Merge tag 'objtool-urgent-2026-03-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fixes from Ingo Molnar:

 - Fix cross-build bug by using HOSTCFLAGS for HAVE_XXHASH test

 - Fix klp bug by fixing detection of corrupt static branch/call entries

 - Handle unsupported pr_debug() usage more gracefully

 - Fix hypothetical klp bug by avoiding NULL pointer dereference when
   printing code symbol name

 - Fix data alignment bug in elf_add_data() causing mangled strings

 - Fix confusing ERROR_INSN() error message

 - Handle unexpected Clang RSP musical chairs causing false positive
   warnings

 - Fix another objtool stack overflow in validate_branch()

* tag 'objtool-urgent-2026-03-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Fix another stack overflow in validate_branch()
  objtool: Handle Clang RSP musical chairs
  objtool: Fix ERROR_INSN() error message
  objtool: Fix data alignment in elf_add_data()
  objtool: Use HOSTCFLAGS for HAVE_XXHASH test
  objtool/klp: Avoid NULL pointer dereference when printing code symbol name
  objtool/klp: Disable unsupported pr_debug() usage
  objtool/klp: Fix detection of corrupt static branch/call entries

6 files changed, 71 insertions, 60 deletions

diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 76bcd4e85de3..b71d1886022e 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -13,7 +13,7 @@ endif
 
 ifeq ($(ARCH_HAS_KLP),y)
 	HAVE_XXHASH = $(shell printf "$(pound)include <xxhash.h>\nXXH3_state_t *state;int main() {}" | \
-		      $(HOSTCC) -xc - -o /dev/null -lxxhash 2> /dev/null && echo y || echo n)
+		      $(HOSTCC) $(HOSTCFLAGS) -xc - -o /dev/null -lxxhash 2> /dev/null && echo y || echo n)
 	ifeq ($(HAVE_XXHASH),y)
 		BUILD_KLP	 := y
 		LIBXXHASH_CFLAGS := $(shell $(HOSTPKG_CONFIG) libxxhash --cflags 2>/dev/null) \
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 73bfea220d1b..c5817829cdfa 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -395,52 +395,36 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
 		if (!rex_w)
 			break;
 
-		if (modrm_reg == CFI_SP) {
-
-			if (mod_is_reg()) {
-				/* mov %rsp, reg */
-				ADD_OP(op) {
-					op->src.type = OP_SRC_REG;
-					op->src.reg = CFI_SP;
-					op->dest.type = OP_DEST_REG;
-					op->dest.reg = modrm_rm;
-				}
-				break;
-
-			} else {
-				/* skip RIP relative displacement */
-				if (is_RIP())
-					break;
-
-				/* skip nontrivial SIB */
-				if (have_SIB()) {
-					modrm_rm = sib_base;
-					if (sib_index != CFI_SP)
-						break;
-				}
-
-				/* mov %rsp, disp(%reg) */
-				ADD_OP(op) {
-					op->src.type = OP_SRC_REG;
-					op->src.reg = CFI_SP;
-					op->dest.type = OP_DEST_REG_INDIRECT;
-					op->dest.reg = modrm_rm;
-					op->dest.offset = ins.displacement.value;
-				}
-				break;
+		if (mod_is_reg()) {
+			/* mov reg, reg */
+			ADD_OP(op) {
+				op->src.type = OP_SRC_REG;
+				op->src.reg = modrm_reg;
+				op->dest.type = OP_DEST_REG;
+				op->dest.reg = modrm_rm;
 			}
-
 			break;
 		}
 
-		if (rm_is_reg(CFI_SP)) {
+		/* skip RIP relative displacement */
+		if (is_RIP())
+			break;
 
