linux-stable.git/include/asm-generic, branch v5.10.243 Linux kernel stable tree asm-generic: Add memory barrier dma_mb() 2025-08-28T14:22:57+00:00 Kefeng Wang wangkefeng.wang@huawei.com 2025-08-22T19:53:29+00:00 5cd4c42f32553270ef09d21bcf547174209c63e0 [ Upstream commit ed59dfd9509d172e4920994ed9cbebf93b0050cc ] The memory barrier dma_mb() is introduced by commit a76a37777f2c ("iommu/arm-smmu-v3: Ensure queue is read after updating prod pointer"), which is used to ensure that prior (both reads and writes) accesses to memory by a CPU are ordered w.r.t. a subsequent MMIO write. Reviewed-by: Arnd Bergmann <arnd@arndb.de> # for asm-generic Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Marco Elver <elver@google.com> Link: https://lore.kernel.org/r/20220523113126.171714-2-wangkefeng.wang@huawei.com Signed-off-by: Will Deacon <will@kernel.org> Stable-dep-of: aa6956150f82 ("wifi: ath11k: fix dest ring-buffer corruption when ring is full") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit ed59dfd9509d172e4920994ed9cbebf93b0050cc ]

The memory barrier dma_mb() is introduced by commit a76a37777f2c
("iommu/arm-smmu-v3: Ensure queue is read after updating prod pointer"),
which is used to ensure that prior (both reads and writes) accesses
to memory by a CPU are ordered w.r.t. a subsequent MMIO write.

Reviewed-by: Arnd Bergmann <arnd@arndb.de> # for asm-generic
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20220523113126.171714-2-wangkefeng.wang@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
Stable-dep-of: aa6956150f82 ("wifi: ath11k: fix dest ring-buffer corruption when ring is full")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
locking/barriers, kcsan: Support generic instrumentation 2025-08-28T14:22:57+00:00 Marco Elver elver@google.com 2025-08-22T19:53:28+00:00 9c301923f336ecf37489122a6b082c8e0f29f0f3 [ Upstream commit 2505a51ac6f249956735e0a369e2404f96eebef0 ] Thus far only smp_*() barriers had been defined by asm-generic/barrier.h based on __smp_*() barriers, because the !SMP case is usually generic. With the introduction of instrumentation, it also makes sense to have asm-generic/barrier.h assist in the definition of instrumented versions of mb(), rmb(), wmb(), dma_rmb(), and dma_wmb(). Because there is no requirement to distinguish the !SMP case, the definition can be simpler: we can avoid also providing fallbacks for the __ prefixed cases, and only check if `defined(__<barrier>)`, to finally define the KCSAN-instrumented versions. This also allows for the compiler to complain if an architecture accidentally defines both the normal and __ prefixed variant. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Stable-dep-of: aa6956150f82 ("wifi: ath11k: fix dest ring-buffer corruption when ring is full") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 2505a51ac6f249956735e0a369e2404f96eebef0 ]

Thus far only smp_*() barriers had been defined by asm-generic/barrier.h
based on __smp_*() barriers, because the !SMP case is usually generic.

With the introduction of instrumentation, it also makes sense to have
asm-generic/barrier.h assist in the definition of instrumented versions
of mb(), rmb(), wmb(), dma_rmb(), and dma_wmb().

Because there is no requirement to distinguish the !SMP case, the
definition can be simpler: we can avoid also providing fallbacks for the
__ prefixed cases, and only check if `defined(__<barrier>)`, to finally
define the KCSAN-instrumented versions.

This also allows for the compiler to complain if an architecture
accidentally defines both the normal and __ prefixed variant.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Stable-dep-of: aa6956150f82 ("wifi: ath11k: fix dest ring-buffer corruption when ring is full")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
vmlinux.lds: Ensure that const vars with relocations are mapped R/O 2025-03-13T11:47:34+00:00 Ard Biesheuvel ardb@kernel.org 2025-02-21T13:57:06+00:00 c348280e03a35b5222eff0ab8303ffcaef760cbc commit 68f3ea7ee199ef77551e090dfef5a49046ea8443 upstream. In the kernel, there are architectures (x86, arm64) that perform boot-time relocation (for KASLR) without relying on PIE codegen. In this case, all const global objects are emitted into .rodata, including const objects with fields that will be fixed up by the boot-time relocation code. This implies that .rodata (and .text in some cases) need to be writable at boot, but they will usually be mapped read-only as soon as the boot completes. When using PIE codegen, the compiler will emit const global objects into .data.rel.ro rather than .rodata if the object contains fields that need such fixups at boot-time. This permits the linker to annotate such regions as requiring read-write access only at load time, but not at execution time (in user space), while keeping .rodata truly const (in user space, this is important for reducing the CoW footprint of dynamic executables). This distinction does not matter for the kernel, but it does imply that const data will end up in writable memory if the .data.rel.ro sections are not treated in a special way, as they will end up in the writable .data segment by default. So emit .data.rel.ro into the .rodata segment. Cc: stable@vger.kernel.org Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20250221135704.431269-5-ardb+git@google.com Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 68f3ea7ee199ef77551e090dfef5a49046ea8443 upstream.

