[Buildroot] [RFC][PATCH] bfin: fix two issues with internal toolchain

[Buildroot] [RFC][PATCH] bfin: fix two issues with internal toolchain

[Waldemar Brodkorb]

Allows to compile DWARF EH.

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
---
Hi,
this is my present work on the Blackfin C++ issues with the internal
toolchain. There is still following problem:
$ ./output/host/usr/bin/bfin-buildroot-linux-uclibc-g++ -o foo foo.cc                                                                                                              
/home/wbx/buildroot/output/host/usr/lib/gcc/bfin-buildroot-linux-uclibc/6.1.0/../../../../bfin-buildroot-linux-uclibc/lib/libstdc++.so:
undefined reference to `_Unwind_GetRegionStart'
..
$ cat foo.cc                                                                                                                                                                       
#include <iostream>
int main(void) { std::cout << "hello, world\n"; }

But libstdc++ should search for __Unwind_GetRegionStart:
nm
/home/wbx/buildroot/output/host/usr/lib/gcc/bfin-buildroot-linux-uclibc/6.1.0/../../../../bfin-buildroot-linux-uclibc/lib/libstdc++.so|grep
_Unwind_GetRegionStart<
         U __Unwind_GetRegionStart

And libgcc_s.so.1 provides it:
./output/host/usr/bin/bfin-buildroot-linux-uclibc-nm
./output/host/usr/bfin-buildroot-linux-uclibc/sysroot/lib/libgcc_s.so.1|grep
_Unwind_GetRegionStart                         
00005d0c t __Unwind_GetRegionStart

So why is ld trying to find _Unwind_GetRegionStart instead of
__Unwind_GetRegionStart when linking?
Does ld ignores __USER_LABEL_PREFIX__?

Any ideas and help is really appreciated.

Here are some g++ verbose output logs from internal and external
buildroot toolchain:
http://debug.openadk.org/buildroot/

---
 package/gcc/6.1.0/892-disable-dwarf-bfin.patch     |   24 -------------
 package/gcc/6.1.0/892-fix-dwarf-fdpic.patch        |   37 ++++++++++++++++++++
 .../6.1.0/893-bfin-add-libgcc-linker-script.patch  |   20 +++++++++++
 3 files changed, 57 insertions(+), 24 deletions(-)
 delete mode 100644 package/gcc/6.1.0/892-disable-dwarf-bfin.patch
 create mode 100644 package/gcc/6.1.0/892-fix-dwarf-fdpic.patch
 create mode 100644 package/gcc/6.1.0/893-bfin-add-libgcc-linker-script.patch

