From be5da15b96a30bf47127a5fd6d63af0483773269 Mon Sep 17 00:00:00 2001
From: Pete Swain <swine@google.com>
Date: Sat, 8 Oct 2022 19:53:45 -0700
Subject: [PATCH] adapt to clang/arm64 naming

New toolchain/arch, new conventions for section/label/etc names

gcc's .LCx symbols point to string literals in '.rodata.<func>.str1.*'
sections. Clang creates similar .Ltmp%d symbols in '.rodata.str'

The function is_string_literal_section()
generalized (too much?) to match either
- clang's/arm64 /^\.rodata\.str$/
- gcc's /^\.rodata\./ && /\.str1\./

Various matchers for .data.unlikely .bss.unlikely
replaced by is_data_unlikely_section()
generalized to match
- gcc's ".data.unlikely"
- clang's ".(data|bss).module_name.unlikely"

.data.once handled similarly

Signed-off-by: Pete Swain <swine@google.com>
---
 kpatch-build/create-diff-object.c | 34 +++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/kpatch-build/create-diff-object.c b/kpatch-build/create-diff-object.c
index ab0d86762..4694379c7 100644
--- a/kpatch-build/create-diff-object.c
+++ b/kpatch-build/create-diff-object.c
@@ -340,6 +340,28 @@ static bool is_string_literal_section(struct section *sec)
 	return !strncmp(sec->name, ".rodata.", 8) && strstr(sec->name, ".str");
 }
 
+/* gcc's ".data.unlikely" or clang's ".(data|bss).module_name.unlikely" */
+static bool is_data_unlikely_section(const char *name)
+{
+	size_t len = strlen(name);
+
+	return (len >= 5 + 8 &&
+		((!strncmp(name, ".data.", 6) ||
+		 !strncmp(name, ".bss.", 5)) &&
+		strstr(name + len - 9, ".unlikely")));
+}
+
+/* either ".data.once" or clang's ".(data|bss).module_name.once" */
+static bool is_data_once_section(const char *name)
+{
+	size_t len = strlen(name);
+
+	return (len >= 5 + 4 &&
+		(!strncmp(name, ".data.", 6) ||
+		 !strncmp(name, ".bss.", 5)) &&
+		strstr(name + len - 5, ".once"));
+}
+
 /*
  * This function detects whether the given symbol is a "special" static local
  * variable (for lack of a better term).
@@ -381,7 +403,7 @@ static bool is_special_static(struct symbol *sym)
 	if (sym->type != STT_OBJECT || sym->bind != STB_LOCAL)
 		return false;
 
-	if  (!strcmp(sym->sec->name, ".data.once"))
+	if (is_data_once_section(sym->sec->name))
 		return true;
 
 	for (var_name = var_names; *var_name; var_name++) {
@@ -1148,9 +1170,11 @@ static void kpatch_correlate_symbols(struct kpatch_elf *kelf_orig,
 			 * The .LCx symbols point to string literals in
 			 * '.rodata.<func>.str1.*' sections.  They get included
 			 * in kpatch_include_standard_elements().
+			 * Clang creates similar .Ltmp%d symbols in .rodata.str
 			 */
 			if (sym_orig->type == STT_NOTYPE &&
-			    !strncmp(sym_orig->name, ".LC", 3))
+			    (!strncmp(sym_orig->name, ".LC", 3) ||
+			     !strncmp(sym_orig->name, ".Ltmp", 5)))
 				continue;
 
 			if (kpatch_is_mapping_symbol(kelf_orig, sym_orig))
@@ -1787,8 +1811,10 @@ static void kpatch_verify_patchability(struct kpatch_elf *kelf)
 		 * (.data.unlikely and .data.once is ok b/c it only has __warned vars)
 		 */
 		if (sec->include && sec->status != NEW &&
-		    (!strncmp(sec->name, ".data", 5) || !strncmp(sec->name, ".bss", 4)) &&
-		    (strcmp(sec->name, ".data.unlikely") && strcmp(sec->name, ".data.once"))) {
+		    (!strncmp(sec->name, ".data", 5) ||
+		     !strncmp(sec->name, ".bss", 4)) &&
+		     !is_data_once_section(sec->name) &&
+		     !is_data_unlikely_section(sec->name)) {
 			log_normal("data section %s selected for inclusion\n",
 				   sec->name);
 			errs++;