* [PATCH 1/1] ARM:r0 is also corrupted after calling __do_div64.
@ 2015-05-12 6:33 Chen Gang
2015-05-12 10:00 ` Russell King - ARM Linux
0 siblings, 1 reply; 5+ messages in thread
From: Chen Gang @ 2015-05-12 6:33 UTC (permalink / raw)
To: linux-arm-kernel
R0 is corrupted after calling __do_div64 and compiler is not informed
about this in macro __do_div_asm. If n is to be used again after this
macro, r0 is not reloaded and n will contain incorrect value
Signed-off-by: Chen Gang <gangchen@rdamicro.com>
---
arch/arm/include/asm/div64.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h
index a66061a..93a9985 100644
--- a/arch/arm/include/asm/div64.h
+++ b/arch/arm/include/asm/div64.h
@@ -34,13 +34,13 @@
register unsigned long long __n asm("r0") = n; \
register unsigned long long __res asm("r2"); \
register unsigned int __rem asm(__xh); \
- asm( __asmeq("%0", __xh) \
+ asm( __asmeq("%R0", __xh) \
__asmeq("%1", "r2") \
__asmeq("%2", "r0") \
__asmeq("%3", "r4") \
"bl __do_div64" \
- : "=r" (__rem), "=r" (__res) \
- : "r" (__n), "r" (__base) \
+ : "=r" (__n), "=r" (__res) \
+ : "0"(__n), "r" (__base) \
: "ip", "lr", "cc"); \
n = __res; \
__rem; \
--
1.9.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 1/1] ARM:r0 is also corrupted after calling __do_div64.
2015-05-12 6:33 [PATCH 1/1] ARM:r0 is also corrupted after calling __do_div64 Chen Gang
@ 2015-05-12 10:00 ` Russell King - ARM Linux
2015-05-12 10:40 ` Chen Gang
2015-05-12 10:42 ` Chen Gang
0 siblings, 2 replies; 5+ messages in thread
From: Russell King - ARM Linux @ 2015-05-12 10:00 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, May 12, 2015 at 02:33:06PM +0800, Chen Gang wrote:
> R0 is corrupted after calling __do_div64 and compiler is not informed
> about this in macro __do_div_asm. If n is to be used again after this
> macro, r0 is not reloaded and n will contain incorrect value
This isn't going to work if we're building for big endian (__ARMEB__
set) because then we end up telling the compiler that __rem and __n
are both in r0, which is impossible.
> diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h
> index a66061a..93a9985 100644
> --- a/arch/arm/include/asm/div64.h
> +++ b/arch/arm/include/asm/div64.h
> @@ -34,13 +34,13 @@
> register unsigned long long __n asm("r0") = n; \
> register unsigned long long __res asm("r2"); \
> register unsigned int __rem asm(__xh); \
register unsigned int __rem_xh asm(__xh); \
register unsigned int __rem_xl asm(__xl); \
> - asm( __asmeq("%0", __xh) \
> + asm( __asmeq("%R0", __xh) \
asm( __asmeq("%0", __xh) \
__asmeq("%1", __xl) \
... and increment each following register %-spec by one...
> __asmeq("%1", "r2") \
> __asmeq("%2", "r0") \
> __asmeq("%3", "r4") \
> "bl __do_div64" \
> - : "=r" (__rem), "=r" (__res) \
> - : "r" (__n), "r" (__base) \
> + : "=r" (__n), "=r" (__res) \
> + : "0"(__n), "r" (__base) \
This is obviously wrong because __rem is left unset, and that's one of
the two values this macro returns.
: "=r" (__rem_xh), "=r" (__rem_xl), "=r" (__res) \
: "r" (__n), "r" (__base) \
> : "ip", "lr", "cc"); \
> n = __res; \
> __rem; \
__rem_xh;
Basically this renames __rem to __rem_xh, and introduces a new __rem_xl
to take the other half of the remainder which we don't use.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH 1/1] ARM:r0 is also corrupted after calling __do_div64.
2015-05-12 10:00 ` Russell King - ARM Linux
@ 2015-05-12 10:40 ` Chen Gang
2015-05-14 3:39 ` Chen Gang
2015-05-12 10:42 ` Chen Gang
1 sibling, 1 reply; 5+ messages in thread
From: Chen Gang @ 2015-05-12 10:40 UTC (permalink / raw)
To: linux-arm-kernel
R0 is corrupted after calling __do_div64 and compiler is not informed
about this in macro __do_div_asm. If n is to be used again after this
macro, r0 is not reloaded and n will contain incorrect value
Signed-off-by: Chen Gang <gangchen@rdamicro.com>
---
arch/arm/include/asm/div64.h | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h
index a66061a..4829618 100644
--- a/arch/arm/include/asm/div64.h
+++ b/arch/arm/include/asm/div64.h
@@ -34,13 +34,15 @@
register unsigned long long __n asm("r0") = n; \
register unsigned long long __res asm("r2"); \
register unsigned int __rem asm(__xh); \
+ register unsigned int __clobber asm(__xl); \
asm( __asmeq("%0", __xh) \
- __asmeq("%1", "r2") \
- __asmeq("%2", "r0") \
- __asmeq("%3", "r4") \
+ __asmeq("%1", __xl) \
+ __asmeq("%2", "r2") \
+ __asmeq("%3", "r0") \
+ __asmeq("%4", "r4") \
"bl __do_div64" \
- : "=r" (__rem), "=r" (__res) \
- : "r" (__n), "r" (__base) \
+ : "=r"(__rem), "=r"(__clobber), "=r"(__res) \
+ : "r"(__n), "r"(__base) \
: "ip", "lr", "cc"); \
n = __res; \
__rem; \
--
1.9.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 1/1] ARM:r0 is also corrupted after calling __do_div64.