-			/* mov reg, %rsp */
+		/* skip nontrivial SIB */
+		if (have_SIB()) {
+			modrm_rm = sib_base;
+			if (sib_index != CFI_SP)
+				break;
+		}
+
+		/* mov %rsp, disp(%reg) */
+		if (modrm_reg == CFI_SP) {
 			ADD_OP(op) {
 				op->src.type = OP_SRC_REG;
-				op->src.reg = modrm_reg;
-				op->dest.type = OP_DEST_REG;
-				op->dest.reg = CFI_SP;
+				op->src.reg = CFI_SP;
+				op->dest.type = OP_DEST_REG_INDIRECT;
+				op->dest.reg = modrm_rm;
+				op->dest.offset = ins.displacement.value;
 			}
 			break;
 		}
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a30379e4ff97..91b3ff4803cf 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3000,6 +3000,20 @@ static int update_cfi_state(struct instruction *insn,
 				cfi->stack_size += 8;
 			}
 
+			else if (cfi->vals[op->src.reg].base == CFI_CFA) {
+				/*
+				 * Clang RSP musical chairs:
+				 *
+				 *   mov %rsp, %rdx [handled above]
+				 *   ...
+				 *   mov %rdx, %rbx [handled here]
+				 *   ...
+				 *   mov %rbx, %rsp [handled above]
+				 */
+				cfi->vals[op->dest.reg].base = CFI_CFA;
+				cfi->vals[op->dest.reg].offset = cfi->vals[op->src.reg].offset;
+			}
+
 
 			break;
 
@@ -3734,7 +3748,7 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
 static int validate_branch(struct objtool_file *file, struct symbol *func,
 			   struct instruction *insn, struct insn_state state);
 static int do_validate_branch(struct objtool_file *file, struct symbol *func,
-			      struct instruction *insn, struct insn_state state);
+			      struct instruction *insn, struct insn_state *state);
 
 static int validate_insn(struct objtool_file *file, struct symbol *func,
 			 struct instruction *insn, struct insn_state *statep,
@@ -3999,7 +4013,7 @@ static int validate_insn(struct objtool_file *file, struct symbol *func,
  * tools/objtool/Documentation/objtool.txt.
  */
 static int do_validate_branch(struct objtool_file *file, struct symbol *func,
-			      struct instruction *insn, struct insn_state state)
+			      struct instruction *insn, struct insn_state *state)
 {
 	struct instruction *next_insn, *prev_insn = NULL;
 	bool dead_end;
@@ -4030,7 +4044,7 @@ static int do_validate_branch(struct objtool_file *file, struct symbol *func,
 			return 1;
 		}
 
-		ret = validate_insn(file, func, insn, &state, prev_insn, next_insn,
+		ret = validate_insn(file, func, insn, state, prev_insn, next_insn,
 				    &dead_end);
 
 		if (!insn->trace) {
@@ -4041,7 +4055,7 @@ static int do_validate_branch(struct objtool_file *file, struct symbol *func,
 		}
 
 		if (!dead_end && !next_insn) {
-			if (state.cfi.cfa.base == CFI_UNDEFINED)
+			if (state->cfi.cfa.base == CFI_UNDEFINED)
 				return 0;
 			if (file->ignore_unreachables)
 				return 0;
@@ -4066,7 +4080,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 	int ret;
 
 	trace_depth_inc();
-	ret = do_validate_branch(file, func, insn, state);
+	ret = do_validate_branch(file, func, insn, &state);
 	trace_depth_dec();
 
 	return ret;
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 2c02c7b49265..3da90686350d 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -1375,7 +1375,7 @@ void *elf_add_data(struct elf *elf, struct section *sec, const void *data, size_
 		memcpy(sec->data->d_buf, data, size);
 
 	sec->data->d_size = size;
-	sec->data->d_align = 1;
+	sec->data->d_align = sec->sh.sh_addralign;
 
 	offset = ALIGN(sec->sh.sh_size, sec->sh.sh_addralign);
 	sec->sh.sh_size = offset + size;
diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
index 2b27b54096b8..fa8b7d292e83 100644
--- a/tools/objtool/include/objtool/warn.h
+++ b/tools/objtool/include/objtool/warn.h
@@ -107,7 +107,7 @@ static inline char *offstr(struct section *sec, unsigned long offset)
 #define ERROR_ELF(format, ...) __WARN_ELF(ERROR_STR, format, ##__VA_ARGS__)
 #define ERROR_GLIBC(format, ...) __WARN_GLIBC(ERROR_STR, format, ##__VA_ARGS__)
 #define ERROR_FUNC(sec, offset, format, ...) __WARN_FUNC(ERROR_STR, sec, offset, format, ##__VA_ARGS__)
-#define ERROR_INSN(insn, format, ...) WARN_FUNC(insn->sec, insn->offset, format, ##__VA_ARGS__)
+#define ERROR_INSN(insn, format, ...) ERROR_FUNC(insn->sec, insn->offset, format, ##__VA_ARGS__)
 
