linux-kernel - Re: [RFC/PATCH v2 02/10] x86

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Date:	Thu, 11 Sep 2014 15:51:37 +0400
From:	Andrey Ryabinin <a.ryabinin@...sung.com>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Dave Hansen <dave.hansen@...el.com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Konstantin Serebryany <kcc@...gle.com>,
	Dmitry Chernenkov <dmitryc@...gle.com>,
	Andrey Konovalov <adech.fo@...il.com>,
	Yuri Gribov <tetra2005@...il.com>,
	Konstantin Khlebnikov <koct9i@...il.com>,
	Christoph Lameter <cl@...ux.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Vegard Nossum <vegard.nossum@...il.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [RFC/PATCH v2 02/10] x86_64: add KASan support

On 09/11/2014 08:29 AM, Sasha Levin wrote:
> On 09/11/2014 12:26 AM, H. Peter Anvin wrote:
>> Except you just broke PVop kernels.
> 
> So is this why v2 refuses to boot on my KVM guest? (was digging
> into that before I send a mail out).
> 

Maybe this will help?


From: Andrey Ryabinin <a.ryabinin@...sung.com>
Subject: [PATCH] x86_64: kasan: fix kernel boot with CONFIG_DEBUG_VIRTUAL=y

Use __pa_nodebug instead of __pa before shadow initialized.
__pa with CONFIG_DEBUG_VIRTUAL=y may result in __asan_load
call before shadow area initialized.

Signed-off-by: Andrey Ryabinin <a.ryabinin@...sung.com>
---
 arch/x86/kernel/head64.c    | 6 +++---
 arch/x86/mm/kasan_init_64.c | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 9d97e3a..5669a8b 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -47,7 +47,7 @@ static void __init reset_early_page_tables(void)

 	next_early_pgt = 0;

-	write_cr3(__pa(early_level4_pgt));
+	write_cr3(__pa_nodebug(early_level4_pgt));
 }

 /* Create a new PMD entry */
@@ -60,7 +60,7 @@ int __init early_make_pgtable(unsigned long address)
 	pmdval_t pmd, *pmd_p;

 	/* Invalid address or early pgt is done ?  */
-	if (physaddr >= MAXMEM || read_cr3() != __pa(early_level4_pgt))
+	if (physaddr >= MAXMEM || read_cr3() != __pa_nodebug(early_level4_pgt))
 		return -1;

 again:
@@ -160,7 +160,7 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 	reset_early_page_tables();

 	kasan_map_zero_shadow(early_level4_pgt);
-	write_cr3(__pa(early_level4_pgt));
+	write_cr3(__pa_nodebug(early_level4_pgt));

 	/* clear bss before set_intr_gate with early_idt_handler */
 	clear_bss();
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index b7c857e..6615bf1 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -35,7 +35,7 @@ void __init kasan_map_zero_shadow(pgd_t *pgd)
 	unsigned long end = KASAN_SHADOW_END;

 	for (i = pgd_index(start); start < end; i++) {
-		pgd[i] = __pgd(__pa(zero_pud) | __PAGE_KERNEL_RO);
+		pgd[i] = __pgd(__pa_nodebug(zero_pud) | __PAGE_KERNEL_RO);
 		start += PGDIR_SIZE;
 	}
 }
-- 
2.1.0


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