Re: + x86-fix-handling-of-the-reservetop-boot-option.patch added to -mm tree

[Liang Li <liang.li@windriver.com>]

On Wed, Apr 07, 2010 at 09:30:39PM -0700, Yinghai wrote:
> On 04/07/2010 06:53 PM, Liang Li wrote:
> > Does this similar modification like this is more preferred?
> > 
> > diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
> > index a1dcfa3..30a3e97 100644
> > --- a/arch/x86/include/asm/io.h
> > +++ b/arch/x86/include/asm/io.h
> > @@ -347,6 +347,7 @@ extern void __iomem *early_ioremap(resource_size_t phys_addr,
> >  extern void __iomem *early_memremap(resource_size_t phys_addr,
> >  				    unsigned long size);
> >  extern void early_iounmap(void __iomem *addr, unsigned long size);
> > +extern void fixup_early_ioremap(void);
> >  
> >  #define IO_SPACE_LIMIT 0xffff
> >  
> > diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> > index ea82ef0..fe06296 100644
> > --- a/arch/x86/mm/ioremap.c
> > +++ b/arch/x86/mm/ioremap.c
> > @@ -448,6 +448,23 @@ static inline void __init early_clear_fixmap(enum fixed_addresses idx)
> >  static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
> >  static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
> >  
> > +void __init fixup_early_ioremap(void)
> > +{
> > +	int i;
> > +	for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
> > +		if (prev_map[i])
> > +			break;
> > +	}
> > +
> > +	if (i == FIX_BTMAPS_SLOTS)
> <
> > +		WARN_ON(1);
> BUG_ON()
> > +
> > +	for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
> > +		slot_virt[i] = __fix_to_virt(FIX_BTMAP_BEGIN - NR_FIX_BTMAPS * i);
> > +
> need to clear the old PMD, and set new PMD.
> 
> so you can clear old PMD and call early_ioremap_init() in fixup_early_ioremap()

Call early_ioremap_init will do the update PMD work. So the preferred
patch would be:
---------------
>From 61fe7a116cbbf6eef98a49b88ed5861ed9ebd32d Mon Sep 17 00:00:00 2001
From: Liang Li <liang.li@windriver.com>
Date: Mon, 22 Mar 2010 18:38:14 +0800
Subject: [PATCH] x86: let 'reservetop' functioning right

When specify 'reservetop=0xbadc0de' kernel parameter, the kernel will
stop booting due to a early_ioremap bug that relate to commit 8827247ff.

The root cause of boot failure problem is the value of 'slot_virt[i]'
was initialized in setup_arch->early_ioremap_init. But later in
setup_arch, the function 'parse_early_param' will modify 'FIXADDR_TOP'
when 'reservetop=0xbadc0de' being specified.

When reservetop being handled then FIXADDR_TOP get adjusted, Hence check
prev_map then re-initialize slot_virt and PMD based on new FIXADDR_TOP.

Signed-off-by: Liang Li <liang.li@windriver.com>
Cc: Wang Chen <wangchen@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 arch/x86/include/asm/io.h |    1 +
 arch/x86/mm/ioremap.c     |   15 +++++++++++++++
 arch/x86/mm/pgtable.c     |    2 ++
 3 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index a1dcfa3..30a3e97 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -347,6 +347,7 @@ extern void __iomem *early_ioremap(resource_size_t phys_addr,
 extern void __iomem *early_memremap(resource_size_t phys_addr,
 				    unsigned long size);
 extern void early_iounmap(void __iomem *addr, unsigned long size);
+extern void fixup_early_ioremap(void);
 
 #define IO_SPACE_LIMIT 0xffff
 
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 5eb1ba7..e4ab706 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -448,6 +448,21 @@ static inline void __init early_clear_fixmap(enum fixed_addresses idx)
 static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
 static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
 
+void __init fixup_early_ioremap(void)
+{
+	int i;
+	for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
+		if (prev_map[i])
+			break;
+	}
+
+	if (i < FIX_BTMAPS_SLOTS)
+		BUG_ON(1);
+
+	early_ioremap_init();
+	return;
+}
+
 static int __init check_early_ioremap_leak(void)
 {
 	int count = 0;
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 5c4ee42..ea4d54c 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -4,6 +4,7 @@
 #include <asm/pgtable.h>
 #include <asm/tlb.h>
 #include <asm/fixmap.h>
+#include <asm/io.h>
 
 #define PGALLOC_GFP GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO
 
@@ -351,6 +352,7 @@ void __init reserve_top_address(unsigned long reserve)
 	printk(KERN_INFO "Reserving virtual address space above 0x%08x\n",
 	       (int)-reserve);
 	__FIXADDR_TOP = -reserve - PAGE_SIZE;
+	fixup_early_ioremap();
 #endif
 }
 
-----------
Acceptable?

Thanks and regards,
	   -Liang Li