linux-kernel - [GIT pull] objtool/urgent for 6.4-rc4

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Date:   Sun, 28 May 2023 09:52:59 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [GIT pull] objtool/urgent for 6.4-rc4

Linus,

please pull the latest objtool/urgent branch from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git objtool-urgent-2023-05-28

up to:  2e4be0d011f2: x86/show_trace_log_lvl: Ensure stack pointer is aligned, again


A set of unwinder and tooling fixes:

  - Ensure that the stack pointer on x86 is aligned again so that the
    unwinder does not read past the end of the stack

  - Discard .note.gnu.property section which has a pointlessly different
    alignment than the other note sections. That confuses tooling of all
    sorts including readelf, libbpf and pahole.

Thanks,

	tglx

------------------>
Josh Poimboeuf (1):
      vmlinux.lds.h: Discard .note.gnu.property section

Vernon Lovejoy (1):
      x86/show_trace_log_lvl: Ensure stack pointer is aligned, again


 arch/x86/kernel/dumpstack.c       | 7 +++++--
 include/asm-generic/vmlinux.lds.h | 9 ++++++++-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 0bf6779187dd..f18ca44c904b 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -195,7 +195,6 @@ static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	printk("%sCall Trace:\n", log_lvl);
 
 	unwind_start(&state, task, regs, stack);
-	stack = stack ? : get_stack_pointer(task, regs);
 	regs = unwind_get_entry_regs(&state, &partial);
 
 	/*
@@ -214,9 +213,13 @@ static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	 * - hardirq stack
 	 * - entry stack
 	 */
-	for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
+	for (stack = stack ?: get_stack_pointer(task, regs);
+	     stack;
+	     stack = stack_info.next_sp) {
 		const char *stack_name;
 
+		stack = PTR_ALIGN(stack, sizeof(long));
+
 		if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
 			/*
 			 * We weren't on a valid stack.  It's possible that
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index d1f57e4868ed..cebdf1ca415d 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -891,9 +891,16 @@
 /*
  * Discard .note.GNU-stack, which is emitted as PROGBITS by the compiler.
  * Otherwise, the type of .notes section would become PROGBITS instead of NOTES.
+ *
+ * Also, discard .note.gnu.property, otherwise it forces the notes section to
+ * be 8-byte aligned which causes alignment mismatches with the kernel's custom
+ * 4-byte aligned notes.
  */
 #define NOTES								\
-	/DISCARD/ : { *(.note.GNU-stack) }				\
+	/DISCARD/ : {							\
+		*(.note.GNU-stack)					\
+		*(.note.gnu.property)					\
+	}								\
 	.notes : AT(ADDR(.notes) - LOAD_OFFSET) {			\
 		BOUNDED_SECTION_BY(.note.*, _notes)			\
 	} NOTES_HEADERS							\