linux-kernel - Re: [tip:x86/boot] x86/boot/compressed/64: Prepare trampoline memory

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Date:   Mon, 26 Feb 2018 11:54:40 +0100
From:   Borislav Petkov <bp@...e.de>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     Ingo Molnar <mingo@...nel.org>, tglx@...utronix.de,
        torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
        willy@...radead.org, hpa@...or.com,
        kirill.shutemov@...ux.intel.com, peterz@...radead.org,
        gorcunov@...nvz.org, luto@...capital.net,
        linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/boot] x86/boot/compressed/64: Prepare trampoline memory

On Mon, Feb 26, 2018 at 11:02:56AM +0300, Kirill A. Shutemov wrote:
> Yeah, good idea.
> 
> Borislav, could you check this?

No joy with:

diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c
index dad5da7b4c1a..4c382409b740 100644
--- a/arch/x86/boot/compressed/pgtable_64.c
+++ b/arch/x86/boot/compressed/pgtable_64.c
@@ -32,6 +32,7 @@ struct paging_config paging_prepare(void)
 			(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31))))
 		paging_config.l5_required = 1;
 
+#if 0
 	/*
 	 * Find a suitable spot for the trampoline.
 	 * This code is based on reserve_bios_regions().
@@ -49,6 +50,9 @@ struct paging_config paging_prepare(void)
 	/* Place the trampoline just below the end of low memory, aligned to 4k */
 	paging_config.trampoline_start = bios_start - TRAMPOLINE_32BIT_SIZE;
 	paging_config.trampoline_start = round_down(paging_config.trampoline_start, PAGE_SIZE);
+#else
+	paging_config.trampoline_start = 0x40000;
+#endif
 
 	trampoline = (unsigned long *)paging_config.trampoline_start;
---
-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--