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x86/kasan: Fix KASAN shadow region page tables

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Currently KASAN shadow region page tables created without
respect of physical offset (phys_base). This causes kernel halt
when phys_base is not zero.

So let's initialize KASAN shadow region page tables in
kasan_early_init() using __pa_nodebug() which considers
phys_base.

This patch also separates x86_64_start_kernel() from KASAN low
level details by moving kasan_map_early_shadow(init_level4_pgt)
into kasan_early_init().

Remove the comment before clear_bss() which stopped bringing
much profit to the code readability. Otherwise describing all
the new order dependencies would be too verbose.

Signed-off-by: Alexander Popov <alpopov@ptsecurity.com>
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: <stable@vger.kernel.org> # 4.0+
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1435828178-10975-3-git-send-email-a.ryabinin@samsung.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Alexander Popov
2015-07-02 12:09:34 +03:00
committed by Ingo Molnar
parent d0f77d4d04
commit 5d5aa3cfca
4 changed files with 38 additions and 42 deletions
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7
arch/x86/kernel/head64.c
View File

@@ -161,13 +161,12 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
/* Kill off the identity-map trampoline */
reset_early_page_tables();
kasan_map_early_shadow(early_level4_pgt);
/* clear bss before set_intr_gate with early_idt_handler */
clear_bss();
clear_page(init_level4_pgt);
kasan_early_init();
for (i = 0; i < NUM_EXCEPTION_VECTORS; i++)
set_intr_gate(i, early_idt_handler_array[i]);
load_idt((const struct desc_ptr *)&idt_descr);
@@ -182,8 +181,6 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
/* set init_level4_pgt kernel high mapping*/
init_level4_pgt[511] = early_level4_pgt[511];
kasan_map_early_shadow(init_level4_pgt);
x86_64_start_reservations(real_mode_data);
}

29
arch/x86/kernel/head_64.S
View File

@@ -516,38 +516,9 @@ ENTRY(phys_base)
/* This must match the first entry in level2_kernel_pgt */
.quad 0x0000000000000000
#ifdef CONFIG_KASAN
#define FILL(VAL, COUNT) \
.rept (COUNT) ; \
.quad (VAL) ; \
.endr
NEXT_PAGE(kasan_zero_pte)
FILL(kasan_zero_page - __START_KERNEL_map + _KERNPG_TABLE, 512)
NEXT_PAGE(kasan_zero_pmd)
FILL(kasan_zero_pte - __START_KERNEL_map + _KERNPG_TABLE, 512)
NEXT_PAGE(kasan_zero_pud)
FILL(kasan_zero_pmd - __START_KERNEL_map + _KERNPG_TABLE, 512)
#undef FILL
#endif
#include "../../x86/xen/xen-head.S"
__PAGE_ALIGNED_BSS
NEXT_PAGE(empty_zero_page)
.skip PAGE_SIZE
#ifdef CONFIG_KASAN
/*
* This page used as early shadow. We don't use empty_zero_page
* at early stages, stack instrumentation could write some garbage
* to this page.
* Latter we reuse it as zero shadow for large ranges of memory
* that allowed to access, but not instrumented by kasan
* (vmalloc/vmemmap ...).
*/
NEXT_PAGE(kasan_zero_page)
.skip PAGE_SIZE
#endif