From: Rich Felker <dalias@aerifal.cx>
Date: Mon, 25 May 2015 04:32:37 +0000 (-0400)
Subject: simplify/shrink relocation processing in dynamic linker stage 1
X-Git-Tag: v1.1.10~16
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=0e0e49421f08cfd670975ecd3604f7f9015e1833;p=musl

simplify/shrink relocation processing in dynamic linker stage 1

the outer-loop approach made sense when we were also processing
DT_JMPREL, which might be in REL or RELA form, to avoid major code
duplication. commit 09db855b35709aa627d7055c57a98e1e471920ab removed
processing of DT_JMPREL, and in the remaining two tables, the format
(REL or RELA) is known by the name of the table. simply writing two
versions of the loop results in smaller and simpler code.
---

diff --git a/src/ldso/dlstart.c b/src/ldso/dlstart.c
index caa974a2..5f84465c 100644
--- a/src/ldso/dlstart.c
+++ b/src/ldso/dlstart.c
@@ -56,30 +56,22 @@ void _dlstart_c(size_t *sp, size_t *dynv)
 		for (i=0; i<local_cnt; i++) got[i] += (size_t)base;
 	}
 
-	/* The use of the reloc_info structure and nested loops is a trick
-	 * to work around the fact that we can't necessarily make function
-	 * calls yet. Each struct in the array serves like the arguments
-	 * to a function call. */
-	struct {
-		void *rel;
-		size_t size;
-		size_t stride;
-	} reloc_info[] = {
-		{ base+dyn[DT_REL], dyn[DT_RELSZ], 2 },
-		{ base+dyn[DT_RELA], dyn[DT_RELASZ], 3 },
-		{ 0, 0, 0 }
-	};
-
-	for (i=0; reloc_info[i].stride; i++) {
-		size_t *rel = reloc_info[i].rel;
-		size_t rel_size = reloc_info[i].size;
-		size_t stride = reloc_info[i].stride;
-		for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
-			if (!IS_RELATIVE(rel[1])) continue;
-			size_t *rel_addr = (void *)(base + rel[0]);
-			size_t addend = stride==3 ? rel[2] : *rel_addr;
-			*rel_addr = (size_t)base + addend;
-		}
+	size_t *rel, rel_size;
+
+	rel = (void *)(base+dyn[DT_REL]);
+	rel_size = dyn[DT_RELSZ];
+	for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t)) {
+		if (!IS_RELATIVE(rel[1])) continue;
+		size_t *rel_addr = (void *)(base + rel[0]);
+		*rel_addr += (size_t)base;
+	}
+
+	rel = (void *)(base+dyn[DT_RELA]);
+	rel_size = dyn[DT_RELASZ];
+	for (; rel_size; rel+=3, rel_size-=3*sizeof(size_t)) {
+		if (!IS_RELATIVE(rel[1])) continue;
+		size_t *rel_addr = (void *)(base + rel[0]);
+		*rel_addr = (size_t)base + rel[2];
 	}
 
 	const char *strings = (void *)(base + dyn[DT_STRTAB]);