From: Andi Kleen <ak@linux.intel.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org, Kai Huang <kai.huang@intel.com>,
Sean Christopherson <seanjc@google.com>
Subject: Re: [PATCHv3, RESEND] x86/trampoline: Bypass compat mode in trampoline_start64() if not needed
Date: Thu, 25 Jan 2024 06:50:07 -0800 [thread overview]
Message-ID: <ZbJ1H77MtNkko02P@tassilo> (raw)
In-Reply-To: <wo4wcvuhvqsqissocu7nz2urg5yt7mx65s5dxkjxqimgnxv3ax@qsa3lqlfsaxi>
> I think it is cleaner to switch to IRET here. Does this work for you?
>
> diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S
> index 608f108cba7d..14d9c7daf90f 100644
> --- a/arch/x86/realmode/rm/trampoline_64.S
> +++ b/arch/x86/realmode/rm/trampoline_64.S
> @@ -243,7 +243,9 @@ SYM_CODE_START(trampoline_start64)
> movl $pa_trampoline_pgd, %eax
> movq %rax, %cr3
>
> - jmpq *tr_start(%rip)
> + pushq $__KERNEL_CS
> + pushq tr_start(%rip)
> + lretq
Looks good. Thanks.
-Andi
next prev parent reply other threads:[~2024-01-25 14:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-24 13:15 [PATCHv3, RESEND] x86/trampoline: Bypass compat mode in trampoline_start64() if not needed Kirill A. Shutemov
2024-01-25 9:57 ` Andi Kleen
2024-01-25 11:44 ` Kirill A. Shutemov
2024-01-25 14:50 ` Andi Kleen [this message]
2024-01-25 13:07 ` H. Peter Anvin
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