--- /dev/null
+From 2fd7e7f9317d3048a14026816d081b08ba98ea8e Mon Sep 17 00:00:00 2001
+From: Mark Rutland <mark.rutland@arm.com>
+Date: Tue, 8 Mar 2022 22:56:13 +0100
+Subject: [PATCH 1/3] Kbuild: use -Wdeclaration-after-statement
+
+The kernel is moving from using `-std=gnu89` to `-std=gnu11`, permitting
+the use of additional C11 features such as for-loop initial declarations.
+
+One contentious aspect of C99 is that it permits mixed declarations and
+code, and for now at least, it seems preferable to enforce that
+declarations must come first.
+
+These warnings were already enabled in the kernel itself, but not
+for KBUILD_USERCFLAGS or the compat VDSO on arch/arm64, which uses
+a separate set of CFLAGS.
+
+This patch fixes an existing violation in modpost.c, which is not
+reported because of the missing flag in KBUILD_USERCFLAGS:
+
+| scripts/mod/modpost.c: In function ‘match’:
+| scripts/mod/modpost.c:837:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
+| 837 | const char *endp = p + strlen(p) - 1;
+| | ^~~~~
+
+Signed-off-by: Mark Rutland <mark.rutland@arm.com>
+[arnd: don't add a duplicate flag to the default set, update changelog]
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Reviewed-by: Nathan Chancellor <nathan@kernel.org>
+Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
+Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 (x86-64)
+Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
+---
+ Makefile | 3 ++-
+ arch/arm64/kernel/vdso32/Makefile | 1 +
+ scripts/mod/modpost.c | 4 +++-
+ 3 files changed, 6 insertions(+), 2 deletions(-)
+
+--- a/Makefile
++++ b/Makefile
+@@ -416,7 +416,8 @@ HOSTCXX = g++
+ endif
+
+ export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
+- -O2 -fomit-frame-pointer -std=gnu89
++ -O2 -fomit-frame-pointer -std=gnu89 \
++ -Wdeclaration-after-statement
+ export KBUILD_USERLDFLAGS :=
+
+ KBUILD_HOSTCFLAGS := $(KBUILD_USERCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)
+--- a/arch/arm64/kernel/vdso32/Makefile
++++ b/arch/arm64/kernel/vdso32/Makefile
+@@ -76,6 +76,7 @@ VDSO_CFLAGS += -Wall -Wundef -Wstrict-pr
+ -fno-strict-aliasing -fno-common \
+ -Werror-implicit-function-declaration \
+ -Wno-format-security \
++ -Wdeclaration-after-statement \
+ -std=gnu89
+ VDSO_CFLAGS += -O2
+ # Some useful compiler-dependent flags from top-level Makefile
+--- a/scripts/mod/modpost.c
++++ b/scripts/mod/modpost.c
+@@ -844,8 +844,10 @@ static int match(const char *sym, const
+ {
+ const char *p;
+ while (*pat) {
++ const char *endp;
++
+ p = *pat++;
+- const char *endp = p + strlen(p) - 1;
++ endp = p + strlen(p) - 1;
+
+ /* "*foo*" */
+ if (*p == '*' && *endp == '*') {
--- /dev/null
+From b810c8e719ea082e47c7a8f7cf878bc84fa2455d Mon Sep 17 00:00:00 2001
+From: Arnd Bergmann <arnd@arndb.de>
+Date: Tue, 8 Mar 2022 22:56:14 +0100
+Subject: [PATCH 2/3] Kbuild: move to -std=gnu11
+
+During a patch discussion, Linus brought up the option of changing
+the C standard version from gnu89 to gnu99, which allows using variable
+declaration inside of a for() loop. While the C99, C11 and later standards
+introduce many other features, most of these are already available in
+gnu89 as GNU extensions as well.
