linux-kernel - [PATCH v6 1/6] x86/mm: sparse warning fix for early

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Date:	Sun,  9 Mar 2014 13:00:39 -0400
From:	Mark Salter <msalter@...hat.com>
To:	x86@...nel.org
Cc:	Dave Young <dyoung@...hat.com>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arnd Bergmann <arnd@...db.de>, Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, patches@...aro.org,
	Mark Salter <msalter@...hat.com>
Subject: [PATCH v6 1/6] x86/mm: sparse warning fix for early_memremap

From: Dave Young <dyoung@...hat.com>

There's a lot of sparse warnings for code like below:
void *a = early_memremap(phys_addr, size);

early_memremap intend to map kernel memory with ioremap facility, the return
pointer should be a kernel ram pointer instead of iomem one.

For making the function clearer and supressing sparse warnings this patch
do below two things:
1. cast to (__force void *) for the return value of early_memremap
2. add early_memunmap function and pass (__force void __iomem *) to iounmap

>>From Boris:
> Ingo told me yesterday, it makes sense too. I'd guess we can try it.
> FWIW, all callers of early_memremap use the memory they get remapped as
> normal memory so we should be safe.

Signed-off-by: Dave Young <dyoung@...hat.com>
Signed-off-by: Mark Salter <msalter@...hat.com>
Acked-by: H. Peter Anvin <hpa@...or.com>
---
 arch/x86/include/asm/io.h |  3 ++-
 arch/x86/mm/ioremap.c     | 10 +++++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 34f69cb..1db414f 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -325,9 +325,10 @@ extern void early_ioremap_init(void);
 extern void early_ioremap_reset(void);
 extern void __iomem *early_ioremap(resource_size_t phys_addr,
 				   unsigned long size);
-extern void __iomem *early_memremap(resource_size_t phys_addr,
+extern void *early_memremap(resource_size_t phys_addr,
 				    unsigned long size);
 extern void early_iounmap(void __iomem *addr, unsigned long size);
+extern void early_memunmap(void *addr, unsigned long size);
 extern void fixup_early_ioremap(void);
 extern bool is_early_ioremap_ptep(pte_t *ptep);
 
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 799580c..bbb4504 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -562,10 +562,9 @@ early_ioremap(resource_size_t phys_addr, unsigned long size)
 }
 
 /* Remap memory */
-void __init __iomem *
-early_memremap(resource_size_t phys_addr, unsigned long size)
+void __init *early_memremap(resource_size_t phys_addr, unsigned long size)
 {
-	return __early_ioremap(phys_addr, size, PAGE_KERNEL);
+	return (__force void *)__early_ioremap(phys_addr, size, PAGE_KERNEL);
 }
 
 void __init early_iounmap(void __iomem *addr, unsigned long size)
@@ -620,3 +619,8 @@ void __init early_iounmap(void __iomem *addr, unsigned long size)
 	}
 	prev_map[slot] = NULL;
 }
+
+void __init early_memunmap(void *addr, unsigned long size)
+{
+	early_iounmap((__force void __iomem *)addr, size);
+}
-- 
1.8.5.3

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