diff mbox

[AArch64] Add Cortex-A53 erratum 843419 configure-time option

Message ID CAD57uCdGEc4PH=V4DQpTVuCvTSJx35pvS_yAE_vQGmUYRDrZBA@mail.gmail.com
State New
Headers show

Commit Message

Yvan Roux May 1, 2015, 9:11 a.m. UTC 
Hi all,

As described in the thread bellow, there is a link-time workaround for
an erratum (843419) of some early revision of Cortex-A53.  Similarly
to what was done for a previous erratum, this patch adds a new
configure-time option --enable-fix-cortex-a53-843419 that pass down
the linker option --fix-cortex-a53-843419.

I haven't implemented flags to explicitly disable/enable it during
compilation as it is only a linker workaround, but I can do it if you
think it's necessary.

https://sourceware.org/ml/binutils-cvs/2015-04/msg00012.html

Is it ok for trunk and/or branches ?

Thanks,
Yvan

2015-05-01  Yvan Roux  <yvan.roux@linaro.org>

    * configure.ac: Add --enable-fix-cortex-a53-843419 option.
    * configure: Regenerate.
    * config/aarch64/aarch64-elf-raw.h (CA53_ERR_843419_SPEC): Define.
    (LINK_SPEC): Include CA53_ERR_843419_SPEC.
    * config/aarch64/aarch64-linux.h (CA53_ERR_843419_SPEC): Define.
    (LINK_SPEC): Include CA53_ERR_843419_SPEC.
    * doc/install.texi (aarch64*-*-*): Document
    new --enable-fix-cortex-a53-843419 option.

Comments

Yvan Roux May 1, 2015, 11:39 a.m. UTC | #1 
Hi Marcus,

(Sorry wanted to cc you in my first mail but seems that gmail prefers
Maxim to Marcus ! ;)

On 1 May 2015 at 13:11, Marcus Shawcroft <marcus.shawcroft@gmail.com> wrote:
> On 1 May 2015 at 10:11, Yvan Roux <yvan.roux@linaro.org> wrote:
>> Hi all,
>>
>> As described in the thread bellow, there is a link-time workaround for
>> an erratum (843419) of some early revision of Cortex-A53.  Similarly
>> to what was done for a previous erratum, this patch adds a new
>> configure-time option --enable-fix-cortex-a53-843419 that pass down
>> the linker option --fix-cortex-a53-843419.
>>
>> I haven't implemented flags to explicitly disable/enable it during
>> compilation as it is only a linker workaround, but I can do it if you
>> think it's necessary.
>
> Hi Yvan,
>
> In the case of the 835769 erratum, providing such GCC configury made
> (some) sense because the workaround included both a GCC and an LD
> component. GCC in effect needed the option to control GCC behaviour
> aswell as LD behaviour. The same is not true of 843419. The net effect
> of the proposed  patch here is to provide a configure option in GCC to
> change the default behaviour of LD, with no other purpose within GCC
> itself.  This seems rather bizarre to me. I would have thought that if
> the sole objective is to change the default behaviour of LD, then
> there should be configure time options on LD, rather than GCC.

Yes indeed.

> That said, I can also see that providing consistent behaviour across
> these various work around configure options and consistent run time
> options for the user will reduce confusion in the future, both for
> folks building toolchains and for the folks using them.  From this
> perspective I think it would be better to go with this patch *and*
> include the flags explicitly such the both of the current workaround
> have equivalent configury behaviour and have equivalent user flags at
> run time.

Ok I'll add the -mfix-cortex-a53-843419 flags to be consistent.

Cheers
Yvan

> Cheers
> /Marcus
>
>>
>> https://sourceware.org/ml/binutils-cvs/2015-04/msg00012.html
>>
>> Is it ok for trunk and/or branches ?
>>
>> Thanks,
>> Yvan
>>
>> 2015-05-01  Yvan Roux  <yvan.roux@linaro.org>
>>
>>     * configure.ac: Add --enable-fix-cortex-a53-843419 option.
>>     * configure: Regenerate.
>>     * config/aarch64/aarch64-elf-raw.h (CA53_ERR_843419_SPEC): Define.
>>     (LINK_SPEC): Include CA53_ERR_843419_SPEC.
>>     * config/aarch64/aarch64-linux.h (CA53_ERR_843419_SPEC): Define.
>>     (LINK_SPEC): Include CA53_ERR_843419_SPEC.
>>     * doc/install.texi (aarch64*-*-*): Document
>>     new --enable-fix-cortex-a53-843419 option.
diff mbox

Patch

diff --git a/gcc/config/aarch64/aarch64-elf-raw.h b/gcc/config/aarch64/aarch64-elf-raw.h
index ebeeb50..09dcfaf 100644
--- a/gcc/config/aarch64/aarch64-elf-raw.h
+++ b/gcc/config/aarch64/aarch64-elf-raw.h
@@ -35,10 +35,17 @@ 
   " %{mfix-cortex-a53-835769:--fix-cortex-a53-835769}"
 #endif
 
+#ifdef TARGET_FIX_ERR_A53_843419_DEFAULT
+#define CA53_ERR_843419_SPEC " --fix-cortex-a53-843419 "
+#else
+#define CA53_ERR_843419_SPEC ""
+#endif
+
 #ifndef LINK_SPEC
 #define LINK_SPEC "%{mbig-endian:-EB} %{mlittle-endian:-EL} -X \
   -maarch64elf%{mabi=ilp32*:32}%{mbig-endian:b}" \
-  CA53_ERR_835769_SPEC
+  CA53_ERR_835769_SPEC \
+  CA53_ERR_843419_SPEC
 #endif
 
