror("elf_strptr");
-			return -1;
-		}
-
-		sec->elf_data = elf_getdata(s, NULL);
-		if (!sec->elf_data) {
-			perror("elf_getdata");
+			WARN_ELF("elf_strptr");
 			return -1;
 		}
 
-		if (sec->elf_data->d_off != 0 ||
-		    sec->elf_data->d_size != sec->sh.sh_size) {
-			WARN("unexpected data attributes for %s", sec->name);
-			return -1;
+		if (sec->sh.sh_size != 0) {
+			sec->data = elf_getdata(s, NULL);
+			if (!sec->data) {
+				WARN_ELF("elf_getdata");
+				return -1;
+			}
+			if (sec->data->d_off != 0 ||
+			    sec->data->d_size != sec->sh.sh_size) {
+				WARN("unexpected data attributes for %s",
+				     sec->name);
+				return -1;
+			}
 		}
-
-		sec->data = (unsigned long)sec->elf_data->d_buf;
-		sec->len = sec->elf_data->d_size;
+		sec->len = sec->sh.sh_size;
 	}
 
 	/* sanity check, one more call to elf_nextscn() should return NULL */
@@ -233,15 +226,15 @@ static int read_symbols(struct elf *elf)
 
 		sym->idx = i;
 
-		if (!gelf_getsym(symtab->elf_data, i, &sym->sym)) {
-			perror("gelf_getsym");
+		if (!gelf_getsym(symtab->data, i, &sym->sym)) {
+			WARN_ELF("gelf_getsym");
 			goto err;
 		}
 
 		sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
 				       sym->sym.st_name);
 		if (!sym->name) {
-			perror("elf_strptr");
+			WARN_ELF("elf_strptr");
 			goto err;
 		}
 
@@ -323,8 +316,8 @@ static int read_relas(struct elf *elf)
 			}
 			memset(rela, 0, sizeof(*rela));
 
-			if (!gelf_getrela(sec->elf_data, i, &rela->rela)) {
-				perror("gelf_getrela");
+			if (!gelf_getrela(sec->data, i, &rela->rela)) {
+				WARN_ELF("gelf_getrela");
 				return -1;
 			}
 
@@ -348,9 +341,10 @@ static int read_relas(struct elf *elf)
 	return 0;
 }
 
-struct elf *elf_open(const char *name)
+struct elf *elf_open(const char *name, int flags)
 {
 	struct elf *elf;
+	Elf_Cmd cmd;
 
 	elf_version(EV_CURRENT);
 
@@ -363,27 +357,28 @@ struct elf *elf_open(const char *name)
 
 	INIT_LIST_HEAD(&elf->sections);
 
-	elf->name = strdup(name);
-	if (!elf->name) {
-		perror("strdup");
-		goto err;
-	}
-
-	elf->fd = open(name, O_RDONLY);
+	elf->fd = open(name, flags);
 	if (elf->fd == -1) {
 		fprintf(stderr, "objtool: Can't open '%s': %s\n",
 			name, strerror(errno));
 		goto err;
 	}
 
-	elf->elf = elf_begin(elf->fd, ELF_C_READ_MMAP, NULL);
+	if ((flags & O_ACCMODE) == O_RDONLY)
+		cmd = ELF_C_READ_MMAP;
+	else if ((flags & O_ACCMODE) == O_RDWR)
+		cmd = ELF_C_RDWR;
+	else /* O_WRONLY */
+		cmd = ELF_C_WRITE;
+
+	elf->elf = elf_begin(elf->fd, cmd, NULL);
 	if (!elf->elf) {
-		perror("elf_begin");
+		WARN_ELF("elf_begin");
 		goto err;
 	}
 
 	if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
-		perror("gelf_getehdr");
+		WARN_ELF("gelf_getehdr");
 		goto err;
 	}
 
