Hi All,
I just tried to boot with the current linus mergewindow tree under Xen.
It fails with a kernel panic at boot with the new "CONFIG_DEBUG_WX"
option enabled.
Disabling it makes the kernel boot fine.
The splat:
[ 18.424241] Freeing unused kernel memory: 1104K (ffffffff822fc000 -
ffffffff82410000)
[ 18.430314] Write protecting the kernel read-only data: 18432k
[ 18.441054] Freeing unused kernel memory: 1144K (ffff880001ae2000 -
ffff880001c00000)
[ 18.447966] Freeing unused kernel memory: 1560K (ffff88000207a000 -
ffff880002200000)
[ 18.453947] BUG: unable to handle kernel paging request at
ffff88055c883000
[ 18.459943] IP: [<ffffffff8105af8e>]
ptdump_walk_pgd_level_core+0x20e/0x440
[ 18.465847] PGD 2212067 PUD 0
[ 18.471564] Oops: 0000 [#1] SMP
[ 18.477248] Modules linked in:
[ 18.482918] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
4.3.0-mw-20151104-linus-doflr+ #1
[ 18.488804] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS
V1.8B1 09/13/2010
[ 18.494778] task: ffff880059b90000 ti: ffff880059b98000 task.ti:
ffff880059b98000
[ 18.500852] RIP: e030:[<ffffffff8105af8e>] [<ffffffff8105af8e>]
ptdump_walk_pgd_level_core+0x20e/0x440
[ 18.507102] RSP: e02b:ffff880059b9be48 EFLAGS: 00010296
[ 18.513351] RAX: ffff88055c883000 RBX: ffffffff81ae2000 RCX:
ffff880000000000
[ 18.519733] RDX: 0000000000000067 RSI: ffff880059b9be98 RDI:
ffff880000001000
[ 18.526129] RBP: ffff880059b9bf00 R08: 0000000000000000 R09:
0000000000000000
[ 18.532522] R10: ffff88005fd0e790 R11: 0000000000000001 R12:
ffff880080000000
[ 18.538891] R13: ffffc00000000fff R14: ffff880059b9be98 R15:
0000000000000000
[ 18.545247] FS: 0000000000000000(0000) GS:ffff88005f680000(0000)
knlGS:0000000000000000
[ 18.551708] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 18.558153] CR2: ffff88055c883000 CR3: 0000000002211000 CR4:
0000000000000660
[ 18.564686] Stack:
[ 18.571106] 0000000159b9be50 ffffffff82211000 ffff88055c884000
0000000000000800
[ 18.577704] 0000800000000000 ffff88055c883000 0000000000000007
ffff88005fd0e790
[ 18.584291] ffff880059b9bed8 ffffffff81156ace 0000000000000001
0000000000000000
[ 18.590916] Call Trace:
[ 18.597458] [<ffffffff81156ace>] ? free_reserved_area+0x11e/0x120
[ 18.604180] [<ffffffff8105b1e2>]
ptdump_walk_pgd_level_checkwx+0x12/0x20
[ 18.611014] [<ffffffff810515b9>] mark_rodata_ro+0xe9/0xf0
[ 18.617819] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
[ 18.624512] [<ffffffff81ad3398>] kernel_init+0x18/0xe0
[ 18.631095] [<ffffffff81adadcf>] ret_from_fork+0x3f/0x70
[ 18.637650] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
[ 18.644178] Code: 70 ff ff ff 48 3b 85 58 ff ff ff 0f 84 c0 fe ff ff
48 8b 85 68 ff ff ff 48 c1 e0 10 48 c1 f8 10 48 89 45 b0 48 8b 85 70 ff
ff ff <48> 8b 38 48 85 ff 0f 85 4e ff ff ff b9 02 00 00 00 31 d2 4c 89
[ 18.658246] RIP [<ffffffff8105af8e>]
ptdump_walk_pgd_level_core+0x20e/0x440
[ 18.665211] RSP <ffff880059b9be48>
[ 18.672073] CR2: ffff88055c883000
[ 18.678852] ---[ end trace d84e34461c40637a ]---
[ 18.685641] Kernel panic - not syncing: Attempted to kill init!
exitcode=0x00000009
[ 18.685641]
[ 18.699520] Kernel Offset: disable
On 11/04/2015 06:55 AM, Sander Eikelenboom wrote:
> Hi All,
>
> I just tried to boot with the current linus mergewindow tree under Xen.
> It fails with a kernel panic at boot with the new "CONFIG_DEBUG_WX"
> option enabled.
> Disabling it makes the kernel boot fine.
>
> The splat:
> [ 18.424241] Freeing unused kernel memory: 1104K (ffffffff822fc000 -
> ffffffff82410000)
> [ 18.430314] Write protecting the kernel read-only data: 18432k
> [ 18.441054] Freeing unused kernel memory: 1144K (ffff880001ae2000 -
> ffff880001c00000)
> [ 18.447966] Freeing unused kernel memory: 1560K (ffff88000207a000 -
> ffff880002200000)
> [ 18.453947] BUG: unable to handle kernel paging request at
> ffff88055c883000
> [ 18.459943] IP: [<ffffffff8105af8e>]
> ptdump_walk_pgd_level_core+0x20e/0x440
> [ 18.465847] PGD 2212067 PUD 0
> [ 18.471564] Oops: 0000 [#1] SMP
> [ 18.477248] Modules linked in:
> [ 18.482918] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
> 4.3.0-mw-20151104-linus-doflr+ #1
> [ 18.488804] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS
> V1.8B1 09/13/2010
> [ 18.494778] task: ffff880059b90000 ti: ffff880059b98000 task.ti:
> ffff880059b98000
> [ 18.500852] RIP: e030:[<ffffffff8105af8e>] [<ffffffff8105af8e>]
> ptdump_walk_pgd_level_core+0x20e/0x440
> [ 18.507102] RSP: e02b:ffff880059b9be48 EFLAGS: 00010296
> [ 18.513351] RAX: ffff88055c883000 RBX: ffffffff81ae2000 RCX:
> ffff880000000000
> [ 18.519733] RDX: 0000000000000067 RSI: ffff880059b9be98 RDI:
> ffff880000001000
> [ 18.526129] RBP: ffff880059b9bf00 R08: 0000000000000000 R09:
> 0000000000000000
> [ 18.532522] R10: ffff88005fd0e790 R11: 0000000000000001 R12:
> ffff880080000000
> [ 18.538891] R13: ffffc00000000fff R14: ffff880059b9be98 R15:
> 0000000000000000
> [ 18.545247] FS: 0000000000000000(0000) GS:ffff88005f680000(0000)
> knlGS:0000000000000000
> [ 18.551708] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 18.558153] CR2: ffff88055c883000 CR3: 0000000002211000 CR4:
> 0000000000000660
> [ 18.564686] Stack:
> [ 18.571106] 0000000159b9be50 ffffffff82211000 ffff88055c884000
> 0000000000000800
> [ 18.577704] 0000800000000000 ffff88055c883000 0000000000000007
> ffff88005fd0e790
> [ 18.584291] ffff880059b9bed8 ffffffff81156ace 0000000000000001
> 0000000000000000
> [ 18.590916] Call Trace:
> [ 18.597458] [<ffffffff81156ace>] ? free_reserved_area+0x11e/0x120
> [ 18.604180] [<ffffffff8105b1e2>]
> ptdump_walk_pgd_level_checkwx+0x12/0x20
> [ 18.611014] [<ffffffff810515b9>] mark_rodata_ro+0xe9/0xf0
> [ 18.617819] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
> [ 18.624512] [<ffffffff81ad3398>] kernel_init+0x18/0xe0
> [ 18.631095] [<ffffffff81adadcf>] ret_from_fork+0x3f/0x70
> [ 18.637650] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
> [ 18.644178] Code: 70 ff ff ff 48 3b 85 58 ff ff ff 0f 84 c0 fe ff ff
> 48 8b 85 68 ff ff ff 48 c1 e0 10 48 c1 f8 10 48 89 45 b0 48 8b 85 70 ff
> ff ff <48> 8b 38 48 85 ff 0f 85 4e ff ff ff b9 02 00 00 00 31 d2 4c 89
> [ 18.658246] RIP [<ffffffff8105af8e>]
> ptdump_walk_pgd_level_core+0x20e/0x440
> [ 18.665211] RSP <ffff880059b9be48>
> [ 18.672073] CR2: ffff88055c883000
> [ 18.678852] ---[ end trace d84e34461c40637a ]---
> [ 18.685641] Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x00000009
> [ 18.685641]
> [ 18.699520] Kernel Offset: disable
>
What's your .config? Does cat /sys/kernel/debug/kernel_page_tables
produce a similar fault even with CONFIG_DEBUG_WX=n?
