target/image: zero-initialize ELF segments up to p_memsz

We were previously not zero-initializing ELF segments between p_filesz
and p_memsz (aka BSS). However, this may be necessary depending on the
user's application. Therefore, start doing so.

Change-Id: I5a743390069583aca7ee276f53afeccf2cac0855
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7513
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

1 files changed, 34 insertions, 20 deletions

diff --git a/src/target/image.c b/src/target/image.c
index f8de7a2..6aa609d 100644
--- a/src/target/image.c
+++ b/src/target/image.c
@@ -407,12 +407,10 @@ static int image_elf32_read_headers(struct image *image)
 		return ERROR_FILEIO_OPERATION_FAILED;
 	}
 
-	/* count useful segments (loadable), ignore BSS section */
+	/* count useful segments (loadable) */
 	image->num_sections = 0;
 	for (i = 0; i < elf->segment_count; i++)
-		if ((field32(elf,
-			elf->segments32[i].p_type) == PT_LOAD) &&
-			(field32(elf, elf->segments32[i].p_filesz) != 0))
+		if (field32(elf, elf->segments32[i].p_type) == PT_LOAD)
 			image->num_sections++;
 
 	if (image->num_sections == 0) {
@@ -449,10 +447,8 @@ static int image_elf32_read_headers(struct image *image)
 	}
 
 	for (i = 0, j = 0; i < elf->segment_count; i++) {
-		if ((field32(elf,
-			elf->segments32[i].p_type) == PT_LOAD) &&
-			(field32(elf, elf->segments32[i].p_filesz) != 0)) {
-			image->sections[j].size = field32(elf, elf->segments32[i].p_filesz);
+		if (field32(elf, elf->segments32[i].p_type) == PT_LOAD) {
+			image->sections[j].size = field32(elf, elf->segments32[i].p_memsz);
 			if (load_to_vaddr)
 				image->sections[j].base_address = field32(elf,
 						elf->segments32[i].p_vaddr);
@@ -532,12 +528,10 @@ static int image_elf64_read_headers(struct image *image)
 		return ERROR_FILEIO_OPERATION_FAILED;
 	}
 
-	/* count useful segments (loadable), ignore BSS section */
+	/* count useful segments (loadable) */
 	image->num_sections = 0;
 	for (i = 0; i < elf->segment_count; i++)
-		if ((field32(elf,
-			elf->segments64[i].p_type) == PT_LOAD) &&
-			(field64(elf, elf->segments64[i].p_filesz) != 0))
+		if (field32(elf, elf->segments64[i].p_type) == PT_LOAD)
 			image->num_sections++;
 
 	if (image->num_sections == 0) {
@@ -574,10 +568,8 @@ static int image_elf64_read_headers(struct image *image)
 	}
 
 	for (i = 0, j = 0; i < elf->segment_count; i++) {
-		if ((field32(elf,
-			elf->segments64[i].p_type) == PT_LOAD) &&
-			(field64(elf, elf->segments64[i].p_filesz) != 0)) {
-			image->sections[j].size = field64(elf, elf->segments64[i].p_filesz);
+		if (field32(elf, elf->segments64[i].p_type) == PT_LOAD) {
+			image->sections[j].size = field64(elf, elf->segments64[i].p_memsz);
 			if (load_to_vaddr)
 				image->sections[j].base_address = field64(elf,
 						elf->segments64[i].p_vaddr);
@@ -651,6 +643,8 @@ static int image_elf32_read_section(struct image *image,
 {
 	struct image_elf *elf = image->type_private;
 	Elf32_Phdr *segment = (Elf32_Phdr *)image->sections[section].private;
+	uint32_t filesz = field32(elf, segment->p_filesz);
+	uint32_t memsz = field32(elf, segment->p_memsz);
 	size_t read_size, really_read;
 	int retval;
 
@@ -659,9 +653,9 @@ static int image_elf32_read_section(struct image *image,
 	LOG_DEBUG("load segment %d at 0x%" TARGET_PRIxADDR " (sz = 0x%" PRIx32 ")", section, offset, size);
 
 	/* read initialized data in current segment if any */
-	if (offset < field32(elf, segment->p_filesz)) {
+	if (offset < filesz) {
 		/* maximal size present in file for the current segment */
-		read_size = MIN(size, field32(elf, segment->p_filesz) - offset);
+		read_size = MIN(size, filesz - offset);
 		LOG_DEBUG("read elf: size = 0x%zx at 0x%" TARGET_PRIxADDR "", read_size,
 			field32(elf, segment->p_offset) + offset);
 		/* read initialized area of the segment */
@@ -675,6 +669,8 @@ static int image_elf32_read_section(struct image *image,
 			LOG_ERROR("cannot read ELF segment content, read failed");
 			return retval;
 		}
+		buffer += read_size;
+		offset += read_size;
 		size -= read_size;
 		*size_read += read_size;
 		/* need more data ? */
@@ -682,6 +678,13 @@ static int image_elf32_read_section(struct image *image,
 			return ERROR_OK;
 	}
 
+	/* clear bss in current segment if any */
+	if (offset >= filesz) {
+		uint32_t memset_size = MIN(size, memsz - filesz);
+		memset(buffer, 0, memset_size);
+		*size_read += memset_size;
+	}
+
 	return ERROR_OK;
 }
 
@@ -694,6 +697,8 @@ static int image_elf64_read_section(struct image *image,
 {
 	struct image_elf *elf = image->type_private;
 	Elf64_Phdr *segment = (Elf64_Phdr *)image->sections[section].private;
+	uint64_t filesz = field64(elf, segment->p_filesz);
+	uint64_t memsz = field64(elf, segment->p_memsz);
 	size_t read_size, really_read;
 	int retval;
 
@@ -702,9 +707,9 @@ static int image_elf64_read_section(struct image *image,
 	LOG_DEBUG("load segment %d at 0x%" TARGET_PRIxADDR " (sz = 0x%" PRIx32 ")", section, offset, size);
 
 	/* read initialized data in current segment if any */
-	if (offset < field64(elf, segment->p_filesz)) {
+	if (offset < filesz) {
 		/* maximal size present in file for the current segment */
-		read_size = MIN(size, field64(elf, segment->p_filesz) - offset);
+		read_size = MIN(size, filesz - offset);
 		LOG_DEBUG("read elf: size = 0x%zx at 0x%" TARGET_PRIxADDR "", read_size,
 			field64(elf, segment->p_offset) + offset);
 		/* read initialized area of the segment */
@@ -718,6 +723,8 @@ static int image_elf64_read_section(struct image *image,
 			LOG_ERROR("cannot read ELF segment content, read failed");
 			return retval;
 		}
+		buffer += read_size;
+		offset += read_size;
 		size -= read_size;
 		*size_read += read_size;
 		/* need more data ? */
@@ -725,6 +732,13 @@ static int image_elf64_read_section(struct image *image,
 			return ERROR_OK;
 	}
 
+	/* clear bss in current segment if any */
+	if (offset >= filesz) {
+		uint64_t memset_size = MIN(size, memsz - filesz);
+		memset(buffer, 0, memset_size);
+		*size_read += memset_size;
+	}
+
 	return ERROR_OK;
 }