FAILED: patch "[PATCH] x86/build: Fix linker fill bytes quirk/incompatibility for" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] x86/build: Fix linker fill bytes quirk/incompatibility for" failed to apply to 5.15-stable tree

[gregkh]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 65e710899fd19f435f40268f3a92dfaa11f14470
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023091033-scone-precinct-e841@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 65e710899fd19f435f40268f3a92dfaa11f14470 Mon Sep 17 00:00:00 2001
From: Song Liu <song@kernel.org>
Date: Wed, 6 Sep 2023 10:52:15 -0700
Subject: [PATCH] x86/build: Fix linker fill bytes quirk/incompatibility for
 ld.lld

With ":text =0xcccc", ld.lld fills unused text area with 0xcccc0000.
Example objdump -D output:

	ffffffff82b04203:       00 00                   add    %al,(%rax)
	ffffffff82b04205:       cc                      int3
	ffffffff82b04206:       cc                      int3
	ffffffff82b04207:       00 00                   add    %al,(%rax)
	ffffffff82b04209:       cc                      int3
	ffffffff82b0420a:       cc                      int3

Replace it with ":text =0xcccccccc", so we get the following instead:

	ffffffff82b04203:       cc                      int3
	ffffffff82b04204:       cc                      int3
	ffffffff82b04205:       cc                      int3
	ffffffff82b04206:       cc                      int3
	ffffffff82b04207:       cc                      int3
	ffffffff82b04208:       cc                      int3

gcc/ld doesn't seem to have the same issue. The generated code stays the
same for gcc/ld.

Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Fixes: 7705dc855797 ("x86/vmlinux: Use INT3 instead of NOP for linker fill bytes")
Link: https://lore.kernel.org/r/20230906175215.2236033-1-song@kernel.org

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 83d41c2601d7..f15fb71f280e 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -156,7 +156,7 @@ SECTIONS
 		ALIGN_ENTRY_TEXT_END
 		*(.gnu.warning)
 
-	} :text =0xcccc
+	} :text = 0xcccccccc
 
 	/* End of text section, which should occupy whole number of pages */
 	_etext = .;