create-diff-object: Refactor rela_equal() using toc_rela()

Heavy lifting of reading .toc rela entries for rela symbols
referring to .toc + offset, can be simplified using toc_rela() in
rela_equal() and remove the #ifdery guarding PowerPC code.

This patch also trims the commentary related to PowerPC.

Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>

kpatch-build/create-diff-object.c

@@ -252,54 +252,22 @@ static int kpatch_mangled_strcmp(char *s1, char *s2)
 
 static int rela_equal(struct rela *rela1, struct rela *rela2)
 {
-#ifdef __powerpc__
+	struct rela *rela_toc1, *rela_toc2;
-	struct section *toc_relasec1, *toc_relasec2;
-	struct rela *r_toc_relasec1, *r_toc_relasec2;
 	unsigned long toc_data1, toc_data2;
-#endif
 
 	if (rela1->type != rela2->type ||
 	    rela1->offset != rela2->offset)
 		return 0;
 
-	if (rela1->string)
-		return rela2->string && !strcmp(rela1->string, rela2->string);
-
-#ifdef __powerpc__
 	/*
- * Relocation section '.rela.toc' at offset 0x91f0 contains 122 entries:
- *     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
- *     [...]
- *     0000000000000090  0000001c00000026 R_PPC64_ADDR64         0000000000000000 .rodata.__dev_remove_pack.str1.8 + 0
- *     0000000000000098  0000001a00000026 R_PPC64_ADDR64         0000000000000000 .rodata.__dev_getfirstbyhwtype.str1.8 + 0
- *     00000000000000a0  0000001a00000026 R_PPC64_ADDR64         0000000000000000 .rodata.__dev_getfirstbyhwtype.str1.8 + 10
- *     00000000000000a8  000000cb00000026 R_PPC64_ADDR64         0000000000000000 dev_base_lock + 0
- *
- * Relocation section '.rela.text.netdev_master_upper_dev_get' at offset 0xe38 contains 10 entries:
- *     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
- *     [...]
- *     00000000000000a0  0000004e00000032 R_PPC64_TOC16_HA       0000000000000000 .toc + 98
- *     00000000000000a8  0000004e00000040 R_PPC64_TOC16_LO_DS    0000000000000000 .toc + 98
- *     00000000000000ac  0000004e00000032 R_PPC64_TOC16_HA       0000000000000000 .toc + a0
- *     00000000000000b0  0000004e00000040 R_PPC64_TOC16_LO_DS    0000000000000000 .toc + a0
- *     00000000000000b4  000000b90000000a R_PPC64_REL24          0000000000000000 printk + 0
- *     00000000000000bc  000000a10000000a R_PPC64_REL24          0000000000000000 dump_stack + 0
- *
 	 * With -mcmodel=large on ppc64le, GCC might generate entries in the .toc
 	 * section for relocation symbol references.   The .toc offsets may change
 	 * between the original and patched .o, so comparing ".toc + offset" isn't
 	 * right.  Compare the .toc-based symbols by reading the corresponding relas
 	 * from the .toc section.
 	 */
-	if (!strcmp(rela1->sym->name, ".toc") &&
+	rela_toc1 = toc_rela(rela1);
-	    !strcmp(rela2->sym->name, ".toc")) {
+	if (!rela_toc1) {
-
-		toc_relasec1 = rela1->sym->sec->rela;
-		if (!toc_relasec1)
-			ERROR("cannot find .rela.toc");
-
-		r_toc_relasec1 = find_rela_by_offset(toc_relasec1, rela1->addend);
-		if (!r_toc_relasec1) {
 		/*
 		 * .toc section entries are mostly place holder for relocation entries, specified
 		 * in .rela.toc section. Sometimes, .toc section may have constants as entries.
@@ -327,54 +295,37 @@ static int rela_equal(struct rela *rela1, struct rela *rela2)
 		 * Relocation section '.rela.text.select_task_rq_fair' at offset 0x90e98 contains 37 entries:
 		 *     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
 		 *     ...
-			 * 0000000000000498  000000c90000000a R_PPC64_REL24          0000000000000000 __update_load_avg_blocked_se.isra.0 + 0
 		 * 00000000000004a0  0000008800000032 R_PPC64_TOC16_HA       0000000000000000 .toc + 148
 		 * 00000000000004ac  0000008800000040 R_PPC64_TOC16_LO_DS    0000000000000000 .toc + 148
 		 * 0000000000000514  0000008800000032 R_PPC64_TOC16_HA       0000000000000000 .toc + 150
 		 * 000000000000051c  0000008800000040 R_PPC64_TOC16_LO_DS    0000000000000000 .toc + 150
-			 * 00000000000005e0  000001870000000a R_PPC64_REL24          0000000000000000 __bitmap_intersects + 0
 		 */
 		memcpy(&toc_data1, rela1->sym->sec->data->d_buf + rela1->addend, sizeof(toc_data1));
 		if (!toc_data1)
 			ERROR(".toc entry not found %s + %x", rela1->sym->name, rela1->addend);
 	}
 
-		toc_relasec2 = rela2->sym->sec->rela;
+	rela_toc2 = toc_rela(rela2);
-		if (!toc_relasec2)
+	if (!rela_toc2) {
-			ERROR("cannot find .rela.toc");
-
-		r_toc_relasec2 = find_rela_by_offset(toc_relasec2, rela2->addend);
-		if (!r_toc_relasec2) {
 		memcpy(&toc_data2, rela2->sym->sec->data->d_buf + rela2->addend, sizeof(toc_data2));
 		if (!toc_data2)
 			ERROR(".toc entry not found %s + %x", rela2->sym->name, rela2->addend);
 	}
 
-		if (!r_toc_relasec1 && !r_toc_relasec2)
+	if (!rela_toc1 && !rela_toc2)
 		return toc_data1 == toc_data2;
 
-		if (r_toc_relasec1->string)
+	if (rela_toc1->string)
-			return r_toc_relasec2->string &&
+		return rela_toc2->string && !strcmp(rela_toc1->string, rela_toc2->string);
-				!strcmp(r_toc_relasec1->string, r_toc_relasec2->string);
 
-		if ((r_toc_relasec1->addend != r_toc_relasec2->addend))
+	if (rela_toc1->addend != rela_toc2->addend)
 		return 0;
 
-		if (is_special_static(r_toc_relasec1->sym))
+	if (is_special_static(rela_toc1->sym))
-			return !kpatch_mangled_strcmp(r_toc_relasec1->sym->name,
+		return !kpatch_mangled_strcmp(rela_toc1->sym->name,
-					r_toc_relasec2->sym->name);
+					      rela_toc2->sym->name);
 
-		return !strcmp(r_toc_relasec1->sym->name, r_toc_relasec2->sym->name);
+	return !strcmp(rela_toc1->sym->name, rela_toc2->sym->name);
-	}
-#endif
-	if (rela1->addend != rela2->addend)
-		return 0;
-
-	if (is_special_static(rela1->sym))
-		return !kpatch_mangled_strcmp(rela1->sym->name,
-					      rela2->sym->name);
-
-	return !strcmp(rela1->sym->name, rela2->sym->name);
 }
 
 static void kpatch_compare_correlated_rela_section(struct section *sec)