* [v5.3-rc1 regression] Hitting a kernel BUG() when trying to load a module on DaVinci SoC
@ 2019-07-22 12:12 Bartosz Golaszewski
2019-07-22 13:05 ` Bartosz Golaszewski
2019-07-22 16:10 ` Jessica Yu
0 siblings, 2 replies; 5+ messages in thread
From: Bartosz Golaszewski @ 2019-07-22 12:12 UTC (permalink / raw)
To: Yang Yingliang, Jian Cheng, Nadav Amit, Jessica Yu,
Linux Kernel Mailing List
Cc: Sekhar Nori, Kevin Hilman, David Lechner, Adam Ford
Hi,
with v5.3-rc1 I'm hitting the following BUG() when trying to load the
gpio-backlight module:
kernel BUG at kernel/module.c:1919!
Internal error: Oops - BUG: 0 [#1] PREEMPT ARM
Modules linked in:
CPU: 0 PID: 1 Comm: systemd Tainted: G W
5.2.0-rc2-00005-g7dabaa5ce05a #19
Hardware name: DaVinci DA850/OMAP-L138/AM18x EVM
PC is at frob_text.constprop.16+0x2c/0x34
LR is at load_module+0x1888/0x21b4
pc : [<c0081bbc>] lr : [<c0083c4c>] psr: 20000013
sp : c6837e58 ip : c6b4fa80 fp : bf00574c
r10: c0601008 r9 : bf005740 r8 : c0493e38
r7 : c00807f8 r6 : 00000000 r5 : 00000001 r4 : c6837f38
r3 : 00000fff r2 : bf000000 r1 : 00004b80 r0 : bf005818
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 0005317f Table: c6b78000 DAC: 00000051
Process systemd (pid: 1, stack limit = 0x(ptrval))
Stack: (0xc6837e58 to 0xc6838000)
7e40: bf005740 c6492a90
7e60: 00000001 c6bf5788 00000003 c6837f38 bf0058c0 bf0058a8 bf00a495 c0493e38
7e80: 00000000 c05368c0 00000001 00000000 c0580030 c0574b28 00000000 00000000
7ea0: 00000000 00000000 00000000 00000000 6e72656b 00006c65 00000000 00000000
7ec0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
7ee0: 00000000 00000000 00000000 aefb2bb8 7fffffff c0601008 00000000 00000004
7f00: b6cee714 c00091e4 c6836000 00000000 005bc668 c00847b0 7fffffff 00000000
7f20: 00000003 00000000 0000b2d0 c884e000 0000b2d0 00000000 c8852dcb c88533a0
7f40: c884e000 0000b2d0 c8858cb8 c8858b34 c88568d4 000058c0 00006190 000023b8
7f60: 00006713 00000000 00000000 00000000 000023a8 00000024 00000025 00000019
7f80: 0000001d 00000011 00000000 aefb2bb8 00000000 00000000 00000000 00000000
7fa0: 0000017b c0009000 00000000 00000000 00000004 b6cee714 00000000 00000000
7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0 60000010 00000004 00000000 00000000
[<c0081bbc>] (frob_text.constprop.16) from [<c0083c4c>]
(load_module+0x1888/0x21b4)
[<c0083c4c>] (load_module) from [<c00847b0>] (sys_finit_module+0xbc/0xdc)
[<c00847b0>] (sys_finit_module) from [<c0009000>] (ret_fast_syscall+0x0/0x50)
Exception stack(0xc6837fa8 to 0xc6837ff0)
7fa0: 00000000 00000000 00000004 b6cee714 00000000 00000000
7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0
Code: e1a01621 e1a00002 eafe4531 e7f001f2 (e7f001f2)
---[ end trace 2cbefb0005882c52 ]---
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
---[ end Kernel panic - not syncing: Attempted to kill init!
exitcode=0x0000000b ]---
I bisected it to commit 06bd260e836d ("modules: fix BUG when load
module with rodata=n") with commit 7dabaa5ce05a ("modules: fix compile
error if don't have strict module rwx") on top to make it build.
