This is a note to let you know that I've just added the patch titled
arch: fix broken BuildID for arm64 and riscv
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arch-fix-broken-buildid-for-arm64-and-riscv.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From stable-owner@xxxxxxxxxxxxxxx Thu Mar 2 03:07:31 2023
From: Tom Saeger <tom.saeger@xxxxxxxxxx>
Date: Wed, 1 Mar 2023 19:07:00 -0700
Subject: arch: fix broken BuildID for arm64 and riscv
To: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Sasha Levin <sashal@xxxxxxxxxx>, Tom Saeger <tom.saeger@xxxxxxxxxx>, stable@xxxxxxxxxxxxxxx, Masahiro Yamada <masahiroy@xxxxxxxxxx>, Dennis Gilmore <dennis@xxxxxxxx>, Ard Biesheuvel <ardb@xxxxxxxxxx>, Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Message-ID: <20230210-tsaeger-upstream-linux-stable-5-4-v3-2-122fc5440d4c@xxxxxxxxxx>
From: Masahiro Yamada <masahiroy@xxxxxxxxxx>
commit 99cb0d917ffa1ab628bb67364ca9b162c07699b1 upstream.
Dennis Gilmore reports that the BuildID is missing in the arm64 vmlinux
since commit 994b7ac1697b ("arm64: remove special treatment for the
link order of head.o").
The issue is that the type of .notes section, which contains the BuildID,
changed from NOTES to PROGBITS.
Ard Biesheuvel figured out that whichever object gets linked first gets
to decide the type of a section. The PROGBITS type is the result of the
compiler emitting .note.GNU-stack as PROGBITS rather than NOTE.
While Ard provided a fix for arm64, I want to fix this globally because
the same issue is happening on riscv since commit 2348e6bf4421 ("riscv:
remove special treatment for the link order of head.o"). This problem
will happen in general for other architectures if they start to drop
unneeded entries from scripts/head-object-list.txt.
Discard .note.GNU-stack in include/asm-generic/vmlinux.lds.h.
Link: https://lore.kernel.org/lkml/CAABkxwuQoz1CTbyb57n0ZX65eSYiTonFCU8-LCQc=74D=xE=rA@xxxxxxxxxxxxxx/
Fixes: 994b7ac1697b ("arm64: remove special treatment for the link order of head.o")
Fixes: 2348e6bf4421 ("riscv: remove special treatment for the link order of head.o")
Reported-by: Dennis Gilmore <dennis@xxxxxxxx>
Suggested-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Acked-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
[Tom: stable backport 5.15.y, 5.10.y, 5.4.y]
Though the above "Fixes:" commits are not in this kernel, the conditions
which lead to a missing Build ID in arm64 vmlinux are similar.
Evidence points to these conditions:
1. ld version > 2.36 (exact binutils commit documented in a494398bde27)
2. first object which gets linked (head.o) has a PROGBITS .note.GNU-stack segment
These conditions can be observed when:
- 5.15.60+ OR 5.10.136+ OR 5.4.210+
- AND ld version > 2.36
- AND arch=arm64
- AND CONFIG_MODVERSIONS=y
There are notable differences in the vmlinux elf files produced
before(bad) and after(good) applying this series.
Good: p_type:PT_NOTE segment exists.
Bad: p_type:PT_NOTE segment is missing.
Good: sh_name_str:.notes section has sh_type:SHT_NOTE
Bad: sh_name_str:.notes section has sh_type:SHT_PROGBITS
`readelf -n` (as of v2.40) searches for Build Id
by processing only the very first note in sh_type:SHT_NOTE sections.
This was previously bisected to the stable backport of 0d362be5b142.
Follow-up experiments were discussed here: https://lore.kernel.org/all/20221221235413.xaisboqmr7dkqwn6@xxxxxxxxxx/
which strongly hints at condition 2.
Signed-off-by: Tom Saeger <tom.saeger@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/asm-generic/vmlinux.lds.h | 5 +++++
1 file changed, 5 insertions(+)
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -825,7 +825,12 @@
#define TRACEDATA
#endif
+/*
+ * Discard .note.GNU-stack, which is emitted as PROGBITS by the compiler.
+ * Otherwise, the type of .notes section would become PROGBITS instead of NOTES.
+ */
#define NOTES \
+ /DISCARD/ : { *(.note.GNU-stack) } \
.notes : AT(ADDR(.notes) - LOAD_OFFSET) { \
__start_notes = .; \
KEEP(*(.note.*)) \
Patches currently in stable-queue which might be from stable-owner@xxxxxxxxxxxxxxx are
queue-5.4/powerpc-vmlinux.lds-don-t-discard-.rela-for-relocatable-builds.patch
queue-5.4/s390-define-runtime_discard_exit-to-fix-link-error-with-gnu-ld-2.36.patch
queue-5.4/powerpc-vmlinux.lds-define-runtime_discard_exit.patch
queue-5.4/sh-define-runtime_discard_exit.patch
queue-5.4/x86-vmlinux.lds-add-runtime_discard_exit-to-generic-discards.patch
queue-5.4/arch-fix-broken-buildid-for-arm64-and-riscv.patch