+
+An earlier attempt to do this when gcc-5 started defaulting to
+-std=gnu11 failed because at the time that caused warnings about
+designated initializers with older compilers. Now that gcc-5.1 is
+the minimum compiler version used for building kernels, that is no
+longer a concern. Similarly, the behavior of 'inline' functions changes
+between gnu89 using gnu_inline behavior and gnu11 using standard c99+
+behavior, but this was taken care of by defining 'inline' to include
+__attribute__((gnu_inline)) in order to allow building with clang a
+while ago.
+
+Nathan Chancellor reported a new -Wdeclaration-after-statement
+warning that appears in a system header on arm, this still needs a
+workaround.
+
+The differences between gnu99, gnu11, gnu1x and gnu17 are fairly
+minimal and mainly impact warnings at the -Wpedantic level that the
+kernel never enables. Between these, gnu11 is the newest version
+that is supported by all supported compiler versions, though it is
+only the default on gcc-5, while all other supported versions of
+gcc or clang default to gnu1x/gnu17.
+
+Link: https://lore.kernel.org/lkml/CAHk-=wiyCH7xeHcmiFJ-YgXUy2Jaj7pnkdKpcovt8fYbVFW3TA@mail.gmail.com/
+Link: https://github.com/ClangBuiltLinux/linux/issues/1603
+Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
+Acked-by: Marco Elver <elver@google.com>
+Acked-by: Jani Nikula <jani.nikula@intel.com>
+Acked-by: David Sterba <dsterba@suse.com>
+Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
+Reviewed-by: Alex Shi <alexs@kernel.org>
+Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
+Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Reviewed-by: Nathan Chancellor <nathan@kernel.org>
+Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
+---
+ Makefile | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/Makefile
++++ b/Makefile
+@@ -498,7 +498,7 @@ KBUILD_CFLAGS := -Wall -Wundef -Werror
+ -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \
+ -Werror=implicit-function-declaration -Werror=implicit-int \
+ -Werror=return-type -Wno-format-security \
+- -std=gnu89
++ -std=gnu11
+ KBUILD_CPPFLAGS := -D__KERNEL__
+ KBUILD_AFLAGS_KERNEL :=
+ KBUILD_CFLAGS_KERNEL :=
--- /dev/null
+From 40337d6f3d677aee7ad3052ae662d3f53dd4d5cb Mon Sep 17 00:00:00 2001
+From: Arnd Bergmann <arnd@arndb.de>
+Date: Tue, 8 Mar 2022 22:56:15 +0100
+Subject: [PATCH 3/3] Kbuild: use -std=gnu11 for KBUILD_USERCFLAGS
+
+As we change the C language standard for the kernel from gnu89 to
+gnu11, it makes sense to also update the version for user space
+compilation.
+
+Some users have older native compilers than what they use for
+kernel builds, so I considered using gnu99 as the default version
+for wider compatibility with gcc-4.6 and earlier.
+
+However, testing with older compilers showed that we already require
+HOSTCC version 5.1 as well because a lot of host tools include
+linux/compiler.h that uses __has_attribute():
+
+ CC tools/objtool/exec-cmd.o
+In file included from tools/include/linux/compiler_types.h:36:0,
+ from tools/include/linux/compiler.h:5,
+ from exec-cmd.c:2:
+tools/include/linux/compiler-gcc.h:19:5: error: "__has_attribute" is not defined [-Werror=undef]
+
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Reviewed-by: Nathan Chancellor <nathan@kernel.org>
+Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
+Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
+Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
+---
+ Makefile | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/Makefile
++++ b/Makefile
+@@ -416,7 +416,7 @@ HOSTCXX = g++
+ endif
+
+ export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
+- -O2 -fomit-frame-pointer -std=gnu89 \
++ -O2 -fomit-frame-pointer -std=gnu11 \
+ -Wdeclaration-after-statement
+ export KBUILD_USERLDFLAGS :=
--- /dev/null
+From 2fd7e7f9317d3048a14026816d081b08ba98ea8e Mon Sep 17 00:00:00 2001
+From: Mark Rutland <mark.rutland@arm.com>
+Date: Tue, 8 Mar 2022 22:56:13 +0100
+Subject: [PATCH 1/3] Kbuild: use -Wdeclaration-after-statement
+
+The kernel is moving from using `-std=gnu89` to `-std=gnu11`, permitting
+the use of additional C11 features such as for-loop initial declarations.
