linux-kernel - Re: [PATCH v5 RESEND 14/17] mm/ioremap: Consider IOREMAP space in generic ioremap

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Date:   Fri, 2 Jun 2023 18:42:59 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-mm@...ck.org, arnd@...db.de, christophe.leroy@...roup.eu,
        agordeev@...ux.ibm.com, wangkefeng.wang@...wei.com,
        schnelle@...ux.ibm.com, David.Laight@...lab.com, shorne@...il.com,
        willy@...radead.org, deller@....de
Subject: Re: [PATCH v5 RESEND 14/17] mm/ioremap: Consider IOREMAP space in
 generic ioremap

On 06/01/23 at 04:13am, Christoph Hellwig wrote:
> On Tue, May 30, 2023 at 05:37:23PM +0800, Baoquan He wrote:
> > If we want to consolidate code, we can move is_ioremap_addr() to
> > include/linux/mm.h libe below. Not sure if it's fine. With it,
> > both kernel/iomem.c and mm/ioremap.c can use is_ioremap_addr().
> 
> Can we just add a ne header for this given that no one else really
> needs it?

Is it OK like below?

>From fe5d4d25afa1e989fa82877c8466a97fc8bd8c93 Mon Sep 17 00:00:00 2001
From: Baoquan He <bhe@...hat.com>
Date: Fri, 2 Jun 2023 18:36:48 +0800
Subject: [PATCH] mm: move is_ioremap_addr() into new header file
Content-type: text/plain

Now is_ioremap_addr() is only used in kernel/iomem.c and gonna be used
in mm/ioremap.c. Move it into its own new header file linux/ioremap.h.

Signed-off-by: Baoquan He <bhe@...hat.com>
---
 include/linux/ioremap.h | 29 +++++++++++++++++++++++++++++
 include/linux/mm.h      |  5 -----
 kernel/iomem.c          |  1 +
 mm/ioremap.c            |  1 +
 4 files changed, 31 insertions(+), 5 deletions(-)
 create mode 100644 include/linux/ioremap.h

diff --git a/include/linux/ioremap.h b/include/linux/ioremap.h
new file mode 100644
index 000000000000..2fd51a77ebdc
--- /dev/null
+++ b/include/linux/ioremap.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_IOREMAP_H
+#define _LINUX_IOREMAP_H
+
+#include <linux/kasan.h>
+#include <asm/pgtable.h>
+
+#if defined(CONFIG_HAS_IOMEM) || defined(CONFIG_GENERIC_IOREMAP)
+/*
+ * Ioremap often, but not always uses the generic vmalloc area. E.g on
+ * Power ARCH, it could have different ioremap space. 
+ */
+#ifndef IOREMAP_START
+#define IOREMAP_START   VMALLOC_START
+#define IOREMAP_END     VMALLOC_END
+#endif
+static inline bool is_ioremap_addr(const void *x)
+{
+	unsigned long addr = (unsigned long)kasan_reset_tag(x);
+	return addr >= IOREMAP_START && addr < IOREMAP_END;
+}
+#else
+static inline bool is_ioremap_addr(const void *x)
+{
+	return false;
+}
+#endif
+
+#endif /* _LINUX_IOREMAP_H */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 27ce77080c79..7379f19768b4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1041,11 +1041,6 @@ unsigned long vmalloc_to_pfn(const void *addr);
  * On nommu, vmalloc/vfree wrap through kmalloc/kfree directly, so there
  * is no special casing required.
  */
-
-#ifndef is_ioremap_addr
-#define is_ioremap_addr(x) is_vmalloc_addr(x)
-#endif
-
 #ifdef CONFIG_MMU
 extern bool is_vmalloc_addr(const void *x);
 extern int is_vmalloc_or_module_addr(const void *x);
diff --git a/kernel/iomem.c b/kernel/iomem.c
index 62c92e43aa0d..9682471e6471 100644
--- a/kernel/iomem.c
+++ b/kernel/iomem.c
@@ -3,6 +3,7 @@
 #include <linux/types.h>
 #include <linux/io.h>
 #include <linux/mm.h>
+#include <linux/ioremap.h>
 
 #ifndef ioremap_cache
 /* temporary while we convert existing ioremap_cache users to memremap */
diff --git a/mm/ioremap.c b/mm/ioremap.c
index 0248e630561b..3dede3302eba 100644
--- a/mm/ioremap.c
+++ b/mm/ioremap.c
@@ -10,6 +10,7 @@
 #include <linux/mm.h>
 #include <linux/io.h>
 #include <linux/export.h>
+#include <linux/ioremap.h>
 
 /*
  * Ioremap often, but not always uses the generic vmalloc area. E.g on
-- 
2.34.1

> 
>