Commit 945fd17a authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/cpu_entry_area: Sync cpu_entry_area to initial_page_table 



The separation of the cpu_entry_area from the fixmap missed the fact that
on 32bit non-PAE kernels the cpu_entry_area mapping might not be covered in
initial_page_table by the previous synchronizations.

This results in suspend/resume failures because 32bit utilizes initial page
table for resume. The absence of the cpu_entry_area mapping results in a
triple fault, aka. insta reboot.

With PAE enabled this works by chance because the PGD entry which covers
the fixmap and other parts incindentally provides the cpu_entry_area
mapping as well.

Synchronize the initial page table after setting up the cpu entry
area. Instead of adding yet another copy of the same code, move it to a
function and invoke it from the various places.

It needs to be investigated if the existing calls in setup_arch() and
setup_per_cpu_areas() can be replaced by the later invocation from
setup_cpu_entry_areas(), but that's beyond the scope of this fix.

Fixes: 92a0f81d ("x86/cpu_entry_area: Move it out of the fixmap")
Reported-by: default avatarWoody Suwalski <terraluna977@gmail.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarWoody Suwalski <terraluna977@gmail.com>
Cc: William Grant <william.grant@canonical.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1802282137290.1392@nanos.tec.linutronix.de
parent 1402fd8e

arch/x86/include/asm/pgtable_32.h

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ extern pmd_t initial_pg_pmd[]; 
static inline void pgtable_cache_init(void) { }

static inline void check_pgt_cache(void) { }

void paging_init(void);

void sync_initial_page_table(void);



/*

 * Define this if things work differently on an i386 and an i486:

arch/x86/include/asm/pgtable_64.h

+1 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ extern pgd_t init_top_pgt[]; 
#define swapper_pg_dir init_top_pgt



extern void paging_init(void);

static inline void sync_initial_page_table(void) { }



#define pte_ERROR(e)					\

	pr_err("%s:%d: bad pte %p(%016lx)\n",		\

arch/x86/kernel/setup.c

+5 −12
Original line number Diff line number Diff line
@@ -1204,20 +1204,13 @@ void __init setup_arch(char **cmdline_p) 


	kasan_init();



#ifdef CONFIG_X86_32

	/* sync back kernel address range */

	clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,

			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,

			KERNEL_PGD_PTRS);



	/*

	 * sync back low identity map too.  It is used for example

	 * in the 32-bit EFI stub.

	 * Sync back kernel address range.

	 *

	 * FIXME: Can the later sync in setup_cpu_entry_areas() replace

	 * this call?

	 */

	clone_pgd_range(initial_page_table,

			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,

			min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));

#endif

	sync_initial_page_table();



	tboot_probe();

arch/x86/kernel/setup_percpu.c

+4 −13
Original line number Diff line number Diff line
@@ -287,24 +287,15 @@ void __init setup_per_cpu_areas(void) 
	/* Setup cpu initialized, callin, callout masks */

	setup_cpu_local_masks();



#ifdef CONFIG_X86_32

	/*

	 * Sync back kernel address range again.  We already did this in

	 * setup_arch(), but percpu data also needs to be available in

	 * the smpboot asm.  We can't reliably pick up percpu mappings

	 * using vmalloc_fault(), because exception dispatch needs

	 * percpu data.

	 *

	 * FIXME: Can the later sync in setup_cpu_entry_areas() replace

	 * this call?

	 */

	clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,

			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,

			KERNEL_PGD_PTRS);



	/*

	 * sync back low identity map too.  It is used for example

	 * in the 32-bit EFI stub.

	 */

	clone_pgd_range(initial_page_table,

			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,

			min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));

#endif

	sync_initial_page_table();

}

arch/x86/mm/cpu_entry_area.c

+6 −0
Original line number Diff line number Diff line
@@ -163,4 +163,10 @@ void __init setup_cpu_entry_areas(void) 


	for_each_possible_cpu(cpu)

		setup_cpu_entry_area(cpu);



	/*

	 * This is the last essential update to swapper_pgdir which needs

	 * to be synchronized to initial_page_table on 32bit.

	 */

	sync_initial_page_table();

}

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