[PATCH AUTOSEL 6.13 3/6] kbuild: suppress stdout from merge_config for silent builds

[PATCH AUTOSEL 6.13 3/6] kbuild: suppress stdout from merge_config for silent builds

[Sasha Levin]

From: Masahiro Yamada <masahiroy@kernel.org>

[ Upstream commit 1f937a4bcb0472015818f30f4d3c5546d3f09933 ]

merge_config does not respect the Make's -s (--silent) option.

Let's sink the stdout from merge_config for silent builds.

This commit does not cater to the direct invocation of merge_config.sh
(e.g. arch/mips/Makefile).

Reported-by: Leon Romanovsky <leon@kernel.org>
Closes: https://lore.kernel.org/all/e534ce33b0e1060eb85ece8429810f087b034c88.1733234008.git.leonro@nvidia.com/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Leon Romanovsky <leon@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 scripts/Makefile.defconf | 13 +++++++------
 scripts/kconfig/Makefile |  4 +++-
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/scripts/Makefile.defconf b/scripts/Makefile.defconf
index 226ea3df3b4b4..a44307f08e9d6 100644
--- a/scripts/Makefile.defconf
+++ b/scripts/Makefile.defconf
@@ -1,6 +1,11 @@
 # SPDX-License-Identifier: GPL-2.0
 # Configuration heplers
 
+cmd_merge_fragments = \
+	$(srctree)/scripts/kconfig/merge_config.sh \
+	$4 -m -O $(objtree) $(srctree)/arch/$(SRCARCH)/configs/$2 \
+	$(foreach config,$3,$(srctree)/arch/$(SRCARCH)/configs/$(config).config)
+
 # Creates 'merged defconfigs'
 # ---------------------------------------------------------------------------
 # Usage:
@@ -8,9 +13,7 @@
 #
 # Input config fragments without '.config' suffix
 define merge_into_defconfig
-	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh \
-		-m -O $(objtree) $(srctree)/arch/$(SRCARCH)/configs/$(1) \
-		$(foreach config,$(2),$(srctree)/arch/$(SRCARCH)/configs/$(config).config)
+	$(call cmd,merge_fragments,$1,$2)
 	+$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
 endef
 
@@ -22,8 +25,6 @@ endef
 #
 # Input config fragments without '.config' suffix
 define merge_into_defconfig_override
-	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh \
-		-Q -m -O $(objtree) $(srctree)/arch/$(SRCARCH)/configs/$(1) \
-		$(foreach config,$(2),$(srctree)/arch/$(SRCARCH)/configs/$(config).config)
+	$(call cmd,merge_fragments,$1,$2,-Q)
 	+$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
 endef
diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
index a0a0be38cbdc1..fb50bd4f4103f 100644
--- a/scripts/kconfig/Makefile
+++ b/scripts/kconfig/Makefile
@@ -105,9 +105,11 @@ configfiles = $(wildcard $(srctree)/kernel/configs/$(1) $(srctree)/arch/$(SRCARC
 all-config-fragments = $(call configfiles,*.config)
 config-fragments = $(call configfiles,$@)
 
+cmd_merge_fragments = $(srctree)/scripts/kconfig/merge_config.sh -m $(KCONFIG_CONFIG) $(config-fragments)
+
 %.config: $(obj)/conf
 	$(if $(config-fragments),, $(error $@ fragment does not exists on this architecture))
-	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh -m $(KCONFIG_CONFIG) $(config-fragments)
+	$(call cmd,merge_fragments)
 	$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
 
 PHONY += tinyconfig
-- 
2.39.5

[PATCH AUTOSEL 6.13 6/6] kbuild: Use -fzero-init-padding-bits=all

[Sasha Levin]

From: Kees Cook <kees@kernel.org>

[ Upstream commit dce4aab8441d285b9a78b33753e0bf583c1320ee ]

GCC 15 introduces a regression in "= { 0 }" style initialization of
unions that Linux has depended on for eliminating uninitialized variable
contents. GCC does not seem likely to fix it[1], instead suggesting[2]
that affected projects start using -fzero-init-padding-bits=unions.

