From 65e710899fd19f435f40268f3a92dfaa11f14470 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 6 Sep 2023 10:52:15 -0700 Subject: 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 Signed-off-by: Ingo Molnar Reviewed-by: Kees Cook Acked-by: Peter Zijlstra (Intel) 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 --- arch/x86/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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 = .; -- cgit v1.2.3