[RFT,v6,3/9] mm: Introduce ARCH_HAS_USER_SHADOW_STACK

Commit Message

Mark Brown June 23, 2024, 11:23 a.m. UTC

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 <[e-mail]>
Acked-by: David Hildenbrand <[e-mail]>
Reviewed-by: Deepak Gupta <[e-mail]>
Reviewed-by: Rick Edgecombe <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>
---
 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(-)

Comments

Thiago Jung Bauermann July 16, 2024, 4:38 a.m. UTC | #1

Hello,

> diff --git a/mm/Kconfig b/mm/Kconfig
> index b4cb45255a54..45416916dec1 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -1249,6 +1249,12 @@ config IOMMU_MM_DATA
>  config EXECMEM
>  	bool
>  
> +config ARCH_HAS_USER_SHADOW_STACK
> +	bool
> +	help
> +	  The architecture has hardware support for userspace shadow call
> +          stacks (eg, x87 CET, arm64 GCS or RISC-V Zicfiss).

s/x87/x86/ ?

Patch

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 1d7122a1883e..4a5e40d4c14e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1949,6 +1949,7 @@  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 f8d35f993fe5..1b56c1077507 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -704,7 +704,7 @@  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
 	};
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9849dfda44d4..5ec7bc355657 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -342,7 +342,7 @@  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 b4cb45255a54..45416916dec1 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1249,6 +1249,12 @@  config IOMMU_MM_DATA
 config EXECMEM
 	bool
 
+config ARCH_HAS_USER_SHADOW_STACK
+	bool
+	help
+	  The architecture has hardware support for userspace shadow call
+          stacks (eg, x87 CET, arm64 GCS or RISC-V Zicfiss).
+
 source "mm/damon/Kconfig"
 
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