The software division functions never had unwinding annotations
added. Currently, when a division by zero occurs the backtrace shown
will stop at Ldiv0 or some completely unrelated function. Add
unwinding annotations in hopes of getting a more useful backtrace
when a division by zero occurs.
Signed-off-by: Laura Abbott <[email protected]>
---
arch/arm/lib/lib1funcs.S | 27 +++++++++++++++++++++------
1 files changed, 21 insertions(+), 6 deletions(-)
diff --git a/arch/arm/lib/lib1funcs.S b/arch/arm/lib/lib1funcs.S
index 6dc0648..63b75df 100644
--- a/arch/arm/lib/lib1funcs.S
+++ b/arch/arm/lib/lib1funcs.S
@@ -35,7 +35,7 @@ Boston, MA 02111-1307, USA. */
#include <linux/linkage.h>
#include <asm/assembler.h>
-
+#include <asm/unwind.h>
.macro ARM_DIV_BODY dividend, divisor, result, curbit
@@ -207,6 +207,7 @@ Boston, MA 02111-1307, USA. */
ENTRY(__udivsi3)
ENTRY(__aeabi_uidiv)
+UNWIND(.fnstart)
subs r2, r1, #1
moveq pc, lr
@@ -230,10 +231,12 @@ ENTRY(__aeabi_uidiv)
mov r0, r0, lsr r2
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__udivsi3)
ENDPROC(__aeabi_uidiv)
ENTRY(__umodsi3)
+UNWIND(.fnstart)
subs r2, r1, #1 @ compare divisor with 1
bcc Ldiv0
@@ -247,10 +250,12 @@ ENTRY(__umodsi3)
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__umodsi3)
ENTRY(__divsi3)
ENTRY(__aeabi_idiv)
+UNWIND(.fnstart)
cmp r1, #0
eor ip, r0, r1 @ save the sign of the result.
@@ -287,10 +292,12 @@ ENTRY(__aeabi_idiv)
rsbmi r0, r0, #0
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__divsi3)
ENDPROC(__aeabi_idiv)
ENTRY(__modsi3)
+UNWIND(.fnstart)
cmp r1, #0
beq Ldiv0
@@ -310,11 +317,14 @@ ENTRY(__modsi3)
rsbmi r0, r0, #0
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__modsi3)
#ifdef CONFIG_AEABI
ENTRY(__aeabi_uidivmod)
+UNWIND(.fnstart)
+UNWIND(.save {r0, r1, ip, lr} )
stmfd sp!, {r0, r1, ip, lr}
bl __aeabi_uidiv
@@ -323,10 +333,12 @@ ENTRY(__aeabi_uidivmod)
sub r1, r1, r3
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__aeabi_uidivmod)
ENTRY(__aeabi_idivmod)
-
+UNWIND(.fnstart)
+UNWIND(.save {r0, r1, ip, lr} )
stmfd sp!, {r0, r1, ip, lr}
bl __aeabi_idiv
ldmfd sp!, {r1, r2, ip, lr}
@@ -334,15 +346,18 @@ ENTRY(__aeabi_idivmod)
sub r1, r1, r3
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__aeabi_idivmod)
#endif
-Ldiv0:
-
+ENTRY(Ldiv0)
+UNWIND(.fnstart)
+UNWIND(.pad #4)
+UNWIND(.save {lr})
str lr, [sp, #-8]!
bl __div0
mov r0, #0 @ About as wrong as it could be.
ldr pc, [sp], #8
-
-
+UNWIND(.fnend)
+ENDPROC(Ldiv0)
--
1.7.3.3
On Thu, May 12, 2011 at 06:24:53PM -0700, Laura Abbott wrote:
> The software division functions never had unwinding annotations
> added. Currently, when a division by zero occurs the backtrace shown
> will stop at Ldiv0 or some completely unrelated function. Add
> unwinding annotations in hopes of getting a more useful backtrace
> when a division by zero occurs.
Definitely a good idea.
