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Message-Id: <20230724-arm64-gcs-v2-10-dc2c1d44c2eb@kernel.org>
Date: Mon, 24 Jul 2023 13:45:57 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Jonathan Corbet <corbet@....net>,
Andrew Morton <akpm@...ux-foundation.org>,
Marc Zyngier <maz@...nel.org>,
Oliver Upton <oliver.upton@...ux.dev>,
James Morse <james.morse@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Arnd Bergmann <arnd@...db.de>, Oleg Nesterov <oleg@...hat.com>,
Eric Biederman <ebiederm@...ssion.com>,
Kees Cook <keescook@...omium.org>,
Shuah Khan <shuah@...nel.org>,
"Rick P. Edgecombe" <rick.p.edgecombe@...el.com>,
Deepak Gupta <debug@...osinc.com>,
Ard Biesheuvel <ardb@...nel.org>,
Szabolcs Nagy <Szabolcs.Nagy@....com>
Cc: "H.J. Lu" <hjl.tools@...il.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
kvmarm@...ts.linux.dev, linux-fsdevel@...r.kernel.org,
linux-arch@...r.kernel.org, linux-mm@...ck.org,
linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-riscv@...ts.infradead.org, Mark Brown <broonie@...nel.org>
Subject: [PATCH v2 10/35] mm: Define VM_SHADOW_STACK for arm64 when we
support GCS
Use VM_HIGH_ARCH_5 for guarded control stack pages.
Signed-off-by: Mark Brown <broonie@...nel.org>
---
Documentation/filesystems/proc.rst | 2 +-
fs/proc/task_mmu.c | 3 +++
include/linux/mm.h | 12 +++++++++++-
3 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index 6ccb57089a06..086a0408a4d7 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -566,7 +566,7 @@ encoded manner. The codes are the following:
mt arm64 MTE allocation tags are enabled
um userfaultfd missing tracking
uw userfaultfd wr-protect tracking
- ss shadow stack page
+ ss shadow/guarded control stack page
== =======================================
Note that there is no guarantee that every flag and associated mnemonic will
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index cfab855fe7e9..e8c50848bb16 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -711,6 +711,9 @@ 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_ARM64_GCS
+ [ilog2(VM_SHADOW_STACK)] = "ss",
#endif
};
size_t i;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c57c5030ef6c..c6af8daceb56 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -372,7 +372,17 @@ extern unsigned int kobjsize(const void *objp);
* having a PAGE_SIZE guard gap.
*/
# define VM_SHADOW_STACK VM_HIGH_ARCH_5
-#else
+#endif
+
+#if defined(CONFIG_ARM64_GCS)
+/*
+ * arm64's Guarded Control Stack implements similar functionality and
+ * has similar constraints to shadow stacks.
+ */
+# define VM_SHADOW_STACK VM_HIGH_ARCH_5
+#endif
+
+#ifndef VM_SHADOW_STACK
# define VM_SHADOW_STACK VM_NONE
#endif
--
2.30.2
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