* [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR
[not found] <20210910234047.1019925-1-ndesaulniers@google.com>
@ 2021-09-10 23:40 ` Nick Desaulniers
2021-09-10 23:48 ` Nathan Chancellor
2021-09-11 15:34 ` Christophe Leroy
0 siblings, 2 replies; 4+ messages in thread
From: Nick Desaulniers @ 2021-09-10 23:40 UTC (permalink / raw)
To: Andrew Morton
Cc: Arnd Bergmann, linuxppc-dev, Stephen Rothwell, Nick Desaulniers,
Masahiro Yamada, llvm, Rasmus Villemoes, linux-kernel,
Nathan Chancellor, Paul Mackerras, Joe Perches, Linus Torvalds
Now that GCC 5.1 is the minimum supported version, we can drop this
workaround for older versions of GCC. This adversely affected clang,
too.
Cc: Michael Ellerman <mpe@ellerman•id.au>
Cc: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: Paul Mackerras <paulus@samba•org>
Cc: Segher Boessenkool <segher@kernel•crashing.org>
Cc: Christophe Leroy <christophe.leroy@csgroup•eu>
Cc: linuxppc-dev@lists•ozlabs.org
Signed-off-by: Nick Desaulniers <ndesaulniers@google•com>
---
arch/powerpc/include/asm/asm-const.h | 10 ----------
1 file changed, 10 deletions(-)
diff --git a/arch/powerpc/include/asm/asm-const.h b/arch/powerpc/include/asm/asm-const.h
index 0ce2368bd20f..dbfa5e1e3198 100644
--- a/arch/powerpc/include/asm/asm-const.h
+++ b/arch/powerpc/include/asm/asm-const.h
@@ -12,16 +12,6 @@
# define ASM_CONST(x) __ASM_CONST(x)
#endif
-/*
- * Inline assembly memory constraint
- *
- * GCC 4.9 doesn't properly handle pre update memory constraint "m<>"
- *
- */
-#if defined(GCC_VERSION) && GCC_VERSION < 50000
-#define UPD_CONSTR ""
-#else
#define UPD_CONSTR "<>"
-#endif
#endif /* _ASM_POWERPC_ASM_CONST_H */
--
2.33.0.309.g3052b89438-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR
2021-09-10 23:40 ` [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR Nick Desaulniers
@ 2021-09-10 23:48 ` Nathan Chancellor
2021-09-11 10:43 ` Michael Ellerman
2021-09-11 15:34 ` Christophe Leroy
1 sibling, 1 reply; 4+ messages in thread
From: Nathan Chancellor @ 2021-09-10 23:48 UTC (permalink / raw)
To: Nick Desaulniers, Andrew Morton
Cc: Stephen Rothwell, linuxppc-dev, Arnd Bergmann, Masahiro Yamada,
llvm, Rasmus Villemoes, linux-kernel, Paul Mackerras, Joe Perches,
Linus Torvalds
On 9/10/2021 4:40 PM, Nick Desaulniers wrote:
> Now that GCC 5.1 is the minimum supported version, we can drop this
> workaround for older versions of GCC. This adversely affected clang,
> too.
>
> Cc: Michael Ellerman <mpe@ellerman•id.au>
> Cc: Benjamin Herrenschmidt <benh@kernel•crashing.org>
> Cc: Paul Mackerras <paulus@samba•org>
> Cc: Segher Boessenkool <segher@kernel•crashing.org>
> Cc: Christophe Leroy <christophe.leroy@csgroup•eu>
> Cc: linuxppc-dev@lists•ozlabs.org
> Signed-off-by: Nick Desaulniers <ndesaulniers@google•com>
> ---
> arch/powerpc/include/asm/asm-const.h | 10 ----------
> 1 file changed, 10 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/asm-const.h b/arch/powerpc/include/asm/asm-const.h
> index 0ce2368bd20f..dbfa5e1e3198 100644
> --- a/arch/powerpc/include/asm/asm-const.h
> +++ b/arch/powerpc/include/asm/asm-const.h
> @@ -12,16 +12,6 @@
> # define ASM_CONST(x) __ASM_CONST(x)
> #endif
>
> -/*
> - * Inline assembly memory constraint
> - *
> - * GCC 4.9 doesn't properly handle pre update memory constraint "m<>"
> - *
> - */
> -#if defined(GCC_VERSION) && GCC_VERSION < 50000
> -#define UPD_CONSTR ""
> -#else
> #define UPD_CONSTR "<>"
> -#endif
The only reason this exists is because of commit 592bbe9c505d
("powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9"). It is
probably just worth sinking "<>" into all of the callsites and removing
UPD_CONSTR.