>
> Signed-off-by: Laura Abbott <[email protected]>
> ---
> arch/arm/lib/lib1funcs.S | 27 +++++++++++++++++++++------
> 1 files changed, 21 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/lib/lib1funcs.S b/arch/arm/lib/lib1funcs.S
> index 6dc0648..63b75df 100644
> --- a/arch/arm/lib/lib1funcs.S
> +++ b/arch/arm/lib/lib1funcs.S
> @@ -35,7 +35,7 @@ Boston, MA 02111-1307, USA. */
>
> #include <linux/linkage.h>
> #include <asm/assembler.h>
> -
> +#include <asm/unwind.h>
>
> .macro ARM_DIV_BODY dividend, divisor, result, curbit
>
> @@ -207,6 +207,7 @@ Boston, MA 02111-1307, USA. */
>
> ENTRY(__udivsi3)
> ENTRY(__aeabi_uidiv)
> +UNWIND(.fnstart)
>
> subs r2, r1, #1
> moveq pc, lr
> @@ -230,10 +231,12 @@ ENTRY(__aeabi_uidiv)
> mov r0, r0, lsr r2
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__udivsi3)
> ENDPROC(__aeabi_uidiv)
>
> ENTRY(__umodsi3)
> +UNWIND(.fnstart)
>
> subs r2, r1, #1 @ compare divisor with 1
> bcc Ldiv0
> @@ -247,10 +250,12 @@ ENTRY(__umodsi3)
>
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__umodsi3)
>
> ENTRY(__divsi3)
> ENTRY(__aeabi_idiv)
> +UNWIND(.fnstart)
>
> cmp r1, #0
> eor ip, r0, r1 @ save the sign of the result.
> @@ -287,10 +292,12 @@ ENTRY(__aeabi_idiv)
> rsbmi r0, r0, #0
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__divsi3)
> ENDPROC(__aeabi_idiv)
>
> ENTRY(__modsi3)
> +UNWIND(.fnstart)
>
> cmp r1, #0
> beq Ldiv0
> @@ -310,11 +317,14 @@ ENTRY(__modsi3)
> rsbmi r0, r0, #0
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__modsi3)
>
> #ifdef CONFIG_AEABI
>
> ENTRY(__aeabi_uidivmod)
> +UNWIND(.fnstart)
> +UNWIND(.save {r0, r1, ip, lr} )
>
> stmfd sp!, {r0, r1, ip, lr}
> bl __aeabi_uidiv
> @@ -323,10 +333,12 @@ ENTRY(__aeabi_uidivmod)
> sub r1, r1, r3
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__aeabi_uidivmod)
>
> ENTRY(__aeabi_idivmod)
> -
> +UNWIND(.fnstart)
> +UNWIND(.save {r0, r1, ip, lr} )
> stmfd sp!, {r0, r1, ip, lr}
> bl __aeabi_idiv
> ldmfd sp!, {r1, r2, ip, lr}
> @@ -334,15 +346,18 @@ ENTRY(__aeabi_idivmod)
> sub r1, r1, r3
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__aeabi_idivmod)
>
> #endif
>
> -Ldiv0:
> -
> +ENTRY(Ldiv0)
There's no reason to make Ldiv0 global and pollute the global namespace.
I suggest you remove ENTRY() here, but keep the ENDPROC() so that the
symbol type and size information is correct.
If CONFIG_KALLSYMS is enabled, local symbols are included in the
kallsyms table, so you still get a sensibly-named backtrace entry without
needing to make the symbol global.
> +UNWIND(.fnstart)
> +UNWIND(.pad #4)
> +UNWIND(.save {lr})
> str lr, [sp, #-8]!
> bl __div0
> mov r0, #0 @ About as wrong as it could be.
> ldr pc, [sp], #8
> -
> -
> +UNWIND(.fnend)
> +ENDPROC(Ldiv0)
> --
> 1.7.3.3
Otherwise, the patch looks sound to me.
With it, I get plausible backtraces, e.g.:
[ 1376.909088] Division by zero in kernel.
[ 1376.909149] [<c0073551>] (unwind_backtrace+0x1/0xa0) from [<c02b83a3>] (Ldiv0+0x9/0x12)
[ 1376.909149] [<c02b83a3>] (Ldiv0+0x9/0x12) from [<bf88c033>] (init+0x32/0x6f [div0])
[ 1376.909179] [<bf88c033>] (init+0x32/0x6f [div0]) from [<c006951b>] (do_one_initcall+0x2b/0x11c)
[ 1376.909210] [<c006951b>] (do_one_initcall+0x2b/0x11c) from [<c00c8c4b>] (sys_init_module+0xc7/0x144c)
[ 1376.909240] [<c00c8c4b>] (sys_init_module+0xc7/0x144c) from [<c006df81>] (ret_fast_syscall+0x1/0x44)
(Tested using a trivial test module which just calls a function which
divides by zero from its init function.)
Tested-by: Dave Martin <[email protected]>
Cheers
---Dave
On Tue, May 17, 2011 8:07 am, Dave Martin wrote:
> On Thu, May 12, 2011 at 06:24:53PM -0700, Laura Abbott wrote:
>> The software division functions never had unwinding annotations
>> added. Currently, when a division by zero occurs the backtrace shown
>> will stop at Ldiv0 or some completely unrelated function. Add
>> unwinding annotations in hopes of getting a more useful backtrace
>> when a division by zero occurs.