Let me know if you need me to provide more info.
Best regards,
Bartosz Golaszewski
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [v5.3-rc1 regression] Hitting a kernel BUG() when trying to load a module on DaVinci SoC
2019-07-22 12:12 [v5.3-rc1 regression] Hitting a kernel BUG() when trying to load a module on DaVinci SoC Bartosz Golaszewski
@ 2019-07-22 13:05 ` Bartosz Golaszewski
2019-07-22 16:10 ` Jessica Yu
1 sibling, 0 replies; 5+ messages in thread
From: Bartosz Golaszewski @ 2019-07-22 13:05 UTC (permalink / raw)
To: Yang Yingliang, Jian Cheng, Nadav Amit, Jessica Yu,
Linux Kernel Mailing List
Cc: Sekhar Nori, Kevin Hilman, David Lechner, Adam Ford
pon., 22 lip 2019 o 14:12 Bartosz Golaszewski <brgl@bgdev.pl> napisał(a):
>
> Hi,
>
> with v5.3-rc1 I'm hitting the following BUG() when trying to load the
> gpio-backlight module:
>
> kernel BUG at kernel/module.c:1919!
> Internal error: Oops - BUG: 0 [#1] PREEMPT ARM
> Modules linked in:
> CPU: 0 PID: 1 Comm: systemd Tainted: G W
> 5.2.0-rc2-00005-g7dabaa5ce05a #19
> Hardware name: DaVinci DA850/OMAP-L138/AM18x EVM
> PC is at frob_text.constprop.16+0x2c/0x34
> LR is at load_module+0x1888/0x21b4
> pc : [<c0081bbc>] lr : [<c0083c4c>] psr: 20000013
> sp : c6837e58 ip : c6b4fa80 fp : bf00574c
> r10: c0601008 r9 : bf005740 r8 : c0493e38
> r7 : c00807f8 r6 : 00000000 r5 : 00000001 r4 : c6837f38
> r3 : 00000fff r2 : bf000000 r1 : 00004b80 r0 : bf005818
> Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
> Control: 0005317f Table: c6b78000 DAC: 00000051
> Process systemd (pid: 1, stack limit = 0x(ptrval))
> Stack: (0xc6837e58 to 0xc6838000)
> 7e40: bf005740 c6492a90
> 7e60: 00000001 c6bf5788 00000003 c6837f38 bf0058c0 bf0058a8 bf00a495 c0493e38
> 7e80: 00000000 c05368c0 00000001 00000000 c0580030 c0574b28 00000000 00000000
> 7ea0: 00000000 00000000 00000000 00000000 6e72656b 00006c65 00000000 00000000
> 7ec0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 7ee0: 00000000 00000000 00000000 aefb2bb8 7fffffff c0601008 00000000 00000004
> 7f00: b6cee714 c00091e4 c6836000 00000000 005bc668 c00847b0 7fffffff 00000000
> 7f20: 00000003 00000000 0000b2d0 c884e000 0000b2d0 00000000 c8852dcb c88533a0
> 7f40: c884e000 0000b2d0 c8858cb8 c8858b34 c88568d4 000058c0 00006190 000023b8
> 7f60: 00006713 00000000 00000000 00000000 000023a8 00000024 00000025 00000019
> 7f80: 0000001d 00000011 00000000 aefb2bb8 00000000 00000000 00000000 00000000
> 7fa0: 0000017b c0009000 00000000 00000000 00000004 b6cee714 00000000 00000000
> 7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
> 7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0 60000010 00000004 00000000 00000000
> [<c0081bbc>] (frob_text.constprop.16) from [<c0083c4c>]
> (load_module+0x1888/0x21b4)
> [<c0083c4c>] (load_module) from [<c00847b0>] (sys_finit_module+0xbc/0xdc)
> [<c00847b0>] (sys_finit_module) from [<c0009000>] (ret_fast_syscall+0x0/0x50)
> Exception stack(0xc6837fa8 to 0xc6837ff0)
> 7fa0: 00000000 00000000 00000004 b6cee714 00000000 00000000
> 7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
> 7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0
> Code: e1a01621 e1a00002 eafe4531 e7f001f2 (e7f001f2)
> ---[ end trace 2cbefb0005882c52 ]---
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> ---[ end Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x0000000b ]---
>
> I bisected it to commit 06bd260e836d ("modules: fix BUG when load
> module with rodata=n") with commit 7dabaa5ce05a ("modules: fix compile
> error if don't have strict module rwx") on top to make it build.
