[PATCH v9 01/26] mm: helper `is_shadow_stack_vma` to check shadow stack vma
From: Deepak Gupta <hidden>
Date: 2025-02-05 01:21:56
Also in:
linux-arch, linux-doc, linux-fsdevel, linux-kselftest, linux-mm, linux-riscv, lkml
Subsystem:
memory management, memory management - gup (get user pages), memory mapping, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Liam R. Howlett, Lorenzo Stoakes, Linus Torvalds
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 <redacted> 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) {
--
2.34.1