In the kernel, there are architectures (x86, arm64) that perform
boot-time relocation (for KASLR) without relying on PIE codegen. In this
case, all const global objects are emitted into .rodata, including const
objects with fields that will be fixed up by the boot-time relocation
code.  This implies that .rodata (and .text in some cases) need to be
writable at boot, but they will usually be mapped read-only as soon as
the boot completes.

When using PIE codegen, the compiler will emit const global objects into
.data.rel.ro rather than .rodata if the object contains fields that need
such fixups at boot-time. This permits the linker to annotate such
regions as requiring read-write access only at load time, but not at
execution time (in user space), while keeping .rodata truly const (in
user space, this is important for reducing the CoW footprint of dynamic
executables).

This distinction does not matter for the kernel, but it does imply that
const data will end up in writable memory if the .data.rel.ro sections
are not treated in a special way, as they will end up in the writable
.data segment by default.

So emit .data.rel.ro into the .rodata segment.

Cc: stable@vger.kernel.org
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250221135704.431269-5-ardb+git@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
asm-generic: qspinlock: fix queued_spin_value_unlocked() implementation 2023-12-20T14:44:35+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-11-10T06:22:13+00:00 09c8ee5f9bb36aea2c5d90576fb7b38e33ddec06 [ Upstream commit 125b0bb95dd6bec81b806b997a4ccb026eeecf8f ] We really don't want to do atomic_read() or anything like that, since we already have the value, not the lock. The whole point of this is that we've loaded the lock from memory, and we want to check whether the value we loaded was a locked one or not. The main use of this is the lockref code, which loads both the lock and the reference count in one atomic operation, and then works on that combined value. With the atomic_read(), the compiler would pointlessly spill the value to the stack, in order to then be able to read it back "atomically". This is the qspinlock version of commit c6f4a9002252 ("asm-generic: ticket-lock: Optimize arch_spin_value_unlocked()") which fixed this same bug for ticket locks. Cc: Guo Ren <guoren@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Waiman Long <longman@redhat.com> Link: https://lore.kernel.org/all/CAHk-=whNRv0v6kQiV5QO6DJhjH4KEL36vWQ6Re8Csrnh4zbRkQ@mail.gmail.com/ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 125b0bb95dd6bec81b806b997a4ccb026eeecf8f ]

We really don't want to do atomic_read() or anything like that, since we
already have the value, not the lock.  The whole point of this is that
we've loaded the lock from memory, and we want to check whether the
value we loaded was a locked one or not.

The main use of this is the lockref code, which loads both the lock and
the reference count in one atomic operation, and then works on that
combined value.  With the atomic_read(), the compiler would pointlessly
spill the value to the stack, in order to then be able to read it back
"atomically".

This is the qspinlock version of commit c6f4a9002252 ("asm-generic:
ticket-lock: Optimize arch_spin_value_unlocked()") which fixed this same
bug for ticket locks.

