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.
Stale commit message. I thought I had fixed it. Sorry about that, will fix it.
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?
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.
Yes I didn't pay attention during rebase, will update the commit message.
Signed-off-by: Deepak Gupta debug@rivosinc.com Reviewed-by: Mark Brown broonie@kernel.org
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) {