From 7ded7d37e5f5b36b4acd74380156cf07b6640c5b Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Mon, 6 Oct 2025 14:39:56 -0700 Subject: scripts/Makefile.extrawarn: Respect CONFIG_WERROR / W=e for hostprogs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit 27758d8c2583 ("kbuild: enable -Werror for hostprogs") unconditionally enabled -Werror for the compiler, assembler, and linker when building the host programs, as the build footprint of the host programs is small (thus risk of build failures from warnings are low) and that stage of the build may not have Kconfig values (thus CONFIG_WERROR could not be used as a precondition). While turning warnings into errors unconditionally happens in a few places within the kernel, it can be disruptive to people who may be building with newer compilers, such as while doing a bisect. While it is possible to avoid this behavior by passing HOSTCFLAGS=-w or HOSTCFLAGS=-Wno-error, it may not be the most intuitive for regular users not intimately familiar with Kbuild. Avoid being disruptive to the entire build by depending on the explicit opt-in of CONFIG_WERROR or W=e to enable -Werror and the like while building the host programs. While this means there is a small portion of the build that does not have -Werror enabled (namely scripts/kconfig/* and scripts/basic/fixdep), it is better than not having it altogether. Fixes: 27758d8c2583 ("kbuild: enable -Werror for hostprogs") Acked-by: Miguel Ojeda Reported-by: Askar Safin Closes: https://lore.kernel.org/20251005011100.1035272-1-safinaskar@gmail.com/ Reviewed-by: Thomas Weißschuh Tested-by: Miguel Ojeda # Rust Link: https://patch.msgid.link/20251006-kbuild-hostprogs-werror-fix-v1-1-23cf1ffced5c@kernel.org Signed-off-by: Nathan Chancellor --- scripts/Makefile.extrawarn | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'scripts') diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 1434cb6208cb..6af392f9cd02 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -223,9 +223,11 @@ KBUILD_USERCFLAGS += -Werror KBUILD_USERLDFLAGS += -Wl,--fatal-warnings KBUILD_RUSTFLAGS += -Dwarnings -endif - -# Hostprog flags are used during build bootstrapping and can not rely on CONFIG_ symbols. +# While hostprog flags are used during build bootstrapping (thus should not +# depend on CONFIG_ symbols), -Werror is disruptive and should be opted into. +# Only apply -Werror to hostprogs built after the initial Kconfig stage. KBUILD_HOSTCFLAGS += -Werror KBUILD_HOSTLDFLAGS += -Wl,--fatal-warnings KBUILD_HOSTRUSTFLAGS += -Dwarnings + +endif -- cgit From 4b47a3aefb29c523ca66f0d28de8db15a10f9352 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Wed, 8 Oct 2025 15:46:44 -0700 Subject: kbuild: Restore pattern to avoid stripping .rela.dyn from vmlinux Commit 0ce5139fd96e ("kbuild: always create intermediate vmlinux.unstripped") removed the pattern to avoid stripping .rela.dyn sections added by commit e9d86b8e17e7 ("scripts: Do not strip .rela.dyn section"). Restore it so that .rela.dyn sections remain in the final vmlinux. Fixes: 0ce5139fd96e ("kbuild: always create intermediate vmlinux.unstripped") Acked-by: Ard Biesheuvel Acked-by: Alexey Gladkov Acked-by: Nicolas Schier Link: https://patch.msgid.link/20251008-kbuild-fix-modinfo-regressions-v1-1-9fc776c5887c@kernel.org Signed-off-by: Nathan Chancellor --- scripts/Makefile.vmlinux | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index 7c6ae9886f8f..a62639982be5 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -82,7 +82,7 @@ endif # --------------------------------------------------------------------------- remove-section-y := .modinfo -remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' +remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' '!.rel*.dyn' remove-symbols := -w --strip-symbol='__mod_device_table__*' -- cgit From 8ec3af916fe3954381cf3555ea03dc5adf4d0e8e Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Wed, 8 Oct 2025 15:46:45 -0700 Subject: kbuild: Add '.rel.*' strip pattern for vmlinux Prior to binutils commit c12d9fa2afe ("Support objcopy --remove-section=.relaFOO") [1] in 2.32, stripping relocation sections required the trailing period (i.e., '.rel.