* Stephen Smalley <[email protected]> wrote:
> On 11/04/2015 06:55 AM, Sander Eikelenboom wrote:
> >Hi All,
> >
> >I just tried to boot with the current linus mergewindow tree under Xen.
> >It fails with a kernel panic at boot with the new "CONFIG_DEBUG_WX"
> >option enabled.
> >Disabling it makes the kernel boot fine.
> >
> >The splat:
> >[ 18.424241] Freeing unused kernel memory: 1104K (ffffffff822fc000 -
> >ffffffff82410000)
> >[ 18.430314] Write protecting the kernel read-only data: 18432k
> >[ 18.441054] Freeing unused kernel memory: 1144K (ffff880001ae2000 -
> >ffff880001c00000)
> >[ 18.447966] Freeing unused kernel memory: 1560K (ffff88000207a000 -
> >ffff880002200000)
> >[ 18.453947] BUG: unable to handle kernel paging request at
> >ffff88055c883000
> >[ 18.459943] IP: [<ffffffff8105af8e>]
> >ptdump_walk_pgd_level_core+0x20e/0x440
> >[ 18.465847] PGD 2212067 PUD 0
> >[ 18.471564] Oops: 0000 [#1] SMP
> >[ 18.477248] Modules linked in:
> >[ 18.482918] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
> >4.3.0-mw-20151104-linus-doflr+ #1
> >[ 18.488804] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS
> >V1.8B1 09/13/2010
> >[ 18.494778] task: ffff880059b90000 ti: ffff880059b98000 task.ti:
> >ffff880059b98000
> >[ 18.500852] RIP: e030:[<ffffffff8105af8e>] [<ffffffff8105af8e>]
> >ptdump_walk_pgd_level_core+0x20e/0x440
It would be nice to see which line of code this corresponds to. Doing this:
gdb vmlinux
list *0xffffffff8105af8e
should normally do the trick.
Thanks,
Ingo
On 2015-11-04 19:06, Ingo Molnar wrote:
> * Stephen Smalley <[email protected]> wrote:
>
>> On 11/04/2015 06:55 AM, Sander Eikelenboom wrote:
>> >Hi All,
>> >
>> >I just tried to boot with the current linus mergewindow tree under Xen.
>> >It fails with a kernel panic at boot with the new "CONFIG_DEBUG_WX"
>> >option enabled.
>> >Disabling it makes the kernel boot fine.
>> >
>> >The splat:
>> >[ 18.424241] Freeing unused kernel memory: 1104K (ffffffff822fc000 -
>> >ffffffff82410000)
>> >[ 18.430314] Write protecting the kernel read-only data: 18432k
>> >[ 18.441054] Freeing unused kernel memory: 1144K (ffff880001ae2000 -
>> >ffff880001c00000)
>> >[ 18.447966] Freeing unused kernel memory: 1560K (ffff88000207a000 -
>> >ffff880002200000)
>> >[ 18.453947] BUG: unable to handle kernel paging request at
>> >ffff88055c883000
>> >[ 18.459943] IP: [<ffffffff8105af8e>]
>> >ptdump_walk_pgd_level_core+0x20e/0x440
>> >[ 18.465847] PGD 2212067 PUD 0
>> >[ 18.471564] Oops: 0000 [#1] SMP
>> >[ 18.477248] Modules linked in:
>> >[ 18.482918] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
>> >4.3.0-mw-20151104-linus-doflr+ #1
>> >[ 18.488804] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS
>> >V1.8B1 09/13/2010
>> >[ 18.494778] task: ffff880059b90000 ti: ffff880059b98000 task.ti:
>> >ffff880059b98000
>> >[ 18.500852] RIP: e030:[<ffffffff8105af8e>] [<ffffffff8105af8e>]
>> >ptdump_walk_pgd_level_core+0x20e/0x440
>
> It would be nice to see which line of code this corresponds to. Doing
> this:
>
> gdb vmlinux
> list *0xffffffff8105af8e
>
> should normally do the trick.
>
> Thanks,
>
> Ingo
Hi Ingo,
(gdb) list *0xffffffff8105af8e
0xffffffff8105af8e is in ptdump_walk_pgd_level_core
(arch/x86/mm/dump_pagetables.c:181).
warning: Source file is more recent than executable.
176 * On 64 bits, sign-extend the 48 bit address to 64 bit
177 */
178 static unsigned long normalize_addr(unsigned long u)
179 {
180 #ifdef CONFIG_X86_64
181 return (signed long)(u << 16) >> 16;
182 #else
183 return u;
184 #endif
185 }
--
Sander
On 2015-11-04 16:52, Stephen Smalley wrote:
> On 11/04/2015 06:55 AM, Sander Eikelenboom wrote:
>> Hi All,
>>
>> I just tried to boot with the current linus mergewindow tree under
>> Xen.
>> It fails with a kernel panic at boot with the new "CONFIG_DEBUG_WX"
>> option enabled.
>> Disabling it makes the kernel boot fine.
