Commit df883873 authored by H. Peter Anvin (Intel)'s avatar H. Peter Anvin (Intel) Committed by Borislav Petkov (AMD)
Browse files

x86/fred: No ESPFIX needed when FRED is enabled 



Because FRED always restores the full value of %rsp, ESPFIX is
no longer needed when it's enabled.

Signed-off-by: default avatarH. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: default avatarXin Li <xin3.li@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Tested-by: default avatarShan Kang <shan.kang@intel.com>
Link: https://lore.kernel.org/r/20231205105030.8698-20-xin3.li@intel.com
parent 09794f68

arch/x86/kernel/espfix_64.c

+8 −0
Original line number Diff line number Diff line
@@ -106,6 +106,10 @@ void __init init_espfix_bsp(void) 
	pgd_t *pgd;

	p4d_t *p4d;



	/* FRED systems always restore the full value of %rsp */

	if (cpu_feature_enabled(X86_FEATURE_FRED))

		return;



	/* Install the espfix pud into the kernel page directory */

	pgd = &init_top_pgt[pgd_index(ESPFIX_BASE_ADDR)];

	p4d = p4d_alloc(&init_mm, pgd, ESPFIX_BASE_ADDR);
@@ -129,6 +133,10 @@ void init_espfix_ap(int cpu) 
	void *stack_page;

	pteval_t ptemask;



	/* FRED systems always restore the full value of %rsp */

	if (cpu_feature_enabled(X86_FEATURE_FRED))

		return;



	/* We only have to do this once... */

	if (likely(per_cpu(espfix_stack, cpu)))

		return;		/* Already initialized */