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Subject[PATCH v2 1/6] x86_64, init: clear init_level4_pgt earlier
Date
Currently x86_64_start_kernel() has two kasan related
function calls. The first call maps shadow to early_level4_pgt,
the second maps shadow to init_level4_pgt.

If we move clear_page(init_level4_pgt) earlier, we could hide
kasan low level detail from generic x86_64 initialization code.
The next patch will do it.

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: <stable@vger.kernel.org> # 4.0+
---
arch/x86/kernel/head64.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 5a46681..65c8985 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -166,6 +166,8 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
/* clear bss before set_intr_gate with early_idt_handler */
clear_bss();

+ clear_page(init_level4_pgt);
+
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);
@@ -177,7 +179,6 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
*/
load_ucode_bsp();

- clear_page(init_level4_pgt);
/* set init_level4_pgt kernel high mapping*/
init_level4_pgt[511] = early_level4_pgt[511];

--
2.4.5


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