Misc fixes and cleanups:

- Fix potential MAX_NAME_LEN limit related build failures
  - Fix scripts/faddr2line symbol filtering bug
  - Fix scripts/faddr2line on LLVM=1
  - Fix scripts/faddr2line to accept readelf output with mapping symbols
  - Minor cleanups
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:
 "Misc fixes and cleanups:

   - Fix potential MAX_NAME_LEN limit related build failures

   - Fix scripts/faddr2line symbol filtering bug

   - Fix scripts/faddr2line on LLVM=1

   - Fix scripts/faddr2line to accept readelf output with mapping
     symbols

   - Minor cleanups"

* tag 'objtool-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  scripts/faddr2line: Skip over mapping symbols in output from readelf
  scripts/faddr2line: Use LLVM addr2line and readelf if LLVM=1
  scripts/faddr2line: Don't filter out non-function symbols from readelf
  objtool: Remove max symbol name length limitation
  objtool: Propagate early errors
  objtool: Use 'the fallthrough' pseudo-keyword
  x86/speculation, objtool: Use absolute relocations for annotations
  x86/unwind/orc: Remove redundant initialization of 'mid' pointer in __orc_find()

arch/x86/include/asm/alternative.h

@@ -58,7 +58,7 @@
 #define ANNOTATE_IGNORE_ALTERNATIVE				\
 	"999:\n\t"						\
 	".pushsection .discard.ignore_alts\n\t"			\
-	".long 999b - .\n\t"					\
+	".long 999b\n\t"					\
 	".popsection\n\t"
 
 /*
@@ -352,7 +352,7 @@ static inline int alternatives_text_reserved(void *start, void *end)
 .macro ANNOTATE_IGNORE_ALTERNATIVE
 	.Lannotate_\@:
 	.pushsection .discard.ignore_alts
-	.long .Lannotate_\@ - .
+	.long .Lannotate_\@
 	.popsection
 .endm
 

arch/x86/include/asm/nospec-branch.h

@@ -196,7 +196,7 @@
 .macro ANNOTATE_RETPOLINE_SAFE
 .Lhere_\@:
 	.pushsection .discard.retpoline_safe
-	.long .Lhere_\@ - .
+	.long .Lhere_\@
 	.popsection
 .endm
 
@@ -320,7 +320,7 @@
 #define ANNOTATE_RETPOLINE_SAFE					\
 	"999:\n\t"						\
 	".pushsection .discard.retpoline_safe\n\t"		\
-	".long 999b - .\n\t"					\
+	".long 999b\n\t"					\
 	".popsection\n\t"
 
 typedef u8 retpoline_thunk_t[RETPOLINE_THUNK_SIZE];

arch/x86/kernel/unwind_orc.c

@@ -85,7 +85,7 @@ static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
 {
 	int *first = ip_table;
 	int *last = ip_table + num_entries - 1;
-	int *mid = first, *found = first;
+	int *mid, *found = first;
 
 	if (!num_entries)
 		return NULL;

include/linux/objtool.h

@@ -48,13 +48,13 @@
 #define ANNOTATE_NOENDBR					\
 	"986: \n\t"						\
 	".pushsection .discard.noendbr\n\t"			\
-	".long 986b - .\n\t"					\
+	".long 986b\n\t"					\
 	".popsection\n\t"
 
 #define ASM_REACHABLE							\
 	"998:\n\t"							\
 	".pushsection .discard.reachable\n\t"				\
-	".long 998b - .\n\t"						\
+	".long 998b\n\t"						\
 	".popsection\n\t"
 
 #else /* __ASSEMBLY__ */
@@ -66,7 +66,7 @@
 #define ANNOTATE_INTRA_FUNCTION_CALL				\
 	999:							\
 	.pushsection .discard.intra_function_calls;		\
-	.long 999b - .;						\
+	.long 999b;						\
 	.popsection;
 
 /*
@@ -118,7 +118,7 @@
 .macro ANNOTATE_NOENDBR
 .Lhere_\@:
 	.pushsection .discard.noendbr
-	.long	.Lhere_\@ - .
+	.long	.Lhere_\@
 	.popsection
 .endm
 
