* Backports of 84ffc79bfbf7 for 6.12 and earlier
@ 2025-04-17 17:10 Nathan Chancellor
2025-04-22 7:23 ` Greg Kroah-Hartman
0 siblings, 1 reply; 2+ messages in thread
From: Nathan Chancellor @ 2025-04-17 17:10 UTC (permalink / raw)
To: Greg Kroah-Hartman, Sasha Levin; +Cc: stable, llvm
[-- Attachment #1: Type: text/plain, Size: 266 bytes --]
Hi Greg and Sasha,
Please find attached backports for commit 84ffc79bfbf7 ("kbuild: Add
'-fno-builtin-wcslen'") to 6.12 and earlier. It has already been queued
for 6.13 and 6.14 since it applied cleanly. If there are any issues,
please let me know.
Cheers,
Nathan
[-- Attachment #2: 5.4-84ffc79bfbf7.patch --]
[-- Type: text/plain, Size: 2635 bytes --]
From 5dc6f440b2309877ab27879fc327ef0dfc58b682 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <nathan@kernel.org>
Date: Mon, 7 Apr 2025 16:22:12 -0700
Subject: [PATCH 5.4] kbuild: Add '-fno-builtin-wcslen'
commit 84ffc79bfbf70c779e60218563f2f3ad45288671 upstream.
A recent optimization change in LLVM [1] aims to transform certain loop
idioms into calls to strlen() or wcslen(). This change transforms the
first while loop in UniStrcat() into a call to wcslen(), breaking the
build when UniStrcat() gets inlined into alloc_path_with_tree_prefix():
ld.lld: error: undefined symbol: wcslen
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
Disable this optimization with '-fno-builtin-wcslen', which prevents the
compiler from assuming that wcslen() is available in the kernel's C
library.
[ More to the point - it's not that we couldn't implement wcslen(), it's
that this isn't an optimization at all in the context of the kernel.
Replacing a simple inlined loop with a function call to the same loop
is just stupid and pointless if you don't have long strings and fancy
libraries with vectorization support etc.
For the regular 'strlen()' cases, we want the compiler to do this in
order to handle the trivial case of constant strings. And we do have
optimized versions of 'strlen()' on some architectures. But for
wcslen? Just no. - Linus ]
Cc: stable@vger.kernel.org
Link: https://github.com/llvm/llvm-project/commit/9694844d7e36fd5e01011ab56b64f27b867aa72d [1]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[nathan: Resolve small conflict in older trees]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Makefile | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Makefile b/Makefile
index 6cb965fe2cb3..05eed26d3e4b 100644
--- a/Makefile
+++ b/Makefile
@@ -930,6 +930,9 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
# Require designated initializers for all marked structures
KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
+# Ensure compilers do not transform certain loops into calls to wcslen()
+KBUILD_CFLAGS += -fno-builtin-wcslen
+
# change __FILE__ to the relative path from the srctree
KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
base-commit: 1b01d9c341770d4dab5a1a04a706a8eb6c389bb1
--
2.49.0
[-- Attachment #3: 5.10-84ffc79bfbf7.patch --]
[-- Type: text/plain, Size: 2638 bytes --]
From b0f27298358b4b6f1b44a586fa0de88ce6ca74d0 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <nathan@kernel.org>
Date: Mon, 7 Apr 2025 16:22:12 -0700
Subject: [PATCH 5.10] kbuild: Add '-fno-builtin-wcslen'
commit 84ffc79bfbf70c779e60218563f2f3ad45288671 upstream.
A recent optimization change in LLVM [1] aims to transform certain loop
idioms into calls to strlen() or wcslen(). This change transforms the
first while loop in UniStrcat() into a call to wcslen(), breaking the
build when UniStrcat() gets inlined into alloc_path_with_tree_prefix():
ld.lld: error: undefined symbol: wcslen
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
Disable this optimization with '-fno-builtin-wcslen', which prevents the
compiler from assuming that wcslen() is available in the kernel's C
library.
[ More to the point - it's not that we couldn't implement wcslen(), it's
that this isn't an optimization at all in the context of the kernel.
Replacing a simple inlined loop with a function call to the same loop
is just stupid and pointless if you don't have long strings and fancy
libraries with vectorization support etc.
For the regular 'strlen()' cases, we want the compiler to do this in
order to handle the trivial case of constant strings. And we do have
optimized versions of 'strlen()' on some architectures. But for
wcslen? Just no. - Linus ]
Cc: stable@vger.kernel.org
Link: https://github.com/llvm/llvm-project/commit/9694844d7e36fd5e01011ab56b64f27b867aa72d [1]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[nathan: Resolve small conflict in older trees]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Makefile | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Makefile b/Makefile
index e13f8f8a9ea9..6f7a5e72bbb9 100644
--- a/Makefile
+++ b/Makefile
@@ -976,6 +976,9 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
# Require designated initializers for all marked structures
KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
+# Ensure compilers do not transform certain loops into calls to wcslen()
+KBUILD_CFLAGS += -fno-builtin-wcslen
+
# change __FILE__ to the relative path from the srctree
KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
base-commit: 7222a9d1c9246944d284902fb9aed25613dd0ece
--
2.49.0
[-- Attachment #4: 5.15-84ffc79bfbf7.patch --]
[-- Type: text/plain, Size: 2640 bytes --]
From bc78bacca3f3f9f7367afc6dbf56a4733f47e3f6 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <nathan@kernel.org>
Date: Mon, 7 Apr 2025 16:22:12 -0700
Subject: [PATCH 5.15] kbuild: Add '-fno-builtin-wcslen'
commit 84ffc79bfbf70c779e60218563f2f3ad45288671 upstream.