>>
>> The splat:
>> [ 18.424241] Freeing unused kernel memory: 1104K (ffffffff822fc000 -
>> ffffffff82410000)
>> [ 18.430314] Write protecting the kernel read-only data: 18432k
>> [ 18.441054] Freeing unused kernel memory: 1144K (ffff880001ae2000 -
>> ffff880001c00000)
>> [ 18.447966] Freeing unused kernel memory: 1560K (ffff88000207a000 -
>> ffff880002200000)
>> [ 18.453947] BUG: unable to handle kernel paging request at
>> ffff88055c883000
>> [ 18.459943] IP: [<ffffffff8105af8e>]
>> ptdump_walk_pgd_level_core+0x20e/0x440
>> [ 18.465847] PGD 2212067 PUD 0
>> [ 18.471564] Oops: 0000 [#1] SMP
>> [ 18.477248] Modules linked in:
>> [ 18.482918] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
>> 4.3.0-mw-20151104-linus-doflr+ #1
>> [ 18.488804] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) ,
>> BIOS
>> V1.8B1 09/13/2010
>> [ 18.494778] task: ffff880059b90000 ti: ffff880059b98000 task.ti:
>> ffff880059b98000
>> [ 18.500852] RIP: e030:[<ffffffff8105af8e>] [<ffffffff8105af8e>]
>> ptdump_walk_pgd_level_core+0x20e/0x440
>> [ 18.507102] RSP: e02b:ffff880059b9be48 EFLAGS: 00010296
>> [ 18.513351] RAX: ffff88055c883000 RBX: ffffffff81ae2000 RCX:
>> ffff880000000000
>> [ 18.519733] RDX: 0000000000000067 RSI: ffff880059b9be98 RDI:
>> ffff880000001000
>> [ 18.526129] RBP: ffff880059b9bf00 R08: 0000000000000000 R09:
>> 0000000000000000
>> [ 18.532522] R10: ffff88005fd0e790 R11: 0000000000000001 R12:
>> ffff880080000000
>> [ 18.538891] R13: ffffc00000000fff R14: ffff880059b9be98 R15:
>> 0000000000000000
>> [ 18.545247] FS: 0000000000000000(0000) GS:ffff88005f680000(0000)
>> knlGS:0000000000000000
>> [ 18.551708] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
>> [ 18.558153] CR2: ffff88055c883000 CR3: 0000000002211000 CR4:
>> 0000000000000660
>> [ 18.564686] Stack:
>> [ 18.571106] 0000000159b9be50 ffffffff82211000 ffff88055c884000
>> 0000000000000800
>> [ 18.577704] 0000800000000000 ffff88055c883000 0000000000000007
>> ffff88005fd0e790
>> [ 18.584291] ffff880059b9bed8 ffffffff81156ace 0000000000000001
>> 0000000000000000
>> [ 18.590916] Call Trace:
>> [ 18.597458] [<ffffffff81156ace>] ? free_reserved_area+0x11e/0x120
>> [ 18.604180] [<ffffffff8105b1e2>]
>> ptdump_walk_pgd_level_checkwx+0x12/0x20
>> [ 18.611014] [<ffffffff810515b9>] mark_rodata_ro+0xe9/0xf0
>> [ 18.617819] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>> [ 18.624512] [<ffffffff81ad3398>] kernel_init+0x18/0xe0
>> [ 18.631095] [<ffffffff81adadcf>] ret_from_fork+0x3f/0x70
>> [ 18.637650] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>> [ 18.644178] Code: 70 ff ff ff 48 3b 85 58 ff ff ff 0f 84 c0 fe ff
>> ff
>> 48 8b 85 68 ff ff ff 48 c1 e0 10 48 c1 f8 10 48 89 45 b0 48 8b 85 70
>> ff
>> ff ff <48> 8b 38 48 85 ff 0f 85 4e ff ff ff b9 02 00 00 00 31 d2 4c 89
>> [ 18.658246] RIP [<ffffffff8105af8e>]
>> ptdump_walk_pgd_level_core+0x20e/0x440
>> [ 18.665211] RSP <ffff880059b9be48>
>> [ 18.672073] CR2: ffff88055c883000
>> [ 18.678852] ---[ end trace d84e34461c40637a ]---
>> [ 18.685641] Kernel panic - not syncing: Attempted to kill init!
>> exitcode=0x00000009
>> [ 18.685641]
>> [ 18.699520] Kernel Offset: disable
>>
>
> What's your .config? Does cat /sys/kernel/debug/kernel_page_tables
> produce a similar fault even with CONFIG_DEBUG_WX=n?
.config is attached
Hmm that sysfs file doesn't seem to exist then:
# cat /sys/kernel/debug/kernel_page_tables
cat: /sys/kernel/debug/kernel_page_tables: No such file or directory
--
Sander
On 11/04/2015 01:28 PM, Sander Eikelenboom wrote:
> On 2015-11-04 16:52, Stephen Smalley wrote:
>> On 11/04/2015 06:55 AM, Sander Eikelenboom wrote:
>>> Hi All,
>>>
>>> I just tried to boot with the current linus mergewindow tree under Xen.
>>> It fails with a kernel panic at boot with the new "CONFIG_DEBUG_WX"
>>> option enabled.
>>> Disabling it makes the kernel boot fine.
>>>
>>> The splat:
>>> [ 18.424241] Freeing unused kernel memory: 1104K (ffffffff822fc000 -
>>> ffffffff82410000)
>>> [ 18.430314] Write protecting the kernel read-only data: 18432k
>>> [ 18.441054] Freeing unused kernel memory: 1144K (ffff880001ae2000 -
>>> ffff880001c00000)
>>> [ 18.447966] Freeing unused kernel memory: 1560K (ffff88000207a000 -
>>> ffff880002200000)
>>> [ 18.453947] BUG: unable to handle kernel paging request at
>>> ffff88055c883000
>>> [ 18.459943] IP: [<ffffffff8105af8e>]
>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>> [ 18.465847] PGD 2212067 PUD 0
>>> [ 18.471564] Oops: 0000 [#1] SMP
>>> [ 18.477248] Modules linked in:
>>> [ 18.482918] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
>>> 4.3.0-mw-20151104-linus-doflr+ #1
>>> [ 18.488804] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS
>>> V1.8B1 09/13/2010
>>> [ 18.494778] task: ffff880059b90000 ti: ffff880059b98000 task.ti:
>>> ffff880059b98000
>>> [ 18.500852] RIP: e030:[<ffffffff8105af8e>] [<ffffffff8105af8e>]
>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>> [ 18.507102] RSP: e02b:ffff880059b9be48 EFLAGS: 00010296
>>> [ 18.513351] RAX: ffff88055c883000 RBX: ffffffff81ae2000 RCX:
>>> ffff880000000000
>>> [ 18.519733] RDX: 0000000000000067 RSI: ffff880059b9be98 RDI:
>>> ffff880000001000
>>> [ 18.526129] RBP: ffff880059b9bf00 R08: 0000000000000000 R09:
>>> 0000000000000000
>>> [ 18.532522] R10: ffff88005fd0e790 R11: 0000000000000001 R12:
>>> ffff880080000000
>>> [ 18.538891] R13: ffffc00000000fff R14: ffff880059b9be98 R15:
>>> 0000000000000000
>>> [ 18.545247] FS: 0000000000000000(0000) GS:ffff88005f680000(0000)
>>> knlGS:0000000000000000
>>> [ 18.551708] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
>>> [ 18.558153] CR2: ffff88055c883000 CR3: 0000000002211000 CR4:
>>> 0000000000000660
>>> [ 18.564686] Stack:
>>> [ 18.571106] 0000000159b9be50 ffffffff82211000 ffff88055c884000
>>> 0000000000000800
>>> [ 18.577704] 0000800000000000 ffff88055c883000 0000000000000007
>>> ffff88005fd0e790
>>> [ 18.584291] ffff880059b9bed8 ffffffff81156ace 0000000000000001
>>> 0000000000000000
>>> [ 18.590916] Call Trace:
>>> [ 18.597458] [<ffffffff81156ace>] ? free_reserved_area+0x11e/0x120
>>> [ 18.604180] [<ffffffff8105b1e2>]
>>> ptdump_walk_pgd_level_checkwx+0x12/0x20
>>> [ 18.611014] [<ffffffff810515b9>] mark_rodata_ro+0xe9/0xf0
>>> [ 18.617819] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>>> [ 18.624512] [<ffffffff81ad3398>] kernel_init+0x18/0xe0
>>> [ 18.631095] [<ffffffff81adadcf>] ret_from_fork+0x3f/0x70
>>> [ 18.637650] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>>> [ 18.644178] Code: 70 ff ff ff 48 3b 85 58 ff ff ff 0f 84 c0 fe ff ff
>>> 48 8b 85 68 ff ff ff 48 c1 e0 10 48 c1 f8 10 48 89 45 b0 48 8b 85 70 ff
>>> ff ff <48> 8b 38 48 85 ff 0f 85 4e ff ff ff b9 02 00 00 00 31 d2 4c 89
>>> [ 18.658246] RIP [<ffffffff8105af8e>]
>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>> [ 18.665211] RSP <ffff880059b9be48>
>>> [ 18.672073] CR2: ffff88055c883000
>>> [ 18.678852] ---[ end trace d84e34461c40637a ]---
>>> [ 18.685641] Kernel panic - not syncing: Attempted to kill init!