>
> Definitely a good idea.
>
>>
>> Signed-off-by: Laura Abbott <[email protected]>
>> ---
>> arch/arm/lib/lib1funcs.S | 27 +++++++++++++++++++++------
>> 1 files changed, 21 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/arm/lib/lib1funcs.S b/arch/arm/lib/lib1funcs.S
>> index 6dc0648..63b75df 100644
>> --- a/arch/arm/lib/lib1funcs.S
>> +++ b/arch/arm/lib/lib1funcs.S
>> @@ -35,7 +35,7 @@ Boston, MA 02111-1307, USA. */
>>
>> #include <linux/linkage.h>
>> #include <asm/assembler.h>
>> -
>> +#include <asm/unwind.h>
>>
>> .macro ARM_DIV_BODY dividend, divisor, result, curbit
>>
>> @@ -207,6 +207,7 @@ Boston, MA 02111-1307, USA. */
>>
>> ENTRY(__udivsi3)
>> ENTRY(__aeabi_uidiv)
>> +UNWIND(.fnstart)
>>
>> subs r2, r1, #1
>> moveq pc, lr
>> @@ -230,10 +231,12 @@ ENTRY(__aeabi_uidiv)
>> mov r0, r0, lsr r2
>> mov pc, lr
>>
>> +UNWIND(.fnend)
>> ENDPROC(__udivsi3)
>> ENDPROC(__aeabi_uidiv)
>>
>> ENTRY(__umodsi3)
>> +UNWIND(.fnstart)
>>
>> subs r2, r1, #1 @ compare divisor with 1
>> bcc Ldiv0
>> @@ -247,10 +250,12 @@ ENTRY(__umodsi3)
>>
>> mov pc, lr
>>
>> +UNWIND(.fnend)
>> ENDPROC(__umodsi3)
>>
>> ENTRY(__divsi3)
>> ENTRY(__aeabi_idiv)
>> +UNWIND(.fnstart)
>>
>> cmp r1, #0
>> eor ip, r0, r1 @ save the sign of the result.
>> @@ -287,10 +292,12 @@ ENTRY(__aeabi_idiv)
>> rsbmi r0, r0, #0
>> mov pc, lr
>>
>> +UNWIND(.fnend)
>> ENDPROC(__divsi3)
>> ENDPROC(__aeabi_idiv)
>>
>> ENTRY(__modsi3)
>> +UNWIND(.fnstart)
>>
>> cmp r1, #0
>> beq Ldiv0
>> @@ -310,11 +317,14 @@ ENTRY(__modsi3)
>> rsbmi r0, r0, #0
>> mov pc, lr
>>
>> +UNWIND(.fnend)
>> ENDPROC(__modsi3)
>>
>> #ifdef CONFIG_AEABI
>>
>> ENTRY(__aeabi_uidivmod)
>> +UNWIND(.fnstart)
>> +UNWIND(.save {r0, r1, ip, lr} )
>>
>> stmfd sp!, {r0, r1, ip, lr}
>> bl __aeabi_uidiv
>> @@ -323,10 +333,12 @@ ENTRY(__aeabi_uidivmod)
>> sub r1, r1, r3
>> mov pc, lr
>>
>> +UNWIND(.fnend)
>> ENDPROC(__aeabi_uidivmod)
>>
>> ENTRY(__aeabi_idivmod)
>> -
>> +UNWIND(.fnstart)
>> +UNWIND(.save {r0, r1, ip, lr} )
>> stmfd sp!, {r0, r1, ip, lr}
>> bl __aeabi_idiv
>> ldmfd sp!, {r1, r2, ip, lr}
>> @@ -334,15 +346,18 @@ ENTRY(__aeabi_idivmod)
>> sub r1, r1, r3
>> mov pc, lr
>>
>> +UNWIND(.fnend)
>> ENDPROC(__aeabi_idivmod)
>>
>> #endif
>>
>> -Ldiv0:
>> -
>> +ENTRY(Ldiv0)
>
> There's no reason to make Ldiv0 global and pollute the global namespace.
> I suggest you remove ENTRY() here, but keep the ENDPROC() so that the
> symbol type and size information is correct.
>
> If CONFIG_KALLSYMS is enabled, local symbols are included in the
> kallsyms table, so you still get a sensibly-named backtrace entry without
> needing to make the symbol global.
>
Okay, I'll get rid of the ENTRY annotation for Ldiv0.
