This is a note to let you know that I've just added the patch titled
x86/boot/32: Defer resyncing initial_page_table until per-cpu is set up
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-boot-32-defer-resyncing-initial_page_table-until-per-cpu-is-set-up.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Sun Mar 18 16:55:33 CET 2018
From: Andy Lutomirski <luto@xxxxxxxxxx>
Date: Wed, 22 Mar 2017 14:32:32 -0700
Subject: x86/boot/32: Defer resyncing initial_page_table until per-cpu is set up
From: Andy Lutomirski <luto@xxxxxxxxxx>
[ Upstream commit 23b2a4ddebdd17fad265b4bb77256c2e4ec37dee ]
The x86 smpboot trampoline expects initial_page_table to have the
GDT mapped. If the GDT ends up in a virtually mapped per-cpu page,
then it won't be in the page tables at all until perc-pu areas are
set up. The result will be a triple fault the first time that the
CPU attempts to access the GDT after LGDT loads the perc-pu GDT.
This appears to be an old bug, but somehow the GDT fixmap rework
is triggering it. This seems to have something to do with the
memory layout.
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Garnier <thgarnie@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/a553264a5972c6a86f9b5caac237470a0c74a720.1490218061.git.luto@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/setup.c | 15 ---------------
arch/x86/kernel/setup_percpu.c | 21 +++++++++++++++++++++
2 files changed, 21 insertions(+), 15 deletions(-)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1200,21 +1200,6 @@ 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.
- */
- clone_pgd_range(initial_page_table,
- swapper_pg_dir + KERNEL_PGD_BOUNDARY,
- min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
-#endif
-
tboot_probe();
map_vsyscall();
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -287,4 +287,25 @@ 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. We want to make sure that
+ * all kernel mappings, including percpu mappings, are available
+ * in the smpboot asm. We can't reliably pick up percpu
+ * mappings using vmalloc_fault(), because exception dispatch
+ * needs percpu data.
+ */
+ 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
}
Patches currently in stable-queue which might be from luto@xxxxxxxxxx are
queue-4.9/perf-tools-make-perf_event__synthesize_mmap_events-scale.patch
queue-4.9/x86-mm-make-mmap-map_32bit-work-correctly.patch
queue-4.9/x86-boot-32-defer-resyncing-initial_page_table-until-per-cpu-is-set-up.patch