>>> exitcode=0x00000009
>>> [ 18.685641]
>>> [ 18.699520] Kernel Offset: disable
>>>
>>
>> What's your .config? Does cat /sys/kernel/debug/kernel_page_tables
>> produce a similar fault even with CONFIG_DEBUG_WX=n?
>
> .config is attached
>
> Hmm that sysfs file doesn't seem to exist then:
> # cat /sys/kernel/debug/kernel_page_tables
> cat: /sys/kernel/debug/kernel_page_tables: No such file or directory
Needs CONFIG_X86_PTDUMP=y.
Also assumes you have debugfs mounted there.
On 2015-11-04 19:47, Stephen Smalley wrote:
> On 11/04/2015 01:28 PM, Sander Eikelenboom wrote:
>> On 2015-11-04 16:52, Stephen Smalley wrote:
>>> On 11/04/2015 06:55 AM, Sander Eikelenboom wrote:
>>>> Hi All,
>>>>
>>>> I just tried to boot with the current linus mergewindow tree under
>>>> Xen.
>>>> It fails with a kernel panic at boot with the new "CONFIG_DEBUG_WX"
>>>> option enabled.
>>>> Disabling it makes the kernel boot fine.
>>>>
>>>> The splat:
>>>> [ 18.424241] Freeing unused kernel memory: 1104K (ffffffff822fc000
>>>> -
>>>> ffffffff82410000)
>>>> [ 18.430314] Write protecting the kernel read-only data: 18432k
>>>> [ 18.441054] Freeing unused kernel memory: 1144K (ffff880001ae2000
>>>> -
>>>> ffff880001c00000)
>>>> [ 18.447966] Freeing unused kernel memory: 1560K (ffff88000207a000
>>>> -
>>>> ffff880002200000)
>>>> [ 18.453947] BUG: unable to handle kernel paging request at
>>>> ffff88055c883000
>>>> [ 18.459943] IP: [<ffffffff8105af8e>]
>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>> [ 18.465847] PGD 2212067 PUD 0
>>>> [ 18.471564] Oops: 0000 [#1] SMP
>>>> [ 18.477248] Modules linked in:
>>>> [ 18.482918] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
>>>> 4.3.0-mw-20151104-linus-doflr+ #1
>>>> [ 18.488804] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) ,
>>>> BIOS
>>>> V1.8B1 09/13/2010
>>>> [ 18.494778] task: ffff880059b90000 ti: ffff880059b98000 task.ti:
>>>> ffff880059b98000
>>>> [ 18.500852] RIP: e030:[<ffffffff8105af8e>] [<ffffffff8105af8e>]
>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>> [ 18.507102] RSP: e02b:ffff880059b9be48 EFLAGS: 00010296
>>>> [ 18.513351] RAX: ffff88055c883000 RBX: ffffffff81ae2000 RCX:
>>>> ffff880000000000
>>>> [ 18.519733] RDX: 0000000000000067 RSI: ffff880059b9be98 RDI:
>>>> ffff880000001000
>>>> [ 18.526129] RBP: ffff880059b9bf00 R08: 0000000000000000 R09:
>>>> 0000000000000000
>>>> [ 18.532522] R10: ffff88005fd0e790 R11: 0000000000000001 R12:
>>>> ffff880080000000
>>>> [ 18.538891] R13: ffffc00000000fff R14: ffff880059b9be98 R15:
>>>> 0000000000000000
>>>> [ 18.545247] FS: 0000000000000000(0000) GS:ffff88005f680000(0000)
>>>> knlGS:0000000000000000
>>>> [ 18.551708] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
>>>> [ 18.558153] CR2: ffff88055c883000 CR3: 0000000002211000 CR4:
>>>> 0000000000000660
>>>> [ 18.564686] Stack:
>>>> [ 18.571106] 0000000159b9be50 ffffffff82211000 ffff88055c884000
>>>> 0000000000000800
>>>> [ 18.577704] 0000800000000000 ffff88055c883000 0000000000000007
>>>> ffff88005fd0e790
>>>> [ 18.584291] ffff880059b9bed8 ffffffff81156ace 0000000000000001
>>>> 0000000000000000
>>>> [ 18.590916] Call Trace:
>>>> [ 18.597458] [<ffffffff81156ace>] ?
>>>> free_reserved_area+0x11e/0x120
>>>> [ 18.604180] [<ffffffff8105b1e2>]
>>>> ptdump_walk_pgd_level_checkwx+0x12/0x20
>>>> [ 18.611014] [<ffffffff810515b9>] mark_rodata_ro+0xe9/0xf0
>>>> [ 18.617819] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>>>> [ 18.624512] [<ffffffff81ad3398>] kernel_init+0x18/0xe0
>>>> [ 18.631095] [<ffffffff81adadcf>] ret_from_fork+0x3f/0x70
>>>> [ 18.637650] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>>>> [ 18.644178] Code: 70 ff ff ff 48 3b 85 58 ff ff ff 0f 84 c0 fe ff
>>>> ff
>>>> 48 8b 85 68 ff ff ff 48 c1 e0 10 48 c1 f8 10 48 89 45 b0 48 8b 85 70
>>>> ff
>>>> ff ff <48> 8b 38 48 85 ff 0f 85 4e ff ff ff b9 02 00 00 00 31 d2 4c
>>>> 89
>>>> [ 18.658246] RIP [<ffffffff8105af8e>]
>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>> [ 18.665211] RSP <ffff880059b9be48>
>>>> [ 18.672073] CR2: ffff88055c883000
>>>> [ 18.678852] ---[ end trace d84e34461c40637a ]---
>>>> [ 18.685641] Kernel panic - not syncing: Attempted to kill init!
>>>> exitcode=0x00000009
>>>> [ 18.685641]
>>>> [ 18.699520] Kernel Offset: disable
>>>>
>>>
>>> What's your .config? Does cat /sys/kernel/debug/kernel_page_tables
>>> produce a similar fault even with CONFIG_DEBUG_WX=n?
>>
>> .config is attached
>>
>> Hmm that sysfs file doesn't seem to exist then:
>> # cat /sys/kernel/debug/kernel_page_tables
>> cat: /sys/kernel/debug/kernel_page_tables: No such file or directory
>
> Needs CONFIG_X86_PTDUMP=y.
> Also assumes you have debugfs mounted there.