2015-05-12 10:40 ` Chen Gang
@ 2015-05-14 3:39 ` Chen Gang
0 siblings, 0 replies; 5+ messages in thread
From: Chen Gang @ 2015-05-14 3:39 UTC (permalink / raw)
To: linux-arm-kernel
Hi, Russell
The following patch is made according to your suggestion. Could you
review or merge it before your context is cleaned? Thanks!
Br, Chen Gang
On 05/12/2015 06:40 PM, Chen Gang wrote:
> R0 is corrupted after calling __do_div64 and compiler is not informed
> about this in macro __do_div_asm. If n is to be used again after this
> macro, r0 is not reloaded and n will contain incorrect value
>
> Signed-off-by: Chen Gang <gangchen@rdamicro.com>
> ---
> arch/arm/include/asm/div64.h | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h
> index a66061a..4829618 100644
> --- a/arch/arm/include/asm/div64.h
> +++ b/arch/arm/include/asm/div64.h
> @@ -34,13 +34,15 @@
> register unsigned long long __n asm("r0") = n; \
> register unsigned long long __res asm("r2"); \
> register unsigned int __rem asm(__xh); \
> + register unsigned int __clobber asm(__xl); \
> asm( __asmeq("%0", __xh) \
> - __asmeq("%1", "r2") \
> - __asmeq("%2", "r0") \
> - __asmeq("%3", "r4") \
> + __asmeq("%1", __xl) \
> + __asmeq("%2", "r2") \
> + __asmeq("%3", "r0") \
> + __asmeq("%4", "r4") \
> "bl __do_div64" \
> - : "=r" (__rem), "=r" (__res) \
> - : "r" (__n), "r" (__base) \
> + : "=r"(__rem), "=r"(__clobber), "=r"(__res) \
> + : "r"(__n), "r"(__base) \
> : "ip", "lr", "cc"); \
> n = __res; \
> __rem; \
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 1/1] ARM:r0 is also corrupted after calling __do_div64.
2015-05-12 10:00 ` Russell King - ARM Linux
2015-05-12 10:40 ` Chen Gang
@ 2015-05-12 10:42 ` Chen Gang
1 sibling, 0 replies; 5+ messages in thread
From: Chen Gang @ 2015-05-12 10:42 UTC (permalink / raw)
To: linux-arm-kernel
On 05/12/2015 06:00 PM, Russell King - ARM Linux wrote:
> On Tue, May 12, 2015 at 02:33:06PM +0800, Chen Gang wrote:
>> R0 is corrupted after calling __do_div64 and compiler is not informed
>> about this in macro __do_div_asm. If n is to be used again after this
>> macro, r0 is not reloaded and n will contain incorrect value
> This isn't going to work if we're building for big endian (__ARMEB__
> set) because then we end up telling the compiler that __rem and __n
> are both in r0, which is impossible.
We tested your suggestion , it works and it feels better. I have
sent another patch based on your suggestions.
>
>> diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h
>> index a66061a..93a9985 100644
>> --- a/arch/arm/include/asm/div64.h
>> +++ b/arch/arm/include/asm/div64.h
>> @@ -34,13 +34,13 @@
>> register unsigned long long __n asm("r0") = n; \
>> register unsigned long long __res asm("r2"); \
>> register unsigned int __rem asm(__xh); \
> register unsigned int __rem_xh asm(__xh); \
> register unsigned int __rem_xl asm(__xl); \
>
>> - asm( __asmeq("%0", __xh) \
>> + asm( __asmeq("%R0", __xh) \
> asm( __asmeq("%0", __xh) \
> __asmeq("%1", __xl) \
>
> ... and increment each following register %-spec by one...
>
>> __asmeq("%1", "r2") \
>> __asmeq("%2", "r0") \
>> __asmeq("%3", "r4") \
>> "bl __do_div64" \
>> - : "=r" (__rem), "=r" (__res) \
>> - : "r" (__n), "r" (__base) \
>> + : "=r" (__n), "=r" (__res) \
>> + : "0"(__n), "r" (__base) \
> This is obviously wrong because __rem is left unset, and that's one of
> the two values this macro returns.
>
> : "=r" (__rem_xh), "=r" (__rem_xl), "=r" (__res) \
> : "r" (__n), "r" (__base) \
>
>> : "ip", "lr", "cc"); \
>> n = __res; \
>> __rem; \
> __rem_xh;
>
> Basically this renames __rem to __rem_xh, and introduces a new __rem_xl
> to take the other half of the remainder which we don't use.
>
^ permalink raw reply [flat|nested] 5+ messages in thread
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2015-05-12 6:33 [PATCH 1/1] ARM:r0 is also corrupted after calling __do_div64 Chen Gang
2015-05-12 10:00 ` Russell King - ARM Linux
2015-05-12 10:40 ` Chen Gang
2015-05-14 3:39 ` Chen Gang
2015-05-12 10:42 ` Chen Gang
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