Received-SPF: pass (google.com: domain of linux-kernel+bounces-130727-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
From: Deepak Gupta <debug@rivosinc.com>
To: paul.walmsley@sifive.com,
	rick.p.edgecombe@intel.com,
	broonie@kernel.org,
	Szabolcs.Nagy@arm.com,
	kito.cheng@sifive.com,
	keescook@chromium.org,
	ajones@ventanamicro.com,
	conor.dooley@microchip.com,
	cleger@rivosinc.com,
	atishp@atishpatra.org,
	alex@ghiti.fr,
	bjorn@rivosinc.com,
	alexghiti@rivosinc.com,
	samuel.holland@sifive.com,
	conor@kernel.org
Cc: linux-doc@vger.kernel.org,
	linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org,
	linux-mm@kvack.org,
	linux-arch@vger.kernel.org,
	linux-kselftest@vger.kernel.org,
	corbet@lwn.net,
	palmer@dabbelt.com,
	aou@eecs.berkeley.edu,
	robh+dt@kernel.org,
	krzysztof.kozlowski+dt@linaro.org,
	oleg@redhat.com,
	akpm@linux-foundation.org,
	arnd@arndb.de,
	ebiederm@xmission.com,
	Liam.Howlett@oracle.com,
	vbabka@suse.cz,
	lstoakes@gmail.com,
	shuah@kernel.org,
	brauner@kernel.org,
	debug@rivosinc.com,
	andy.chiu@sifive.com,
	jerry.shih@sifive.com,
	hankuan.chen@sifive.com,
	greentime.hu@sifive.com,
	evan@rivosinc.com,
	xiao.w.wang@intel.com,
	charlie@rivosinc.com,
	apatel@ventanamicro.com,
	mchitale@ventanamicro.com,
	dbarboza@ventanamicro.com,
	sameo@rivosinc.com,
	shikemeng@huaweicloud.com,
	willy@infradead.org,
	vincent.chen@sifive.com,
	guoren@kernel.org,
	samitolvanen@google.com,
	songshuaishuai@tinylab.org,
	gerg@kernel.org,
	heiko@sntech.de,
	bhe@redhat.com,
	jeeheng.sia@starfivetech.com,
	cyy@cyyself.name,
	maskray@google.com,
	ancientmodern4@gmail.com,
	mathis.salmen@matsal.de,
	cuiyunhui@bytedance.com,
	bgray@linux.ibm.com,
	mpe@ellerman.id.au,
	baruch@tkos.co.il,
	alx@kernel.org,
	david@redhat.com,
	catalin.marinas@arm.com,
	revest@chromium.org,
	josh@joshtriplett.org,
	shr@devkernel.io,
	deller@gmx.de,
	omosnace@redhat.com,
	ojeda@kernel.org,
	jhubbard@nvidia.com
Subject: [PATCH v3 08/29] mm: Define VM_SHADOW_STACK for RISC-V
Date: Wed,  3 Apr 2024 16:34:56 -0700
Message-ID: <20240403234054.2020347-9-debug@rivosinc.com>
In-Reply-To: <20240403234054.2020347-1-debug@rivosinc.com>
References: <20240403234054.2020347-1-debug@rivosinc.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

VM_SHADOW_STACK is defined by x86 as vm flag to mark a shadow stack vma.

x86 uses VM_HIGH_ARCH_5 bit but that limits shadow stack vma to 64bit only.
arm64 follows same path (see links)

To keep things simple, RISC-V follows the same.
This patch adds `ss` for shadow stack in process maps.

Links:
https://lore.kernel.org/lkml/20231009-arm64-gcs-v6-12-78e55deaa4dd@kernel.org/#r

Signed-off-by: Deepak Gupta <debug@rivosinc.com>
---
 fs/proc/task_mmu.c |  3 +++
 include/linux/mm.h | 11 ++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 3f78ebbb795f..d9d63eb74f0d 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -702,6 +702,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
 #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
 #ifdef CONFIG_X86_USER_SHADOW_STACK
 		[ilog2(VM_SHADOW_STACK)] = "ss",
+#endif
+#ifdef CONFIG_RISCV_USER_CFI
+		[ilog2(VM_SHADOW_STACK)] = "ss",
 #endif
 	};
 	size_t i;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index f5a97dec5169..64109f6c70f5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -352,7 +352,16 @@ extern unsigned int kobjsize(const void *objp);
  * for more details on the guard size.
  */
 # define VM_SHADOW_STACK	VM_HIGH_ARCH_5
-#else
+#endif
+
+#ifdef CONFIG_RISCV_USER_CFI
+/*
+ * RISC-V is going along with using VM_HIGH_ARCH_5 bit position for shadow stack
+ */
+#define VM_SHADOW_STACK	VM_HIGH_ARCH_5
+#endif
+
+#ifndef VM_SHADOW_STACK
 # define VM_SHADOW_STACK	VM_NONE
 #endif
 
-- 
2.43.2