*') to work properly. After commit 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped"), there is an error with binutils 2.31.1 or earlier because these sections are not properly removed: s390-linux-objcopy: st6tO8Ev: symbol `.modinfo' required but not present s390-linux-objcopy:st6tO8Ev: no symbols Add the old pattern to resolve this issue (along with a comment to allow cleaning this when binutils 2.32 or newer is the minimum supported version). While the aforementioned kbuild change exposes this, the pattern was originally changed by commit 71d815bf5dfd ("kbuild: Strip runtime const RELA sections correctly"), where it would still be incorrect with binutils older than 2.32. Fixes: 71d815bf5dfd ("kbuild: Strip runtime const RELA sections correctly") Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c12d9fa2afe7abcbe407a00e15719e1a1350c2a7 [1] Reported-by: Linux Kernel Functional Testing Closes: https://lore.kernel.org/CA+G9fYvVktRhFtZXdNgVOL8j+ArsJDpvMLgCitaQvQmCx=hwOQ@mail.gmail.com/ Acked-by: Ard Biesheuvel Acked-by: Alexey Gladkov Acked-by: Nicolas Schier Link: https://patch.msgid.link/20251008-kbuild-fix-modinfo-regressions-v1-2-9fc776c5887c@kernel.org Signed-off-by: Nathan Chancellor --- scripts/Makefile.vmlinux | 3 +++ 1 file changed, 3 insertions(+) (limited to 'scripts') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index a62639982be5..c02f85c2e241 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -83,6 +83,9 @@ endif remove-section-y := .modinfo remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' '!.rel*.dyn' +# for compatibility with binutils < 2.32 +# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c12d9fa2afe7abcbe407a00e15719e1a1350c2a7 +remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel.*' remove-symbols := -w --strip-symbol='__mod_device_table__*' -- cgit From b0f2942a16017f88395d768afedd7373860968ce Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Fri, 10 Oct 2025 14:49:27 -0700 Subject: kbuild: Use '--strip-unneeded-symbol' for removing module device table symbols After commit 5ab23c7923a1 ("modpost: Create modalias for builtin modules"), relocatable RISC-V kernels with CONFIG_KASAN=y start failing when attempting to strip the module device table symbols: riscv64-linux-objcopy: not stripping symbol `__mod_device_table__kmod_irq_starfive_jh8100_intc__of__starfive_intc_irqchip_match_table' because it is named in a relocation make[4]: *** [scripts/Makefile.vmlinux:97: vmlinux] Error 1 The relocation appears to come from .LASANLOC5 in .data.rel.local: $ llvm-objdump --disassemble-symbols=.LASANLOC5 --disassemble-all -r drivers/irqchip/irq-starfive-jh8100-intc.o drivers/irqchip/irq-starfive-jh8100-intc.o: file format elf64-littleriscv Disassembly of section .data.rel.local: 0000000000000180 <.LASANLOC5>: ... 1d0: 0000 unimp 00000000000001d0: R_RISCV_64 __mod_device_table__kmod_irq_starfive_jh8100_intc__of__starfive_intc_irqchip_match_table ... This section appears to come from GCC for including additional information about global variables that may be protected by KASAN. There appears to be no way to opt out of the generation of these symbols through either a flag or attribute. Attempting to remove '.LASANLOC*' with '--strip-symbol' results in the same error as above because these symbols may refer to (thus have relocation between) each other. Avoid this build breakage by switching to '--strip-unneeded-symbol' for removing __mod_device_table__ symbols, as it will only remove the symbol when there is no relocation pointing to it. While this may result in a little more bloat in the symbol table in certain configurations, it is not as bad as outright build failures. Fixes: 5ab23c7923a1 ("modpost: Create modalias for builtin modules") Reported-by: Charles Mirabile Closes: https://lore.kernel.org/20251007011637.2512413-1-cmirabil@redhat.com/ Suggested-by: Alexey Gladkov Tested-by: Nicolas Schier Signed-off-by: Nathan Chancellor --- scripts/Makefile.vmlinux | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index c02f85c2e241..ced4379550d7 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -87,7 +87,7 @@ remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' '!.rel*.dyn' # https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c12d9fa2afe7abcbe407a00e15719e1a1350c2a7 remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel.*' -remove-symbols := -w --strip-symbol='__mod_device_table__*' +remove-symbols := -w --strip-unneeded-symbol='__mod_device_table__*' # To avoid warnings: "empty loadable segment detected at ..." from GNU objcopy, # it is necessary to remove the PT_LOAD flag from the segment. -- cgit