* [PATCH 5.15 v3 1/5] arch: fix broken BuildID for arm64 and riscv
2023-03-02 2:03 [PATCH 5.15 v3 0/5] Fix Build ID on arm64 if CONFIG_MODVERSIONS=y Tom Saeger
@ 2023-03-02 2:03 ` Tom Saeger
2023-03-02 2:03 ` [PATCH 5.15 v3 2/5] powerpc/vmlinux.lds: Define RUNTIME_DISCARD_EXIT Tom Saeger
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Tom Saeger @ 2023-03-02 2:03 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: Sasha Levin, Tom Saeger, stable, Masahiro Yamada, Dennis Gilmore,
Ard Biesheuvel, Palmer Dabbelt
From: Masahiro Yamada <masahiroy@kernel.org>
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@mail.gmail.com/
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@ausil.us>
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
[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@oracle.com/
which strongly hints at condition 2.
Signed-off-by: Tom Saeger <tom.saeger@oracle.com>
---
include/asm-generic/vmlinux.lds.h | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index e28792ca25a1..8471717c5085 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -903,7 +903,12 @@
#define PRINTK_INDEX
#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.*)) \
--
2.39.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 5.15 v3 2/5] powerpc/vmlinux.lds: Define RUNTIME_DISCARD_EXIT
2023-03-02 2:03 [PATCH 5.15 v3 0/5] Fix Build ID on arm64 if CONFIG_MODVERSIONS=y Tom Saeger
2023-03-02 2:03 ` [PATCH 5.15 v3 1/5] arch: fix broken BuildID for arm64 and riscv Tom Saeger
@ 2023-03-02 2:03 ` Tom Saeger
2023-03-02 2:03 ` [PATCH 5.15 v3 3/5] powerpc/vmlinux.lds: Don't discard .rela* for relocatable builds Tom Saeger
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Tom Saeger @ 2023-03-02 2:03 UTC (permalink / raw)
To: Greg Kroah-Hartman; +Cc: Sasha Levin, Tom Saeger, stable, Michael Ellerman
From: Michael Ellerman <mpe@ellerman.id.au>
commit 4b9880dbf3bdba3a7c56445137c3d0e30aaa0a40 upstream.
The powerpc linker script explicitly includes .exit.text, because
otherwise the link fails due to references from __bug_table and
__ex_table. The code is freed (discarded) at runtime along with
.init.text and data.
That has worked in the past despite powerpc not defining
RUNTIME_DISCARD_EXIT because DISCARDS appears late in the powerpc linker
script (line 410), and the explicit inclusion of .exit.text
earlier (line 280) supersedes the discard.
However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and
riscv") introduced an earlier use of DISCARD as part of the RO_DATA
macro (line 136). With binutils < 2.36 that causes the DISCARD
directives later in the script to be applied earlier [1], causing
.exit.text to actually be discarded at link time, leading to build
errors:
'.exit.text' referenced in section '__bug_table' of crypto/algboss.o: defined in
discarded section '.exit.text' of crypto/algboss.o
'.exit.text' referenced in section '__ex_table' of drivers/nvdimm/core.o: defined in
discarded section '.exit.text' of drivers/nvdimm/core.o
Fix it by defining RUNTIME_DISCARD_EXIT, which causes the generic
DISCARDS macro to not include .exit.text at all.
1: https://lore.kernel.org/lkml/87fscp2v7k.fsf@igel.home/
Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230105132349.384666-1-mpe@ellerman.id.au
Signed-off-by: Tom Saeger <tom.saeger@oracle.com>
---
arch/powerpc/kernel/vmlinux.lds.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index a664d0c4344a..fda97c3dca4c 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -8,6 +8,7 @@
#define BSS_FIRST_SECTIONS *(.bss.prominit)
#define EMITS_PT_NOTE
#define RO_EXCEPTION_TABLE_ALIGN 0
+#define RUNTIME_DISCARD_EXIT
#define SOFT_MASK_TABLE(align) \
. = ALIGN(align); \
--
2.39.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 5.15 v3 3/5] powerpc/vmlinux.lds: Don't discard .rela* for relocatable builds
2023-03-02 2:03 [PATCH 5.15 v3 0/5] Fix Build ID on arm64 if CONFIG_MODVERSIONS=y Tom Saeger
2023-03-02 2:03 ` [PATCH 5.15 v3 1/5] arch: fix broken BuildID for arm64 and riscv Tom Saeger
2023-03-02 2:03 ` [PATCH 5.15 v3 2/5] powerpc/vmlinux.lds: Define RUNTIME_DISCARD_EXIT Tom Saeger
@ 2023-03-02 2:03 ` Tom Saeger
2023-03-02 2:03 ` [PATCH 5.15 v3 4/5] s390: define RUNTIME_DISCARD_EXIT to fix link error with GNU ld < 2.36 Tom Saeger
2023-03-02 2:03 ` [PATCH 5.15 v3 5/5] sh: define RUNTIME_DISCARD_EXIT Tom Saeger
4 siblings, 0 replies; 6+ messages in thread
From: Tom Saeger @ 2023-03-02 2:03 UTC (permalink / raw)
To: Greg Kroah-Hartman; +Cc: Sasha Levin, Tom Saeger, stable, Michael Ellerman
From: Michael Ellerman <mpe@ellerman.id.au>
commit 07b050f9290ee012a407a0f64151db902a1520f5 upstream.