diff --git a/package/gcc/6.1.0/892-disable-dwarf-bfin.patch b/package/gcc/6.1.0/892-disable-dwarf-bfin.patch
deleted file mode 100644
index ebd31a1..0000000
--- a/package/gcc/6.1.0/892-disable-dwarf-bfin.patch
+++ /dev/null
@@ -1,24 +0,0 @@
-Dwarf support does not compile on Blackfin
-
-Reported upstream:
-https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68468
-
-Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
-
-diff -Nur gcc-6.1.0.orig/libgcc/config.host gcc-6.1.0/libgcc/config.host
---- gcc-6.1.0.orig/libgcc/config.host	2016-02-26 21:02:28.000000000 +0100
-+++ gcc-6.1.0/libgcc/config.host	2016-05-12 19:26:30.973350274 +0200
-@@ -230,6 +230,13 @@
-       ;;
-   esac
-   ;;
-+bfin-*-*linux*)
-+  tmake_file="$tmake_file t-crtstuff-pic t-libgcc-pic t-slibgcc t-slibgcc-gld t-slibgcc-elf-ver t-linux"
-+  extra_parts="crtbegin.o crtbeginS.o crtbeginT.o crtend.o crtendS.o"
-+  if test x$enable_vtable_verify = xyes; then
-+    extra_parts="$extra_parts vtv_start.o vtv_end.o vtv_start_preinit.o vtv_end_preinit.o"
-+  fi
-+  ;;
- *-*-linux* | frv-*-*linux* | *-*-kfreebsd*-gnu | *-*-knetbsd*-gnu | *-*-gnu* | *-*-kopensolaris*-gnu)
-   tmake_file="$tmake_file t-crtstuff-pic t-libgcc-pic t-eh-dw2-dip t-slibgcc t-slibgcc-gld t-slibgcc-elf-ver t-linux"
-   extra_parts="crtbegin.o crtbeginS.o crtbeginT.o crtend.o crtendS.o"
diff --git a/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch b/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch
new file mode 100644
index 0000000..315b406
--- /dev/null
+++ b/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch
@@ -0,0 +1,37 @@
+Fix DWARF compilation for FDPIC targets
+
+Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
+
+diff -Nur gcc-6.1.0.orig/libgcc/unwind-dw2-fde-dip.c gcc-6.1.0/libgcc/unwind-dw2-fde-dip.c
+--- gcc-6.1.0.orig/libgcc/unwind-dw2-fde-dip.c	2016-01-04 15:30:50.000000000 +0100
++++ gcc-6.1.0/libgcc/unwind-dw2-fde-dip.c	2016-08-05 02:17:40.424195128 +0200
+@@ -124,7 +124,11 @@
+ {
+   _Unwind_Ptr pc_low;
+   _Unwind_Ptr pc_high;
++#if defined __FRV_FDPIC__ || defined __BFIN_FDPIC__
++  struct elf32_fdpic_loadaddr load_base;
++#else
+   _Unwind_Ptr load_base;
++#endif
+   const ElfW(Phdr) *p_eh_frame_hdr;
+   const ElfW(Phdr) *p_dynamic;
+   struct frame_hdr_cache_element *link;
+@@ -163,7 +167,7 @@
+   struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr;
+   const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic;
+   long n, match;
+-#ifdef __FRV_FDPIC__
++#if defined __FRV_FDPIC__ || defined __BFIN_FDPIC__
+   struct elf32_fdpic_loadaddr load_base;
+ #else
+   _Unwind_Ptr load_base;
+@@ -347,7 +351,7 @@
+ 	    break;
+ 	  }
+     }
+-# elif defined __FRV_FDPIC__ && defined __linux__
++# elif (defined __FRV_FDPIC__ || defined __BFIN_FDPIC__) && defined __linux__
+   data->dbase = load_base.got_value;
+ # else
+ #  error What is DW_EH_PE_datarel base on this platform?
diff --git a/package/gcc/6.1.0/893-bfin-add-libgcc-linker-script.patch b/package/gcc/6.1.0/893-bfin-add-libgcc-linker-script.patch
new file mode 100644
index 0000000..88548fc
--- /dev/null
+++ b/package/gcc/6.1.0/893-bfin-add-libgcc-linker-script.patch
@@ -0,0 +1,20 @@
+Add libgcc linker script for Blackfin FDPIC.
+
+Solves following linking error:
+# bfin-openadk-linux-uclibc-g++ -o foo t.c
+bfin-openadk-linux-uclibc/bin/ld: foo: hidden symbol `___udivsi3' in libgcc.a(_udivsi3.o) is referenced by DSO
+
+Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
+
+diff -Nur gcc-6.1.0.orig/libgcc/config.host gcc-6.1.0/libgcc/config.host
+--- gcc-6.1.0.orig/libgcc/config.host	2016-02-26 21:02:28.000000000 +0100
++++ gcc-6.1.0/libgcc/config.host	2016-07-25 02:47:05.818797217 +0200
+@@ -444,7 +444,7 @@
+ 	md_unwind_header=bfin/linux-unwind.h
+         ;;
+ bfin*-linux-uclibc*)
+-	tmake_file="$tmake_file bfin/t-bfin bfin/t-crtstuff t-libgcc-pic t-fdpbit bfin/t-linux"
++	tmake_file="$tmake_file bfin/t-bfin bfin/t-crtstuff t-libgcc-pic t-slibgcc-libgcc t-fdpbit bfin/t-linux"
+ 	# No need to build crtbeginT.o on uClibc systems.  Should probably
+ 	# be moved to the OS specific section above.
+ 	extra_parts="crtbegin.o crtbeginS.o crtend.o crtendS.o"
-- 
1.7.10.4

[Buildroot] [RFC][PATCH] bfin: fix two issues with internal toolchain

[Thomas Petazzoni]

Hello,

On Fri, 5 Aug 2016 21:52:47 +0200, Waldemar Brodkorb wrote:

> And libgcc_s.so.1 provides it:
> ./output/host/usr/bin/bfin-buildroot-linux-uclibc-nm
> ./output/host/usr/bfin-buildroot-linux-uclibc/sysroot/lib/libgcc_s.so.1|grep
> _Unwind_GetRegionStart                         
> 00005d0c t __Unwind_GetRegionStart

We are currently discussing it on IRC, but I believe the problem is
that "t" indicates that the symbol is not visible. It should be a "T".