To avoid future surprises beyond just the current situation with unions,
enable -fzero-init-padding-bits=all when available (GCC 15+). This will
correctly zero padding bits in unions and structs that might have been
left uninitialized, and will make sure there is no immediate regression
in union initializations. As seen in the stackinit KUnit selftest union
cases, which were passing before, were failing under GCC 15:

    not ok 18 test_small_start_old_zero
    ok 29 test_small_start_dynamic_partial # SKIP XFAIL uninit bytes: 63
    ok 32 test_small_start_assigned_dynamic_partial # SKIP XFAIL uninit bytes: 63
    ok 67 test_small_start_static_partial # SKIP XFAIL uninit bytes: 63
    ok 70 test_small_start_static_all # SKIP XFAIL uninit bytes: 56
    ok 73 test_small_start_dynamic_all # SKIP XFAIL uninit bytes: 56
    ok 82 test_small_start_assigned_static_partial # SKIP XFAIL uninit bytes: 63
    ok 85 test_small_start_assigned_static_all # SKIP XFAIL uninit bytes: 56
    ok 88 test_small_start_assigned_dynamic_all # SKIP XFAIL uninit bytes: 56

The above all now pass again with -fzero-init-padding-bits=all added.

This also fixes the following cases for struct initialization that had
been XFAIL until now because there was no compiler support beyond the
larger "-ftrivial-auto-var-init=zero" option:

    ok 38 test_small_hole_static_all # SKIP XFAIL uninit bytes: 3
    ok 39 test_big_hole_static_all # SKIP XFAIL uninit bytes: 124
    ok 40 test_trailing_hole_static_all # SKIP XFAIL uninit bytes: 7
    ok 42 test_small_hole_dynamic_all # SKIP XFAIL uninit bytes: 3
    ok 43 test_big_hole_dynamic_all # SKIP XFAIL uninit bytes: 124
    ok 44 test_trailing_hole_dynamic_all # SKIP XFAIL uninit bytes: 7
    ok 58 test_small_hole_assigned_static_all # SKIP XFAIL uninit bytes: 3
    ok 59 test_big_hole_assigned_static_all # SKIP XFAIL uninit bytes: 124
    ok 60 test_trailing_hole_assigned_static_all # SKIP XFAIL uninit bytes: 7
    ok 62 test_small_hole_assigned_dynamic_all # SKIP XFAIL uninit bytes: 3
    ok 63 test_big_hole_assigned_dynamic_all # SKIP XFAIL uninit bytes: 124
    ok 64 test_trailing_hole_assigned_dynamic_all # SKIP XFAIL uninit bytes: 7

All of the above now pass when built under GCC 15. Tests can be seen
with:

    ./tools/testing/kunit/kunit.py run stackinit --arch=x86_64 \
        --make_option CC=gcc-15

Clang continues to fully initialize these kinds of variables[3] without
additional flags.

Suggested-by: Jakub Jelinek <jakub@redhat.com>
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118403 [1]
Link: https://lore.kernel.org/linux-toolchains/Z0hRrrNU3Q+ro2T7@tucnak/ [2]
Link: https://github.com/llvm/llvm-project/commit/7a086e1b2dc05f54afae3591614feede727601fa [3]
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20250127191031.245214-3-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 scripts/Makefile.extrawarn | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 1d13cecc7cc78..eb719f6d8d536 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -77,6 +77,9 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
 # Warn if there is an enum types mismatch
 KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion)
 
+# Explicitly clear padding bits during variable initialization
+KBUILD_CFLAGS += $(call cc-option,-fzero-init-padding-bits=all)
+
 KBUILD_CFLAGS += -Wextra
 KBUILD_CFLAGS += -Wunused
 
-- 
2.39.5