@@ -403,12 +398,212 @@ err:
 	return NULL;
 }
 
+struct section *elf_create_section(struct elf *elf, const char *name,
+				   size_t entsize, int nr)
+{
+	struct section *sec, *shstrtab;
+	size_t size = entsize * nr;
+	struct Elf_Scn *s;
+	Elf_Data *data;
+
+	sec = malloc(sizeof(*sec));
+	if (!sec) {
+		perror("malloc");
+		return NULL;
+	}
+	memset(sec, 0, sizeof(*sec));
+
+	INIT_LIST_HEAD(&sec->symbol_list);
+	INIT_LIST_HEAD(&sec->rela_list);
+	hash_init(sec->rela_hash);
+	hash_init(sec->symbol_hash);
+
+	list_add_tail(&sec->list, &elf->sections);
+
+	s = elf_newscn(elf->elf);
+	if (!s) {
+		WARN_ELF("elf_newscn");
+		return NULL;
+	}
+
+	sec->name = strdup(name);
+	if (!sec->name) {
+		perror("strdup");
+		return NULL;
+	}
+
+	sec->idx = elf_ndxscn(s);
+	sec->len = size;
+	sec->changed = true;
+
+	sec->data = elf_newdata(s);
+	if (!sec->data) {
+		WARN_ELF("elf_newdata");
+		return NULL;
+	}
+
+	sec->data->d_size = size;
+	sec->data->d_align = 1;
+
+	if (size) {
+		sec->data->d_buf = malloc(size);
+		if (!sec->data->d_buf) {
+			perror("malloc");
+			return NULL;
+		}
+		memset(sec->data->d_buf, 0, size);
+	}
+
+	if (!gelf_getshdr(s, &sec->sh)) {
+		WARN_ELF("gelf_getshdr");
+		return NULL;
+	}
+
+	sec->sh.sh_size = size;
+	sec->sh.sh_entsize = entsize;
+	sec->sh.sh_type = SHT_PROGBITS;
+	sec->sh.sh_addralign = 1;
+	sec->sh.sh_flags = SHF_ALLOC;
+
+
+	/* Add section name to .shstrtab */
+	shstrtab = find_section_by_name(elf, ".shstrtab");
+	if (!shstrtab) {
+		WARN("can't find .shstrtab 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");
+		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;
+
+	return sec;
+}
+
+struct section *elf_create_rela_section(struct elf *elf, struct section *base)
+{
+	char *relaname;
+	struct section *sec;
+
+	relaname = malloc(strlen(base->name) + strlen(".rela") + 1);
+	if (!relaname) {
+		perror("malloc");
+		return NULL;
+	}
+	strcpy(relaname, ".rela");
+	strcat(relaname, base->name);
+
+	sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0);
+	free(relaname);
+	if (!sec)
+		return NULL;
+
+	base->rela = sec;
+	sec->base = base;
+
+	sec->sh.sh_type = SHT_RELA;
+	sec->sh.sh_addralign = 8;
+	sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
+	sec->sh.sh_info = base->idx;
+	sec->sh.sh_flags = SHF_INFO_LINK;
+
+	return sec;
+}
+
+int elf_rebuild_rela_section(struct section *sec)
+{
+	struct rela *rela;
+	int nr, idx = 0, size;
+	GElf_Rela *relas;
+
+	nr = 0;
+	list_for_each_entry(rela, &sec->rela_list, list)
+		nr++;
+
+	size = nr * sizeof(*relas);
+	relas = malloc(size);
+	if (!relas) {
+		perror("malloc");
+		return -1;
+	}
+
+	sec->data->d_buf = relas;
+	sec->data->d_size = size;
+
+	sec->sh.sh_size = size;
+
+	idx = 0;
+	list_for_each_entry(rela, &sec->rela_list, list) {
+		relas[idx].r_offset = rela->offset;
+		relas[idx].r_addend = rela->addend;
+		relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type);
+		idx++;
+	}
+
+	return 0;
+}
+
+int elf_write(struct elf *elf)
+{
+	struct section *sec;
+	Elf_Scn *s;
+
+	/* Update section headers for changed sections: */
+	list_for_each_entry(sec, &elf->sections, list) {
+		if (sec->changed) {
+			s = elf_getscn(elf->elf, sec->idx);
+			if (!s) {
+				WARN_ELF("elf_getscn");
+				return -1;
+			}
+			if (!gelf_update_shdr(s, &sec->sh)) {
+				WARN_ELF("gelf_update_shdr");
+				return -1;
+			}
+		}
+	}
+
+	/* Make sure the new section header entries get updated properly. */
+	elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
+
+	/* Write all changes to the file. */
+	if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
+		WARN_ELF("elf_update");
+		return -1;
+	}
+
+	return 0;
+}
+
 void elf_close(struct elf *elf)
 {
 	struct section *sec, *tmpsec;
 	struct symbol *sym, *tmpsym;
 	struct rela *rela, *tmprela;
 
+	if (elf->elf)
+		elf_end(elf->elf);
+
+	if (elf->fd > 0)
+		close(elf->fd);
+
 	list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
 		list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
 			list_del(&sym->list);
@@ -423,11 +618,6 @@ void elf_close(struct elf *elf)
 		list_del(&sec->list);
 		free(sec);
 	}
-	if (elf->name)
-		free(elf->name);
-	if (elf->fd > 0)
-		close(elf->fd);
-	if (elf->elf)
-		elf_end(elf->elf);
+
 	free(elf);
 }