| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <YzNyAVmsUMdZl5OA@dev-arch.thelio-3990X>
Date: Tue, 27 Sep 2022 14:58:25 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Li Zetao <lizetao1@...wei.com>
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
kirill.shutemov@...ux.intel.com, akpm@...ux-foundation.org,
ndesaulniers@...gle.com, masahiroy@...nel.org,
sathyanarayanan.kuppuswamy@...ux.intel.com, michael.roth@....com,
brijesh.singh@....com, venu.busireddy@...cle.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next v2 0/2] Remove unused variables in x86/boot
On Tue, Sep 27, 2022 at 02:50:19PM -0700, Nathan Chancellor wrote:
> 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@...nel.org>
Oops, missed another one on second glance of my build logs:
3.
arch/x86/boot/compressed/acpi.c:23:1: warning: unused function '__efi_get_rsdp_addr' [-Wunused-function]
__efi_get_rsdp_addr(unsigned long cfg_tbl_pa, unsigned int cfg_tbl_len)
^
1 warning generated.
This happens when CONFIG_EFI is disabled. This will resolve it:
diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index 21febd9f21ab..5f2b8966e723 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -19,10 +19,10 @@
*/
struct mem_vector immovable_mem[MAX_NUMNODES*2];
+#ifdef CONFIG_EFI
static acpi_physical_address
__efi_get_rsdp_addr(unsigned long cfg_tbl_pa, unsigned int cfg_tbl_len)
{
-#ifdef CONFIG_EFI
unsigned long rsdp_addr;
/*
@@ -41,9 +41,9 @@ __efi_get_rsdp_addr(unsigned long cfg_tbl_pa, unsigned int cfg_tbl_len)
return (acpi_physical_address)rsdp_addr;
debug_putstr("Error getting RSDP address.\n");
-#endif
return 0;
}
+#endif
static acpi_physical_address efi_get_rsdp_addr(void)
{
Powered by blists - more mailing lists