[PATCH v8 01/29] mm: Introduce ARCH_HAS_USER_SHADOW_STACK

Deepak Gupta
2024-11-11T21:06:18Z

From: Mark Brown <broonie@kernel.org>

Since multiple architectures have support for shadow stacks and we need to
select support for this feature in several places in the generic code
provide a generic config option that the architectures can select.

Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Deepak Gupta <debug@rivosinc.com>
Reviewed-by: Carlos Bilbao <carlos.bilbao.osdev@gmail.com>
---
arch/x86/Kconfig | 1 +
fs/proc/task_mmu.c | 2 +-
include/linux/mm.h | 2 +-
mm/Kconfig | 6 ++++++
4 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 16354dfa6d96..fe6e9ece64b9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1954,6 +1954,7 @@ config X86_USER_SHADOW_STACK
depends on AS_WRUSS
depends on X86_64
select ARCH_USES_HIGH_VMA_FLAGS
+ select ARCH_HAS_USER_SHADOW_STACK
select X86_CET
help
Shadow stack protection is a hardware feature that detects function
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e52bd96137a6..f57ea9b308bb 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -978,7 +978,7 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
[ilog2(VM_UFFD_MINOR)] = "ui",
#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
-#ifdef CONFIG_X86_USER_SHADOW_STACK
+#ifdef CONFIG_ARCH_HAS_USER_SHADOW_STACK
[ilog2(VM_SHADOW_STACK)] = "ss",
#endif
#if defined(CONFIG_64BIT) || defined(CONFIG_PPC32)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 61fff5d34ed5..2291c02c74d2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -354,7 +354,7 @@ extern unsigned int kobjsize(const void *objp);
#endif
#endif /* CONFIG_ARCH_HAS_PKEYS */

-#ifdef CONFIG_X86_USER_SHADOW_STACK
+#ifdef CONFIG_ARCH_HAS_USER_SHADOW_STACK
/*
* VM_SHADOW_STACK should not be set with VM_SHARED because of lack of
* support core mm.
diff --git a/mm/Kconfig b/mm/Kconfig
index 4c9f5ea13271..4b2a1ef9a161 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1296,6 +1296,12 @@ config NUMA_EMU
into virtual nodes when booted with "numa=fake=N", where N is the
number of nodes. This is only useful for debugging.

+config ARCH_HAS_USER_SHADOW_STACK
+ bool
+ help
+ The architecture has hardware support for userspace shadow call
+ stacks (eg, x86 CET, arm64 GCS or RISC-V Zicfiss).
+
source "mm/damon/Kconfig"

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