objtool/klp: klp-build LTO support and tests

index a3198a63c2f0..57606bc3390a 100644
@@ -454,7 +454,7 @@ static int correlate_symbols(struct elfs *e)
 
 		sym2 = find_global_symbol_by_name(e->patched, sym1->name);
 
-		if (sym2 && !sym2->twin && !strcmp(sym1->name, sym2->name)) {
+		if (sym2 && !sym2->twin) {
 			sym1->twin = sym2;
 			sym2->twin = sym1;
 		}

index 2c02c7b49265..0d93e8496e8d 100644
@@ -441,6 +441,19 @@ static int read_sections(struct elf *elf)
 	return 0;
 }
 
+/*
+ * Remove number suffix of a symbol.
+ *
+ * Specifically, remove trailing numbers for "__UNIQUE_ID_" symbols and
+ * symbols with '.'.
+ *
+ * With CONFIG_LTO_CLANG_THIN, it is possible to have nested __UNIQUE_ID_,
+ * such as
+ *
+ *   __UNIQUE_ID_addressable___UNIQUE_ID_pci_invalid_bar_694_695
+ *
+ * to remove both trailing numbers, also remove trailing '_'.
+ */
 static const char *demangle_name(struct symbol *sym)
 {
 	char *str;

@@ -463,7 +476,7 @@ static const char *demangle_name(struct symbol *sym)
 	for (int i = strlen(str) - 1; i >= 0; i--) {
 		char c = str[i];
 
-		if (!isdigit(c) && c != '.') {
+		if (!isdigit(c) && c != '.' && c != '_') {
 			str[i + 1] = '\0';
 			break;
 		}

index 0d93e8496e8d..c784a0484270 100644
@@ -26,11 +26,18 @@
 #include <objtool/elf.h>
 #include <objtool/warn.h>
 
+static ssize_t demangled_name_len(const char *name);
+
 static inline u32 str_hash(const char *str)
 {
 	return jhash(str, strlen(str), 0);
 }
 
+static inline u32 str_hash_demangled(const char *str)
+{
+	return jhash(str, demangled_name_len(str), 0);
+}
+
 #define __elf_table(name)	(elf->name##_hash)
 #define __elf_bits(name)	(elf->name##_bits)
 

@@ -294,7 +301,7 @@ static struct symbol *find_local_symbol_by_file_and_name(const struct elf *elf,
 {
 	struct symbol *sym;
 
-	elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
+	elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash_demangled(name)) {
 		if (sym->bind == STB_LOCAL && sym->file == file &&
 		    !strcmp(sym->name, name)) {
 			return sym;

@@ -308,7 +315,7 @@ struct symbol *find_global_symbol_by_name(const struct elf *elf, const char *nam
 {
 	struct symbol *sym;
 
-	elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
+	elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash_demangled(name)) {
 		if (!strcmp(sym->name, name) && !is_local_sym(sym))
 			return sym;
 	}

@@ -441,6 +448,28 @@ static int read_sections(struct elf *elf)
 	return 0;
 }
 
+/*
+ * Returns desired length of the demangled name.
+ * If name doesn't need demangling, return strlen(name).
+ */
+static ssize_t demangled_name_len(const char *name)
+{
+	ssize_t len;
+
+	if (!strstarts(name, "__UNIQUE_ID_") && !strchr(name, '.'))
+		return strlen(name);
+
+	for (len = strlen(name) - 1; len >= 0; len--) {
+		char c = name[len];
+
+		if (!isdigit(c) && c != '.' && c != '_')
+			break;
+	}
+	if (len <= 0)
+		return strlen(name);
+	return len;
+}
+
 /*
  * Remove number suffix of a symbol.
  *

@@ -457,6 +486,7 @@ static int read_sections(struct elf *elf)
 static const char *demangle_name(struct symbol *sym)
 {
 	char *str;
+	ssize_t len;
 
 	if (!is_local_sym(sym))
 		return sym->name;

@@ -464,24 +494,16 @@ static const char *demangle_name(struct symbol *sym)
 	if (!is_func_sym(sym) && !is_object_sym(sym))
 		return sym->name;
 
-	if (!strstarts(sym->name, "__UNIQUE_ID_") && !strchr(sym->name, '.'))
+	len = demangled_name_len(sym->name);
+	if (len == strlen(sym->name))
 		return sym->name;
 
-	str = strdup(sym->name);
+	str = strndup(sym->name, len);
 	if (!str) {
 		ERROR_GLIBC("strdup");
 		return NULL;
 	}
 
-	for (int i = strlen(str) - 1; i >= 0; i--) {
-		char c = str[i];
-
-		if (!isdigit(c) && c != '.' && c != '_') {
-			str[i + 1] = '\0';
-			break;
-		}
-	}
-
 	return str;
 }
 

@@ -517,9 +539,13 @@ static int elf_add_symbol(struct elf *elf, struct symbol *sym)
 		entry = &sym->sec->symbol_list;
 	list_add(&sym->list, entry);
 
+	sym->demangled_name = demangle_name(sym);
+	if (!sym->demangled_name)
+		return -1;
+
 	list_add_tail(&sym->global_list, &elf->symbols);
 	elf_hash_add(symbol, &sym->hash, sym->idx);
-	elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
+	elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->demangled_name));
 
 	if (is_func_sym(sym) &&
 	    (strstarts(sym->name, "__pfx_") ||

@@ -543,10 +569,6 @@ static int elf_add_symbol(struct elf *elf, struct symbol *sym)
 
 	sym->pfunc = sym->cfunc = sym;
 