+
+One contentious aspect of C99 is that it permits mixed declarations and
+code, and for now at least, it seems preferable to enforce that
+declarations must come first.
+
+These warnings were already enabled in the kernel itself, but not
+for KBUILD_USERCFLAGS or the compat VDSO on arch/arm64, which uses
+a separate set of CFLAGS.
+
+This patch fixes an existing violation in modpost.c, which is not
+reported because of the missing flag in KBUILD_USERCFLAGS:
+
+| scripts/mod/modpost.c: In function ‘match’:
+| scripts/mod/modpost.c:837:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
+| 837 | const char *endp = p + strlen(p) - 1;
+| | ^~~~~
+
+Signed-off-by: Mark Rutland <mark.rutland@arm.com>
+[arnd: don't add a duplicate flag to the default set, update changelog]
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Reviewed-by: Nathan Chancellor <nathan@kernel.org>
+Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
+Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 (x86-64)
+Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
+---
+ Makefile | 3 ++-
+ arch/arm64/kernel/vdso32/Makefile | 1 +
+ scripts/mod/modpost.c | 4 +++-
+ 3 files changed, 6 insertions(+), 2 deletions(-)
+
+diff --git a/Makefile b/Makefile
+index b9e0b5c604af..cfe400032f96 100644
+--- a/Makefile
++++ b/Makefile
+@@ -416,7 +416,8 @@ HOSTCXX = g++
+ endif
+
+ export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
+- -O2 -fomit-frame-pointer -std=gnu89
++ -O2 -fomit-frame-pointer -std=gnu89 \
++ -Wdeclaration-after-statement
+ export KBUILD_USERLDFLAGS :=
+
+ KBUILD_HOSTCFLAGS := $(KBUILD_USERCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)
+diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
+index abad38c576e1..33cd7ed3f94f 100644
+--- a/arch/arm64/kernel/vdso32/Makefile
++++ b/arch/arm64/kernel/vdso32/Makefile
+@@ -76,6 +76,7 @@ VDSO_CFLAGS += -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
+ -fno-strict-aliasing -fno-common \
+ -Werror-implicit-function-declaration \
+ -Wno-format-security \
++ -Wdeclaration-after-statement \
+ -std=gnu89
+ VDSO_CFLAGS += -O2
+ # Some useful compiler-dependent flags from top-level Makefile
+diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
+index 3c27a177b28b..d2b17ed27e6e 100644
+--- a/scripts/mod/modpost.c
++++ b/scripts/mod/modpost.c
+@@ -844,8 +844,10 @@ static int match(const char *sym, const char * const pat[])
+ {
+ const char *p;
+ while (*pat) {
++ const char *endp;
++
+ p = *pat++;
+- const char *endp = p + strlen(p) - 1;
++ endp = p + strlen(p) - 1;
+
+ /* "*foo*" */
+ if (*p == '*' && *endp == '*') {
+--
+2.37.2
--- /dev/null
+From b810c8e719ea082e47c7a8f7cf878bc84fa2455d Mon Sep 17 00:00:00 2001
+From: Arnd Bergmann <arnd@arndb.de>
+Date: Tue, 8 Mar 2022 22:56:14 +0100
+Subject: [PATCH 2/3] Kbuild: move to -std=gnu11
+
+During a patch discussion, Linus brought up the option of changing
+the C standard version from gnu89 to gnu99, which allows using variable
+declaration inside of a for() loop. While the C99, C11 and later standards
+introduce many other features, most of these are already available in
+gnu89 as GNU extensions as well.