>
I got the commit hashes wrong, because I was playing with a modified
tree. They are 2eef1399a866 ("modules: fix BUG when load module with
rodata=n") and 93651f80dcb6 ("modules: fix compile error if don't have
strict module rwx") respectively.
Bart
> Let me know if you need me to provide more info.
>
> Best regards,
> Bartosz Golaszewski
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [v5.3-rc1 regression] Hitting a kernel BUG() when trying to load a module on DaVinci SoC
2019-07-22 12:12 [v5.3-rc1 regression] Hitting a kernel BUG() when trying to load a module on DaVinci SoC Bartosz Golaszewski
2019-07-22 13:05 ` Bartosz Golaszewski
@ 2019-07-22 16:10 ` Jessica Yu
2019-07-22 19:38 ` David Lechner
2019-07-23 7:45 ` Bartosz Golaszewski
1 sibling, 2 replies; 5+ messages in thread
From: Jessica Yu @ 2019-07-22 16:10 UTC (permalink / raw)
To: Bartosz Golaszewski
Cc: Yang Yingliang, Jian Cheng, Nadav Amit,
Linux Kernel Mailing List, Sekhar Nori, Kevin Hilman,
David Lechner, Adam Ford
+++ Bartosz Golaszewski [22/07/19 14:12 +0200]:
>Hi,
>
>with v5.3-rc1 I'm hitting the following BUG() when trying to load the
>gpio-backlight module:
>
>kernel BUG at kernel/module.c:1919!
>Internal error: Oops - BUG: 0 [#1] PREEMPT ARM
>Modules linked in:
>CPU: 0 PID: 1 Comm: systemd Tainted: G W
>5.2.0-rc2-00005-g7dabaa5ce05a #19
>Hardware name: DaVinci DA850/OMAP-L138/AM18x EVM
>PC is at frob_text.constprop.16+0x2c/0x34
>LR is at load_module+0x1888/0x21b4
>pc : [<c0081bbc>] lr : [<c0083c4c>] psr: 20000013
>sp : c6837e58 ip : c6b4fa80 fp : bf00574c
>r10: c0601008 r9 : bf005740 r8 : c0493e38
>r7 : c00807f8 r6 : 00000000 r5 : 00000001 r4 : c6837f38
>r3 : 00000fff r2 : bf000000 r1 : 00004b80 r0 : bf005818
>Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
>Control: 0005317f Table: c6b78000 DAC: 00000051
>Process systemd (pid: 1, stack limit = 0x(ptrval))
>Stack: (0xc6837e58 to 0xc6838000)
>7e40: bf005740 c6492a90
>7e60: 00000001 c6bf5788 00000003 c6837f38 bf0058c0 bf0058a8 bf00a495 c0493e38
>7e80: 00000000 c05368c0 00000001 00000000 c0580030 c0574b28 00000000 00000000
>7ea0: 00000000 00000000 00000000 00000000 6e72656b 00006c65 00000000 00000000
>7ec0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
>7ee0: 00000000 00000000 00000000 aefb2bb8 7fffffff c0601008 00000000 00000004
>7f00: b6cee714 c00091e4 c6836000 00000000 005bc668 c00847b0 7fffffff 00000000
>7f20: 00000003 00000000 0000b2d0 c884e000 0000b2d0 00000000 c8852dcb c88533a0
>7f40: c884e000 0000b2d0 c8858cb8 c8858b34 c88568d4 000058c0 00006190 000023b8
>7f60: 00006713 00000000 00000000 00000000 000023a8 00000024 00000025 00000019
>7f80: 0000001d 00000011 00000000 aefb2bb8 00000000 00000000 00000000 00000000
>7fa0: 0000017b c0009000 00000000 00000000 00000004 b6cee714 00000000 00000000
>7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
>7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0 60000010 00000004 00000000 00000000
>[<c0081bbc>] (frob_text.constprop.16) from [<c0083c4c>]
>(load_module+0x1888/0x21b4)
>[<c0083c4c>] (load_module) from [<c00847b0>] (sys_finit_module+0xbc/0xdc)
>[<c00847b0>] (sys_finit_module) from [<c0009000>] (ret_fast_syscall+0x0/0x50)
>Exception stack(0xc6837fa8 to 0xc6837ff0)
>7fa0: 00000000 00000000 00000004 b6cee714 00000000 00000000
>7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
>7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0
>Code: e1a01621 e1a00002 eafe4531 e7f001f2 (e7f001f2)
>---[ end trace 2cbefb0005882c52 ]---
>Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
>---[ end Kernel panic - not syncing: Attempted to kill init!
