linux-kernel - [PATCH 11/11] x86/xip: update _va() and

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Date:	Mon, 23 Mar 2015 00:46:40 -0700
From:	Jim Kukunas <james.t.kukunas@...ux.intel.com>
To:	Linux Kernel <linux-kernel@...r.kernel.org>,
	tom.zanussi@...ux.intel.com
Cc:	Arjan van de Ven <arjan@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>, tglx@...utronix.de,
	mingo@...hat.com, x86@...nel.org
Subject: [PATCH 11/11] x86/xip: update _va() and _pa() macros

For obtaining the physical address, we always take the slow path
of slow_virt_to_phys(). In the future, we should probably special
case data addresses to avoid walking the page table. For obtaining
a virtual address, this patch introduces a slow path of
slow_xip_phys_to_virt().

Signed-off-by: Jim Kukunas <james.t.kukunas@...ux.intel.com>
---
 arch/x86/include/asm/page.h | 15 +++++++++++++++
 arch/x86/mm/pageattr.c      | 11 +++++++++++
 2 files changed, 26 insertions(+)

diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index 802dde3..b54c7be 100644
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -6,6 +6,7 @@
 #ifdef __KERNEL__
 
 #include <asm/page_types.h>
+#include <asm/pgtable_types.h>
 
 #ifdef CONFIG_X86_64
 #include <asm/page_64.h>
@@ -37,8 +38,15 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
 	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
 #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
 
+
+#ifdef CONFIG_XIP_KERNEL	/* TODO special case text translations */
+#define __pa(x)		slow_virt_to_phys((void *)(x))
+#define __pa_nodebug	slow_virt_to_phys((void *)(x))
+#else
 #define __pa(x)		__phys_addr((unsigned long)(x))
 #define __pa_nodebug(x)	__phys_addr_nodebug((unsigned long)(x))
+#endif
+
 /* __pa_symbol should be used for C visible symbols.
    This seems to be the official gcc blessed way to do such arithmetic. */
 /*
@@ -51,7 +59,14 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
 #define __pa_symbol(x) \
 	__phys_addr_symbol(__phys_reloc_hide((unsigned long)(x)))
 
+
+#ifdef CONFIG_XIP_KERNEL
+extern unsigned long slow_xip_phys_to_virt(phys_addr_t);
+
+#define __va(x)			((void *)slow_xip_phys_to_virt((phys_addr_t)x))
+#else
 #define __va(x)			((void *)((unsigned long)(x)+PAGE_OFFSET))
+#endif
 
 #define __boot_va(x)		__va(x)
 #define __boot_pa(x)		__pa(x)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 536ea2f..ca9e2ca 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -383,6 +383,17 @@ static pte_t *_lookup_address_cpa(struct cpa_data *cpa, unsigned long address,
         return lookup_address(address, level);
 }
 
+#ifdef CONFIG_XIP_KERNEL
+unsigned long slow_xip_phys_to_virt(phys_addr_t x)
+{
+	if (x >= CONFIG_XIP_BASE && x <= (phys_addr_t)phys_sdata) {
+		unsigned long off = x - CONFIG_XIP_BASE;
+		return PAGE_OFFSET + off;
+	}
+	return x + PAGE_OFFSET;
+}
+#endif
+
 /*
  * Lookup the PMD entry for a virtual address. Return a pointer to the entry
  * or NULL if not present.
-- 
2.1.0

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