Messages in this thread Patches in this message | | | Date | Tue, 27 Sep 2022 14:50:19 -0700 | From | Nathan Chancellor <> | Subject | Re: [PATCH -next v2 0/2] Remove unused variables in x86/boot |
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Hi Li,
On Tue, Sep 27, 2022 at 08:15:10AM +0000, Li Zetao wrote: > This patch set removes some unused variables in x86/boot, and add the > "-Wall" flag to Makefile, which is the old problem of x86 not sharing > makefiles. > > Changes since v1: > - Add "-Wall" flag to x86/boot/compressed/Makefile > - Remove unused variables "et" in efi_get_system_table() and "ret" in > efi_get_conf_table() > - Remove unused variables "ret" in __efi_get_rsdp_addr() and > "nr_tables" in efi_get_rsdp_addr() > > v1 at: > https://lore.kernel.org/all/20220923113209.3046960-1-lizetao1@huawei.com/ > > Li Zetao (2): > x86/boot/compressed: Add "-Wall" flag to Makefile > x86/boot: Remove unused variables > > arch/x86/boot/compressed/Makefile | 2 +- > arch/x86/boot/compressed/acpi.c | 2 -- > arch/x86/boot/compressed/efi.c | 2 -- > arch/x86/boot/compressed/sev.c | 1 - > 4 files changed, 1 insertion(+), 6 deletions(-)
I took this series for a spin with clang and found a few extra warnings.
1.
In file included from arch/x86/boot/compressed/misc.c:15: In file included from arch/x86/boot/compressed/misc.h:24: In file included from ./include/linux/elf.h:6: In file included from ./arch/x86/include/asm/elf.h:8: In file included from ./include/linux/thread_info.h:60: ./arch/x86/include/asm/thread_info.h:175:13: warning: calling '__builtin_frame_address' with a nonzero argument is unsafe [-Wframe-address] oldframe = __builtin_frame_address(1); ^~~~~~~~~~~~~~~~~~~~~~~~~~ ./arch/x86/include/asm/thread_info.h:177:11: warning: calling '__builtin_frame_address' with a nonzero argument is unsafe [-Wframe-address] frame = __builtin_frame_address(2); ^~~~~~~~~~~~~~~~~~~~~~~~~~
This warning is disabled in the main Makefile for this reason so we should just be able to disable it:
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 10abb7c45d04..3f004567f3d5 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -43,6 +43,7 @@ KBUILD_CFLAGS += -mno-mmx -mno-sse KBUILD_CFLAGS += -ffreestanding -fshort-wchar KBUILD_CFLAGS += -fno-stack-protector KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member) +KBUILD_CFLAGS += $(call cc-disable-warning, frame-address) KBUILD_CFLAGS += $(call cc-disable-warning, gnu) KBUILD_CFLAGS += -Wno-pointer-sign KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=) 2.
arch/x86/boot/compressed/kaslr.c:627:6: warning: unused variable 'i' [-Wunused-variable] int i; ^
This happens when CONFIG_MEMORY_HOTREMOVE or CONFIG_ACPI are 'n'. I think it can just be fixed by aligning arch/x86/boot/compressed with the rest of the kernel and explicitly compiling with '-std=gnu11', which will allow us to declare the variable within the for loop, like so.
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 3f004567f3d5..6c7e366a437b 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -34,7 +34,7 @@ targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \ # be valid. KBUILD_CFLAGS := -m$(BITS) -O2 $(CLANG_FLAGS) KBUILD_CFLAGS += -fno-strict-aliasing -fPIE -KBUILD_CFLAGS += -Wundef -Wall +KBUILD_CFLAGS += -Wundef -Wall -std=gnu11 KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING cflags-$(CONFIG_X86_32) := -march=i386 cflags-$(CONFIG_X86_64) := -mcmodel=small -mno-red-zone diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 4a3f223973f4..be859c7e7f6b 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -624,7 +624,6 @@ static bool process_mem_region(struct mem_vector *region, unsigned long minimum, unsigned long image_size) { - int i; /* * If no immovable memory found, or MEMORY_HOTREMOVE disabled, * use @region directly. @@ -644,7 +643,7 @@ static bool process_mem_region(struct mem_vector *region, * If immovable memory found, filter the intersection between * immovable memory and @region. */ - for (i = 0; i < num_immovable_mem; i++) { + for (int i = 0; i < num_immovable_mem; i++) { u64 start, end, entry_end, region_end; struct mem_vector entry; Additionally, I think these two patches should be reordered so that the warnings are fixed before they are enabled.
With those comments addressed, consider the series:
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Cheers, Nathan
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