Commit cd4126d4 authored by Tiwei Bie's avatar Tiwei Bie Committed by Johannes Berg
Browse files

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: default avatarTiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20260302235224.1915380-3-tiwei.btw@antgroup.com


Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 102331b6

arch/um/include/asm/pgtable.h

+4 −5
Original line number Diff line number Diff line
@@ -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

+1 −2
Original line number Diff line number Diff line
@@ -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,