package/gcc: fix xtensa uclinux code generation

Message ID 20181107212050.32439-1-jcmvbkbc@gmail.com
State Accepted
Commit 4debb2fbb7d60ed7f81ddab82d8b48ac9c4c3055
Headers show
Series
  • package/gcc: fix xtensa uclinux code generation
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Commit Message

Max Filippov Nov. 7, 2018, 9:20 p.m.
xtensa-uclinux uses bFLT executable file format that cannot relocate
fields representing offsets from data to code. C++ objects built as PIC
use offsets to encode FDE structures. As a result C++ exception handling
doesn't work correctly on xtensa-uclinux. Don't use PIC by default on
xtensa-uclinux.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 ...xtensa-don-t-force-PIC-for-uclinux-target.patch | 41 ++++++++++++++++++++++
 ...xtensa-don-t-force-PIC-for-uclinux-target.patch | 41 ++++++++++++++++++++++
 ...xtensa-don-t-force-PIC-for-uclinux-target.patch | 41 ++++++++++++++++++++++
 3 files changed, 123 insertions(+)
 create mode 100644 package/gcc/6.4.0/0004-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch
 create mode 100644 package/gcc/7.3.0/0005-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch
 create mode 100644 package/gcc/8.2.0/0005-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch

Comments

Thomas Petazzoni Nov. 8, 2018, 10:35 a.m. | #1
Hello Max,

On Wed,  7 Nov 2018 13:20:50 -0800, Max Filippov wrote:
> xtensa-uclinux uses bFLT executable file format that cannot relocate
> fields representing offsets from data to code. C++ objects built as PIC
> use offsets to encode FDE structures. As a result C++ exception handling
> doesn't work correctly on xtensa-uclinux. Don't use PIC by default on
> xtensa-uclinux.
> 
> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Do we actually support xtensa-uclinux (i.e noMMU Xtensa with BFLT) in
the context of Buildroot ?

Best regards,

Thomas
Max Filippov Nov. 8, 2018, 6:28 p.m. | #2
Hi Thomas,

On Thu, Nov 8, 2018 at 2:35 AM Thomas Petazzoni
<thomas.petazzoni@bootlin.com> wrote:
> Do we actually support xtensa-uclinux (i.e noMMU Xtensa with BFLT) in
> the context of Buildroot ?

We do. There's even configs/qemu_xtensa_lx60_nommu_defconfig
with an example config that builds working image.
Thomas Petazzoni Nov. 8, 2018, 7:51 p.m. | #3
Hello,

On Thu, 8 Nov 2018 10:28:01 -0800, Max Filippov wrote:

> On Thu, Nov 8, 2018 at 2:35 AM Thomas Petazzoni
> <thomas.petazzoni@bootlin.com> wrote:
> > Do we actually support xtensa-uclinux (i.e noMMU Xtensa with BFLT) in
> > the context of Buildroot ?  
> 
> We do. There's even configs/qemu_xtensa_lx60_nommu_defconfig
> with an example config that builds working image.

Ah, forgot about this! Nice. Perhaps we should be testing this in the
autobuilders ?

Best regards,

Thomas
Max Filippov Nov. 8, 2018, 8:17 p.m. | #4
On Thu, Nov 8, 2018 at 11:51 AM Thomas Petazzoni
<thomas.petazzoni@bootlin.com> wrote:
> On Thu, 8 Nov 2018 10:28:01 -0800, Max Filippov wrote:
> > On Thu, Nov 8, 2018 at 2:35 AM Thomas Petazzoni
> > <thomas.petazzoni@bootlin.com> wrote:
> > > Do we actually support xtensa-uclinux (i.e noMMU Xtensa with BFLT) in
> > > the context of Buildroot ?
> >
> > We do. There's even configs/qemu_xtensa_lx60_nommu_defconfig
> > with an example config that builds working image.
>
> Ah, forgot about this! Nice. Perhaps we should be testing this in the
> autobuilders ?

I will definitely support that (:
Peter Korsgaard Nov. 9, 2018, 2:51 p.m. | #5
>>>>> "Max" == Max Filippov <jcmvbkbc@gmail.com> writes:

 > xtensa-uclinux uses bFLT executable file format that cannot relocate
 > fields representing offsets from data to code. C++ objects built as PIC
 > use offsets to encode FDE structures. As a result C++ exception handling
 > doesn't work correctly on xtensa-uclinux. Don't use PIC by default on
 > xtensa-uclinux.

 > Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Committed, thanks.