>exitcode=0x0000000b ]---
>
>I bisected it to commit 06bd260e836d ("modules: fix BUG when load
>module with rodata=n") with commit 7dabaa5ce05a ("modules: fix compile
>error if don't have strict module rwx") on top to make it build.
>
>Let me know if you need me to provide more info.
>
>Best regards,
>Bartosz Golaszewski
Hi Bartosz,
Thanks for reporting this, I was able to reproduce this on qemu.
This is due to hitting the BUG_ON() in frob_text() due to layout->base
and/or layout->text_size not being page-aligned. These values are
always page-aligned when CONFIG_STRICT_MODULE_RWX=y, but in commit
2eef1399a86 ("modules: fix BUG when load module with rodata=n"), the
frob_text()+set_memory_x() calls got moved *outside* of the
STRICT_MODULE_RWX block since some arches (like x86 and arm64)
allocate non-executable module memory via module_alloc(), so naturally
the module text needed to be made executable at a later stage of
load_module(), regardless of whether STRICT_MODULE_RWX is set or not.
In your case, you must've had CONFIG_STRICT_MODULE_RWX=n and so we
were calling frob_text() with non-page-aligned values, triggering the
BUG_ON().
In any case, could you please try and see if the following patch fixes
the issue for you?
diff --git a/kernel/module.c b/kernel/module.c
index 5933395af9a0..cd8df516666d 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -64,14 +64,9 @@
/*
* Modules' sections will be aligned on page boundaries
- * to ensure complete separation of code and data, but
- * only when CONFIG_STRICT_MODULE_RWX=y
+ * to ensure complete separation of code and data
*/
-#ifdef CONFIG_STRICT_MODULE_RWX
# define debug_align(X) ALIGN(X, PAGE_SIZE)
-#else
-# define debug_align(X) (X)
-#endif
/* If this is set, the section belongs in the init part of the module */
#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [v5.3-rc1 regression] Hitting a kernel BUG() when trying to load a module on DaVinci SoC
2019-07-22 16:10 ` Jessica Yu
@ 2019-07-22 19:38 ` David Lechner
2019-07-23 7:45 ` Bartosz Golaszewski
1 sibling, 0 replies; 5+ messages in thread
From: David Lechner @ 2019-07-22 19:38 UTC (permalink / raw)
To: Jessica Yu, Bartosz Golaszewski
Cc: Yang Yingliang, Jian Cheng, Nadav Amit,
Linux Kernel Mailing List, Sekhar Nori, Kevin Hilman, Adam Ford
On 7/22/19 11:10 AM, Jessica Yu wrote:
> +++ Bartosz Golaszewski [22/07/19 14:12 +0200]:
>> Hi,
>>
>> with v5.3-rc1 I'm hitting the following BUG() when trying to load the
>> gpio-backlight module:
>>
>> kernel BUG at kernel/module.c:1919!
