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Subject[PATCH 2/6] kexec jump: check code size in control page
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Date
Kexec/Kexec-jump requires code size in control page is less than
PAGE_SIZE/2. This patch adds runtime checking for this.

Signed-off-by: Huang Ying <ying.huang@intel.com>

---
arch/x86/kernel/machine_kexec_32.c | 4 ++++
arch/x86/kernel/relocate_kernel_32.S | 3 +++
include/asm-x86/kexec.h | 1 +
3 files changed, 8 insertions(+)

--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -92,6 +92,10 @@ int machine_kexec_prepare(struct kimage
{
if (nx_enabled)
set_pages_x(image->control_code_page, 1);
+
+ BUG_ON((unsigned long)kexec_control_page_code_end - \
+ (unsigned long)relocate_kernel >= PAGE_SIZE/2);
+
return 0;
}

--- a/arch/x86/kernel/relocate_kernel_32.S
+++ b/arch/x86/kernel/relocate_kernel_32.S
@@ -376,3 +376,6 @@ swap_pages:
popl %ebx
popl %ebp
ret
+
+ .globl kexec_control_page_code_end
+kexec_control_page_code_end:
--- a/include/asm-x86/kexec.h
+++ b/include/asm-x86/kexec.h
@@ -159,6 +159,7 @@ relocate_kernel(unsigned long indirectio
unsigned long start_address,
unsigned int has_pae,
unsigned int preserve_context);
+void kexec_control_page_code_end(void);
#else
NORET_TYPE void
relocate_kernel(unsigned long indirection_page,



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