The following commit has been merged into the x86/fred branch of tip: Commit-ID: bc49cef5e02ab95b5235acbbc4cb5bb6a0bdec7f Gitweb: https://git.kernel.org/tip/bc49cef5e02ab95b5235acbbc4cb5bb6a0bdec7f Author: H. Peter Anvin (Intel) <hpa@xxxxxxxxx> AuthorDate: Tue, 05 Dec 2023 02:50:08 -08:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Thu, 25 Jan 2024 19:10:31 +01:00 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: H. Peter Anvin (Intel) <hpa@xxxxxxxxx> Signed-off-by: Xin Li <xin3.li@xxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Tested-by: Shan Kang <shan.kang@xxxxxxxxx> Link: https://lore.kernel.org/r/20231205105030.8698-20-xin3.li@xxxxxxxxx --- arch/x86/kernel/espfix_64.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c index 16f9814..6726e04 100644 --- a/arch/x86/kernel/espfix_64.c +++ b/arch/x86/kernel/espfix_64.c @@ -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 */
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