[v6,12/15] arm64: vdso: disable Shadow Call Stack
diff mbox series

Message ID 20191206221351.38241-13-samitolvanen@google.com
State New
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Series
  • [v6,01/15] arm64: mm: avoid x18 in idmap_kpti_install_ng_mappings
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Commit Message

Sami Tolvanen Dec. 6, 2019, 10:13 p.m. UTC
Shadow stacks are only available in the kernel, so disable SCS
instrumentation for the vDSO.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
---
 arch/arm64/kernel/vdso/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Will Deacon Jan. 16, 2020, 5:46 p.m. UTC | #1
On Fri, Dec 06, 2019 at 02:13:48PM -0800, Sami Tolvanen wrote:
> Shadow stacks are only available in the kernel, so disable SCS
> instrumentation for the vDSO.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Reviewed-by: Mark Rutland <mark.rutland@arm.com>
> ---
>  arch/arm64/kernel/vdso/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
> index dd2514bb1511..a87a4f11724e 100644
> --- a/arch/arm64/kernel/vdso/Makefile
> +++ b/arch/arm64/kernel/vdso/Makefile
> @@ -25,7 +25,7 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING
>  
>  VDSO_LDFLAGS := -Bsymbolic
>  
> -CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
> +CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS)

Should we be removing -ffixed-x18 too, or does that not propagate here
anyway?

Will
Sami Tolvanen Jan. 16, 2020, 6:14 p.m. UTC | #2
On Thu, Jan 16, 2020 at 9:46 AM Will Deacon <will@kernel.org> wrote:
> Should we be removing -ffixed-x18 too, or does that not propagate here
> anyway?

No, we shouldn't touch -ffixed-x18 here. The vDSO is always built with
x18 reserved since commit 98cd3c3f83fbb ("arm64: vdso: Build vDSO with
-ffixed-x18").

Sami
Will Deacon Jan. 16, 2020, 6:18 p.m. UTC | #3
On Thu, Jan 16, 2020 at 10:14:24AM -0800, Sami Tolvanen wrote:
> On Thu, Jan 16, 2020 at 9:46 AM Will Deacon <will@kernel.org> wrote:
> > Should we be removing -ffixed-x18 too, or does that not propagate here
> > anyway?
> 
> No, we shouldn't touch -ffixed-x18 here. The vDSO is always built with
> x18 reserved since commit 98cd3c3f83fbb ("arm64: vdso: Build vDSO with
> -ffixed-x18").

Thanks, in which case:

Acked-by: Will Deacon <will@kernel.org>

Will

Patch
diff mbox series

diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index dd2514bb1511..a87a4f11724e 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -25,7 +25,7 @@  ccflags-y += -DDISABLE_BRANCH_PROFILING
 
 VDSO_LDFLAGS := -Bsymbolic
 
-CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
+CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS)
 KBUILD_CFLAGS			+= $(DISABLE_LTO)
 KASAN_SANITIZE			:= n
 UBSAN_SANITIZE			:= n