 #endif /* GCC_AARCH64_ELF_RAW_H */
diff --git a/gcc/config/aarch64/aarch64-linux.h b/gcc/config/aarch64/aarch64-linux.h
index 9abb252..2219ead 100644
--- a/gcc/config/aarch64/aarch64-linux.h
+++ b/gcc/config/aarch64/aarch64-linux.h
@@ -49,8 +49,15 @@ 
   " %{mfix-cortex-a53-835769:--fix-cortex-a53-835769}"
 #endif
 
+#ifdef TARGET_FIX_ERR_A53_843419_DEFAULT
+#define CA53_ERR_843419_SPEC " --fix-cortex-a53-843419 "
+#else
+#define CA53_ERR_843419_SPEC ""
+#endif
+
 #define LINK_SPEC LINUX_TARGET_LINK_SPEC \
-                  CA53_ERR_835769_SPEC
+                  CA53_ERR_835769_SPEC \
+                  CA53_ERR_843419_SPEC
 
 #define GNU_USER_TARGET_MATHFILE_SPEC \
   "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s}"
diff --git a/gcc/configure b/gcc/configure
index 84f58ce..e563e94 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -923,6 +923,7 @@  enable_gnu_indirect_function
 enable_initfini_array
 enable_comdat
 enable_fix_cortex_a53_835769
+enable_fix_cortex_a53_843419
 with_glibc_version
 enable_gnu_unique_object
 enable_linker_build_id
@@ -1648,6 +1649,14 @@  Optional Features:
                           disable workaround for AArch64 Cortex-A53 erratum
                           835769 by default
 
+
+  --enable-fix-cortex-a53-843419
+                          enable workaround for AArch64 Cortex-A53 erratum
+                          843419 by default
+  --disable-fix-cortex-a53-843419
+                          disable workaround for AArch64 Cortex-A53 erratum
+                          843419 by default
+
   --enable-gnu-unique-object
                           enable the use of the @gnu_unique_object ELF
                           extension on glibc systems
@@ -18153,7 +18162,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18156 "configure"
+#line 18165 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -18259,7 +18268,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18262 "configure"
+#line 18271 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -24102,6 +24111,25 @@  if test "${enable_fix_cortex_a53_835769+set}" = set; then :
 
 fi
 
+    # Enable default workaround for AArch64 Cortex-A53 erratum 843419.
+    # Check whether --enable-fix-cortex-a53-843419 was given.
+if test "${enable_fix_cortex_a53_843419+set}" = set; then :
+  enableval=$enable_fix_cortex_a53_843419;
+        case $enableval in
+          yes)
+            tm_defines="${tm_defines} TARGET_FIX_ERR_A53_843419_DEFAULT=1"
+            ;;
+          no)
+            ;;
+          *)
+            as_fn_error "'$enableval' is an invalid value for --enable-fix-cortex-a53-843419.\
+  Valid choices are 'yes' and 'no'." "$LINENO" 5
+            ;;
+
+        esac
+
+fi
+
     ;;
 
   # All TARGET_ABI_OSF targets.
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 7fb6131..55fe633 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -3592,6 +3592,29 @@  AS_HELP_STRING([--disable-fix-cortex-a53-835769],
         esac
       ],
     [])
+    # Enable default workaround for AArch64 Cortex-A53 erratum 843419.
+    AC_ARG_ENABLE(fix-cortex-a53-843419,
+    [
+AS_HELP_STRING([--enable-fix-cortex-a53-843419],
+        [enable workaround for AArch64 Cortex-A53 erratum 843419 by default])
+AS_HELP_STRING([--disable-fix-cortex-a53-843419],
+        [disable workaround for AArch64 Cortex-A53 erratum 843419 by default])
+    ],
+      [
+        case $enableval in
+          yes)
+            tm_defines="${tm_defines} TARGET_FIX_ERR_A53_843419_DEFAULT=1"
+            ;;
+          no)
+            ;;
+          *)
+            AC_MSG_ERROR(['$enableval' is an invalid value for --enable-fix-cortex-a53-843419.\
+  Valid choices are 'yes' and 'no'.])
+            ;;
+
+        esac
+      ],
+    [])
     ;;
 
   # All TARGET_ABI_OSF targets.
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 783116e..7810696 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -3415,6 +3415,16 @@  default.  The workaround is disabled by default if neither of
 @option{--enable-fix-cortex-a53-835769} or
 @option{--disable-fix-cortex-a53-835769} is given at configure time.
 
+To enable a workaround for the Cortex-A53 erratum number 843419 by default
+(for all CPUs regardless of -mcpu option given) at configure time use the
+@option{--enable-fix-cortex-a53-843419} option.  This erratum workaround is
+made at link time and enabling it by default in GCC will only pass the
+corresponding flag to the linker.  Conversely,
+@option{--disable-fix-cortex-a53-843419} will disable the workaround by
+default.  The workaround is disabled by default if neither of
+@option{--enable-fix-cortex-a53-843419} or
+@option{--disable-fix-cortex-a53-843419} is given at configure time.
+
 @html
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