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Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c106
1 files changed, 77 insertions, 29 deletions
diff --git a/mm/memory.c b/mm/memory.c
index e48945ab362b..ce22a250926f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1410,6 +1410,13 @@ no_page_table:
return page;
}
+static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
+{
+ return (vma->vm_flags & VM_GROWSDOWN) &&
+ (vma->vm_start == addr) &&
+ !vma_stack_continue(vma->vm_prev, addr);
+}
+
/**
* __get_user_pages() - pin user pages in memory
* @tsk: task_struct of target task
@@ -1486,9 +1493,8 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
struct vm_area_struct *vma;
vma = find_extend_vma(mm, start);
- if (!vma && in_gate_area(tsk, start)) {
+ if (!vma && in_gate_area(mm, start)) {
unsigned long pg = start & PAGE_MASK;
- struct vm_area_struct *gate_vma = get_gate_vma(tsk);
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
@@ -1513,10 +1519,11 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
pte_unmap(pte);
return i ? : -EFAULT;
}
+ vma = get_gate_vma(mm);
if (pages) {
struct page *page;
- page = vm_normal_page(gate_vma, start, *pte);
+ page = vm_normal_page(vma, start, *pte);
if (!page) {
if (!(gup_flags & FOLL_DUMP) &&
is_zero_pfn(pte_pfn(*pte)))
@@ -1530,12 +1537,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
get_page(page);
}
pte_unmap(pte);
- if (vmas)
- vmas[i] = gate_vma;
- i++;
- start += PAGE_SIZE;
- nr_pages--;
- continue;
+ goto next_page;
}
if (!vma ||
@@ -1549,6 +1551,13 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
continue;
}
+ /*
+ * If we don't actually want the page itself,
+ * and it's the stack guard page, just skip it.
+ */
+ if (!pages && stack_guard_page(vma, start))
+ goto next_page;
+
do {
struct page *page;
unsigned int foll_flags = gup_flags;
@@ -1569,6 +1578,8 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
fault_flags |= FAULT_FLAG_WRITE;
if (nonblocking)
fault_flags |= FAULT_FLAG_ALLOW_RETRY;
+ if (foll_flags & FOLL_NOWAIT)
+ fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
ret = handle_mm_fault(mm, vma, start,
fault_flags);
@@ -1589,13 +1600,17 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
return i ? i : -EFAULT;
BUG();
}
- if (ret & VM_FAULT_MAJOR)
- tsk->maj_flt++;
- else
- tsk->min_flt++;
+
+ if (tsk) {
+ if (ret & VM_FAULT_MAJOR)
+ tsk->maj_flt++;
+ else
+ tsk->min_flt++;
+ }
if (ret & VM_FAULT_RETRY) {
- *nonblocking = 0;
+ if (nonblocking)
+ *nonblocking = 0;
return i;
}
@@ -1625,6 +1640,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
flush_anon_page(vma, page, start);
flush_dcache_page(page);
}
+next_page:
if (vmas)
vmas[i] = vma;
i++;
@@ -1638,7 +1654,8 @@ EXPORT_SYMBOL(__get_user_pages);
/**
* get_user_pages() - pin user pages in memory
- * @tsk: task_struct of target task
+ * @tsk: the task_struct to use for page fault accounting, or
+ * NULL if faults are not to be recorded.
* @mm: mm_struct of target mm
* @start: starting user address
* @nr_pages: number of pages from start to pin
@@ -2764,7 +2781,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
swp_entry_t entry;
pte_t pte;
int locked;
- struct mem_cgroup *ptr = NULL;
+ struct mem_cgroup *ptr;
int exclusive = 0;
int ret = 0;
@@ -3496,7 +3513,7 @@ static int __init gate_vma_init(void)
__initcall(gate_vma_init);
#endif
-struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
+struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
#ifdef AT_SYSINFO_EHDR
return &gate_vma;
@@ -3505,7 +3522,7 @@ struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
#endif
}
-int in_gate_area_no_task(unsigned long addr)
+int in_gate_area_no_mm(unsigned long addr)
{
#ifdef AT_SYSINFO_EHDR
if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
@@ -3646,20 +3663,15 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
#endif
/*
- * Access another process' address space.
- * Source/target buffer must be kernel space,
- * Do not walk the page table directly, use get_user_pages
+ * Access another process' address space as given in mm. If non-NULL, use the
+ * given task for page fault accounting.
*/
-int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
+ unsigned long addr, void *buf, int len, int write)
{
- struct mm_struct *mm;
struct vm_area_struct *vma;
void *old_buf = buf;
- mm = get_task_mm(tsk);
- if (!mm)
- return 0;
-
down_read(&mm->mmap_sem);
/* ignore errors, just check how much was successfully transferred */
while (len) {
@@ -3676,7 +3688,7 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
*/
#ifdef CONFIG_HAVE_IOREMAP_PROT
vma = find_vma(mm, addr);
- if (!vma)
+ if (!vma || vma->vm_start > addr)
break;
if (vma->vm_ops && vma->vm_ops->access)
ret = vma->vm_ops->access(vma, addr, buf,
@@ -3708,11 +3720,47 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
addr += bytes;
}
up_read(&mm->mmap_sem);
- mmput(mm);
return buf - old_buf;
}
+/**
+ * access_remote_vm - access another process' address space
+ * @mm: the mm_struct of the target address space
+ * @addr: start address to access
+ * @buf: source or destination buffer
+ * @len: number of bytes to transfer
+ * @write: whether the access is a write
+ *
+ * The caller must hold a reference on @mm.
+ */
+int access_remote_vm(struct mm_struct *mm, unsigned long addr,
+ void *buf, int len, int write)
+{
+ return __access_remote_vm(NULL, mm, addr, buf, len, write);
+}
+
+/*
+ * Access another process' address space.
+ * Source/target buffer must be kernel space,
+ * Do not walk the page table directly, use get_user_pages
+ */
+int access_process_vm(struct task_struct *tsk, unsigned long addr,
+ void *buf, int len, int write)
+{
+ struct mm_struct *mm;
+ int ret;
+
+ mm = get_task_mm(tsk);
+ if (!mm)
+ return 0;
+
+ ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
+ mmput(mm);
+
+ return ret;
+}
+
/*
* Print the name of a VMA.
*/
generated by cgit v1.2.3 (git 2.39.0) at 2024-07-12 00:25:12 +0300