Cc: Guo Ren <guoren@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/all/CAHk-=whNRv0v6kQiV5QO6DJhjH4KEL36vWQ6Re8Csrnh4zbRkQ@mail.gmail.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
word-at-a-time: use the same return type for has_zero regardless of endianness 2023-08-11T09:57:47+00:00 ndesaulniers@google.com ndesaulniers@google.com 2023-08-01T22:22:17+00:00 4241cfc973ad8bc3d3a68b532b014e880c21b35f [ Upstream commit 79e8328e5acbe691bbde029a52c89d70dcbc22f3 ] Compiling big-endian targets with Clang produces the diagnostic: fs/namei.c:2173:13: warning: use of bitwise '|' with boolean operands [-Wbitwise-instead-of-logical] } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ || fs/namei.c:2173:13: note: cast one or both operands to int to silence this warning It appears that when has_zero was introduced, two definitions were produced with different signatures (in particular different return types). Looking at the usage in hash_name() in fs/namei.c, I suspect that has_zero() is meant to be invoked twice per while loop iteration; using logical-or would not update `bdata` when `a` did not have zeros. So I think it's preferred to always return an unsigned long rather than a bool than update the while loop in hash_name() to use a logical-or rather than bitwise-or. [ Also changed powerpc version to do the same - Linus ] Link: https://github.com/ClangBuiltLinux/linux/issues/1832 Link: https://lore.kernel.org/lkml/20230801-bitwise-v1-1-799bec468dc4@google.com/ Fixes: 36126f8f2ed8 ("word-at-a-time: make the interfaces truly generic") Debugged-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Acked-by: Heiko Carstens <hca@linux.ibm.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 79e8328e5acbe691bbde029a52c89d70dcbc22f3 ]

Compiling big-endian targets with Clang produces the diagnostic:

  fs/namei.c:2173:13: warning: use of bitwise '|' with boolean operands [-Wbitwise-instead-of-logical]
	} while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants)));
	          ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                                               ||
  fs/namei.c:2173:13: note: cast one or both operands to int to silence this warning

It appears that when has_zero was introduced, two definitions were
produced with different signatures (in particular different return
types).

Looking at the usage in hash_name() in fs/namei.c, I suspect that
has_zero() is meant to be invoked twice per while loop iteration; using
logical-or would not update `bdata` when `a` did not have zeros.  So I
think it's preferred to always return an unsigned long rather than a
bool than update the while loop in hash_name() to use a logical-or
rather than bitwise-or.

[ Also changed powerpc version to do the same  - Linus ]

Link: https://github.com/ClangBuiltLinux/linux/issues/1832
Link: https://lore.kernel.org/lkml/20230801-bitwise-v1-1-799bec468dc4@google.com/
Fixes: 36126f8f2ed8 ("word-at-a-time: make the interfaces truly generic")
Debugged-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
init: Remove check_bugs() leftovers 2023-08-08T17:57:37+00:00 Thomas Gleixner tglx@linutronix.de 2023-06-13T23:39:38+00:00 bf2fa3a9d0e65326917273d17a8e9c6880d7b97c commit 61235b24b9cb37c13fcad5b9596d59a1afdcec30 upstream Everything is converted over to arch_cpu_finalize_init(). Remove the check_bugs() leftovers including the empty stubs in asm-generic, alpha, parisc, powerpc and xtensa. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Link: https://lore.kernel.org/r/20230613224545.553215951@linutronix.de Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 61235b24b9cb37c13fcad5b9596d59a1afdcec30 upstream

Everything is converted over to arch_cpu_finalize_init(). Remove the
check_bugs() leftovers including the empty stubs in asm-generic, alpha,
parisc, powerpc and xtensa.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Link: https://lore.kernel.org/r/20230613224545.553215951@linutronix.de
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm: rename p4d_page_vaddr to p4d_pgtable and make it return pud_t * 2023-07-27T06:43:58+00:00 Aneesh Kumar K.V aneesh.kumar@linux.ibm.com 2021-07-08T01:09:56+00:00 7289ca7a51704e6c3f8d30cbd8ed980637e1267a [ Upstream commit dc4875f0e791de554bdc45aa1dbd6e45e107e50f ] No functional change in this patch. [aneesh.kumar@linux.ibm.com: m68k build error reported by kernel robot] Link: https://lkml.kernel.org/r/87tulxnb2v.fsf@linux.ibm.com Link: https://lkml.kernel.org/r/20210615110859.320299-2-aneesh.kumar@linux.ibm.com Link: https://lore.kernel.org/linuxppc-dev/CAHk-=wi+J+iodze9FtjM3Zi4j4OeS+qqbKxME9QN4roxPEXH9Q@mail.gmail.com/ Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Hugh Dickins <hughd@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Stable-dep-of: 0da90af431ab ("powerpc/book3s64/mm: Fix DirectMap stats in /proc/meminfo") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit dc4875f0e791de554bdc45aa1dbd6e45e107e50f ]

No functional change in this patch.