Recompiled, and the result is that it also blows up:
[ 902.389247] BUG: unable to handle kernel paging request at
ffff88055c883000
[ 902.402749] IP: [<ffffffff8105af7e>]
ptdump_walk_pgd_level_core+0x20e/0x440
[ 902.416261] PGD 2212067 PUD 0
[ 902.427768] Oops: 0000 [#1] SMP
[ 902.438137] Modules linked in:
[ 902.448299] CPU: 2 PID: 21951 Comm: cat Not tainted
4.3.0-mw-20151104-linus-doflr-nodebugwx-withptdump+ #1
[ 902.458581] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS
V1.8B1 09/13/2010
[ 902.468850] task: ffff88004b49e300 ti: ffff88005928c000 task.ti:
ffff88005928c000
[ 902.479133] RIP: e030:[<ffffffff8105af7e>] [<ffffffff8105af7e>]
ptdump_walk_pgd_level_core+0x20e/0x440
[ 902.489536] RSP: e02b:ffff88005928fd20 EFLAGS: 00010296
[ 902.499692] RAX: ffff88055c883000 RBX: 0000000000000000 RCX:
ffff880000000000
[ 902.509755] RDX: 0000000000000067 RSI: ffff88005928fd70 RDI:
ffff880000001000
[ 902.519680] RBP: ffff88005928fdd8 R08: 0000000000001000 R09:
000000000000ffff
[ 902.529555] R10: 0000000000000000 R11: 0000000000000246 R12:
ffff88005928ff20
[ 902.539349] R13: ffffc00000000fff R14: ffff88005928fd70 R15:
ffff880033c773c0
[ 902.549081] FS: 00007f56b07d4700(0000) GS:ffff88005f680000(0000)
knlGS:0000000000000000
[ 902.558690] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 902.568111] CR2: ffff88055c883000 CR3: 000000004563f000 CR4:
0000000000000660
[ 902.577508] Stack:
[ 902.586741] 00000000810ffd21 ffffffff82211000 ffff88055c884000
0000000000000800
[ 902.596090] 0000800000000000 ffff88055c883000 00007f56b0629000
0000000000000001
[ 902.605395] ffff88005928ff20 ffffffff81ad88ba 0000000000000001
0000000000000000
[ 902.614452] Call Trace:
[ 902.623254] [<ffffffff81ad88ba>] ? __mutex_lock_slowpath+0x27a/0x3a0
[ 902.632067] [<ffffffff8105b1bd>] ptdump_show+0xd/0x20
[ 902.640767] [<ffffffff811c857b>] seq_read+0xcb/0x380
[ 902.649379] [<ffffffff811a8273>] __vfs_read+0x23/0xd0
[ 902.657909] [<ffffffff81167cb5>] ? vm_mmap_pgoff+0x75/0xa0
[ 902.666195] [<ffffffff811a8a01>] vfs_read+0x81/0x130
[ 902.674248] [<ffffffff811a96f4>] SyS_read+0x44/0xb0
[ 902.682220] [<ffffffff81ada6ae>] entry_SYSCALL_64_fastpath+0x12/0x71
[ 902.690182] Code: 70 ff ff ff 48 3b 85 58 ff ff ff 0f 84 c0 fe ff ff
48 8b 85 68 ff ff ff 48 c1 e0 10 48 c1 f8 10 48 89 45 b0 48 8b 85 70 ff
ff ff <48> 8b 38 48 85 ff 0f 85 4e ff ff ff b9 02 00 00 00 31 d2 4c 89
[ 902.706831] RIP [<ffffffff8105af7e>]
ptdump_walk_pgd_level_core+0x20e/0x440
[ 902.715008] RSP <ffff88005928fd20>
[ 902.722955] CR2: ffff88055c883000
[ 902.730630] ---[ end trace 5d94ee3d1b42814b ]---
On 11/04/2015 01:47 PM, Stephen Smalley wrote:
> On 11/04/2015 01:28 PM, Sander Eikelenboom wrote:
>> On 2015-11-04 16:52, Stephen Smalley wrote:
>>> On 11/04/2015 06:55 AM, Sander Eikelenboom wrote:
>>>> Hi All,
>>>>
>>>> I just tried to boot with the current linus mergewindow tree under
>>>> Xen.
>>>> It fails with a kernel panic at boot with the new "CONFIG_DEBUG_WX"
>>>> option enabled.
>>>> Disabling it makes the kernel boot fine.
>>>>
>>>> The splat:
>>>> [ 18.424241] Freeing unused kernel memory: 1104K (ffffffff822fc000 -
>>>> ffffffff82410000)
>>>> [ 18.430314] Write protecting the kernel read-only data: 18432k
>>>> [ 18.441054] Freeing unused kernel memory: 1144K (ffff880001ae2000 -
>>>> ffff880001c00000)
>>>> [ 18.447966] Freeing unused kernel memory: 1560K (ffff88000207a000 -
>>>> ffff880002200000)
>>>> [ 18.453947] BUG: unable to handle kernel paging request at
>>>> ffff88055c883000
>>>> [ 18.459943] IP: [<ffffffff8105af8e>]
>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>> [ 18.465847] PGD 2212067 PUD 0
>>>> [ 18.471564] Oops: 0000 [#1] SMP
>>>> [ 18.477248] Modules linked in:
>>>> [ 18.482918] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
>>>> 4.3.0-mw-20151104-linus-doflr+ #1
>>>> [ 18.488804] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) ,
>>>> BIOS
>>>> V1.8B1 09/13/2010
>>>> [ 18.494778] task: ffff880059b90000 ti: ffff880059b98000 task.ti:
>>>> ffff880059b98000
>>>> [ 18.500852] RIP: e030:[<ffffffff8105af8e>] [<ffffffff8105af8e>]
>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>> [ 18.507102] RSP: e02b:ffff880059b9be48 EFLAGS: 00010296
>>>> [ 18.513351] RAX: ffff88055c883000 RBX: ffffffff81ae2000 RCX:
>>>> ffff880000000000
>>>> [ 18.519733] RDX: 0000000000000067 RSI: ffff880059b9be98 RDI:
>>>> ffff880000001000
>>>> [ 18.526129] RBP: ffff880059b9bf00 R08: 0000000000000000 R09:
>>>> 0000000000000000
>>>> [ 18.532522] R10: ffff88005fd0e790 R11: 0000000000000001 R12:
>>>> ffff880080000000
>>>> [ 18.538891] R13: ffffc00000000fff R14: ffff880059b9be98 R15:
>>>> 0000000000000000
>>>> [ 18.545247] FS: 0000000000000000(0000) GS:ffff88005f680000(0000)
>>>> knlGS:0000000000000000
>>>> [ 18.551708] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
>>>> [ 18.558153] CR2: ffff88055c883000 CR3: 0000000002211000 CR4:
>>>> 0000000000000660
>>>> [ 18.564686] Stack:
>>>> [ 18.571106] 0000000159b9be50 ffffffff82211000 ffff88055c884000
>>>> 0000000000000800
>>>> [ 18.577704] 0000800000000000 ffff88055c883000 0000000000000007
>>>> ffff88005fd0e790
>>>> [ 18.584291] ffff880059b9bed8 ffffffff81156ace 0000000000000001
>>>> 0000000000000000
>>>> [ 18.590916] Call Trace:
>>>> [ 18.597458] [<ffffffff81156ace>] ? free_reserved_area+0x11e/0x120
>>>> [ 18.604180] [<ffffffff8105b1e2>]
>>>> ptdump_walk_pgd_level_checkwx+0x12/0x20
>>>> [ 18.611014] [<ffffffff810515b9>] mark_rodata_ro+0xe9/0xf0
>>>> [ 18.617819] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>>>> [ 18.624512] [<ffffffff81ad3398>] kernel_init+0x18/0xe0
>>>> [ 18.631095] [<ffffffff81adadcf>] ret_from_fork+0x3f/0x70
>>>> [ 18.637650] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>>>> [ 18.644178] Code: 70 ff ff ff 48 3b 85 58 ff ff ff 0f 84 c0 fe
>>>> ff ff
>>>> 48 8b 85 68 ff ff ff 48 c1 e0 10 48 c1 f8 10 48 89 45 b0 48 8b 85
>>>> 70 ff
>>>> ff ff <48> 8b 38 48 85 ff 0f 85 4e ff ff ff b9 02 00 00 00 31 d2 4c 89
>>>> [ 18.658246] RIP [<ffffffff8105af8e>]
>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>> [ 18.665211] RSP <ffff880059b9be48>
>>>> [ 18.672073] CR2: ffff88055c883000
>>>> [ 18.678852] ---[ end trace d84e34461c40637a ]---
>>>> [ 18.685641] Kernel panic - not syncing: Attempted to kill init!