> diff --git a/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch b/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch
> new file mode 100644
> index 0000000..315b406
> --- /dev/null
> +++ b/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch
> @@ -0,0 +1,37 @@
> +Fix DWARF compilation for FDPIC targets
> +
> +Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
> +
> +diff -Nur gcc-6.1.0.orig/libgcc/unwind-dw2-fde-dip.c gcc-6.1.0/libgcc/unwind-dw2-fde-dip.c
> +--- gcc-6.1.0.orig/libgcc/unwind-dw2-fde-dip.c	2016-01-04 15:30:50.000000000 +0100
> ++++ gcc-6.1.0/libgcc/unwind-dw2-fde-dip.c	2016-08-05 02:17:40.424195128 +0200
> +@@ -124,7 +124,11 @@
> + {
> +   _Unwind_Ptr pc_low;
> +   _Unwind_Ptr pc_high;
> ++#if defined __FRV_FDPIC__ || defined __BFIN_FDPIC__
> ++  struct elf32_fdpic_loadaddr load_base;
> ++#else

I'm surprised by this part of the patch, since you are changing the
behavior for __FRV_FDPIC__ as well. It wasn't working before?

In all other chunks you simply add __BFIN_FDPIC__ as behaving the same
as __FRV_FDPIC__ but you're not doing the same here. Is this expected?

> ++#if defined __FRV_FDPIC__ || defined __BFIN_FDPIC__

Obvious question: is there a symbol that says "I'm using FDPIC" and
which would make such conditions simpler?

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] [RFC][PATCH] bfin: fix two issues with internal toolchain

[Waldemar Brodkorb]

Hi Thomas,
Thomas Petazzoni wrote,

> Hello,
> 
> On Fri, 5 Aug 2016 21:52:47 +0200, Waldemar Brodkorb wrote:
> 
> > And libgcc_s.so.1 provides it:
> > ./output/host/usr/bin/bfin-buildroot-linux-uclibc-nm
> > ./output/host/usr/bfin-buildroot-linux-uclibc/sysroot/lib/libgcc_s.so.1|grep
> > _Unwind_GetRegionStart                         
> > 00005d0c t __Unwind_GetRegionStart
> 
> We are currently discussing it on IRC, but I believe the problem is
> that "t" indicates that the symbol is not visible. It should be a "T".

You are right, this seems to be the problem. You nailed it down!
It seems ELF has two different concepts for symbol visibility:
https://www.technovelty.org/code/why-symbol-visibility-is-good.html

The symbols in the libgcc_s.so.1 generated by internal toolchain are
bind "LOCAL", so not visible for linking the c++ application.
The Unwind* symbols in libgcc_s.so.1 from the external toolchain are
bind "GLOBAL".

Next thing is to find the reason for it.
 
> > diff --git a/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch b/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch
> > new file mode 100644
> > index 0000000..315b406
> > --- /dev/null
> > +++ b/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch
> > @@ -0,0 +1,37 @@
> > +Fix DWARF compilation for FDPIC targets
> > +
> > +Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
> > +
> > +diff -Nur gcc-6.1.0.orig/libgcc/unwind-dw2-fde-dip.c gcc-6.1.0/libgcc/unwind-dw2-fde-dip.c
> > +--- gcc-6.1.0.orig/libgcc/unwind-dw2-fde-dip.c	2016-01-04 15:30:50.000000000 +0100
> > ++++ gcc-6.1.0/libgcc/unwind-dw2-fde-dip.c	2016-08-05 02:17:40.424195128 +0200
> > +@@ -124,7 +124,11 @@
> > + {
> > +   _Unwind_Ptr pc_low;
> > +   _Unwind_Ptr pc_high;
> > ++#if defined __FRV_FDPIC__ || defined __BFIN_FDPIC__
> > ++  struct elf32_fdpic_loadaddr load_base;
> > ++#else
> 
> I'm surprised by this part of the patch, since you are changing the
> behavior for __FRV_FDPIC__ as well. It wasn't working before?

No, DWARF compiling for FR-V architecture is broken/bitrotted as
well. So this patch will be what I am suggesting upstream.
 
> In all other chunks you simply add __BFIN_FDPIC__ as behaving the same
> as __FRV_FDPIC__ but you're not doing the same here. Is this expected?
> 
> > ++#if defined __FRV_FDPIC__ || defined __BFIN_FDPIC__
> 
> Obvious question: is there a symbol that says "I'm using FDPIC" and
> which would make such conditions simpler?

