2022-09-02 08:31:05

by Christophe Leroy

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Subject: [PATCH] powerpc/vdso: link with -z noexecstack

With recent binutils, the following warning appears:

VDSO32L arch/powerpc/kernel/vdso/vdso32.so.dbg
/opt/gcc-12.2.0-nolibc/powerpc64-linux/bin/../lib/gcc/powerpc64-linux/12.2.0/../../../../powerpc64-linux/bin/ld: warning: arch/powerpc/kernel/vdso/getcpu-32.o: missing .note.GNU-stack section implies executable stack
/opt/gcc-12.2.0-nolibc/powerpc64-linux/bin/../lib/gcc/powerpc64-linux/12.2.0/../../../../powerpc64-linux/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker

To avoid that, explicitely tell the linker we don't
want executable stack.

For more explanations, see commit ffcf9c5700e4 ("x86: link vdso
and boot with -z noexecstack --no-warn-rwx-segments")

Signed-off-by: Christophe Leroy <[email protected]>
---
arch/powerpc/kernel/Makefile | 3 ++-
arch/powerpc/kernel/vdso/Makefile | 4 ++--
2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 06d2d1f78f71..b071e15dd574 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -128,7 +128,8 @@ extra-y += vmlinux.lds

obj-$(CONFIG_RELOCATABLE) += reloc_$(BITS).o

-obj-$(CONFIG_PPC32) += entry_32.o setup_32.o early_32.o static_call.o
+obj-$(CONFIG_PPC32) += entry_32.o setup_32.o early_32.o
+obj-$(CONFIG_HAVE_STATIC_CALL) += static_call.o
obj-$(CONFIG_PPC64) += dma-iommu.o iommu.o
obj-$(CONFIG_KGDB) += kgdb.o
obj-$(CONFIG_BOOTX_TEXT) += btext.o
diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index 096b0bf1335f..a2e7b0ce5b19 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -92,13 +92,13 @@ include/generated/vdso64-offsets.h: $(obj)/vdso64.so.dbg FORCE

# actual build commands
quiet_cmd_vdso32ld_and_check = VDSO32L $@
- cmd_vdso32ld_and_check = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) ; $(cmd_vdso_check)
+ cmd_vdso32ld_and_check = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) -z noexecstack ; $(cmd_vdso_check)
quiet_cmd_vdso32as = VDSO32A $@
cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) $(AS32FLAGS) -c -o $@ $<
quiet_cmd_vdso32cc = VDSO32C $@
cmd_vdso32cc = $(VDSOCC) $(c_flags) $(CC32FLAGS) -c -o $@ $<

quiet_cmd_vdso64ld_and_check = VDSO64L $@
- cmd_vdso64ld_and_check = $(VDSOCC) $(c_flags) $(CC64FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) ; $(cmd_vdso_check)
+ cmd_vdso64ld_and_check = $(VDSOCC) $(c_flags) $(CC64FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) -z noexecstack ; $(cmd_vdso_check)
quiet_cmd_vdso64as = VDSO64A $@
cmd_vdso64as = $(VDSOCC) $(a_flags) $(CC64FLAGS) $(AS64FLAGS) -c -o $@ $<
--
2.37.1


2022-09-02 15:56:39

by Segher Boessenkool

[permalink] [raw]
Subject: Re: [PATCH] powerpc/vdso: link with -z noexecstack

Hi!

On Fri, Sep 02, 2022 at 09:57:09AM +0200, Christophe Leroy wrote:
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -128,7 +128,8 @@ extra-y += vmlinux.lds
>
> obj-$(CONFIG_RELOCATABLE) += reloc_$(BITS).o
>
> -obj-$(CONFIG_PPC32) += entry_32.o setup_32.o early_32.o static_call.o
> +obj-$(CONFIG_PPC32) += entry_32.o setup_32.o early_32.o
> +obj-$(CONFIG_HAVE_STATIC_CALL) += static_call.o

Did you want to commit this part? The commit message doesn't mention it.


Segher

2022-09-02 16:12:19

by Christophe Leroy

[permalink] [raw]
Subject: Re: [PATCH] powerpc/vdso: link with -z noexecstack



Le 02/09/2022 à 17:16, Segher Boessenkool a écrit :
> Hi!
>
> On Fri, Sep 02, 2022 at 09:57:09AM +0200, Christophe Leroy wrote:
>> --- a/arch/powerpc/kernel/Makefile
>> +++ b/arch/powerpc/kernel/Makefile
>> @@ -128,7 +128,8 @@ extra-y += vmlinux.lds
>>
>> obj-$(CONFIG_RELOCATABLE) += reloc_$(BITS).o
>>
>> -obj-$(CONFIG_PPC32) += entry_32.o setup_32.o early_32.o static_call.o
>> +obj-$(CONFIG_PPC32) += entry_32.o setup_32.o early_32.o
>> +obj-$(CONFIG_HAVE_STATIC_CALL) += static_call.o
>
> Did you want to commit this part? The commit message doesn't mention it.
>
>

Oops. No I didn't, thanks for seeing it.