>> Internal error: Oops - BUG: 0 [#1] PREEMPT ARM
>> Modules linked in:
>> CPU: 0 PID: 1 Comm: systemd Tainted: G W
>> 5.2.0-rc2-00005-g7dabaa5ce05a #19
>> Hardware name: DaVinci DA850/OMAP-L138/AM18x EVM
>> PC is at frob_text.constprop.16+0x2c/0x34
>> LR is at load_module+0x1888/0x21b4
>> pc : [<c0081bbc>] lr : [<c0083c4c>] psr: 20000013
>> sp : c6837e58 ip : c6b4fa80 fp : bf00574c
>> r10: c0601008 r9 : bf005740 r8 : c0493e38
>> r7 : c00807f8 r6 : 00000000 r5 : 00000001 r4 : c6837f38
>> r3 : 00000fff r2 : bf000000 r1 : 00004b80 r0 : bf005818
>> Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
>> Control: 0005317f Table: c6b78000 DAC: 00000051
>> Process systemd (pid: 1, stack limit = 0x(ptrval))
>> Stack: (0xc6837e58 to 0xc6838000)
>> 7e40: bf005740 c6492a90
>> 7e60: 00000001 c6bf5788 00000003 c6837f38 bf0058c0 bf0058a8 bf00a495 c0493e38
>> 7e80: 00000000 c05368c0 00000001 00000000 c0580030 c0574b28 00000000 00000000
>> 7ea0: 00000000 00000000 00000000 00000000 6e72656b 00006c65 00000000 00000000
>> 7ec0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
>> 7ee0: 00000000 00000000 00000000 aefb2bb8 7fffffff c0601008 00000000 00000004
>> 7f00: b6cee714 c00091e4 c6836000 00000000 005bc668 c00847b0 7fffffff 00000000
>> 7f20: 00000003 00000000 0000b2d0 c884e000 0000b2d0 00000000 c8852dcb c88533a0
>> 7f40: c884e000 0000b2d0 c8858cb8 c8858b34 c88568d4 000058c0 00006190 000023b8
>> 7f60: 00006713 00000000 00000000 00000000 000023a8 00000024 00000025 00000019
>> 7f80: 0000001d 00000011 00000000 aefb2bb8 00000000 00000000 00000000 00000000
>> 7fa0: 0000017b c0009000 00000000 00000000 00000004 b6cee714 00000000 00000000
>> 7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
>> 7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0 60000010 00000004 00000000 00000000
>> [<c0081bbc>] (frob_text.constprop.16) from [<c0083c4c>]
>> (load_module+0x1888/0x21b4)
>> [<c0083c4c>] (load_module) from [<c00847b0>] (sys_finit_module+0xbc/0xdc)
>> [<c00847b0>] (sys_finit_module) from [<c0009000>] (ret_fast_syscall+0x0/0x50)
>> Exception stack(0xc6837fa8 to 0xc6837ff0)
>> 7fa0: 00000000 00000000 00000004 b6cee714 00000000 00000000
>> 7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
>> 7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0
>> Code: e1a01621 e1a00002 eafe4531 e7f001f2 (e7f001f2)
>> ---[ end trace 2cbefb0005882c52 ]---
>> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
>> ---[ end Kernel panic - not syncing: Attempted to kill init!
>> exitcode=0x0000000b ]---
>>
>> I bisected it to commit 06bd260e836d ("modules: fix BUG when load
>> module with rodata=n") with commit 7dabaa5ce05a ("modules: fix compile
>> error if don't have strict module rwx") on top to make it build.
>>
>> Let me know if you need me to provide more info.
>>
>> Best regards,
>> Bartosz Golaszewski
>
> Hi Bartosz,
>
> Thanks for reporting this, I was able to reproduce this on qemu.
