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Fri, 14 Mar 2025 14:40:28 -0700 (PDT) Received: from debug.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-225c68a6e09sm33368855ad.55.2025.03.14.14.40.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Mar 2025 14:40:27 -0700 (PDT) From: Deepak Gupta Date: Fri, 14 Mar 2025 14:39:42 -0700 Subject: [PATCH v12 23/28] riscv: kernel command line option to opt out of user cfi 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="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250314-v5_user_cfi_series-v12-23-e51202b53138@rivosinc.com> References: <20250314-v5_user_cfi_series-v12-0-e51202b53138@rivosinc.com> In-Reply-To: <20250314-v5_user_cfi_series-v12-0-e51202b53138@rivosinc.com> To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Arnd Bergmann , Christian Brauner , Peter Zijlstra , Oleg Nesterov , Eric Biederman , Kees Cook , Jonathan Corbet , Shuah Khan , Jann Horn , Conor Dooley Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, alistair.francis@wdc.com, richard.henderson@linaro.org, jim.shu@sifive.com, andybnac@gmail.com, kito.cheng@sifive.com, charlie@rivosinc.com, atishp@rivosinc.com, evan@rivosinc.com, cleger@rivosinc.com, alexghiti@rivosinc.com, samitolvanen@google.com, broonie@kernel.org, rick.p.edgecombe@intel.com, Deepak Gupta X-Mailer: b4 0.14.0 This commit adds a kernel command line option using which user cfi can be disabled. Signed-off-by: Deepak Gupta --- arch/riscv/kernel/usercfi.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/riscv/kernel/usercfi.c b/arch/riscv/kernel/usercfi.c index d31d89618763..813162ce4f15 100644 --- a/arch/riscv/kernel/usercfi.c +++ b/arch/riscv/kernel/usercfi.c @@ -17,6 +17,8 @@ #include #include =20 +bool disable_riscv_usercfi; + #define SHSTK_ENTRY_SIZE sizeof(void *) =20 bool is_shstk_enabled(struct task_struct *task) @@ -396,6 +398,9 @@ int arch_set_shadow_stack_status(struct task_struct *t,= unsigned long status) unsigned long size =3D 0, addr =3D 0; bool enable_shstk =3D false; =20 + if (disable_riscv_usercfi) + return 0; + if (!cpu_supports_shadow_stack()) return -EINVAL; =20 @@ -475,6 +480,9 @@ int arch_set_indir_br_lp_status(struct task_struct *t, = unsigned long status) { bool enable_indir_lp =3D false; =20 + if (disable_riscv_usercfi) + return 0; + if (!cpu_supports_indirect_br_lp_instr()) return -EINVAL; =20 @@ -507,3 +515,16 @@ int arch_lock_indir_br_lp_status(struct task_struct *t= ask, =20 return 0; } + +static int __init setup_global_riscv_enable(char *str) +{ + if (strcmp(str, "true") =3D=3D 0) + disable_riscv_usercfi =3D true; + + pr_info("Setting riscv usercfi to be %s\n", + (disable_riscv_usercfi ? "disabled" : "enabled")); + + return 1; +} + +__setup("disable_riscv_usercfi=3D", setup_global_riscv_enable); --=20 2.34.1