>>>> exitcode=0x00000009
>>>> [ 18.685641]
>>>> [ 18.699520] Kernel Offset: disable
>>>>
>>>
>>> What's your .config? Does cat /sys/kernel/debug/kernel_page_tables
>>> produce a similar fault even with CONFIG_DEBUG_WX=n?
>>
>> .config is attached
>>
>> Hmm that sysfs file doesn't seem to exist then:
>> # cat /sys/kernel/debug/kernel_page_tables
>> cat: /sys/kernel/debug/kernel_page_tables: No such file or directory
>
> Needs CONFIG_X86_PTDUMP=y.
> Also assumes you have debugfs mounted there.
I don't think this code (including original page tables dump) can work
on Xen PV guests: we are walking full PGD, including the hypervisor hole
(entries 256-272).
-boris
On 11/04/2015 03:02 PM, Sander Eikelenboom wrote:
> On 2015-11-04 19:47, Stephen Smalley wrote:
>> On 11/04/2015 01:28 PM, Sander Eikelenboom wrote:
>>> On 2015-11-04 16:52, Stephen Smalley wrote:
>>>> On 11/04/2015 06:55 AM, Sander Eikelenboom wrote:
>>>>> Hi All,
>>>>>
>>>>> I just tried to boot with the current linus mergewindow tree under
>>>>> Xen.
>>>>> It fails with a kernel panic at boot with the new "CONFIG_DEBUG_WX"
>>>>> option enabled.
>>>>> Disabling it makes the kernel boot fine.
>>>>>
>>>>> The splat:
>>>>> [ 18.424241] Freeing unused kernel memory: 1104K
>>>>> (ffffffff822fc000 -
>>>>> ffffffff82410000)
>>>>> [ 18.430314] Write protecting the kernel read-only data: 18432k
>>>>> [ 18.441054] Freeing unused kernel memory: 1144K
>>>>> (ffff880001ae2000 -
>>>>> ffff880001c00000)
>>>>> [ 18.447966] Freeing unused kernel memory: 1560K
>>>>> (ffff88000207a000 -
>>>>> ffff880002200000)
>>>>> [ 18.453947] BUG: unable to handle kernel paging request at
>>>>> ffff88055c883000
>>>>> [ 18.459943] IP: [<ffffffff8105af8e>]
>>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>>> [ 18.465847] PGD 2212067 PUD 0
>>>>> [ 18.471564] Oops: 0000 [#1] SMP
>>>>> [ 18.477248] Modules linked in:
>>>>> [ 18.482918] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
>>>>> 4.3.0-mw-20151104-linus-doflr+ #1
>>>>> [ 18.488804] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) ,
>>>>> BIOS
>>>>> V1.8B1 09/13/2010
>>>>> [ 18.494778] task: ffff880059b90000 ti: ffff880059b98000 task.ti:
>>>>> ffff880059b98000
>>>>> [ 18.500852] RIP: e030:[<ffffffff8105af8e>] [<ffffffff8105af8e>]
>>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>>> [ 18.507102] RSP: e02b:ffff880059b9be48 EFLAGS: 00010296
>>>>> [ 18.513351] RAX: ffff88055c883000 RBX: ffffffff81ae2000 RCX:
>>>>> ffff880000000000
>>>>> [ 18.519733] RDX: 0000000000000067 RSI: ffff880059b9be98 RDI:
>>>>> ffff880000001000
>>>>> [ 18.526129] RBP: ffff880059b9bf00 R08: 0000000000000000 R09:
>>>>> 0000000000000000
>>>>> [ 18.532522] R10: ffff88005fd0e790 R11: 0000000000000001 R12:
>>>>> ffff880080000000
>>>>> [ 18.538891] R13: ffffc00000000fff R14: ffff880059b9be98 R15:
>>>>> 0000000000000000
>>>>> [ 18.545247] FS: 0000000000000000(0000) GS:ffff88005f680000(0000)
>>>>> knlGS:0000000000000000
>>>>> [ 18.551708] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
>>>>> [ 18.558153] CR2: ffff88055c883000 CR3: 0000000002211000 CR4:
>>>>> 0000000000000660
>>>>> [ 18.564686] Stack:
>>>>> [ 18.571106] 0000000159b9be50 ffffffff82211000 ffff88055c884000
>>>>> 0000000000000800
>>>>> [ 18.577704] 0000800000000000 ffff88055c883000 0000000000000007
>>>>> ffff88005fd0e790
>>>>> [ 18.584291] ffff880059b9bed8 ffffffff81156ace 0000000000000001
>>>>> 0000000000000000
>>>>> [ 18.590916] Call Trace:
>>>>> [ 18.597458] [<ffffffff81156ace>] ? free_reserved_area+0x11e/0x120
>>>>> [ 18.604180] [<ffffffff8105b1e2>]
>>>>> ptdump_walk_pgd_level_checkwx+0x12/0x20
>>>>> [ 18.611014] [<ffffffff810515b9>] mark_rodata_ro+0xe9/0xf0
>>>>> [ 18.617819] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>>>>> [ 18.624512] [<ffffffff81ad3398>] kernel_init+0x18/0xe0
>>>>> [ 18.631095] [<ffffffff81adadcf>] ret_from_fork+0x3f/0x70
>>>>> [ 18.637650] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>>>>> [ 18.644178] Code: 70 ff ff ff 48 3b 85 58 ff ff ff 0f 84 c0 fe
>>>>> ff ff
>>>>> 48 8b 85 68 ff ff ff 48 c1 e0 10 48 c1 f8 10 48 89 45 b0 48 8b 85
>>>>> 70 ff
>>>>> ff ff <48> 8b 38 48 85 ff 0f 85 4e ff ff ff b9 02 00 00 00 31 d2
>>>>> 4c 89
>>>>> [ 18.658246] RIP [<ffffffff8105af8e>]
>>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>>> [ 18.665211] RSP <ffff880059b9be48>
>>>>> [ 18.672073] CR2: ffff88055c883000
>>>>> [ 18.678852] ---[ end trace d84e34461c40637a ]---
>>>>> [ 18.685641] Kernel panic - not syncing: Attempted to kill init!
>>>>> exitcode=0x00000009
>>>>> [ 18.685641]
>>>>> [ 18.699520] Kernel Offset: disable
>>>>>
>>>>
>>>> What's your .config? Does cat /sys/kernel/debug/kernel_page_tables
>>>> produce a similar fault even with CONFIG_DEBUG_WX=n?
>>>
>>> .config is attached
>>>
>>> Hmm that sysfs file doesn't seem to exist then:
>>> # cat /sys/kernel/debug/kernel_page_tables
>>> cat: /sys/kernel/debug/kernel_page_tables: No such file or directory
>>
>> Needs CONFIG_X86_PTDUMP=y.
>> Also assumes you have debugfs mounted there.