[aneesh.kumar@linux.ibm.com: m68k build error reported by kernel robot]
  Link: https://lkml.kernel.org/r/87tulxnb2v.fsf@linux.ibm.com

Link: https://lkml.kernel.org/r/20210615110859.320299-2-aneesh.kumar@linux.ibm.com
Link: https://lore.kernel.org/linuxppc-dev/CAHk-=wi+J+iodze9FtjM3Zi4j4OeS+qqbKxME9QN4roxPEXH9Q@mail.gmail.com/
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stable-dep-of: 0da90af431ab ("powerpc/book3s64/mm: Fix DirectMap stats in /proc/meminfo")
Signed-off-by: Sasha Levin <sashal@kernel.org>
mm: rename pud_page_vaddr to pud_pgtable and make it return pmd_t * 2023-07-27T06:43:58+00:00 Aneesh Kumar K.V aneesh.kumar@linux.ibm.com 2021-07-08T01:09:53+00:00 bfad11018806e5e33b7b20d2d046bde699309457 [ Upstream commit 9cf6fa2458443118b84090aa1bf7a3630b5940e8 ] No functional change in this patch. [aneesh.kumar@linux.ibm.com: fix] Link: https://lkml.kernel.org/r/87wnqtnb60.fsf@linux.ibm.com [sfr@canb.auug.org.au: another fix] Link: https://lkml.kernel.org/r/20210619134410.89559-1-aneesh.kumar@linux.ibm.com Link: https://lkml.kernel.org/r/20210615110859.320299-1-aneesh.kumar@linux.ibm.com Link: https://lore.kernel.org/linuxppc-dev/CAHk-=wi+J+iodze9FtjM3Zi4j4OeS+qqbKxME9QN4roxPEXH9Q@mail.gmail.com/ Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Hugh Dickins <hughd@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Stable-dep-of: 0da90af431ab ("powerpc/book3s64/mm: Fix DirectMap stats in /proc/meminfo") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 9cf6fa2458443118b84090aa1bf7a3630b5940e8 ]

No functional change in this patch.

[aneesh.kumar@linux.ibm.com: fix]
  Link: https://lkml.kernel.org/r/87wnqtnb60.fsf@linux.ibm.com
[sfr@canb.auug.org.au: another fix]
  Link: https://lkml.kernel.org/r/20210619134410.89559-1-aneesh.kumar@linux.ibm.com

Link: https://lkml.kernel.org/r/20210615110859.320299-1-aneesh.kumar@linux.ibm.com
Link: https://lore.kernel.org/linuxppc-dev/CAHk-=wi+J+iodze9FtjM3Zi4j4OeS+qqbKxME9QN4roxPEXH9Q@mail.gmail.com/
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stable-dep-of: 0da90af431ab ("powerpc/book3s64/mm: Fix DirectMap stats in /proc/meminfo")
Signed-off-by: Sasha Levin <sashal@kernel.org>
asm-generic/io.h: suppress endianness warnings for readq() and writeq() 2023-05-17T09:47:30+00:00 Vladimir Oltean vladimir.oltean@nxp.com 2023-01-09T13:11:52+00:00 69fdbb334d6e6d33e27b0adc3234607af6135861 [ Upstream commit d564fa1ff19e893e2971d66e5c8f49dc1cdc8ffc ] Commit c1d55d50139b ("asm-generic/io.h: Fix sparse warnings on big-endian architectures") missed fixing the 64-bit accessors. Arnd explains in the attached link why the casts are necessary, even if __raw_readq() and __raw_writeq() do not take endian-specific types. Link: https://lore.kernel.org/lkml/9105d6fc-880b-4734-857d-e3d30b87ccf6@app.fastmail.com/ Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d564fa1ff19e893e2971d66e5c8f49dc1cdc8ffc ]

Commit c1d55d50139b ("asm-generic/io.h: Fix sparse warnings on
big-endian architectures") missed fixing the 64-bit accessors.

Arnd explains in the attached link why the casts are necessary, even if
__raw_readq() and __raw_writeq() do not take endian-specific types.

Link: https://lore.kernel.org/lkml/9105d6fc-880b-4734-857d-e3d30b87ccf6@app.fastmail.com/
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
arch: fix broken BuildID for arm64 and riscv 2023-03-17T07:45:16+00:00 Masahiro Yamada masahiroy@kernel.org 2023-03-02T02:04:52+00:00 d367c5ebe94359b0ac38c0d91c4c10654460bb03 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>