Commit af227003 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

x86/ibt,kexec: Disable CET on kexec 



Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.641454603@infradead.org
parent 991625f3

arch/x86/include/asm/cpu.h

+3 −0
Original line number Diff line number Diff line
@@ -73,4 +73,7 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c); 
#else

static inline void init_ia32_feat_ctl(struct cpuinfo_x86 *c) {}

#endif



extern __noendbr void cet_disable(void);



#endif /* _ASM_X86_CPU_H */

arch/x86/kernel/cpu/common.c

+6 −0
Original line number Diff line number Diff line
@@ -535,6 +535,12 @@ static __always_inline void setup_cet(struct cpuinfo_x86 *c) 
	}

}



__noendbr void cet_disable(void)

{

	if (cpu_feature_enabled(X86_FEATURE_IBT))

		wrmsrl(MSR_IA32_S_CET, 0);

}



/*

 * Some CPU features depend on higher CPUID levels, which may not always

 * be available due to CPUID level capping or broken virtualization

arch/x86/kernel/machine_kexec_64.c

+3 −1
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <asm/kexec-bzimage64.h>

#include <asm/setup.h>

#include <asm/set_memory.h>

#include <asm/cpu.h>



#ifdef CONFIG_ACPI

/*
@@ -310,6 +311,7 @@ void machine_kexec(struct kimage *image) 
	/* Interrupts aren't acceptable while we reboot */

	local_irq_disable();

	hw_breakpoint_disable();

	cet_disable();



	if (image->preserve_context) {

#ifdef CONFIG_X86_IO_APIC
@@ -325,7 +327,7 @@ void machine_kexec(struct kimage *image) 
	}



	control_page = page_address(image->control_code_page) + PAGE_SIZE;

	memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);

	__memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);



	page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);

	page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;

arch/x86/kernel/relocate_kernel_64.S

+8 −0
Original line number Diff line number Diff line
@@ -114,6 +114,14 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) 
	/* store the start address on the stack */

	pushq   %rdx



	/*

	 * Clear X86_CR4_CET (if it was set) such that we can clear CR0_WP

	 * below.

	 */

	movq	%cr4, %rax

	andq	$~(X86_CR4_CET), %rax

	movq	%rax, %cr4



	/*

	 * Set cr0 to a known state:

	 *  - Paging enabled