Messages in this thread Patch in this message | | | Date | Wed, 06 Sep 2023 21:57:17 -0000 | From | "tip-bot2 for Song Liu" <> | Subject | [tip: x86/urgent] x86/build: Fix linker fill bytes quirk/incompatibility for ld.lld |
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The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 65e710899fd19f435f40268f3a92dfaa11f14470 Gitweb: https://git.kernel.org/tip/65e710899fd19f435f40268f3a92dfaa11f14470 Author: Song Liu <song@kernel.org> AuthorDate: Wed, 06 Sep 2023 10:52:15 -07:00 Committer: Ingo Molnar <mingo@kernel.org> CommitterDate: Wed, 06 Sep 2023 23:49:12 +02:00
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 --- 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 83d41c2..f15fb71 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 = .;
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