[PATCH] uprobes: replace deprecated kmap_atomic() with kmap_local_page()

[Carlos López]

kmap_atomic() has been deprecated for a few years, and kmap_local_page()
should be used instead, so replace it. Since the uprobes code relied on
kmap_atomic() disabling page faults to access user pages, add the
required calls to keep the existing behavior.

Signed-off-by: Carlos López <clopez@xxxxxxx>
---
 kernel/events/uprobes.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index d546d32390a8..38898435acfe 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -179,16 +179,24 @@ bool __weak is_trap_insn(uprobe_opcode_t *insn)
 
 void uprobe_copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len)
 {
-	void *kaddr = kmap_atomic(page);
+	void *kaddr = kmap_local_page(page);
+
+	pagefault_disable();
 	memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len);
-	kunmap_atomic(kaddr);
+	pagefault_enable();
+
+	kunmap_local(kaddr);
 }
 
 static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len)
 {
-	void *kaddr = kmap_atomic(page);
+	void *kaddr = kmap_local_page(page);
+
+	pagefault_disable();
 	memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len);
-	kunmap_atomic(kaddr);
+	pagefault_enable();
+
+	kunmap_local(kaddr);
 }
 
 static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *insn,
@@ -323,9 +331,10 @@ __update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d)
 		return ret == 0 ? -EBUSY : ret;
 	}
 
-	kaddr = kmap_atomic(page);
+	kaddr = kmap_local_page(page);
 	ptr = kaddr + (vaddr & ~PAGE_MASK);
 
+	pagefault_disable();
 	if (unlikely(*ptr + d < 0)) {
 		pr_warn("ref_ctr going negative. vaddr: 0x%lx, "
 			"curr val: %d, delta: %d\n", vaddr, *ptr, d);
@@ -336,7 +345,8 @@ __update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d)
 	*ptr += d;
 	ret = 0;
 out:
-	kunmap_atomic(kaddr);
+	pagefault_enable();
+	kunmap_local(kaddr);
 	put_page(page);
 	return ret;
 }

base-commit: f14faaf3a1fb3b9e4cf2e56269711fb85fba9458
-- 
2.51.0