A recent optimization change in LLVM [1] aims to transform certain loop
idioms into calls to strlen() or wcslen(). This change transforms the
first while loop in UniStrcat() into a call to wcslen(), breaking the
build when UniStrcat() gets inlined into alloc_path_with_tree_prefix():
ld.lld: error: undefined symbol: wcslen
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
Disable this optimization with '-fno-builtin-wcslen', which prevents the
compiler from assuming that wcslen() is available in the kernel's C
library.
[ More to the point - it's not that we couldn't implement wcslen(), it's
that this isn't an optimization at all in the context of the kernel.
Replacing a simple inlined loop with a function call to the same loop
is just stupid and pointless if you don't have long strings and fancy
libraries with vectorization support etc.
For the regular 'strlen()' cases, we want the compiler to do this in
order to handle the trivial case of constant strings. And we do have
optimized versions of 'strlen()' on some architectures. But for
wcslen? Just no. - Linus ]
Cc: stable@vger.kernel.org
Link: https://github.com/llvm/llvm-project/commit/9694844d7e36fd5e01011ab56b64f27b867aa72d [1]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[nathan: Resolve small conflict in older trees]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Makefile | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Makefile b/Makefile
index 619f4ec0f613..035578b9fafc 100644
--- a/Makefile
+++ b/Makefile
@@ -1066,6 +1066,9 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
# Require designated initializers for all marked structures
KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
+# Ensure compilers do not transform certain loops into calls to wcslen()
+KBUILD_CFLAGS += -fno-builtin-wcslen
+
# change __FILE__ to the relative path from the srctree
KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
base-commit: f7347f4005727f3155551c0550f4deb9c40b56c2
--
2.49.0
[-- Attachment #5: 6.1-84ffc79bfbf7.patch --]
[-- Type: text/plain, Size: 2639 bytes --]
From a87930300e5abe2d100b17d7941eb2a4357b88b6 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <nathan@kernel.org>
Date: Mon, 7 Apr 2025 16:22:12 -0700
Subject: [PATCH 6.1] kbuild: Add '-fno-builtin-wcslen'
commit 84ffc79bfbf70c779e60218563f2f3ad45288671 upstream.
A recent optimization change in LLVM [1] aims to transform certain loop
idioms into calls to strlen() or wcslen(). This change transforms the
first while loop in UniStrcat() into a call to wcslen(), breaking the
build when UniStrcat() gets inlined into alloc_path_with_tree_prefix():
ld.lld: error: undefined symbol: wcslen
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
Disable this optimization with '-fno-builtin-wcslen', which prevents the
compiler from assuming that wcslen() is available in the kernel's C
library.
[ More to the point - it's not that we couldn't implement wcslen(), it's
that this isn't an optimization at all in the context of the kernel.
Replacing a simple inlined loop with a function call to the same loop
is just stupid and pointless if you don't have long strings and fancy
libraries with vectorization support etc.
For the regular 'strlen()' cases, we want the compiler to do this in
order to handle the trivial case of constant strings. And we do have
optimized versions of 'strlen()' on some architectures. But for
wcslen? Just no. - Linus ]
Cc: stable@vger.kernel.org
Link: https://github.com/llvm/llvm-project/commit/9694844d7e36fd5e01011ab56b64f27b867aa72d [1]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[nathan: Resolve small conflict in older trees]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Makefile | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Makefile b/Makefile
index 50f1a283b67d..eae097d3db6c 100644
--- a/Makefile
+++ b/Makefile
@@ -1075,6 +1075,9 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
# Require designated initializers for all marked structures
KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
+# Ensure compilers do not transform certain loops into calls to wcslen()
+KBUILD_CFLAGS += -fno-builtin-wcslen
+
# change __FILE__ to the relative path from the srctree
KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
base-commit: 420102835862f49ec15c545594278dc5d2712f42
--
2.49.0
[-- Attachment #6: 6.6-84ffc79bfbf7.patch --]
[-- Type: text/plain, Size: 2511 bytes --]
From 1b9fbad11767ed56fdc7da1b252913e2f2a155e9 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <nathan@kernel.org>
Date: Mon, 7 Apr 2025 16:22:12 -0700
Subject: [PATCH 6.6] kbuild: Add '-fno-builtin-wcslen'
commit 84ffc79bfbf70c779e60218563f2f3ad45288671 upstream.
A recent optimization change in LLVM [1] aims to transform certain loop
idioms into calls to strlen() or wcslen(). This change transforms the
first while loop in UniStrcat() into a call to wcslen(), breaking the
build when UniStrcat() gets inlined into alloc_path_with_tree_prefix():
ld.lld: error: undefined symbol: wcslen
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
Disable this optimization with '-fno-builtin-wcslen', which prevents the
compiler from assuming that wcslen() is available in the kernel's C
library.
