Commit 1fcd0091 authored by Arvind Sankar's avatar Arvind Sankar Committed by Borislav Petkov
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x86/mm/ident_map: Check for errors from ident_pud_init() 



Commit

  ea3b5e60 ("x86/mm/ident_map: Add 5-level paging support")

added ident_p4d_init() to support 5-level paging, but this function
doesn't check and return errors from ident_pud_init().

For example, the decompressor stub uses this code to create an identity
mapping. If it runs out of pages while trying to allocate a PMD
pagetable, the error will be currently ignored.

Fix this to propagate errors.

 [ bp: Space out statements for better readability. ]

Fixes: ea3b5e60 ("x86/mm/ident_map: Add 5-level paging support")
Signed-off-by: default avatarArvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarJoerg Roedel <jroedel@suse.de>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20201027230648.1885111-1-nivedita@alum.mit.edu
parent 3650b228

arch/x86/mm/ident_map.c

+10 −2
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page, 
			  unsigned long addr, unsigned long end)

{

	unsigned long next;

	int result;



	for (; addr < end; addr = next) {

		p4d_t *p4d = p4d_page + p4d_index(addr);
@@ -73,13 +74,20 @@ static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page, 


		if (p4d_present(*p4d)) {

			pud = pud_offset(p4d, 0);

			ident_pud_init(info, pud, addr, next);

			result = ident_pud_init(info, pud, addr, next);

			if (result)

				return result;



			continue;

		}

		pud = (pud_t *)info->alloc_pgt_page(info->context);

		if (!pud)

			return -ENOMEM;

		ident_pud_init(info, pud, addr, next);



		result = ident_pud_init(info, pud, addr, next);

		if (result)

			return result;



		set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag));

	}