Patch

diff --git a/package/gcc/6.4.0/0004-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch b/package/gcc/6.4.0/0004-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch
new file mode 100644
index 000000000000..360947cbb180
--- /dev/null
+++ b/package/gcc/6.4.0/0004-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch
@@ -0,0 +1,41 @@ 
+From 960a2552f7b418134cdf7a31e96023a3811b98dd Mon Sep 17 00:00:00 2001
+From: Max Filippov <jcmvbkbc@gmail.com>
+Date: Sun, 4 Nov 2018 23:55:59 -0800
+Subject: [PATCH] gcc: xtensa: don't force PIC for uclinux target
+
+xtensa-uclinux uses bFLT executable file format that cannot relocate
+fields representing offsets from data to code. C++ objects built as PIC
+use offsets to encode FDE structures. As a result C++ exception handling
+doesn't work correctly on xtensa-uclinux. Don't use PIC by default on
+xtensa-uclinux.
+
+gcc/
+2018-11-05  Max Filippov  <jcmvbkbc@gmail.com>
+
+	* config/xtensa/uclinux.h (XTENSA_ALWAYS_PIC): Change to 0.
+
+Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
+---
+Backported from: r265823
+
+ gcc/config/xtensa/uclinux.h | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/gcc/config/xtensa/uclinux.h b/gcc/config/xtensa/uclinux.h
+index ba26187c8f7a..c7743df9d97c 100644
+--- a/gcc/config/xtensa/uclinux.h
++++ b/gcc/config/xtensa/uclinux.h
+@@ -59,8 +59,8 @@ along with GCC; see the file COPYING3.  If not see
+ #undef LOCAL_LABEL_PREFIX
+ #define LOCAL_LABEL_PREFIX	"."
+ 
+-/* Always enable "-fpic" for Xtensa Linux.  */
+-#define XTENSA_ALWAYS_PIC 1
++/* Don't enable "-fpic" for Xtensa uclinux.  */
++#define XTENSA_ALWAYS_PIC 0
+ 
+ #undef TARGET_LIBC_HAS_FUNCTION
+ #define TARGET_LIBC_HAS_FUNCTION no_c99_libc_has_function
+-- 
+2.11.0
+
diff --git a/package/gcc/7.3.0/0005-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch b/package/gcc/7.3.0/0005-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch
new file mode 100644
index 000000000000..360947cbb180
--- /dev/null
+++ b/package/gcc/7.3.0/0005-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch
@@ -0,0 +1,41 @@ 
+From 960a2552f7b418134cdf7a31e96023a3811b98dd Mon Sep 17 00:00:00 2001
+From: Max Filippov <jcmvbkbc@gmail.com>
+Date: Sun, 4 Nov 2018 23:55:59 -0800
+Subject: [PATCH] gcc: xtensa: don't force PIC for uclinux target
+
+xtensa-uclinux uses bFLT executable file format that cannot relocate
+fields representing offsets from data to code. C++ objects built as PIC
+use offsets to encode FDE structures. As a result C++ exception handling
+doesn't work correctly on xtensa-uclinux. Don't use PIC by default on
+xtensa-uclinux.
+
+gcc/
+2018-11-05  Max Filippov  <jcmvbkbc@gmail.com>
+
+	* config/xtensa/uclinux.h (XTENSA_ALWAYS_PIC): Change to 0.
+
+Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
+---
+Backported from: r265823
+
+ gcc/config/xtensa/uclinux.h | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/gcc/config/xtensa/uclinux.h b/gcc/config/xtensa/uclinux.h
+index ba26187c8f7a..c7743df9d97c 100644
+--- a/gcc/config/xtensa/uclinux.h
++++ b/gcc/config/xtensa/uclinux.h
+@@ -59,8 +59,8 @@ along with GCC; see the file COPYING3.  If not see
+ #undef LOCAL_LABEL_PREFIX
+ #define LOCAL_LABEL_PREFIX	"."
+ 
+-/* Always enable "-fpic" for Xtensa Linux.  */
+-#define XTENSA_ALWAYS_PIC 1
++/* Don't enable "-fpic" for Xtensa uclinux.  */
++#define XTENSA_ALWAYS_PIC 0
+ 
+ #undef TARGET_LIBC_HAS_FUNCTION
+ #define TARGET_LIBC_HAS_FUNCTION no_c99_libc_has_function
+-- 
+2.11.0
+
diff --git a/package/gcc/8.2.0/0005-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch b/package/gcc/8.2.0/0005-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch
new file mode 100644
index 000000000000..360947cbb180
--- /dev/null
+++ b/package/gcc/8.2.0/0005-gcc-xtensa-don-t-force-PIC-for-uclinux-target.patch
@@ -0,0 +1,41 @@ 
+From 960a2552f7b418134cdf7a31e96023a3811b98dd Mon Sep 17 00:00:00 2001
+From: Max Filippov <jcmvbkbc@gmail.com>
+Date: Sun, 4 Nov 2018 23:55:59 -0800
+Subject: [PATCH] gcc: xtensa: don't force PIC for uclinux target
+
+xtensa-uclinux uses bFLT executable file format that cannot relocate
+fields representing offsets from data to code. C++ objects built as PIC
+use offsets to encode FDE structures. As a result C++ exception handling
+doesn't work correctly on xtensa-uclinux. Don't use PIC by default on
+xtensa-uclinux.
+
+gcc/
+2018-11-05  Max Filippov  <jcmvbkbc@gmail.com>
+
+	* config/xtensa/uclinux.h (XTENSA_ALWAYS_PIC): Change to 0.
+
+Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
+---
+Backported from: r265823
+
+ gcc/config/xtensa/uclinux.h | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/gcc/config/xtensa/uclinux.h b/gcc/config/xtensa/uclinux.h
+index ba26187c8f7a..c7743df9d97c 100644
+--- a/gcc/config/xtensa/uclinux.h
++++ b/gcc/config/xtensa/uclinux.h
+@@ -59,8 +59,8 @@ along with GCC; see the file COPYING3.  If not see
+ #undef LOCAL_LABEL_PREFIX
+ #define LOCAL_LABEL_PREFIX	"."
+ 
+-/* Always enable "-fpic" for Xtensa Linux.  */
+-#define XTENSA_ALWAYS_PIC 1
++/* Don't enable "-fpic" for Xtensa uclinux.  */
++#define XTENSA_ALWAYS_PIC 0
+ 
+ #undef TARGET_LIBC_HAS_FUNCTION
+ #define TARGET_LIBC_HAS_FUNCTION no_c99_libc_has_function
+-- 
+2.11.0
+