>
> Recompiled, and the result is that it also blows up:
>
Can you try this:
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 1bf417e..b534216 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -362,8 +362,13 @@ static void ptdump_walk_pgd_level_core(struct
seq_file *m, pgd_t *pgd,
bool checkwx)
{
#ifdef CONFIG_X86_64
+/* ffff800000000000 - ffff87ffffffffff is reserved for hypervisor */
+#define is_hypervisor_range(idx) (paravirt_enabled() && \
+ ((idx >= pgd_index(__PAGE_OFFSET) - 16) && \
+ (idx < pgd_index(__PAGE_OFFSET))))
pgd_t *start = (pgd_t *) &init_level4_pgt;
#else
+#define is_hypervisor_range(idx) 0
pgd_t *start = swapper_pg_dir;
#endif
pgprotval_t prot;
@@ -381,7 +386,7 @@ static void ptdump_walk_pgd_level_core(struct
seq_file *m, pgd_t *pgd,
for (i = 0; i < PTRS_PER_PGD; i++) {
st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
- if (!pgd_none(*start)) {
+ if (!pgd_none(*start) && !is_hypervisor_range(i)) {
if (pgd_large(*start) || !pgd_present(*start)) {
prot = pgd_flags(*start);
note_page(m, &st, __pgprot(prot), 1);
On 2015-11-05 00:13, Boris Ostrovsky wrote:
> On 11/04/2015 03:02 PM, Sander Eikelenboom wrote:
>> On 2015-11-04 19:47, Stephen Smalley wrote:
>>> On 11/04/2015 01:28 PM, Sander Eikelenboom wrote:
>>>> On 2015-11-04 16:52, Stephen Smalley wrote:
>>>>> On 11/04/2015 06:55 AM, Sander Eikelenboom wrote:
>>>>>> Hi All,
>>>>>>
>>>>>> I just tried to boot with the current linus mergewindow tree under
>>>>>> Xen.
>>>>>> It fails with a kernel panic at boot with the new
>>>>>> "CONFIG_DEBUG_WX"
>>>>>> option enabled.
>>>>>> Disabling it makes the kernel boot fine.
>>>>>>
>>>>>> The splat:
>>>>>> [ 18.424241] Freeing unused kernel memory: 1104K
>>>>>> (ffffffff822fc000 -
>>>>>> ffffffff82410000)
>>>>>> [ 18.430314] Write protecting the kernel read-only data: 18432k
>>>>>> [ 18.441054] Freeing unused kernel memory: 1144K
>>>>>> (ffff880001ae2000 -
>>>>>> ffff880001c00000)
>>>>>> [ 18.447966] Freeing unused kernel memory: 1560K
>>>>>> (ffff88000207a000 -
>>>>>> ffff880002200000)
>>>>>> [ 18.453947] BUG: unable to handle kernel paging request at
>>>>>> ffff88055c883000
>>>>>> [ 18.459943] IP: [<ffffffff8105af8e>]
>>>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>>>> [ 18.465847] PGD 2212067 PUD 0
>>>>>> [ 18.471564] Oops: 0000 [#1] SMP
>>>>>> [ 18.477248] Modules linked in:
>>>>>> [ 18.482918] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
>>>>>> 4.3.0-mw-20151104-linus-doflr+ #1
>>>>>> [ 18.488804] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) ,
>>>>>> BIOS
>>>>>> V1.8B1 09/13/2010
>>>>>> [ 18.494778] task: ffff880059b90000 ti: ffff880059b98000
>>>>>> task.ti:
>>>>>> ffff880059b98000
>>>>>> [ 18.500852] RIP: e030:[<ffffffff8105af8e>] [<ffffffff8105af8e>]
>>>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>>>> [ 18.507102] RSP: e02b:ffff880059b9be48 EFLAGS: 00010296
>>>>>> [ 18.513351] RAX: ffff88055c883000 RBX: ffffffff81ae2000 RCX:
>>>>>> ffff880000000000
>>>>>> [ 18.519733] RDX: 0000000000000067 RSI: ffff880059b9be98 RDI:
>>>>>> ffff880000001000
>>>>>> [ 18.526129] RBP: ffff880059b9bf00 R08: 0000000000000000 R09:
>>>>>> 0000000000000000
>>>>>> [ 18.532522] R10: ffff88005fd0e790 R11: 0000000000000001 R12:
>>>>>> ffff880080000000
>>>>>> [ 18.538891] R13: ffffc00000000fff R14: ffff880059b9be98 R15:
>>>>>> 0000000000000000
>>>>>> [ 18.545247] FS: 0000000000000000(0000)
>>>>>> GS:ffff88005f680000(0000)
>>>>>> knlGS:0000000000000000
>>>>>> [ 18.551708] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
>>>>>> [ 18.558153] CR2: ffff88055c883000 CR3: 0000000002211000 CR4:
>>>>>> 0000000000000660
>>>>>> [ 18.564686] Stack:
>>>>>> [ 18.571106] 0000000159b9be50 ffffffff82211000 ffff88055c884000
>>>>>> 0000000000000800
>>>>>> [ 18.577704] 0000800000000000 ffff88055c883000 0000000000000007
>>>>>> ffff88005fd0e790
>>>>>> [ 18.584291] ffff880059b9bed8 ffffffff81156ace 0000000000000001
>>>>>> 0000000000000000
>>>>>> [ 18.590916] Call Trace:
>>>>>> [ 18.597458] [<ffffffff81156ace>] ?
>>>>>> free_reserved_area+0x11e/0x120
>>>>>> [ 18.604180] [<ffffffff8105b1e2>]
>>>>>> ptdump_walk_pgd_level_checkwx+0x12/0x20
>>>>>> [ 18.611014] [<ffffffff810515b9>] mark_rodata_ro+0xe9/0xf0
>>>>>> [ 18.617819] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>>>>>> [ 18.624512] [<ffffffff81ad3398>] kernel_init+0x18/0xe0
>>>>>> [ 18.631095] [<ffffffff81adadcf>] ret_from_fork+0x3f/0x70
>>>>>> [ 18.637650] [<ffffffff81ad3380>] ? rest_init+0x80/0x80
>>>>>> [ 18.644178] Code: 70 ff ff ff 48 3b 85 58 ff ff ff 0f 84 c0 fe
>>>>>> ff ff
>>>>>> 48 8b 85 68 ff ff ff 48 c1 e0 10 48 c1 f8 10 48 89 45 b0 48 8b 85
>>>>>> 70 ff
>>>>>> ff ff <48> 8b 38 48 85 ff 0f 85 4e ff ff ff b9 02 00 00 00 31 d2
>>>>>> 4c 89
>>>>>> [ 18.658246] RIP [<ffffffff8105af8e>]
>>>>>> ptdump_walk_pgd_level_core+0x20e/0x440
>>>>>> [ 18.665211] RSP <ffff880059b9be48>
>>>>>> [ 18.672073] CR2: ffff88055c883000
>>>>>> [ 18.678852] ---[ end trace d84e34461c40637a ]---
>>>>>> [ 18.685641] Kernel panic - not syncing: Attempted to kill init!
>>>>>> exitcode=0x00000009
>>>>>> [ 18.685641]
>>>>>> [ 18.699520] Kernel Offset: disable
>>>>>>
>>>>>
>>>>> What's your .config? Does cat /sys/kernel/debug/kernel_page_tables
>>>>> produce a similar fault even with CONFIG_DEBUG_WX=n?
>>>>
>>>> .config is attached
>>>>
>>>> Hmm that sysfs file doesn't seem to exist then:
>>>> # cat /sys/kernel/debug/kernel_page_tables
>>>> cat: /sys/kernel/debug/kernel_page_tables: No such file or directory
>>>
>>> Needs CONFIG_X86_PTDUMP=y.
