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Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Nick Desaulniers , Bill Wendling , Monk Chiang , Kito Cheng , Justin Stitt , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev, rick.p.edgecombe@intel.com, broonie@kernel.org, cleger@rivosinc.com, samitolvanen@google.com, apatel@ventanamicro.com, ajones@ventanamicro.com, conor.dooley@microchip.com, charlie@rivosinc.com, samuel.holland@sifive.com, bjorn@rivosinc.com, fweimer@redhat.com, jeffreyalaw@gmail.com, heinrich.schuchardt@canonical.com, andrew@sifive.com, ved@rivosinc.com Subject: Re: [PATCH 06/11] mm: Introduce ARCH_HAS_KERNEL_SHADOW_STACK Message-ID: References: <20250724-riscv_kcfi-v1-0-04b8fa44c98c@rivosinc.com> <20250724-riscv_kcfi-v1-6-04b8fa44c98c@rivosinc.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: On Sat, Jul 26, 2025 at 10:42:02AM +0300, Mike Rapoport wrote: >On Thu, Jul 24, 2025 at 04:36:59PM -0700, Deepak Gupta wrote: >> commit bcc9d04e74 ("mm: Introduce ARCH_HAS_USER_SHADOW_STACK") introduced >> `ARCH_HAS_USER_SHADOW_STACK`. Introducing `ARCH_HAS_KERNEL_SHADOW_STACK` >> so that arches can enable hardware assistance for kernel shadow stack. >> >> If `CONFIG_DYNAMIC_SCS` or `CONFIG_ARCH_HAS_KERNEL_SHADOW_STACK` are >> selected, skip compiler flag `-fsanitizer=shadow-call-stack`. >> >> Signed-off-by: Deepak Gupta >> --- >> Makefile | 2 +- >> mm/Kconfig | 6 ++++++ >> 2 files changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/Makefile b/Makefile >> index 35e6e5240c61..7e3ecca9353d 100644 >> --- a/Makefile >> +++ b/Makefile >> @@ -987,7 +987,7 @@ LDFLAGS_vmlinux += --gc-sections >> endif >> >> ifdef CONFIG_SHADOW_CALL_STACK >> -ifndef CONFIG_DYNAMIC_SCS >> +ifeq ($(or $(CONFIG_DYNAMIC_SCS),$(CONFIG_ARCH_HAS_KERNEL_SHADOW_STACK)),false) >> CC_FLAGS_SCS := -fsanitize=shadow-call-stack >> KBUILD_CFLAGS += $(CC_FLAGS_SCS) >> KBUILD_RUSTFLAGS += -Zsanitizer=shadow-call-stack >> diff --git a/mm/Kconfig b/mm/Kconfig >> index 781be3240e21..f295ea611cdb 100644 >> --- a/mm/Kconfig >> +++ b/mm/Kconfig >> @@ -1367,6 +1367,12 @@ config ARCH_HAS_USER_SHADOW_STACK >> The architecture has hardware support for userspace shadow call >> stacks (eg, x86 CET, arm64 GCS or RISC-V Zicfiss). >> >> +config ARCH_HAS_KERNEL_SHADOW_STACK >> + bool >> + help >> + The architecture has hardware support for kernel shadow call >> + stacks (eg, x86 CET, arm64 GCS or RISC-V Zicfiss). > >nit: tab and two space for indentation of the help text Will fix it. > >> + > >I think both ARCH_HAS_USER_SHADOW_STACK and ARCH_HAS_KERNEL_SHADOW_STACK >belong to arch/Kconfig rather than mm/Kconfig Do you want me to move it? This basically means that hardware shadow stack is supported or not. It needs mm support. I think thats why user one landed here. I followed. If it impacts mm, it should be here, right? > >> config ARCH_SUPPORTS_PT_RECLAIM >> def_bool n >> >> >> -- >> 2.43.0 >> > >-- >Sincerely yours, >Mike.