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Re: [Xen-devel] [PATCH v3 09/27] x86/acpi: Adapt assembly for PIE support
- To: Thomas Garnier <thgarnie@xxxxxxxxxx>
- From: Pavel Machek <pavel@xxxxxx>
- Date: Thu, 24 May 2018 13:03:06 +0200
- Cc: Kate Stewart <kstewart@xxxxxxxxxxxxxxxxxxx>, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>, x86@xxxxxxxxxx, Sergey Senozhatsky <sergey.senozhatsky.work@xxxxxxxxx>, Petr Mladek <pmladek@xxxxxxxx>, Len Brown <len.brown@xxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, Yonghong Song <yhs@xxxxxx>, Christopher Li <sparse@xxxxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxx>, "H . Peter Anvin" <hpa@xxxxxxxxx>, kernel-hardening@xxxxxxxxxxxxxxxxxx, Christoph Lameter <cl@xxxxxxxxx>, Alok Kataria <akataria@xxxxxxxxxx>, linux-doc@xxxxxxxxxxxxxxx, linux-arch@xxxxxxxxxxxxxxx, Jonathan Corbet <corbet@xxxxxxx>, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>, Baoquan He <bhe@xxxxxxxxxx>, David Woodhouse <dwmw@xxxxxxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Radim Krčmář <rkrcmar@xxxxxxxxxx>, Daniel Micay <danielmicay@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, linux-sparse@xxxxxxxxxxxxxxx, Ingo Molnar <mingo@xxxxxxxxxx>, Jan Kiszka <jan.kiszka@xxxxxxxxxxx>, Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>, Borislav Petkov <bp@xxxxxxx>, Alexey Dobriyan <adobriyan@xxxxxxxxx>, kvm@xxxxxxxxxxxxxxx, linux-crypto@xxxxxxxxxxxxxxx, Tom Lendacky <thomas.lendacky@xxxxxxx>, Rik van Riel <riel@xxxxxxxxxx>, Jan H . Schönherr <jschoenh@xxxxxxxxx>, Kees Cook <keescook@xxxxxxxxxxxx>, Arnd Bergmann <arnd@xxxxxxxx>, linux-pm@xxxxxxxxxxxxxxx, Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>, "H . J . Lu" <hjl.tools@xxxxxxxxx>, Matthias Kaehlcke <mka@xxxxxxxxxxxx>, Steven Rostedt <rostedt@xxxxxxxxxxx>, Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>, Dennis Zhou <dennisszhou@xxxxxxxxx>, Cao jin <caoj.fnst@xxxxxxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Nicholas Piggin <npiggin@xxxxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxx>, Josh Poimboeuf <jpoimboe@xxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx, Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>, "Paul E . McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>, Francis Deslauriers <francis.deslauriers@xxxxxxxxxxxx>, Randy Dunlap <rdunlap@xxxxxxxxxxxxx>, "Rafael J . Wysocki" <rjw@xxxxxxxxxxxxx>, Jason Baron <jbaron@xxxxxxxxxx>, Jia Zhang <qianyue.zj@xxxxxxxxxxxxxxx>, "Luis R . Rodriguez" <mcgrof@xxxxxxxxxx>, Lukas Wunner <lukas@xxxxxxxxx>, Masami Hiramatsu <mhiramat@xxxxxxxxxx>, Philippe Ombredanne <pombredanne@xxxxxxxx>, Tejun Heo <tj@xxxxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, "David S . Miller" <davem@xxxxxxxxxxxxx>, "Kirill A . Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>, Joerg Roedel <joro@xxxxxxxxxx>
- Delivery-date: Thu, 24 May 2018 11:03:14 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On Wed 2018-05-23 12:54:03, Thomas Garnier wrote:
> Change the assembly code to use only relative references of symbols for the
> kernel to be PIE compatible.
>
> Position Independent Executable (PIE) support will allow to extended the
> KASLR randomization range below the -2G memory limit.
What testing did this get?
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S
> b/arch/x86/kernel/acpi/wakeup_64.S
> index 50b8ed0317a3..472659c0f811 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/arch/x86/kernel/acpi/wakeup_64.S
> @@ -14,7 +14,7 @@
> * Hooray, we are in Long 64-bit mode (but still running in low memory)
> */
> ENTRY(wakeup_long64)
> - movq saved_magic, %rax
> + movq saved_magic(%rip), %rax
> movq $0x123456789abcdef0, %rdx
> cmpq %rdx, %rax
> jne bogus_64_magic
Because, as comment says, this is rather tricky code.
Pavel
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