>>> Also assumes you have debugfs mounted there.
>>
>> Recompiled, and the result is that it also blows up:
>>
>
> Can you try this:
>
>
> diff --git a/arch/x86/mm/dump_pagetables.c
> b/arch/x86/mm/dump_pagetables.c
> index 1bf417e..b534216 100644
> --- a/arch/x86/mm/dump_pagetables.c
> +++ b/arch/x86/mm/dump_pagetables.c
> @@ -362,8 +362,13 @@ static void ptdump_walk_pgd_level_core(struct
> seq_file *m, pgd_t *pgd,
> bool checkwx)
> {
> #ifdef CONFIG_X86_64
> +/* ffff800000000000 - ffff87ffffffffff is reserved for hypervisor */
> +#define is_hypervisor_range(idx) (paravirt_enabled() && \
> + ((idx >= pgd_index(__PAGE_OFFSET) - 16) && \
> + (idx < pgd_index(__PAGE_OFFSET))))
> pgd_t *start = (pgd_t *) &init_level4_pgt;
> #else
> +#define is_hypervisor_range(idx) 0
> pgd_t *start = swapper_pg_dir;
> #endif
> pgprotval_t prot;
> @@ -381,7 +386,7 @@ static void ptdump_walk_pgd_level_core(struct
> seq_file *m, pgd_t *pgd,
>
> for (i = 0; i < PTRS_PER_PGD; i++) {
> st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
> - if (!pgd_none(*start)) {
> + if (!pgd_none(*start) && !is_hypervisor_range(i)) {
> if (pgd_large(*start) || !pgd_present(*start)) {
> prot = pgd_flags(*start);
> note_page(m, &st, __pgprot(prot), 1);
Hi Boris,
Thank for your patch !
It makes "cat /sys/kernel/debug/kernel_page_tables" work and
prevents a kernel with CONFIG_DEBUG_WX=y from crashing at boot.
It now does give a warning about an insecure W+X mapping, so
CONFIG_DEBUG_WX=y
seems to be working. No idea how to interpret it though (and if it's a
legit
warning).
--
Sander
[ 19.034706] Freeing unused kernel memory: 1104K (ffffffff822fc000 -
ffffffff82410000)
[ 19.041339] Write protecting the kernel read-only data: 18432k
[ 19.052596] Freeing unused kernel memory: 1144K (ffff880001ae2000 -
ffff880001c00000)
[ 19.060285] Freeing unused kernel memory: 1560K (ffff88000207a000 -
ffff880002200000)
[ 19.067079] ------------[ cut here ]------------
[ 19.073931] WARNING: CPU: 5 PID: 1 at
arch/x86/mm/dump_pagetables.c:225 note_page+0x619/0x7e0()
[ 19.081039] x86/mm: Found insecure W+X mapping at address
ffff880000000000/0xffff880000000000
[ 19.088293] Modules linked in:
[ 19.095477] CPU: 5 PID: 1 Comm: swapper/0 Not tainted
4.3.0-mw-20151104-linus-doflr-withdebugwx-noptdump-ptdumppatch+ #1
[ 19.102971] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS
V1.8B1 09/13/2010
[ 19.110594] ffffffff81f381d3 ffff880059b9bd60 ffffffff81428992
ffff880059b9bda8
[ 19.118239] ffff880059b9bd98 ffffffff810ca7ec ffff8800025d8010
0000000000000004
[ 19.125870] 0010000000000067 ffff880059b9be98 0000000000000000
ffff880059b9bdf8
[ 19.133526] Call Trace:
[ 19.141212] [<ffffffff81428992>] dump_stack+0x44/0x62
[ 19.148983] [<ffffffff810ca7ec>] warn_slowpath_common+0x7c/0xb0
[ 19.156877] [<ffffffff810ca867>] warn_slowpath_fmt+0x47/0x50
[ 19.164813] [<ffffffff8105abb9>] note_page+0x619/0x7e0
[ 19.172656] [<ffffffff8105b135>]
ptdump_walk_pgd_level_core+0x3b5/0x450
[ 19.180583] [<ffffffff8105b1f2>]
ptdump_walk_pgd_level_checkwx+0x12/0x20
[ 19.188427] [<ffffffff810515b9>] mark_rodata_ro+0xe9/0xf0
[ 19.196221] [<ffffffff81ad2f70>] ? rest_init+0x80/0x80
[ 19.204012] [<ffffffff81ad2f88>] kernel_init+0x18/0xe0
[ 19.211732] [<ffffffff81ada98f>] ret_from_fork+0x3f/0x70
[ 19.219467] [<ffffffff81ad2f70>] ? rest_init+0x80/0x80
[ 19.227145] ---[ end trace 5fc0f4297b911570 ]---
[ 19.244382] x86/mm: Checked W+X mappings: FAILED, 4602 W+X pages
found.
On 11/05/2015 04:13 AM, Sander Eikelenboom wrote:
>
> It makes "cat /sys/kernel/debug/kernel_page_tables" work and
> prevents a kernel with CONFIG_DEBUG_WX=y from crashing at boot.
Great. Our nightly runs also failed spectacularly due to this bug.
>
> It now does give a warning about an insecure W+X mapping, so
> CONFIG_DEBUG_WX=y
> seems to be working. No idea how to interpret it though (and if it's a
> legit
> warning).
>
> --
> Sander
>
> [ 19.034706] Freeing unused kernel memory: 1104K (ffffffff822fc000 -
> ffffffff82410000)
> [ 19.041339] Write protecting the kernel read-only data: 18432k
> [ 19.052596] Freeing unused kernel memory: 1144K (ffff880001ae2000 -
> ffff880001c00000)
> [ 19.060285] Freeing unused kernel memory: 1560K (ffff88000207a000 -
> ffff880002200000)
> [ 19.067079] ------------[ cut here ]------------
> [ 19.073931] WARNING: CPU: 5 PID: 1 at
> arch/x86/mm/dump_pagetables.c:225 note_page+0x619/0x7e0()
Yes, this apparently is a known issue: https://lkml.org/lkml/2015/11/4/476
-boris
Thursday, November 5, 2015, 2:53:40 PM, you wrote:
> On 11/05/2015 04:13 AM, Sander Eikelenboom wrote:
>>
>> It makes "cat /sys/kernel/debug/kernel_page_tables" work and
>> prevents a kernel with CONFIG_DEBUG_WX=y from crashing at boot.
> Great. Our nightly runs also failed spectacularly due to this bug.
>>
>> It now does give a warning about an insecure W+X mapping, so
>> CONFIG_DEBUG_WX=y
>> seems to be working. No idea how to interpret it though (and if it's a
>> legit
>> warning).
>>
>> --
>> Sander
>>
>> [ 19.034706] Freeing unused kernel memory: 1104K (ffffffff822fc000 -
>> ffffffff82410000)
>> [ 19.041339] Write protecting the kernel read-only data: 18432k
>> [ 19.052596] Freeing unused kernel memory: 1144K (ffff880001ae2000 -
>> ffff880001c00000)
>> [ 19.060285] Freeing unused kernel memory: 1560K (ffff88000207a000 -
>> ffff880002200000)
>> [ 19.067079] ------------[ cut here ]------------
>> [ 19.073931] WARNING: CPU: 5 PID: 1 at
>> arch/x86/mm/dump_pagetables.c:225 note_page+0x619/0x7e0()
> Yes, this apparently is a known issue: https://lkml.org/lkml/2015/11/4/476
> -boris
Ah thx for the pointer :)
--
Sander