Relocatable kernels must not discard relocations, they need to be
processed at runtime. As such they are included for CONFIG_RELOCATABLE
builds in the powerpc linker script (line 340).
However they are also unconditionally discarded later in the
script (line 414). Previously that worked because the earlier inclusion
superseded the discard.
However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and
riscv") introduced an earlier use of DISCARD as part of the RO_DATA
macro (line 137). With binutils < 2.36 that causes the DISCARD
directives later in the script to be applied earlier, causing .rela* to
actually be discarded at link time, leading to build warnings and a
kernel that doesn't boot:
ld: warning: discarding dynamic section .rela.init.rodata
Fix it by conditionally discarding .rela* only when CONFIG_RELOCATABLE
is disabled.
Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230105132349.384666-2-mpe@ellerman.id.au
Signed-off-by: Tom Saeger <tom.saeger@oracle.com>
---
arch/powerpc/kernel/vmlinux.lds.S | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index fda97c3dca4c..d4531902d8c6 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -408,9 +408,12 @@ SECTIONS
DISCARDS
/DISCARD/ : {
*(*.EMB.apuinfo)
- *(.glink .iplt .plt .rela* .comment)
+ *(.glink .iplt .plt .comment)
*(.gnu.version*)
*(.gnu.attributes)
*(.eh_frame)
+#ifndef CONFIG_RELOCATABLE
+ *(.rela*)
+#endif
}
}
--
2.39.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 5.15 v3 4/5] s390: define RUNTIME_DISCARD_EXIT to fix link error with GNU ld < 2.36
2023-03-02 2:03 [PATCH 5.15 v3 0/5] Fix Build ID on arm64 if CONFIG_MODVERSIONS=y Tom Saeger
` (2 preceding siblings ...)
2023-03-02 2:03 ` [PATCH 5.15 v3 3/5] powerpc/vmlinux.lds: Don't discard .rela* for relocatable builds Tom Saeger
@ 2023-03-02 2:03 ` Tom Saeger
2023-03-02 2:03 ` [PATCH 5.15 v3 5/5] sh: define RUNTIME_DISCARD_EXIT Tom Saeger
4 siblings, 0 replies; 6+ messages in thread
From: Tom Saeger @ 2023-03-02 2:03 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: Sasha Levin, Tom Saeger, stable, Masahiro Yamada,
Nathan Chancellor, Heiko Carstens
From: Masahiro Yamada <masahiroy@kernel.org>
commit a494398bde273143c2352dd373cad8211f7d94b2 upstream.
Nathan Chancellor reports that the s390 vmlinux fails to link with
GNU ld < 2.36 since commit 99cb0d917ffa ("arch: fix broken BuildID
for arm64 and riscv").
It happens for defconfig, or more specifically for CONFIG_EXPOLINE=y.
$ s390x-linux-gnu-ld --version | head -n1
GNU ld (GNU Binutils for Debian) 2.35.2
$ make -s ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- allnoconfig
$ ./scripts/config -e CONFIG_EXPOLINE
$ make -s ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- olddefconfig
$ make -s ARCH=s390 CROSS_COMPILE=s390x-linux-gnu-
`.exit.text' referenced in section `.s390_return_reg' of drivers/base/dd.o: defined in discarded section `.exit.text' of drivers/base/dd.o
make[1]: *** [scripts/Makefile.vmlinux:34: vmlinux] Error 1
make: *** [Makefile:1252: vmlinux] Error 2
arch/s390/kernel/vmlinux.lds.S wants to keep EXIT_TEXT:
.exit.text : {
EXIT_TEXT
}
But, at the same time, EXIT_TEXT is thrown away by DISCARD because
s390 does not define RUNTIME_DISCARD_EXIT.
I still do not understand why the latter wins after 99cb0d917ffa,
but defining RUNTIME_DISCARD_EXIT seems correct because the comment
line in arch/s390/kernel/vmlinux.lds.S says:
/*
* .exit.text is discarded at runtime, not link time,
* to deal with references from __bug_table
*/
Nathan also found that binutils commit 21401fc7bf67 ("Duplicate output
sections in scripts") cured this issue, so we cannot reproduce it with
binutils 2.36+, but it is better to not rely on it.
Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv")
Link: https://lore.kernel.org/all/Y7Jal56f6UBh1abE@dev-arch.thelio-3990X/
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20230105031306.1455409-1-masahiroy@kernel.org
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Tom Saeger <tom.saeger@oracle.com>
---
arch/s390/kernel/vmlinux.lds.S | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 8ce1615c1046..cdc8b84b2db4 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -17,6 +17,8 @@
/* Handle ro_after_init data on our own. */
#define RO_AFTER_INIT_DATA
+#define RUNTIME_DISCARD_EXIT
+
#define EMITS_PT_NOTE
#include <asm-generic/vmlinux.lds.h>
--
2.39.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 5.15 v3 5/5] sh: define RUNTIME_DISCARD_EXIT
2023-03-02 2:03 [PATCH 5.15 v3 0/5] Fix Build ID on arm64 if CONFIG_MODVERSIONS=y Tom Saeger
` (3 preceding siblings ...)
2023-03-02 2:03 ` [PATCH 5.15 v3 4/5] s390: define RUNTIME_DISCARD_EXIT to fix link error with GNU ld < 2.36 Tom Saeger
@ 2023-03-02 2:03 ` Tom Saeger
4 siblings, 0 replies; 6+ messages in thread
From: Tom Saeger @ 2023-03-02 2:03 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: Sasha Levin, Tom Saeger, stable, John Paul Adrian Glaubitz,
Ard Biesheuvel, Arnd Bergmann, Christoph Hellwig, Dennis Gilmore,
Masahiro Yamada, Naresh Kamboju, Nathan Chancellor,
Palmer Dabbelt, Rich Felker, Yoshinori Sato, Andrew Morton
commit c1c551bebf928889e7a8fef7415b44f9a64975f4 upstream.
sh vmlinux fails to link with GNU ld < 2.40 (likely < 2.36) since
commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv").
This is similar to fixes for powerpc and s390:
commit 4b9880dbf3bd ("powerpc/vmlinux.lds: Define RUNTIME_DISCARD_EXIT").
commit a494398bde27 ("s390: define RUNTIME_DISCARD_EXIT to fix link error
with GNU ld < 2.36").
$ sh4-linux-gnu-ld --version | head -n1
GNU ld (GNU Binutils for Debian) 2.35.2
$ make ARCH=sh CROSS_COMPILE=sh4-linux-gnu- microdev_defconfig
$ make ARCH=sh CROSS_COMPILE=sh4-linux-gnu-
`.exit.text' referenced in section `__bug_table' of crypto/algboss.o:
defined in discarded section `.exit.text' of crypto/algboss.o
`.exit.text' referenced in section `__bug_table' of
drivers/char/hw_random/core.o: defined in discarded section
`.exit.text' of drivers/char/hw_random/core.o
make[2]: *** [scripts/Makefile.vmlinux:34: vmlinux] Error 1
make[1]: *** [Makefile:1252: vmlinux] Error 2
arch/sh/kernel/vmlinux.lds.S keeps EXIT_TEXT:
/*
* .exit.text is discarded at runtime, not link time, to deal with
* references from __bug_table
*/
.exit.text : AT(ADDR(.exit.text)) { EXIT_TEXT }
However, EXIT_TEXT is thrown away by
DISCARD(include/asm-generic/vmlinux.lds.h) because
sh does not define RUNTIME_DISCARD_EXIT.
GNU ld 2.40 does not have this issue and builds fine.
This corresponds with Masahiro's comments in a494398bde27:
"Nathan [Chancellor] also found that binutils
commit 21401fc7bf67 ("Duplicate output sections in scripts") cured this
issue, so we cannot reproduce it with binutils 2.36+, but it is better
to not rely on it."
Link: https://lkml.kernel.org/r/9166a8abdc0f979e50377e61780a4bba1dfa2f52.1674518464.git.tom.saeger@oracle.com
Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv")
Link: https://lore.kernel.org/all/Y7Jal56f6UBh1abE@dev-arch.thelio-3990X/
Link: https://lore.kernel.org/all/20230123194218.47ssfzhrpnv3xfez@oracle.com/
Signed-off-by: Tom Saeger <tom.saeger@oracle.com>
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dennis Gilmore <dennis@ausil.us>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tom Saeger <tom.saeger@oracle.com>
---
arch/sh/kernel/vmlinux.lds.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/sh/kernel/vmlinux.lds.S b/arch/sh/kernel/vmlinux.lds.S
index 3161b9ccd2a5..b6276a3521d7 100644
--- a/arch/sh/kernel/vmlinux.lds.S
+++ b/arch/sh/kernel/vmlinux.lds.S
@@ -4,6 +4,7 @@
* Written by Niibe Yutaka and Paul Mundt
*/
OUTPUT_ARCH(sh)
+#define RUNTIME_DISCARD_EXIT
#include <asm/thread_info.h>
#include <asm/cache.h>
#include <asm/vmlinux.lds.h>
--
2.39.2
^ permalink raw reply related [flat|nested] 6+ messages in thread