[PATCH] arm64: relocate-rela: Add support for ld.lld

[Alistair Delva <adelva@google.com>]

Cap end of relocations by the binary size.

Linkers like to insert some auxiliary sections between .rela.dyn and
.bss_start. These sections don't make their way to the final binary, but
reloc_rela still tries to relocate them, resulting in attempted read
past the end of file.

When linking U-Boot with ld.lld, the STATIC_RELA feature (enabled by
default on arm64) breaks the build. After this patch, U-Boot can be
linked successfully with and without CONFIG_STATIC_RELA.

Originally-from: Elena Petrova <lenaptr@google.com>
Signed-off-by: Alistair Delva <adelva@google.com>
Cc: David Brazdil <dbrazdil@google.com>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Tom Rini <trini@konsulko.com>
---
 tools/relocate-rela.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/tools/relocate-rela.c b/tools/relocate-rela.c
index 6a524014b7..f0bc548617 100644
--- a/tools/relocate-rela.c
+++ b/tools/relocate-rela.c
@@ -63,7 +63,7 @@ int main(int argc, char **argv)
 {
 	FILE *f;
 	int i, num;
-	uint64_t rela_start, rela_end, text_base;
+	uint64_t rela_start, rela_end, text_base, file_size;
 
 	if (argc != 5) {
 		fprintf(stderr, "Statically apply ELF rela relocations\n");
@@ -87,8 +87,7 @@ int main(int argc, char **argv)
 		return 3;
 	}
 
-	if (rela_start > rela_end || rela_start < text_base ||
-	    (rela_end - rela_start) % sizeof(Elf64_Rela)) {
+	if (rela_start > rela_end || rela_start < text_base) {
 		fprintf(stderr, "%s: bad rela bounds\n", argv[0]);
 		return 3;
 	}
@@ -96,6 +95,21 @@ int main(int argc, char **argv)
 	rela_start -= text_base;
 	rela_end -= text_base;
 
+	fseek(f, 0, SEEK_END);
+	file_size = ftell(f);
+	rewind(f);
+
+	if (rela_end > file_size) {
+		// Most likely compiler inserted some section that didn't get
+		// objcopy-ed into the final binary
+		rela_end = file_size;
+	}
+
+	if ((rela_end - rela_start) % sizeof(Elf64_Rela)) {
+		fprintf(stderr, "%s: rela size isn't a multiple of Elf64_Rela\n", argv[0]);
+		return 3;
+	}
+
 	num = (rela_end - rela_start) / sizeof(Elf64_Rela);
 
 	for (i = 0; i < num; i++) {
-- 
2.30.2