On Fri, Feb 07, 2025 at 10:27:10AM +0100, Vlastimil Babka wrote:
On 2/5/25 02:21, Deepak Gupta wrote:
VM_SHADOW_STACK (alias to VM_HIGH_ARCH_5) is used to encode shadow stack
I see that arm GCS uses VM_HIGH_ARCH_6.
VMA on three architectures (x86 shadow stack, arm GCS and RISC-V shadow
And RISC-V doesn't define it at all, not even in this patchset, or did I
miss it somewhere?
hmm...
Something wrong in my workflow and rebasing.
Thanks for catching this.
stack). In case architecture doesn't implement shadow stack, it's VM_NONE
Introducing a helper `is_shadow_stack_vma` to determine shadow stack vma
or not.
This looks like an unfinished sentence. As if it was to continue with "...
will allow us to ..." what?
I'm not against a helper but this changelog is rather confusing and also
code in arch/x86 and arch/arm64 isn't converted to the helper but testing
VM_SHADOW_STACK still.
Signed-off-by: Deepak Gupta <debug@xxxxxxxxxxxx>
Reviewed-by: Mark Brown <broonie@xxxxxxxxxx>
---
mm/gup.c | 2 +-
mm/mmap.c | 2 +-
mm/vma.h | 10 +++++++---
3 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 3883b307780e..8c64f3ff34ab 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1291,7 +1291,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
!writable_file_mapping_allowed(vma, gup_flags))
return -EFAULT;
- if (!(vm_flags & VM_WRITE) || (vm_flags & VM_SHADOW_STACK)) {
+ if (!(vm_flags & VM_WRITE) || is_shadow_stack_vma(vm_flags)) {
if (!(gup_flags & FOLL_FORCE))
return -EFAULT;
/*
diff --git a/mm/mmap.c b/mm/mmap.c
index cda01071c7b1..7b6be4eec35d 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -648,7 +648,7 @@ SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
*/
static inline unsigned long stack_guard_placement(vm_flags_t vm_flags)
{
- if (vm_flags & VM_SHADOW_STACK)
+ if (is_shadow_stack_vma(vm_flags))
return PAGE_SIZE;
return 0;
diff --git a/mm/vma.h b/mm/vma.h
index a2e8710b8c47..47482a25f5c3 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -278,7 +278,7 @@ static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi,
}
/*
- * These three helpers classifies VMAs for virtual memory accounting.
+ * These four helpers classifies VMAs for virtual memory accounting.
*/
/*
@@ -289,6 +289,11 @@ static inline bool is_exec_mapping(vm_flags_t flags)
return (flags & (VM_EXEC | VM_WRITE | VM_STACK)) == VM_EXEC;
}
+static inline bool is_shadow_stack_vma(vm_flags_t vm_flags)
+{
+ return !!(vm_flags & VM_SHADOW_STACK);
+}
+
/*
* Stack area (including shadow stacks)
*
@@ -297,7 +302,7 @@ static inline bool is_exec_mapping(vm_flags_t flags)
*/
static inline bool is_stack_mapping(vm_flags_t flags)
{
- return ((flags & VM_STACK) == VM_STACK) || (flags & VM_SHADOW_STACK);
+ return ((flags & VM_STACK) == VM_STACK) || is_shadow_stack_vma(flags);
}
/*
@@ -308,7 +313,6 @@ static inline bool is_data_mapping(vm_flags_t flags)
return (flags & (VM_WRITE | VM_SHARED | VM_STACK)) == VM_WRITE;
}
-
static inline void vma_iter_config(struct vma_iterator *vmi,
unsigned long index, unsigned long last)
{
