um: Fix pte_read() and pte_exec() for kernel mappings

The pte_read() and pte_exec() helpers are only used during the TLB
sync to determine the read/exec permissions for mmap. However, for
kernel mappings, they will always return 0. This leads to kern_map()
having to unconditionally set the exec flag to 1 and the read flag
unexpectedly always being 0. Remove the unnecessary check for the
_PAGE_USER bit in these helpers to ensure that the kernel mapping
permissions can be correctly determined.

Signed-off-by: Tiwei Bie <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Johannes Berg <[email protected]>

Author: btw616

arch/um/include/asm/pgtable.h

@@ -121,13 +121,12 @@ static inline int pte_none(pte_t pte)
  */
 static inline int pte_read(pte_t pte)
 {
-	return((pte_get_bits(pte, _PAGE_USER)) &&
-	       !(pte_get_bits(pte, _PAGE_PROTNONE)));
+	return !pte_get_bits(pte, _PAGE_PROTNONE);
 }
 
-static inline int pte_exec(pte_t pte){
-	return((pte_get_bits(pte, _PAGE_USER)) &&
-	       !(pte_get_bits(pte, _PAGE_PROTNONE)));
+static inline int pte_exec(pte_t pte)
+{
+	return !pte_get_bits(pte, _PAGE_PROTNONE);
 }
 
 static inline int pte_write(pte_t pte)

arch/um/kernel/tlb.c

@@ -29,10 +29,9 @@ static int kern_map(struct mm_id *mm_idp,
 		    unsigned long virt, unsigned long len, int prot,
 		    int phys_fd, unsigned long long offset)
 {
-	/* TODO: Why is executable needed to be always set in the kernel? */
 	return os_map_memory((void *)virt, phys_fd, offset, len,
 			     prot & UM_PROT_READ, prot & UM_PROT_WRITE,
-			     1);
+			     prot & UM_PROT_EXEC);
 }
 
 static int kern_unmap(struct mm_id *mm_idp,