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 01:57:18 -0800 [thread overview]
Message-ID: <ZbIwfp-jOOlPNb1z@tassilo> (raw)
In-Reply-To: <20240124131510.496803-1-kirill.shutemov@linux.intel.com>
> + /* Paging mode is correct proceed in 64-bit mode */
> +
> + LOCK_AND_LOAD_REALMODE_ESP lock_rip=1
> +
> + movw $__KERNEL_DS, %dx
> + movl %edx, %ss
> + addl $pa_real_mode_base, %esp
> + movl %edx, %ds
> + movl %edx, %es
> + movl %edx, %fs
> + movl %edx, %gs
> +
> + movl $pa_trampoline_pgd, %eax
> + movq %rax, %cr3
> +
> + jmpq *tr_start(%rip)
Still think we should add a far jump here so that we run on a defined
code segment. It probably doesn't matter since there are likely no
IRETs before reloading anyways, but it seems cleaner.
-Andi
next prev parent reply other threads:[~2024-01-25 9:57 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 [this message]
2024-01-25 11:44 ` Kirill A. Shutemov
2024-01-25 14:50 ` Andi Kleen
2024-01-25 13:07 ` H. Peter Anvin
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