>
> This is due to hitting the BUG_ON() in frob_text() due to layout->base
> and/or layout->text_size not being page-aligned. These values are
> always page-aligned when CONFIG_STRICT_MODULE_RWX=y, but in commit
> 2eef1399a86 ("modules: fix BUG when load module with rodata=n"), the
> frob_text()+set_memory_x() calls got moved *outside* of the
> STRICT_MODULE_RWX block since some arches (like x86 and arm64)
> allocate non-executable module memory via module_alloc(), so naturally
> the module text needed to be made executable at a later stage of
> load_module(), regardless of whether STRICT_MODULE_RWX is set or not.
> In your case, you must've had CONFIG_STRICT_MODULE_RWX=n and so we
> were calling frob_text() with non-page-aligned values, triggering the
> BUG_ON().
>
> In any case, could you please try and see if the following patch fixes
> the issue for you?
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 5933395af9a0..cd8df516666d 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -64,14 +64,9 @@
>
> /*
> * Modules' sections will be aligned on page boundaries
> - * to ensure complete separation of code and data, but
> - * only when CONFIG_STRICT_MODULE_RWX=y
> + * to ensure complete separation of code and data
> */
> -#ifdef CONFIG_STRICT_MODULE_RWX
> # define debug_align(X) ALIGN(X, PAGE_SIZE)
> -#else
> -# define debug_align(X) (X)
> -#endif
>
> /* If this is set, the section belongs in the init part of the module */
> #define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
Works for me.
Tested-by: David Lechner <david@lechnology.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [v5.3-rc1 regression] Hitting a kernel BUG() when trying to load a module on DaVinci SoC
2019-07-22 16:10 ` Jessica Yu
2019-07-22 19:38 ` David Lechner
@ 2019-07-23 7:45 ` Bartosz Golaszewski
1 sibling, 0 replies; 5+ messages in thread
From: Bartosz Golaszewski @ 2019-07-23 7:45 UTC (permalink / raw)
To: Jessica Yu
Cc: Yang Yingliang, Jian Cheng, Nadav Amit,
Linux Kernel Mailing List, Sekhar Nori, Kevin Hilman,
David Lechner, Adam Ford
pon., 22 lip 2019 o 18:10 Jessica Yu <jeyu@kernel.org> napisał(a):
>
> +++ Bartosz Golaszewski [22/07/19 14:12 +0200]:
> >Hi,
> >
> >with v5.3-rc1 I'm hitting the following BUG() when trying to load the
> >gpio-backlight module:
> >
> >kernel BUG at kernel/module.c:1919!
> >Internal error: Oops - BUG: 0 [#1] PREEMPT ARM
> >Modules linked in:
> >CPU: 0 PID: 1 Comm: systemd Tainted: G W
> >5.2.0-rc2-00005-g7dabaa5ce05a #19
> >Hardware name: DaVinci DA850/OMAP-L138/AM18x EVM
> >PC is at frob_text.constprop.16+0x2c/0x34
> >LR is at load_module+0x1888/0x21b4
> >pc : [<c0081bbc>] lr : [<c0083c4c>] psr: 20000013
> >sp : c6837e58 ip : c6b4fa80 fp : bf00574c
> >r10: c0601008 r9 : bf005740 r8 : c0493e38
> >r7 : c00807f8 r6 : 00000000 r5 : 00000001 r4 : c6837f38
> >r3 : 00000fff r2 : bf000000 r1 : 00004b80 r0 : bf005818
> >Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
> >Control: 0005317f Table: c6b78000 DAC: 00000051
> >Process systemd (pid: 1, stack limit = 0x(ptrval))
> >Stack: (0xc6837e58 to 0xc6838000)
> >7e40: bf005740 c6492a90
> >7e60: 00000001 c6bf5788 00000003 c6837f38 bf0058c0 bf0058a8 bf00a495 c0493e38
> >7e80: 00000000 c05368c0 00000001 00000000 c0580030 c0574b28 00000000 00000000
> >7ea0: 00000000 00000000 00000000 00000000 6e72656b 00006c65 00000000 00000000
> >7ec0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> >7ee0: 00000000 00000000 00000000 aefb2bb8 7fffffff c0601008 00000000 00000004
> >7f00: b6cee714 c00091e4 c6836000 00000000 005bc668 c00847b0 7fffffff 00000000
> >7f20: 00000003 00000000 0000b2d0 c884e000 0000b2d0 00000000 c8852dcb c88533a0