>
> #endif /* _ASM_POWERPC_ASM_CONST_H */
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR
2021-09-10 23:48 ` Nathan Chancellor
@ 2021-09-11 10:43 ` Michael Ellerman
0 siblings, 0 replies; 4+ messages in thread
From: Michael Ellerman @ 2021-09-11 10:43 UTC (permalink / raw)
To: Nathan Chancellor, Nick Desaulniers, Andrew Morton
Cc: Stephen Rothwell, linuxppc-dev, Arnd Bergmann, Masahiro Yamada,
llvm, Rasmus Villemoes, linux-kernel, Paul Mackerras, Joe Perches,
Linus Torvalds
Nathan Chancellor <nathan@kernel•org> writes:
> On 9/10/2021 4:40 PM, Nick Desaulniers wrote:
>> Now that GCC 5.1 is the minimum supported version, we can drop this
>> workaround for older versions of GCC. This adversely affected clang,
>> too.
>>
>> Cc: Michael Ellerman <mpe@ellerman•id.au>
>> Cc: Benjamin Herrenschmidt <benh@kernel•crashing.org>
>> Cc: Paul Mackerras <paulus@samba•org>
>> Cc: Segher Boessenkool <segher@kernel•crashing.org>
>> Cc: Christophe Leroy <christophe.leroy@csgroup•eu>
>> Cc: linuxppc-dev@lists•ozlabs.org
>> Signed-off-by: Nick Desaulniers <ndesaulniers@google•com>
>> ---
>> arch/powerpc/include/asm/asm-const.h | 10 ----------
>> 1 file changed, 10 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/asm-const.h b/arch/powerpc/include/asm/asm-const.h
>> index 0ce2368bd20f..dbfa5e1e3198 100644
>> --- a/arch/powerpc/include/asm/asm-const.h
>> +++ b/arch/powerpc/include/asm/asm-const.h
>> @@ -12,16 +12,6 @@
>> # define ASM_CONST(x) __ASM_CONST(x)
>> #endif
>>
>> -/*
>> - * Inline assembly memory constraint
>> - *
>> - * GCC 4.9 doesn't properly handle pre update memory constraint "m<>"
>> - *
>> - */
>> -#if defined(GCC_VERSION) && GCC_VERSION < 50000
>> -#define UPD_CONSTR ""
>> -#else
>> #define UPD_CONSTR "<>"
>> -#endif
>
> The only reason this exists is because of commit 592bbe9c505d
> ("powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9"). It is
> probably just worth sinking "<>" into all of the callsites and removing
> UPD_CONSTR.
Yeah that would be great if you're doing a v2. Or we can do it as a
follow-up.
cheers
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR
2021-09-10 23:40 ` [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR Nick Desaulniers
2021-09-10 23:48 ` Nathan Chancellor
@ 2021-09-11 15:34 ` Christophe Leroy
1 sibling, 0 replies; 4+ messages in thread
From: Christophe Leroy @ 2021-09-11 15:34 UTC (permalink / raw)
To: Nick Desaulniers, Andrew Morton
Cc: Arnd Bergmann, linuxppc-dev, Stephen Rothwell, Masahiro Yamada,
llvm, Rasmus Villemoes, linux-kernel, Nathan Chancellor,
Paul Mackerras, Joe Perches, Linus Torvalds
Le 11/09/2021 à 01:40, Nick Desaulniers a écrit :
> Now that GCC 5.1 is the minimum supported version, we can drop this
> workaround for older versions of GCC. This adversely affected clang,
> too.
Why do you say that GCC 5.1 is the minimum supported ?
As far as I can see, the minimum supported is still 4.9, see
https://github.com/torvalds/linux/blob/master/Documentation/process/changes.rst
>
> Cc: Michael Ellerman <mpe@ellerman•id.au>
> Cc: Benjamin Herrenschmidt <benh@kernel•crashing.org>
> Cc: Paul Mackerras <paulus@samba•org>
> Cc: Segher Boessenkool <segher@kernel•crashing.org>
> Cc: Christophe Leroy <christophe.leroy@csgroup•eu>
> Cc: linuxppc-dev@lists•ozlabs.org
> Signed-off-by: Nick Desaulniers <ndesaulniers@google•com>
> ---
> arch/powerpc/include/asm/asm-const.h | 10 ----------
> 1 file changed, 10 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/asm-const.h b/arch/powerpc/include/asm/asm-const.h
> index 0ce2368bd20f..dbfa5e1e3198 100644
> --- a/arch/powerpc/include/asm/asm-const.h
> +++ b/arch/powerpc/include/asm/asm-const.h
> @@ -12,16 +12,6 @@
> # define ASM_CONST(x) __ASM_CONST(x)
> #endif
>
> -/*
> - * Inline assembly memory constraint
> - *
> - * GCC 4.9 doesn't properly handle pre update memory constraint "m<>"
> - *
> - */
> -#if defined(GCC_VERSION) && GCC_VERSION < 50000
> -#define UPD_CONSTR ""
> -#else
> #define UPD_CONSTR "<>"
> -#endif
There is no point in keeping UPD_CONSTR if it becomes invariant. You
should just replace all instances of UPD_CONSTR with <> and drop
UPD_CONSTR completely.
Christophe
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-09-10 23:40 ` [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR Nick Desaulniers
2021-09-10 23:48 ` Nathan Chancellor
2021-09-11 10:43 ` Michael Ellerman
2021-09-11 15:34 ` Christophe Leroy
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