-	sym->demangled_name = demangle_name(sym);
-	if (!sym->demangled_name)
-		return -1;
-
 	return 0;
 }
 

index c784a0484270..d66452d66fb4 100644
@@ -488,9 +488,6 @@ static const char *demangle_name(struct symbol *sym)
 	char *str;
 	ssize_t len;
 
-	if (!is_local_sym(sym))
-		return sym->name;
-
 	if (!is_func_sym(sym) && !is_object_sym(sym))
 		return sym->name;
 

index d66452d66fb4..efb13ec0a89d 100644
@@ -455,10 +455,15 @@ static int read_sections(struct elf *elf)
 static ssize_t demangled_name_len(const char *name)
 {
 	ssize_t len;
+	const char *p;
 
 	if (!strstarts(name, "__UNIQUE_ID_") && !strchr(name, '.'))
 		return strlen(name);
 
+	p = strstr(name, ".llvm.");
+	if (p)
+		return p - name;
+
 	for (len = strlen(name) - 1; len >= 0; len--) {
 		char c = name[len];
 

@@ -482,6 +487,9 @@ static ssize_t demangled_name_len(const char *name)
  *   __UNIQUE_ID_addressable___UNIQUE_ID_pci_invalid_bar_694_695
  *
  * to remove both trailing numbers, also remove trailing '_'.
+ *
+ * For symbols with llvm suffix, i.e., foo.llvm.<hash>, remove the
+ * .llvm.<hash> part.
  */
 static const char *demangle_name(struct symbol *sym)
 {

index efb13ec0a89d..5ddbfa8f8701 100644
@@ -323,6 +323,19 @@ struct symbol *find_global_symbol_by_name(const struct elf *elf, const char *nam
 	return NULL;
 }
 
+void iterate_global_symbol_by_demangled_name(const struct elf *elf,
+					     const char *demangled_name,
+					     void (*process)(struct symbol *sym, void *data),
+					     void *data)
+{
+	struct symbol *sym;
+
+	elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(demangled_name)) {
+		if (!strcmp(sym->demangled_name, demangled_name) && !is_local_sym(sym))
+			process(sym, data);
+	}
+}
+
 struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
 				     unsigned long offset, unsigned int len)
 {

index e12c516bd320..25573e5af76e 100644
@@ -186,6 +186,9 @@ struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
 struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
 struct symbol *find_symbol_by_name(const struct elf *elf, const char *name);
 struct symbol *find_global_symbol_by_name(const struct elf *elf, const char *name);
+void iterate_global_symbol_by_demangled_name(const struct elf *elf, const char *demangled_name,
+					     void (*process)(struct symbol *sym, void *data),
+					     void *data);
 struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset);
 int find_symbol_hole_containing(const struct section *sec, unsigned long offset);
 struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset);

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index 147e7e7176fb..07fcaca46160 100644
@@ -519,6 +519,37 @@ static int correlate_symbols(struct elfs *e)
 		}
 	}
 
+	/* Correlate original locals with patched globals */
+	for_each_sym(e->orig, sym1) {
+		if (sym1->twin || dont_correlate(sym1) || !is_local_sym(sym1))
+			continue;
+		sym2 = find_global_symbol_by_name(e->patched, sym1->name);
+		if (!sym2 && find_global_symbol_by_demangled_name(e->patched, sym1, &sym2))
+			return -1;
+		if (sym2 && !sym2->twin) {
+			sym1->twin = sym2;
+			sym2->twin = sym1;
+			WARN("correlate LOCAL %s (original) to GLOBAL %s (patched)",
+			     sym1->name, sym2->name);
+		}
+	}
+
+	/* Correlate original globals with patched locals */
+	for_each_sym(e->patched, sym2) {
+		if (sym2->twin || dont_correlate(sym2) || !is_local_sym(sym2))
+			continue;
+		sym1 = find_global_symbol_by_name(e->orig, sym2->name);
+		if (!sym1 && find_global_symbol_by_demangled_name(e->patched, sym2, &sym1))
+			return -1;
+
+		if (sym1 && !sym1->twin) {
+			sym2->twin = sym1;
+			sym1->twin = sym2;
+			WARN("correlate GLOBAL %s (origial) to LOCAL %s (patched)",
+			     sym1->name, sym2->name);
+		}
+	}
+
 	for_each_sym(e->orig, sym1) {
 		if (sym1->twin || dont_correlate(sym1))
 			continue;

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new file mode 100644
index 000000000000..56a766f4744b
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _KLP_TEST_MODULE_H
+#define _KLP_TEST_MODULE_H
+
+ssize_t klp_test_module_func1(char *buf, int len);
+ssize_t klp_test_module_func2(char *buf, int len);
+
+#endif /* _KLP_TEST_MODULE_H */

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new file mode 100644
index 000000000000..56d9f7b6d350
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _KLP_TEST_VMLINUX_H
+#define _KLP_TEST_VMLINUX_H
+
+#include <linux/kobject.h>
+
+extern struct kobject *klp_test_kobj;
+
+ssize_t klp_test_vmlinux_func1(char *buf, int len);
+ssize_t klp_test_vmlinux_func2(char *buf, int len);
+ssize_t klp_test_vmlinux_func3(char *buf, int len);
+
+int klp_test_vmlinux_aux_init(struct kobject *parent);
+void klp_test_vmlinux_aux_exit(struct kobject *parent);
+
+#endif /* _KLP_TEST_VMLINUX_H */

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