linux-kernel - [PATCH 2/2] x86: remove high_memory check from valid_phys_addr

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Message-Id: <1408548326-18665-3-git-send-email-fhrbata@redhat.com>
Date:	Wed, 20 Aug 2014 17:25:26 +0200
From:	Frantisek Hrbata <fhrbata@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-mm@...ck.org, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, oleg@...hat.com,
	kamaleshb@...ibm.com, hechjie@...ibm.com,
	akpm@...ux-foundation.org, dave.hansen@...el.com,
	dvlasenk@...hat.com, prarit@...hat.com, lwoodman@...hat.com,
	hannsj_uhl@...ibm.com
Subject: [PATCH 2/2] x86: remove high_memory check from valid_phys_addr_range

There is no need to block read/write access to /dev/mem for phys. addr. above
high_memory for non-system RAM. The only limitation should be
boot_cpu_data.x86_phys_bits(max phys. addr. size).

Signed-off-by: Frantisek Hrbata <fhrbata@...hat.com>
---
 arch/x86/mm/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 110473e..16f222d 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -127,7 +127,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 
 int valid_phys_addr_range(phys_addr_t addr, size_t count)
 {
-	return addr + count <= __pa(high_memory);
+	return arch_pfn_possible((addr + count) >> PAGE_SHIFT);
 }
 
 int valid_mmap_phys_addr_range(unsigned long pfn, size_t count)
-- 
1.9.3

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