elf loader: The rproc elf loading problem

The elf loader assumes that the last ELF program segment will always
be a LOAD type segment. I deduce this from the fact that the elf_load()
function, when loading the remote ELF sections during the
RPROC_LOADER_READY_TO_LOAD stage, compares the last load segment num
to the total ELF sections to determine if the loading is complete and
it can move to the next stage RPROC_LOADER_POST_DATA_LOAD. If the last
program segment in the ELF is not of type LOAD, the last loaded LOAD
segment never equals total ELF sections. This creates an error
condition and the firmware loading fails. This patch fixes this issue
by comparing the last loaded LOAD segment number with the max LOAD
segment number in the ELF.

Signed-off-by: Muhammad Umair Khan <umair_khan@mentor.com>

lib/include/openamp/elf_loader.h

@@ -290,6 +290,7 @@ struct elf32_info {
 	Elf32_Phdr *phdrs;
 	Elf32_Shdr *shdrs;
 	void *shstrtab;
+	int max_load_phnum;
 };
 
 struct elf64_info {
@@ -298,6 +299,7 @@ struct elf64_info {
 	Elf64_Phdr *phdrs;
 	Elf64_Shdr *shdrs;
 	void *shstrtab;
+	int max_load_phnum;
 };
 
 #define ELF_STATE_INIT              0x0L

lib/remoteproc/elf_loader.c

@@ -161,6 +161,19 @@ static void **elf_shstrtab_ptr(void *elf_info)
 	}
 }
 
+static int *elf_max_load_phnum(void *elf_info)
+{
+	if (elf_is_64(elf_info) == 0) {
+		struct elf32_info *einfo = elf_info;
+
+		return &einfo->max_load_phnum;
+	} else {
+		struct elf64_info *einfo = elf_info;
+
+		return &einfo->max_load_phnum;
+	}
+}
+
 static int *elf_load_state(void *elf_info)
 {
 	if (elf_is_64(elf_info) == 0) {
@@ -374,6 +387,25 @@ static const void *elf_next_load_segment(void *elf_info, int *nseg,
 	return phdr;
 }
 
+static void elf_find_max_load_phnum(void *elf_info)
+{
+	const void *phdr = PT_NULL;
+	unsigned int p_type = PT_NULL;
+	int nseg = 0;
+	int *max_load_seg;
+
+	max_load_seg = elf_max_load_phnum(elf_info);
+	phdr = elf_get_segment_from_index(elf_info, nseg);
+	while (phdr != PT_NULL) {
+		elf_parse_segment(elf_info, phdr, &p_type, NULL,
+				  NULL, NULL, NULL, NULL);
+		if (p_type == PT_LOAD)
+			*max_load_seg = nseg;
+		nseg++;
+		phdr = elf_get_segment_from_index(elf_info, nseg);
+	}
+}
+
 static size_t elf_info_size(const void *img_data)
 {
 	if (elf_is_64(img_data) == 0)
@@ -453,6 +485,7 @@ int elf_load_header(const void *img_data, size_t offset, size_t len,
 		if (!*phdrs)
 			return -RPROC_ENOMEM;
 		memcpy(*phdrs, img_phdrs, phdrs_size);
+		elf_find_max_load_phnum(*img_info);
 		*load_state = ELF_STATE_WAIT_FOR_SHDRS |
 			       RPROC_LOADER_READY_TO_LOAD;
 	}
@@ -566,7 +599,7 @@ int elf_load(struct remoteproc *rproc,
 		int nsegment;
 		size_t nsegmsize = 0;
 		size_t nsize = 0;
-		int phnums = 0;
+		int *max_load_phnum = 0;
 
 		nsegment = *load_state & ELF_NEXT_SEGMENT_MASK;
 		phdr = elf_next_load_segment(*img_info, &nsegment, da,
@@ -579,10 +612,10 @@ int elf_load(struct remoteproc *rproc,
 		}
 		*nlen = nsize;
 		*nmemsize = nsegmsize;
-		phnums = elf_phnum(*img_info);
-		metal_log(METAL_LOG_DEBUG, "segment: %d, total segs %d\r\n",
-			  nsegment, phnums);
-		if (nsegment == phnums) {
+		max_load_phnum = elf_max_load_phnum(*img_info);
+		metal_log(METAL_LOG_DEBUG, "segment: %d, last load seg %d\r\n",
+			  nsegment, *max_load_phnum);
+		if (nsegment == *max_load_phnum) {
 			*load_state = (*load_state & (~RPROC_LOADER_MASK)) |
 				      RPROC_LOADER_POST_DATA_LOAD;
 		}