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

This reverts commit 047b1a8fc237af480e3bab66a9827a358afd7547.

Commit 047b1a8fc237 ("target/image: zero-initialize ELF segments
up to p_memsz") breaks the backward compatibility introducing some
problem:
- an empty bss segment with paddr in SRAM gets zero filled at load
  but does not survive after a reset, causing verify to fail;
- an empty bss segment with paddr in FLASH causes excessive flash
  usage, which can exceed flash size (causing error) and makes
  flash aging faster.

Revert it while looking for a better implementation.

Change-Id: Iaaf926dafce46a220a5bbe20c8576eb449996d76
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reported-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Reviewed-on: https://review.openocd.org/c/openocd/+/7658
Reviewed-by: Bohdan Tymkiv <bohdan200@gmail.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Nemui Trinomius <nemuisan_kawausogasuki@live.jp>
Reviewed-by: Peter Collingbourne <pcc@google.com>
Tested-by: jenkins

1 files changed, 20 insertions, 34 deletions

diff --git a/src/target/image.c b/src/target/image.c
index 6aa609d..f8de7a2 100644
--- a/src/target/image.c
+++ b/src/target/image.c
@@ -407,10 +407,12 @@ static int image_elf32_read_headers(struct image *image)
 		return ERROR_FILEIO_OPERATION_FAILED;
 	}
 
-	/* count useful segments (loadable) */
+	/* count useful segments (loadable), ignore BSS section */
 	image->num_sections = 0;
 	for (i = 0; i < elf->segment_count; i++)
-		if (field32(elf, elf->segments32[i].p_type) == PT_LOAD)
+		if ((field32(elf,
+			elf->segments32[i].p_type) == PT_LOAD) &&
+			(field32(elf, elf->segments32[i].p_filesz) != 0))
 			image->num_sections++;
 
 	if (image->num_sections == 0) {
@@ -447,8 +449,10 @@ 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) {
-			image->sections[j].size = field32(elf, elf->segments32[i].p_memsz);
+		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 (load_to_vaddr)
 				image->sections[j].base_address = field32(elf,
 						elf->segments32[i].p_vaddr);
@@ -528,10 +532,12 @@ static int image_elf64_read_headers(struct image *image)
 		return ERROR_FILEIO_OPERATION_FAILED;
 	}
 
-	/* count useful segments (loadable) */
+	/* count useful segments (loadable), ignore BSS section */
 	image->num_sections = 0;
 	for (i = 0; i < elf->segment_count; i++)
-		if (field32(elf, elf->segments64[i].p_type) == PT_LOAD)
+		if ((field32(elf,
+			elf->segments64[i].p_type) == PT_LOAD) &&
+			(field64(elf, elf->segments64[i].p_filesz) != 0))
 			image->num_sections++;
 
 	if (image->num_sections == 0) {
@@ -568,8 +574,10 @@ 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) {
-			image->sections[j].size = field64(elf, elf->segments64[i].p_memsz);
+		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 (load_to_vaddr)
 				image->sections[j].base_address = field64(elf,
 						elf->segments64[i].p_vaddr);
@@ -643,8 +651,6 @@ 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;
 
@@ -653,9 +659,9 @@ 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 < filesz) {
+	if (offset < field32(elf, segment->p_filesz)) {
 		/* maximal size present in file for the current segment */
-		read_size = MIN(size, filesz - offset);
+		read_size = MIN(size, field32(elf, segment->p_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 */
@@ -669,8 +675,6 @@ 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 ? */
@@ -678,13 +682,6 @@ 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;
 }
 
@@ -697,8 +694,6 @@ 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;
 
@@ -707,9 +702,9 @@ 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 < filesz) {
+	if (offset < field64(elf, segment->p_filesz)) {
 		/* maximal size present in file for the current segment */
-		read_size = MIN(size, filesz - offset);
+		read_size = MIN(size, field64(elf, segment->p_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 */
@@ -723,8 +718,6 @@ 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 ? */
@@ -732,13 +725,6 @@ 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;
 }