linux-kernel - [PATCH v2 3/5] powerpc/mm/32: Use page_is

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Message-Id: <20180328002544.18526-4-j.neuschaefer@gmx.net>
Date:   Wed, 28 Mar 2018 02:25:42 +0200
From:   Jonathan Neuschäfer <j.neuschaefer@....net>
To:     linuxppc-dev@...ts.ozlabs.org
Cc:     linux-kernel@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>,
        Christophe Leroy <christophe.leroy@....fr>,
        Jonathan Neuschäfer <j.neuschaefer@....net>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Balbir Singh <bsingharora@...il.com>,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH v2 3/5] powerpc/mm/32: Use page_is_ram to check for RAM

On systems where there is MMIO space between different blocks of RAM in
the physical address space, __ioremap_caller did not allow mapping these
MMIO areas, because they were below the end RAM and thus considered RAM
as well.  Use the memblock-based page_is_ram function, which returns
false for such MMIO holes.

v2:
  Keep the check for p < virt_to_phys(high_memory). On 32-bit systems
  with high memory (memory above physical address 4GiB), the high memory
  is expected to be available though ioremap. The high_memory variable
  marks the end of low memory; comparing against it means that only
  ioremap requests for low RAM will be denied.
  Reported by Michael Ellerman.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@....net>
---
 arch/powerpc/mm/pgtable_32.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index d35d9ad3c1cd..6668ecc041ad 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -148,6 +148,7 @@ __ioremap_caller(phys_addr_t addr, unsigned long size, unsigned long flags,
 	 * mem_init() sets high_memory so only do the check after that.
 	 */
 	if (slab_is_available() && (p < virt_to_phys(high_memory)) &&
+	    page_is_ram(__phys_to_pfn(p)) &&
 	    !(__allow_ioremap_reserved && memblock_is_region_reserved(p, size))) {
 		printk("__ioremap(): phys addr 0x%llx is RAM lr %ps\n",
 		       (unsigned long long)p, __builtin_return_address(0));
-- 
2.16.2