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Message-ID: <20100408085814.GD26543@localhost>
Date: Thu, 8 Apr 2010 16:58:14 +0800
From: Liang Li <liang.li@...driver.com>
To: Yinghai <yinghai.lu@...cle.com>
Cc: Jeremy Fitzhardinge <jeremy@...p.org>,
Rusty Russell <rusty@...tcorp.com.au>,
akpm@...ux-foundation.org, hpa@...or.com, mingo@...e.hu,
tglx@...utronix.de, wangchen@...fujitsu.com,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: + x86-fix-handling-of-the-reservetop-boot-option.patch added to
-mm tree
On Wed, Apr 07, 2010 at 11:57:22PM -0700, Yinghai wrote:
> On 04/07/2010 09:59 PM, Liang Li wrote:
> > 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@...driver.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@...driver.com>
> > Cc: Wang Chen <wangchen@...fujitsu.com>
> > Cc: Ingo Molnar <mingo@...e.hu>
> > Cc: Thomas Gleixner <tglx@...utronix.de>
> > Cc: "H. Peter Anvin" <hpa@...or.com>
> > Cc: Yinghai Lu <yinghai@...nel.org>
> > Cc: Andrew Morton <akpm@...ux-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?
> >
> good to me.
>
> may need to ask xen/lguest/vmi related to check that too.
>
> arch/x86/kernel/vmi_32.c: reserve_top_address(-vmi_rom->virtual_top);
> arch/x86/lguest/boot.c: reserve_top_address(lguest_data.reserve_mem);
> arch/x86/mm/pgtable_32.c: reserve_top_address(address);
> arch/x86/xen/mmu.c: reserve_top_address(-top);
When linux as vmi/xen/lguest guest OS, kernel call reserve_top_address
before start_kernel. It is far before the start_kernel hence far before
setup_arch->early_ioremap_init. So it is unsafe to place
fixup_early_ioremap inside reserve_top_address. So I think the patch
should be:
>From 7cefa9a80c4434f2941a7072d39b1f1ffc08a40f Mon Sep 17 00:00:00 2001
From: Liang Li <liang.li@...driver.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@...driver.com>
Cc: Wang Chen <wangchen@...fujitsu.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Yinghai Lu <yinghai@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
---
arch/x86/include/asm/io.h | 1 +
arch/x86/mm/ioremap.c | 15 +++++++++++++++
arch/x86/mm/pgtable_32.c | 1 +
3 files changed, 17 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_32.c b/arch/x86/mm/pgtable_32.c
index 1a8faf0..26eadaa 100644
--- a/arch/x86/mm/pgtable_32.c
+++ b/arch/x86/mm/pgtable_32.c
@@ -128,6 +128,7 @@ static int __init parse_reservetop(char *arg)
address = memparse(arg, &arg);
reserve_top_address(address);
+ fixup_early_ioremap();
return 0;
}
early_param("reservetop", parse_reservetop);
--
1.6.6
Thanks and best regards,
-Liang Li
>
>
> YH
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