+
+An earlier attempt to do this when gcc-5 started defaulting to
+-std=gnu11 failed because at the time that caused warnings about
+designated initializers with older compilers. Now that gcc-5.1 is
+the minimum compiler version used for building kernels, that is no
+longer a concern. Similarly, the behavior of 'inline' functions changes
+between gnu89 using gnu_inline behavior and gnu11 using standard c99+
+behavior, but this was taken care of by defining 'inline' to include
+__attribute__((gnu_inline)) in order to allow building with clang a
+while ago.
+
+Nathan Chancellor reported a new -Wdeclaration-after-statement
+warning that appears in a system header on arm, this still needs a
+workaround.
+
+The differences between gnu99, gnu11, gnu1x and gnu17 are fairly
+minimal and mainly impact warnings at the -Wpedantic level that the
+kernel never enables. Between these, gnu11 is the newest version
+that is supported by all supported compiler versions, though it is
+only the default on gcc-5, while all other supported versions of
+gcc or clang default to gnu1x/gnu17.
+
+Link: https://lore.kernel.org/lkml/CAHk-=wiyCH7xeHcmiFJ-YgXUy2Jaj7pnkdKpcovt8fYbVFW3TA@mail.gmail.com/
+Link: https://github.com/ClangBuiltLinux/linux/issues/1603
+Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
+Acked-by: Marco Elver <elver@google.com>
+Acked-by: Jani Nikula <jani.nikula@intel.com>
+Acked-by: David Sterba <dsterba@suse.com>
+Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
+Reviewed-by: Alex Shi <alexs@kernel.org>
+Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
+Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Reviewed-by: Nathan Chancellor <nathan@kernel.org>
+Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
+---
+ Makefile | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/Makefile b/Makefile
+index cfe400032f96..fe86758acaaa 100644
+--- a/Makefile
++++ b/Makefile
+@@ -498,7 +498,7 @@ KBUILD_CFLAGS := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \
+ -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \
+ -Werror=implicit-function-declaration -Werror=implicit-int \
+ -Werror=return-type -Wno-format-security \
+- -std=gnu89
++ -std=gnu11
+ KBUILD_CPPFLAGS := -D__KERNEL__
+ KBUILD_AFLAGS_KERNEL :=
+ KBUILD_CFLAGS_KERNEL :=
+--
+2.37.2
--- /dev/null
+From 40337d6f3d677aee7ad3052ae662d3f53dd4d5cb Mon Sep 17 00:00:00 2001
+From: Arnd Bergmann <arnd@arndb.de>
+Date: Tue, 8 Mar 2022 22:56:15 +0100
+Subject: [PATCH 3/3] Kbuild: use -std=gnu11 for KBUILD_USERCFLAGS
+
+As we change the C language standard for the kernel from gnu89 to
+gnu11, it makes sense to also update the version for user space
+compilation.
+
+Some users have older native compilers than what they use for
+kernel builds, so I considered using gnu99 as the default version
+for wider compatibility with gcc-4.6 and earlier.
+
+However, testing with older compilers showed that we already require
+HOSTCC version 5.1 as well because a lot of host tools include
+linux/compiler.h that uses __has_attribute():
+
+ CC tools/objtool/exec-cmd.o
+In file included from tools/include/linux/compiler_types.h:36:0,
+ from tools/include/linux/compiler.h:5,
+ from exec-cmd.c:2:
+tools/include/linux/compiler-gcc.h:19:5: error: "__has_attribute" is not defined [-Werror=undef]
+
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Reviewed-by: Nathan Chancellor <nathan@kernel.org>
+Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
+Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
+Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
+---
+ Makefile | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/Makefile b/Makefile
+index fe86758acaaa..e569fccfb009 100644
+--- a/Makefile
++++ b/Makefile
+@@ -416,7 +416,7 @@ HOSTCXX = g++
+ endif
+
+ export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
+- -O2 -fomit-frame-pointer -std=gnu89 \
++ -O2 -fomit-frame-pointer -std=gnu11 \
+ -Wdeclaration-after-statement
+ export KBUILD_USERLDFLAGS :=
+
+--
+2.37.2
projects / openwrt / staging / hauke.git / commitdiff