[ More to the point - it's not that we couldn't implement wcslen(), it's
that this isn't an optimization at all in the context of the kernel.
Replacing a simple inlined loop with a function call to the same loop
is just stupid and pointless if you don't have long strings and fancy
libraries with vectorization support etc.
For the regular 'strlen()' cases, we want the compiler to do this in
order to handle the trivial case of constant strings. And we do have
optimized versions of 'strlen()' on some architectures. But for
wcslen? Just no. - Linus ]
Cc: stable@vger.kernel.org
Link: https://github.com/llvm/llvm-project/commit/9694844d7e36fd5e01011ab56b64f27b867aa72d [1]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[nathan: Resolve small conflict in older trees]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Makefile | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Makefile b/Makefile
index 45f6b7d3d51e..18ca8d458fa4 100644
--- a/Makefile
+++ b/Makefile
@@ -1004,6 +1004,9 @@ ifdef CONFIG_CC_IS_GCC
KBUILD_CFLAGS += -fconserve-stack
endif
+# Ensure compilers do not transform certain loops into calls to wcslen()
+KBUILD_CFLAGS += -fno-builtin-wcslen
+
# change __FILE__ to the relative path from the srctree
KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
base-commit: 814637ca257f4faf57a73fd4e38888cce88b5911
--
2.49.0
[-- Attachment #7: 6.12-84ffc79bfbf7.patch --]
[-- Type: text/plain, Size: 2512 bytes --]
From 99d01048fc148dc10471b67da642df190a9727bb Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <nathan@kernel.org>
Date: Mon, 7 Apr 2025 16:22:12 -0700
Subject: [PATCH 6.12] kbuild: Add '-fno-builtin-wcslen'
commit 84ffc79bfbf70c779e60218563f2f3ad45288671 upstream.
A recent optimization change in LLVM [1] aims to transform certain loop
idioms into calls to strlen() or wcslen(). This change transforms the
first while loop in UniStrcat() into a call to wcslen(), breaking the
build when UniStrcat() gets inlined into alloc_path_with_tree_prefix():
ld.lld: error: undefined symbol: wcslen
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
>>> referenced by nls_ucs2_utils.h:54 (fs/smb/client/../../nls/nls_ucs2_utils.h:54)
>>> vmlinux.o:(alloc_path_with_tree_prefix)
Disable this optimization with '-fno-builtin-wcslen', which prevents the
compiler from assuming that wcslen() is available in the kernel's C
library.
[ More to the point - it's not that we couldn't implement wcslen(), it's
that this isn't an optimization at all in the context of the kernel.
Replacing a simple inlined loop with a function call to the same loop
is just stupid and pointless if you don't have long strings and fancy
libraries with vectorization support etc.
For the regular 'strlen()' cases, we want the compiler to do this in
order to handle the trivial case of constant strings. And we do have
optimized versions of 'strlen()' on some architectures. But for
wcslen? Just no. - Linus ]
Cc: stable@vger.kernel.org
Link: https://github.com/llvm/llvm-project/commit/9694844d7e36fd5e01011ab56b64f27b867aa72d [1]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[nathan: Resolve small conflict in older trees]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Makefile | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Makefile b/Makefile
index 6a2a60eb67a3..1e0ec6317c17 100644
--- a/Makefile
+++ b/Makefile
@@ -1013,6 +1013,9 @@ ifdef CONFIG_CC_IS_GCC
KBUILD_CFLAGS += -fconserve-stack
endif
+# Ensure compilers do not transform certain loops into calls to wcslen()
+KBUILD_CFLAGS += -fno-builtin-wcslen
+
# change __FILE__ to the relative path from the srctree
KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
base-commit: 83b4161a63b87ce40d9f24f09b5b006f63d95b7c
--
2.49.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: Backports of 84ffc79bfbf7 for 6.12 and earlier
2025-04-17 17:10 Backports of 84ffc79bfbf7 for 6.12 and earlier Nathan Chancellor
@ 2025-04-22 7:23 ` Greg Kroah-Hartman
0 siblings, 0 replies; 2+ messages in thread
From: Greg Kroah-Hartman @ 2025-04-22 7:23 UTC (permalink / raw)
To: Nathan Chancellor; +Cc: Sasha Levin, stable, llvm
On Thu, Apr 17, 2025 at 10:10:24AM -0700, Nathan Chancellor wrote:
> Hi Greg and Sasha,
>
> Please find attached backports for commit 84ffc79bfbf7 ("kbuild: Add
> '-fno-builtin-wcslen'") to 6.12 and earlier. It has already been queued
> for 6.13 and 6.14 since it applied cleanly. If there are any issues,
> please let me know.
Now applied, thanks.
greg k-h
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2025-04-22 7:24 UTC | newest]
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2025-04-17 17:10 Backports of 84ffc79bfbf7 for 6.12 and earlier Nathan Chancellor
2025-04-22 7:23 ` Greg Kroah-Hartman
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