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x86/ibt,kexec: Disable CET on kexec

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Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.641454603@infradead.org
This commit is contained in:
Peter Zijlstra 2022-03-08 16:30:36 +01:00
parent 991625f3dd
commit af22700390
4 changed files with 20 additions and 1 deletions
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3
arch/x86/include/asm/cpu.h
View File

@ -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 */

6
arch/x86/kernel/cpu/common.c
View File

@ -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

4
arch/x86/kernel/machine_kexec_64.c
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@ -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;

8
arch/x86/kernel/relocate_kernel_64.S
View File

@ -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