VM_SHADOW_STACK (alias to VM_HIGH_ARCH_5) is used to encode shadow stack VMA on three architectures (x86 shadow stack, arm GCS and RISC-V shadow 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.
Signed-off-by: Deepak Gupta debug@rivosinc.com --- include/linux/mm.h | 7 ++++++- mm/gup.c | 2 +- mm/internal.h | 2 +- 3 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h index e39796ea17db..f0dc94fb782a 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -361,6 +361,11 @@ extern unsigned int kobjsize(const void *objp); # define VM_SHADOW_STACK VM_NONE #endif
+static inline bool is_shadow_stack_vma(vm_flags_t vm_flags) +{ + return !!(vm_flags & VM_SHADOW_STACK); +} + #if defined(CONFIG_X86) # define VM_PAT VM_ARCH_1 /* PAT reserves whole VMA at once (x86) */ #elif defined(CONFIG_PPC) @@ -3504,7 +3509,7 @@ static inline unsigned long stack_guard_start_gap(struct vm_area_struct *vma) return stack_guard_gap;
/* See reasoning around the VM_SHADOW_STACK definition */ - if (vma->vm_flags & VM_SHADOW_STACK) + if (is_shadow_stack_vma(vma->vm_flags)) return PAGE_SIZE;
return 0; diff --git a/mm/gup.c b/mm/gup.c index 54d0dc3831fb..2f84a0a80cfe 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1289,7 +1289,7 @@ 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; /* hugetlb does not support FOLL_FORCE|FOLL_WRITE. */ diff --git a/mm/internal.h b/mm/internal.h index b4d86436565b..f7732c793f3f 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -798,7 +798,7 @@ 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); }
/*