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Commit 05189820 authored by Joerg Roedel's avatar Joerg Roedel Committed by Thomas Gleixner
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x86/power/64: Fix page-table setup for temporary text mapping 



On a system with 4-level page-tables there is no p4d, so the pud in the pgd
should be mapped. The old code before commit fb43d6cb already did that.

The change from above commit causes an invalid page-table which causes
undefined behavior. In one report it caused triple faults.

Fix it by changing the p4d back to pud.

Fixes: fb43d6cb ('x86/mm: Do not auto-massage page protections')
Reported-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarMichal Kubecek <mkubecek@suse.cz>
Tested-by: default avatarBorislav Petkov <bp@suse.de>
Cc: linux-pm@vger.kernel.org
Cc: rjw@rjwysocki.net
Cc: pavel@ucw.cz
Cc: hpa@zytor.com
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/1524162360-26179-1-git-send-email-joro@8bytes.org
parent d6ef1f19

arch/x86/power/hibernate_64.c

+1 −1
Original line number Diff line number Diff line
@@ -98,7 +98,7 @@ static int set_up_temporary_text_mapping(pgd_t *pgd) 
		set_pgd(pgd + pgd_index(restore_jump_address), new_pgd);

	} else {

		/* No p4d for 4-level paging: point the pgd to the pud page table */

		pgd_t new_pgd = __pgd(__pa(p4d) | pgprot_val(pgtable_prot));

		pgd_t new_pgd = __pgd(__pa(pud) | pgprot_val(pgtable_prot));

		set_pgd(pgd + pgd_index(restore_jump_address), new_pgd);

	}