diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2026-02-25 19:13:58 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-04-05 23:53:05 +0300 |
| commit | 2b8acf8450f577d3785dacfd616630b76dc8f88d (patch) | |
| tree | 4f2bf6dfca84884b2ecac60d7bb92587799780a6 | |
| parent | 03375203e1da8f4782ec5cd7023eb1b4adfba739 (diff) | |
| download | linux-2b8acf8450f577d3785dacfd616630b76dc8f88d.tar.xz | |
mm: introduce vm_mmap_shadow_stack() as a helper for VM_SHADOW_STACK mappings
Patch series "mm: arch/shstk: Common shadow stack mapping helper and
VM_NOHUGEPAGE", v2.
A series to extract the common shadow stack mmap into a separate helper
for arm64, riscv and x86.
This patch (of 5):
arm64, riscv and x86 use a similar pattern for mapping the user shadow
stack (cloned from x86). Extract this into a helper to facilitate code
reuse.
The call to do_mmap() from the new helper uses PROT_READ|PROT_WRITE prot
bits instead of the PROT_READ with an explicit VM_WRITE vm_flag. The x86
intent was to avoid PROT_WRITE implying normal write since the shadow
stack is not writable by normal stores. However, from a kernel
perspective, the vma is writeable. Functionally there is no difference.
Link: https://lkml.kernel.org/r/20260225161404.3157851-1-catalin.marinas@arm.com
Link: https://lkml.kernel.org/r/20260225161404.3157851-2-catalin.marinas@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Deepak Gupta <debug@rivosinc.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | include/linux/mm.h | 2 | ||||
| -rw-r--r-- | mm/util.c | 25 |
2 files changed, 27 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index abb4963c1f06..bb0cfe38ca19 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3903,6 +3903,8 @@ extern int vm_munmap(unsigned long, size_t); extern unsigned long __must_check vm_mmap(struct file *, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); +extern unsigned long __must_check vm_mmap_shadow_stack(unsigned long addr, + unsigned long len, unsigned long flags); struct vm_unmapped_area_info { #define VM_UNMAPPED_AREA_TOPDOWN 1 diff --git a/mm/util.c b/mm/util.c index b05ab6f97e11..51f7f417e91f 100644 --- a/mm/util.c +++ b/mm/util.c @@ -618,6 +618,31 @@ unsigned long vm_mmap(struct file *file, unsigned long addr, } EXPORT_SYMBOL(vm_mmap); +#ifdef CONFIG_ARCH_HAS_USER_SHADOW_STACK +/* + * Perform a userland memory mapping for a shadow stack into the current + * process address space. This is intended to be used by architectures that + * support user shadow stacks. + */ +unsigned long vm_mmap_shadow_stack(unsigned long addr, unsigned long len, + unsigned long flags) +{ + struct mm_struct *mm = current->mm; + unsigned long ret, unused; + + flags |= MAP_ANONYMOUS | MAP_PRIVATE; + if (addr) + flags |= MAP_FIXED_NOREPLACE; + + mmap_write_lock(mm); + ret = do_mmap(NULL, addr, len, PROT_READ | PROT_WRITE, flags, + VM_SHADOW_STACK, 0, &unused, NULL); + mmap_write_unlock(mm); + + return ret; +} +#endif /* CONFIG_ARCH_HAS_USER_SHADOW_STACK */ + /** * __vmalloc_array - allocate memory for a virtually contiguous array. * @n: number of elements. |