> >7f40: c884e000 0000b2d0 c8858cb8 c8858b34 c88568d4 000058c0 00006190 000023b8
> >7f60: 00006713 00000000 00000000 00000000 000023a8 00000024 00000025 00000019
> >7f80: 0000001d 00000011 00000000 aefb2bb8 00000000 00000000 00000000 00000000
> >7fa0: 0000017b c0009000 00000000 00000000 00000004 b6cee714 00000000 00000000
> >7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
> >7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0 60000010 00000004 00000000 00000000
> >[<c0081bbc>] (frob_text.constprop.16) from [<c0083c4c>]
> >(load_module+0x1888/0x21b4)
> >[<c0083c4c>] (load_module) from [<c00847b0>] (sys_finit_module+0xbc/0xdc)
> >[<c00847b0>] (sys_finit_module) from [<c0009000>] (ret_fast_syscall+0x0/0x50)
> >Exception stack(0xc6837fa8 to 0xc6837ff0)
> >7fa0: 00000000 00000000 00000004 b6cee714 00000000 00000000
> >7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
> >7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0
> >Code: e1a01621 e1a00002 eafe4531 e7f001f2 (e7f001f2)
> >---[ end trace 2cbefb0005882c52 ]---
> >Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> >---[ end Kernel panic - not syncing: Attempted to kill init!
> >exitcode=0x0000000b ]---
> >
> >I bisected it to commit 06bd260e836d ("modules: fix BUG when load
> >module with rodata=n") with commit 7dabaa5ce05a ("modules: fix compile
> >error if don't have strict module rwx") on top to make it build.
> >
> >Let me know if you need me to provide more info.
> >
> >Best regards,
> >Bartosz Golaszewski
>
> Hi Bartosz,
>
> Thanks for reporting this, I was able to reproduce this on qemu.
>
> This is due to hitting the BUG_ON() in frob_text() due to layout->base
> and/or layout->text_size not being page-aligned. These values are
> always page-aligned when CONFIG_STRICT_MODULE_RWX=y, but in commit
> 2eef1399a86 ("modules: fix BUG when load module with rodata=n"), the
> frob_text()+set_memory_x() calls got moved *outside* of the
> STRICT_MODULE_RWX block since some arches (like x86 and arm64)
> allocate non-executable module memory via module_alloc(), so naturally
> the module text needed to be made executable at a later stage of
> load_module(), regardless of whether STRICT_MODULE_RWX is set or not.
> In your case, you must've had CONFIG_STRICT_MODULE_RWX=n and so we
> were calling frob_text() with non-page-aligned values, triggering the
> BUG_ON().
>
> In any case, could you please try and see if the following patch fixes
> the issue for you?
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 5933395af9a0..cd8df516666d 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -64,14 +64,9 @@
>
> /*
> * Modules' sections will be aligned on page boundaries
> - * to ensure complete separation of code and data, but
> - * only when CONFIG_STRICT_MODULE_RWX=y
> + * to ensure complete separation of code and data
> */
> -#ifdef CONFIG_STRICT_MODULE_RWX
> # define debug_align(X) ALIGN(X, PAGE_SIZE)
> -#else
> -# define debug_align(X) (X)
> -#endif
>
> /* If this is set, the section belongs in the init part of the module */
> #define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
That helps, thanks!
Please Cc me on the actual submitted patch.
Bart
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-07-23 7:45 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-07-22 12:12 [v5.3-rc1 regression] Hitting a kernel BUG() when trying to load a module on DaVinci SoC Bartosz Golaszewski
2019-07-22 13:05 ` Bartosz Golaszewski
2019-07-22 16:10 ` Jessica Yu
2019-07-22 19:38 ` David Lechner
2019-07-23 7:45 ` Bartosz Golaszewski
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