>> +UNWIND(.fnstart)
>> +UNWIND(.pad #4)
>> +UNWIND(.save {lr})
>> str lr, [sp, #-8]!
>> bl __div0
>> mov r0, #0 @ About as wrong as it could be.
>> ldr pc, [sp], #8
>> -
>> -
>> +UNWIND(.fnend)
>> +ENDPROC(Ldiv0)
>> --
>> 1.7.3.3
>
> Otherwise, the patch looks sound to me.
>
> With it, I get plausible backtraces, e.g.:
> [ 1376.909088] Division by zero in kernel.
> [ 1376.909149] [<c0073551>] (unwind_backtrace+0x1/0xa0) from [<c02b83a3>]
> (Ldiv0+0x9/0x12)
> [ 1376.909149] [<c02b83a3>] (Ldiv0+0x9/0x12) from [<bf88c033>]
> (init+0x32/0x6f [div0])
> [ 1376.909179] [<bf88c033>] (init+0x32/0x6f [div0]) from [<c006951b>]
> (do_one_initcall+0x2b/0x11c)
> [ 1376.909210] [<c006951b>] (do_one_initcall+0x2b/0x11c) from [<c00c8c4b>]
> (sys_init_module+0xc7/0x144c)
> [ 1376.909240] [<c00c8c4b>] (sys_init_module+0xc7/0x144c) from
> [<c006df81>] (ret_fast_syscall+0x1/0x44)
>
> (Tested using a trivial test module which just calls a function which
> divides by zero from its init function.)
>
> Tested-by: Dave Martin <[email protected]>
>
> Cheers
> ---Dave
>
Thanks for reviewing and testing
Laura
--
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
The software division functions never had unwinding annotations
added. Currently, when a division by zero occurs the backtrace shown
will stop at Ldiv0 or some completely unrelated function. Add
unwinding annotations in hopes of getting a more useful backtrace
when a division by zero occurs.
Signed-off-by: Laura Abbott <[email protected]>
---
arch/arm/lib/lib1funcs.S | 25 ++++++++++++++++++++-----
1 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/arch/arm/lib/lib1funcs.S b/arch/arm/lib/lib1funcs.S
index 6dc0648..c562f64 100644
--- a/arch/arm/lib/lib1funcs.S
+++ b/arch/arm/lib/lib1funcs.S
@@ -35,7 +35,7 @@ Boston, MA 02111-1307, USA. */
#include <linux/linkage.h>
#include <asm/assembler.h>
-
+#include <asm/unwind.h>
.macro ARM_DIV_BODY dividend, divisor, result, curbit
@@ -207,6 +207,7 @@ Boston, MA 02111-1307, USA. */
ENTRY(__udivsi3)
ENTRY(__aeabi_uidiv)
+UNWIND(.fnstart)
subs r2, r1, #1
moveq pc, lr
@@ -230,10 +231,12 @@ ENTRY(__aeabi_uidiv)
mov r0, r0, lsr r2
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__udivsi3)
ENDPROC(__aeabi_uidiv)
ENTRY(__umodsi3)
+UNWIND(.fnstart)
subs r2, r1, #1 @ compare divisor with 1
bcc Ldiv0
@@ -247,10 +250,12 @@ ENTRY(__umodsi3)
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__umodsi3)
ENTRY(__divsi3)
ENTRY(__aeabi_idiv)
+UNWIND(.fnstart)
cmp r1, #0
eor ip, r0, r1 @ save the sign of the result.
@@ -287,10 +292,12 @@ ENTRY(__aeabi_idiv)
rsbmi r0, r0, #0
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__divsi3)
ENDPROC(__aeabi_idiv)
ENTRY(__modsi3)
+UNWIND(.fnstart)
cmp r1, #0
beq Ldiv0
@@ -310,11 +317,14 @@ ENTRY(__modsi3)
rsbmi r0, r0, #0
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__modsi3)
#ifdef CONFIG_AEABI
ENTRY(__aeabi_uidivmod)
+UNWIND(.fnstart)
+UNWIND(.save {r0, r1, ip, lr} )
stmfd sp!, {r0, r1, ip, lr}
bl __aeabi_uidiv
@@ -323,10 +333,12 @@ ENTRY(__aeabi_uidivmod)
sub r1, r1, r3
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__aeabi_uidivmod)
ENTRY(__aeabi_idivmod)
-
+UNWIND(.fnstart)
+UNWIND(.save {r0, r1, ip, lr} )
stmfd sp!, {r0, r1, ip, lr}
bl __aeabi_idiv
ldmfd sp!, {r1, r2, ip, lr}
@@ -334,15 +346,18 @@ ENTRY(__aeabi_idivmod)
sub r1, r1, r3
mov pc, lr
+UNWIND(.fnend)
ENDPROC(__aeabi_idivmod)
#endif
Ldiv0:
-
+UNWIND(.fnstart)
+UNWIND(.pad #4)
+UNWIND(.save {lr})
str lr, [sp, #-8]!
