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Date: Thu, 08 Apr 2010 10:12:01 -0700
From: Jeremy Fitzhardinge <jeremy@...p.org>
To: Liang Li <liang.li@...driver.com>
CC: Yinghai <yinghai.lu@...cle.com>,
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 04/08/2010 01:58 AM, Liang Li wrote:
> 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:
>
Yes indeed. That looks better.
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Thanks,
J
> 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);
>
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