 extern bool debug;
 extern int indent;
diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index 9f1f4011eb9c..a3198a63c2f0 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c
@@ -1334,25 +1334,25 @@ static bool should_keep_special_sym(struct elf *elf, struct symbol *sym)
  * be applied after static branch/call init, resulting in code corruption.
  *
  * Validate a special section entry to avoid that.  Note that an inert
- * tracepoint is harmless enough, in that case just skip the entry and print a
- * warning.  Otherwise, return an error.
+ * tracepoint or pr_debug() is harmless enough, in that case just skip the
+ * entry and print a warning.  Otherwise, return an error.
  *
- * This is only a temporary limitation which will be fixed when livepatch adds
- * support for submodules: fully self-contained modules which are embedded in
- * the top-level livepatch module's data and which can be loaded on demand when
- * their corresponding to-be-patched module gets loaded.  Then klp relocs can
- * be retired.
+ * TODO: This is only a temporary limitation which will be fixed when livepatch
+ * adds support for submodules: fully self-contained modules which are embedded
+ * in the top-level livepatch module's data and which can be loaded on demand
+ * when their corresponding to-be-patched module gets loaded.  Then klp relocs
+ * can be retired.
  *
  * Return:
  *   -1: error: validation failed
- *    1: warning: tracepoint skipped
+ *    1: warning: disabled tracepoint or pr_debug()
  *    0: success
  */
 static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym)
 {
 	bool static_branch = !strcmp(sym->sec->name, "__jump_table");
 	bool static_call   = !strcmp(sym->sec->name, ".static_call_sites");
-	struct symbol *code_sym = NULL;
+	const char *code_sym = NULL;
 	unsigned long code_offset = 0;
 	struct reloc *reloc;
 	int ret = 0;
@@ -1364,12 +1364,15 @@ static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym
 		const char *sym_modname;
 		struct export *export;
 
+		if (convert_reloc_sym(e->patched, reloc))
+			continue;
+
 		/* Static branch/call keys are always STT_OBJECT */
 		if (reloc->sym->type != STT_OBJECT) {
 
 			/* Save code location which can be printed below */
 			if (reloc->sym->type == STT_FUNC && !code_sym) {
-				code_sym = reloc->sym;
+				code_sym = reloc->sym->name;
 				code_offset = reloc_addend(reloc);
 			}
 
@@ -1392,16 +1395,26 @@ static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym
 		if (!strcmp(sym_modname, "vmlinux"))
 			continue;
 
+		if (!code_sym)
+			code_sym = "<unknown>";
+
 		if (static_branch) {
 			if (strstarts(reloc->sym->name, "__tracepoint_")) {
 				WARN("%s: disabling unsupported tracepoint %s",
-				     code_sym->name, reloc->sym->name + 13);
+				     code_sym, reloc->sym->name + 13);
+				ret = 1;
+				continue;
+			}
+
+			if (strstr(reloc->sym->name, "__UNIQUE_ID_ddebug_")) {
+				WARN("%s: disabling unsupported pr_debug()",
+				     code_sym);
 				ret = 1;
 				continue;
 			}
 
 			ERROR("%s+0x%lx: unsupported static branch key %s.  Use static_key_enabled() instead",
-			      code_sym->name, code_offset, reloc->sym->name);
+			      code_sym, code_offset, reloc->sym->name);
 			return -1;
 		}
 
@@ -1412,7 +1425,7 @@ static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym
 		}
 
 		ERROR("%s()+0x%lx: unsupported static call key %s.  Use KLP_STATIC_CALL() instead",
-		      code_sym->name, code_offset, reloc->sym->name);
+		      code_sym, code_offset, reloc->sym->name);
 		return -1;
 	}