@@ -142,7 +142,7 @@
 .macro REACHABLE
 .Lhere_\@:
 	.pushsection .discard.reachable
-	.long	.Lhere_\@ - .
+	.long	.Lhere_\@
 	.popsection
 .endm
 

scripts/faddr2line

@@ -58,8 +58,21 @@ die() {
 	exit 1
 }
 
-READELF="${CROSS_COMPILE:-}readelf"
-ADDR2LINE="${CROSS_COMPILE:-}addr2line"
+UTIL_SUFFIX=""
+if [[ "${LLVM:-}" == "" ]]; then
+	UTIL_PREFIX=${CROSS_COMPILE:-}
+else
+	UTIL_PREFIX=llvm-
+
+	if [[ "${LLVM}" == *"/" ]]; then
+		UTIL_PREFIX=${LLVM}${UTIL_PREFIX}
+	elif [[ "${LLVM}" == "-"* ]]; then
+		UTIL_SUFFIX=${LLVM}
+	fi
+fi
+
+READELF="${UTIL_PREFIX}readelf${UTIL_SUFFIX}"
+ADDR2LINE="${UTIL_PREFIX}addr2line${UTIL_SUFFIX}"
 AWK="awk"
 GREP="grep"
 
@@ -166,6 +179,11 @@ __faddr2line() {
 			local cur_sym_elf_size=${fields[2]}
 			local cur_sym_name=${fields[7]:-}
 
+			# is_mapping_symbol(cur_sym_name)
+			if [[ ${cur_sym_name} =~ ^(\.L|L0|\$) ]]; then
+				continue
+			fi
+
 			if [[ $cur_sym_addr = $sym_addr ]] &&
 			   [[ $cur_sym_elf_size = $sym_elf_size ]] &&
 			   [[ $cur_sym_name = $sym_name ]]; then
@@ -260,7 +278,7 @@ __faddr2line() {
 
 		DONE=1
 
-	done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v fn=$sym_name '$4 == "FUNC" && $8 == fn')
+	done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v fn=$sym_name '$8 == fn')
 }
 
 [[ $# -lt 2 ]] && usage

tools/objtool/arch/x86/decode.c

@@ -291,7 +291,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
 		switch (modrm_reg & 7) {
 		case 5:
 			imm = -imm;
-			/* fallthrough */
+			fallthrough;
 		case 0:
 			/* add/sub imm, %rsp */
 			ADD_OP(op) {
@@ -375,7 +375,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
 			break;
 		}
 
-		/* fallthrough */
+		fallthrough;
 	case 0x88:
 		if (!rex_w)
 			break;
@@ -656,7 +656,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
 			break;
 		}
 
-		/* fallthrough */
+		fallthrough;
 
 	case 0xca: /* retf */
 	case 0xcb: /* retf */

tools/objtool/elf.c

@@ -22,8 +22,6 @@
 #include <objtool/elf.h>
 #include <objtool/warn.h>
 
-#define MAX_NAME_LEN 128
-
 static inline u32 str_hash(const char *str)
 {
 	return jhash(str, strlen(str), 0);
@@ -515,7 +513,7 @@ static int read_symbols(struct elf *elf)
 	/* Create parent/child links for any cold subfunctions */
 	list_for_each_entry(sec, &elf->sections, list) {
 		sec_for_each_sym(sec, sym) {
-			char pname[MAX_NAME_LEN + 1];
+			char *pname;
 			size_t pnamelen;
 			if (sym->type != STT_FUNC)
 				continue;
@@ -531,15 +529,15 @@ static int read_symbols(struct elf *elf)
 				continue;
 
 			pnamelen = coldstr - sym->name;
-			if (pnamelen > MAX_NAME_LEN) {
-				WARN("%s(): parent function name exceeds maximum length of %d characters",
-				     sym->name, MAX_NAME_LEN);
+			pname = strndup(sym->name, pnamelen);
+			if (!pname) {
+				WARN("%s(): failed to allocate memory",
+				     sym->name);
 				return -1;
 			}
 
-			strncpy(pname, sym->name, pnamelen);
-			pname[pnamelen] = '\0';
 			pfunc = find_symbol_by_name(elf, pname);
+			free(pname);
 
 			if (!pfunc) {
 				WARN("%s(): can't find parent function",

tools/objtool/objtool.c

@@ -146,7 +146,5 @@ int main(int argc, const char **argv)
 	exec_cmd_init("objtool", UNUSED, UNUSED, UNUSED);
 	pager_init(UNUSED);
 
-	objtool_run(argc, argv);
-
-	return 0;
+	return objtool_run(argc, argv);
 }