bl __div0
mov r0, #0 @ About as wrong as it could be.
ldr pc, [sp], #8
-
-
+UNWIND(.fnend)
+ENDPROC(Ldiv0)
--
1.7.3.3
On Wed, May 18, 2011 at 10:33:26AM -0700, Laura Abbott wrote:
> The software division functions never had unwinding annotations
> added. Currently, when a division by zero occurs the backtrace shown
> will stop at Ldiv0 or some completely unrelated function. Add
> unwinding annotations in hopes of getting a more useful backtrace
> when a division by zero occurs.
>
> Signed-off-by: Laura Abbott <[email protected]>
> ---
> arch/arm/lib/lib1funcs.S | 25 ++++++++++++++++++++-----
> 1 files changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/lib/lib1funcs.S b/arch/arm/lib/lib1funcs.S
> index 6dc0648..c562f64 100644
> --- a/arch/arm/lib/lib1funcs.S
> +++ b/arch/arm/lib/lib1funcs.S
> @@ -35,7 +35,7 @@ Boston, MA 02111-1307, USA. */
>
> #include <linux/linkage.h>
> #include <asm/assembler.h>
> -
> +#include <asm/unwind.h>
>
> .macro ARM_DIV_BODY dividend, divisor, result, curbit
>
> @@ -207,6 +207,7 @@ Boston, MA 02111-1307, USA. */
>
> ENTRY(__udivsi3)
> ENTRY(__aeabi_uidiv)
> +UNWIND(.fnstart)
>
> subs r2, r1, #1
> moveq pc, lr
> @@ -230,10 +231,12 @@ ENTRY(__aeabi_uidiv)
> mov r0, r0, lsr r2
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__udivsi3)
> ENDPROC(__aeabi_uidiv)
>
> ENTRY(__umodsi3)
> +UNWIND(.fnstart)
>
> subs r2, r1, #1 @ compare divisor with 1
> bcc Ldiv0
> @@ -247,10 +250,12 @@ ENTRY(__umodsi3)
>
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__umodsi3)
>
> ENTRY(__divsi3)
> ENTRY(__aeabi_idiv)
> +UNWIND(.fnstart)
>
> cmp r1, #0
> eor ip, r0, r1 @ save the sign of the result.
> @@ -287,10 +292,12 @@ ENTRY(__aeabi_idiv)
> rsbmi r0, r0, #0
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__divsi3)
> ENDPROC(__aeabi_idiv)
>
> ENTRY(__modsi3)
> +UNWIND(.fnstart)
>
> cmp r1, #0
> beq Ldiv0
> @@ -310,11 +317,14 @@ ENTRY(__modsi3)
> rsbmi r0, r0, #0
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__modsi3)
>
> #ifdef CONFIG_AEABI
>
> ENTRY(__aeabi_uidivmod)
> +UNWIND(.fnstart)
> +UNWIND(.save {r0, r1, ip, lr} )
>
> stmfd sp!, {r0, r1, ip, lr}
> bl __aeabi_uidiv
> @@ -323,10 +333,12 @@ ENTRY(__aeabi_uidivmod)
> sub r1, r1, r3
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__aeabi_uidivmod)
>
> ENTRY(__aeabi_idivmod)
> -
> +UNWIND(.fnstart)
> +UNWIND(.save {r0, r1, ip, lr} )
> stmfd sp!, {r0, r1, ip, lr}
> bl __aeabi_idiv
> ldmfd sp!, {r1, r2, ip, lr}
> @@ -334,15 +346,18 @@ ENTRY(__aeabi_idivmod)
> sub r1, r1, r3
> mov pc, lr
>
> +UNWIND(.fnend)
> ENDPROC(__aeabi_idivmod)
>
> #endif
>
> Ldiv0:
> -
> +UNWIND(.fnstart)
> +UNWIND(.pad #4)
> +UNWIND(.save {lr})
> str lr, [sp, #-8]!
> bl __div0
> mov r0, #0 @ About as wrong as it could be.
> ldr pc, [sp], #8
> -
> -
> +UNWIND(.fnend)
> +ENDPROC(Ldiv0)
> --
> 1.7.3.3
>
OK, that looks good to me.
Tested with CONFIG_THUMB2_KERNEL on omap4.
Acked-by: Dave Martin <[email protected]>