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Mon, 28 Jul 2025 17:36:12 -0700 (PDT) Date: Mon, 28 Jul 2025 17:36:09 -0700 From: Deepak Gupta To: Mike Rapoport Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: AEEC51C0003 X-Stat-Signature: yzq4jeyur1h5dw1sz6qfxoeiib4jiyf6 X-Rspam-User: X-HE-Tag: 1753749374-315727 X-HE-Meta: U2FsdGVkX1/OxJ8SyztodM6bIANVdSotsvf5u/YM4ZVHT+fAa/2CiMg5712KK/A2FJrc2NXcxMcXFYGIfE0fCRH5gy97NvCtYKTXtpV1FrFMvuCJs5/s9365P/jpN9ZKlvr7dJB0yWAsVOJy2IQUGooXDW4rMvflqQkzCETG0y2hz68RZyQUBJf2a04sh0aFHX9ViU/P10U15Va0vvN0v3a7EyTg7aE28gPsa84SV2FbWUGJzTlkLZC5SFu5NtCOOVpebzBrdxnIJ1h6ZgBO3tKGTbFQC/Gv0fQXyCBXoB2m6deZtWDaIF1FnEBnmXmF2l5NmtmCPxDSBqN98qvrOxdm/Nxn1kvaBOfpP61u5YEQo8anuWpdeBuGeM0pom7UcWPZOO/6fJVzNRHWecl/WsIaLxDjLbFLDht/UfwAHJPlZTyYz8XJsFgmywJotfyOLBSGYFh8eOi19J41nm8m1xU9dZnzxeiMjtg+TFNEFUv2k4ezpUrOz/sZN4s0zNLEsk29yF7zNB0eIGPT3mCOBPyrV8crQRAP2fgKUUjsL9UnmvYj0rrxX2wwjJFnYOHErqgDt9edXQRDIUlL5ylGrVB9d8tUQx64zselWrYQhcKAJrjj8TNbTzFFuogS4NVZOcIa3RWLAV4hJrfjxZtDdPf9HUpFaRaqbv+8pmcQomNYXRr5gbdT5ArMyNTg9Sw8Ifg9wNFjway4DQlPCBJmSuvRDMjP/GzeGTBct0xj1q8rPvA52i2aACO1hNyRhH87LVb4kkOOeHAwtiIiPbba1sHY5l3aAe6YzKOih3WhUdqUxUFuugUVwpXw1X842OiMCbS+T25CYL/FGea3/w0pOINy3cMEs9urVqUE5iT0TddYxT/TFltl7oY7NlTEt06XEiav118vI1E25VvOk0sL3VUyRbkvJHJHafmWM817o+0bGtdlrOEbL7j7S+3dycFBqw+rxDPwJlpVDLrmiVt oMTHOpdT 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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.