Instead of having every architecture to define vdso_base/vdso_addr etc, provide a generic mechanism to track vdso_base for landing in userspace. It'll minimize per-architecture difference, the number of callbacks to provide. Originally, it started from thread [1] where the need for .close() callback on vm_special_mapping was pointed, this generic code besides removing duplicated .mremap() callbacks provides a cheaper way to support munmap() on vdso mappings without introducing .close() callbacks for every architecture (which would bring even more code duplication). [1]: https://lore.kernel.org/linux-arch/CAJwJo6ZANqYkSHbQ+3b+Fi_VT80MtrzEV5yreQAWx-L8j8x2zA@xxxxxxxxxxxxxx/ Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxxx Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx> --- arch/Kconfig | 3 +++ arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 3 ++- fs/aio.c | 3 ++- include/linux/mm.h | 3 ++- include/linux/mm_types.h | 17 +++++++++++++++++ kernel/fork.c | 1 + mm/mmap.c | 19 ++++++++++++++++++- mm/mremap.c | 2 +- 8 files changed, 46 insertions(+), 5 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index c45b770d3579..0e648a1ae412 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -1235,6 +1235,9 @@ config HAVE_SPARSE_SYSCALL_NR config ARCH_HAS_VDSO_DATA bool +config ARCH_HAS_VDSO_BASE + bool + config HAVE_STATIC_CALL bool diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c index 05a89e33fde2..5ab191855816 100644 --- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c +++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c @@ -1458,7 +1458,8 @@ static int pseudo_lock_dev_release(struct inode *inode, struct file *filp) return 0; } -static int pseudo_lock_dev_mremap(struct vm_area_struct *area) +static int pseudo_lock_dev_mremap(struct vm_area_struct *old_vma, + struct vm_area_struct *new_vma) { /* Not supported */ return -EINVAL; diff --git a/fs/aio.c b/fs/aio.c index 76ce0cc3ee4e..0b27e9300d0f 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -323,7 +323,8 @@ static void aio_free_ring(struct kioctx *ctx) } } -static int aio_ring_mremap(struct vm_area_struct *vma) +static int aio_ring_mremap(struct vm_area_struct *old_vma, + struct vm_area_struct *vma) { struct file *file = vma->vm_file; struct mm_struct *mm = vma->vm_mm; diff --git a/include/linux/mm.h b/include/linux/mm.h index c274f75efcf9..6ef91b337f9d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -589,7 +589,8 @@ struct vm_operations_struct { void (*close)(struct vm_area_struct * area); /* Called any time before splitting to check if it's allowed */ int (*may_split)(struct vm_area_struct *area, unsigned long addr); - int (*mremap)(struct vm_area_struct *area); + int (*mremap)(struct vm_area_struct *old_vma, + struct vm_area_struct *new_vma); /* * Called by mprotect() to make driver-specific permission * checks before mprotect() is finalised. The VMA must not diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index e9c5f2051f08..49ad34410132 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -497,6 +497,16 @@ struct mm_struct { /* Architecture-specific MM context */ mm_context_t context; +#ifdef CONFIG_ARCH_HAS_VDSO_BASE + /* + * Address of special mapping VMA to land after processing + * a signal. Reads are unprotected: if a thread unmaps or + * mremaps the mapping while another thread is processing + * a signal, it can segfault while landing. + */ + void __user *vdso_base; +#endif +#define UNMAPPED_VDSO_BASE TASK_SIZE_MAX unsigned long flags; /* Must use atomic bitops to access */ @@ -598,6 +608,13 @@ static inline void init_tlb_flush_pending(struct mm_struct *mm) atomic_set(&mm->tlb_flush_pending, 0); } +static inline void init_vdso_base(struct mm_struct *mm) +{ +#ifdef CONFIG_ARCH_HAS_VDSO_BASE + mm->vdso_base = (void __user *)UNMAPPED_VDSO_BASE; +#endif +} + static inline void inc_tlb_flush_pending(struct mm_struct *mm) { atomic_inc(&mm->tlb_flush_pending); diff --git a/kernel/fork.c b/kernel/fork.c index dc06afd725cb..eb4ad74d042e 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1082,6 +1082,7 @@ struct mm_struct *mm_alloc(void) return NULL; memset(mm, 0, sizeof(*mm)); + init_vdso_base(mm); return mm_init(mm, current, current_user_ns()); } diff --git a/mm/mmap.c b/mm/mmap.c index 4f0d62409b1c..5d1ffce51119 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3381,11 +3381,25 @@ void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) static vm_fault_t special_mapping_fault(struct vm_fault *vmf); +static void update_vdso_base(struct vm_area_struct *old_vma, + unsigned long new_addr) +{ +#ifdef CONFIG_ARCH_HAS_VDSO_BASE + struct mm_struct *mm = old_vma->vm_mm; + + if (WARN_ON_ONCE(!mm)) + return; + if (old_vma->vm_start == (unsigned long)mm->vdso_base) + mm->vdso_base = (void __user *)new_addr; +#endif +} + /* * Having a close hook prevents vma merging regardless of flags. */ static void special_mapping_close(struct vm_area_struct *vma) { + update_vdso_base(vma, UNMAPPED_VDSO_BASE); } static const char *special_mapping_name(struct vm_area_struct *vma) @@ -3393,7 +3407,8 @@ static const char *special_mapping_name(struct vm_area_struct *vma) return ((struct vm_special_mapping *)vma->vm_private_data)->name; } -static int special_mapping_mremap(struct vm_area_struct *new_vma) +static int special_mapping_mremap(struct vm_area_struct *old_vma, + struct vm_area_struct *new_vma) { struct vm_special_mapping *sm = new_vma->vm_private_data; @@ -3403,6 +3418,8 @@ static int special_mapping_mremap(struct vm_area_struct *new_vma) if (sm->mremap) sm->mremap(sm, new_vma); + update_vdso_base(old_vma, new_vma->vm_start); + return 0; } diff --git a/mm/mremap.c b/mm/mremap.c index 47c255b60150..d28ba49d607c 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -545,7 +545,7 @@ static unsigned long move_vma(struct vm_area_struct *vma, if (moved_len < old_len) { err = -ENOMEM; } else if (vma->vm_ops && vma->vm_ops->mremap) { - err = vma->vm_ops->mremap(new_vma); + err = vma->vm_ops->mremap(vma, new_vma); } if (unlikely(err)) { -- 2.31.1