There is a symbol __FDPIC__ for Bfin and FR-V, but it is exposed
_after_ the full gcc is build and can not be used while
bootstrapping the toolchain. I tried it.

best regards
 Waldemar

[Buildroot] [RFC][PATCH] bfin: fix two issues with internal toolchain

[Waldemar Brodkorb]

Hi,
Waldemar Brodkorb wrote,

I think the patch is okay and should be used. But I give up on the
remaining problem for this release. 

I tried all version of binutils from 2.27 down to ADI toolchain
binutils 2.21. It seems not a binutils or linker problem.

I tried to convert the LOCAL symbols with objcopy to GLOBAL, but
the problem persist.

I recognized that the missing symbols in libstdc++.so are NOTYPE,
but in the working external toolchain they are FUNC.

Without help from some Blackfin developer from Analog Devices I see
no chance to fix it right now.

@Thomas: Can you disable C++ for internal Blackfin toolchain?
Thanks.

best regards
 Waldemar

> Allows to compile DWARF EH.
> 
> Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
> ---
> Hi,
> this is my present work on the Blackfin C++ issues with the internal
> toolchain. There is still following problem:
> $ ./output/host/usr/bin/bfin-buildroot-linux-uclibc-g++ -o foo foo.cc                                                                                                              
> /home/wbx/buildroot/output/host/usr/lib/gcc/bfin-buildroot-linux-uclibc/6.1.0/../../../../bfin-buildroot-linux-uclibc/lib/libstdc++.so:
> undefined reference to `_Unwind_GetRegionStart'
> ..
> $ cat foo.cc                                                                                                                                                                       
> #include <iostream>
> int main(void) { std::cout << "hello, world\n"; }
> 
> But libstdc++ should search for __Unwind_GetRegionStart:
> nm
> /home/wbx/buildroot/output/host/usr/lib/gcc/bfin-buildroot-linux-uclibc/6.1.0/../../../../bfin-buildroot-linux-uclibc/lib/libstdc++.so|grep
> _Unwind_GetRegionStart<
>          U __Unwind_GetRegionStart
> 
> And libgcc_s.so.1 provides it:
> ./output/host/usr/bin/bfin-buildroot-linux-uclibc-nm
> ./output/host/usr/bfin-buildroot-linux-uclibc/sysroot/lib/libgcc_s.so.1|grep
> _Unwind_GetRegionStart                         
> 00005d0c t __Unwind_GetRegionStart
> 
> So why is ld trying to find _Unwind_GetRegionStart instead of
> __Unwind_GetRegionStart when linking?
> Does ld ignores __USER_LABEL_PREFIX__?
> 
> Any ideas and help is really appreciated.
> 
> Here are some g++ verbose output logs from internal and external
> buildroot toolchain:
> http://debug.openadk.org/buildroot/
> 
> ---
>  package/gcc/6.1.0/892-disable-dwarf-bfin.patch     |   24 -------------
>  package/gcc/6.1.0/892-fix-dwarf-fdpic.patch        |   37 ++++++++++++++++++++
>  .../6.1.0/893-bfin-add-libgcc-linker-script.patch  |   20 +++++++++++
>  3 files changed, 57 insertions(+), 24 deletions(-)
>  delete mode 100644 package/gcc/6.1.0/892-disable-dwarf-bfin.patch
>  create mode 100644 package/gcc/6.1.0/892-fix-dwarf-fdpic.patch
>  create mode 100644 package/gcc/6.1.0/893-bfin-add-libgcc-linker-script.patch
> 
> diff --git a/package/gcc/6.1.0/892-disable-dwarf-bfin.patch b/package/gcc/6.1.0/892-disable-dwarf-bfin.patch
> deleted file mode 100644
> index ebd31a1..0000000
> --- a/package/gcc/6.1.0/892-disable-dwarf-bfin.patch
> +++ /dev/null
> @@ -1,24 +0,0 @@
> -Dwarf support does not compile on Blackfin
> -
> -Reported upstream:
> -https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68468
> -
> -Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
> -
> -diff -Nur gcc-6.1.0.orig/libgcc/config.host gcc-6.1.0/libgcc/config.host
> ---- gcc-6.1.0.orig/libgcc/config.host	2016-02-26 21:02:28.000000000 +0100
> -+++ gcc-6.1.0/libgcc/config.host	2016-05-12 19:26:30.973350274 +0200
> -@@ -230,6 +230,13 @@
> -       ;;
> -   esac
> -   ;;
> -+bfin-*-*linux*)
> -+  tmake_file="$tmake_file t-crtstuff-pic t-libgcc-pic t-slibgcc t-slibgcc-gld t-slibgcc-elf-ver t-linux"
> -+  extra_parts="crtbegin.o crtbeginS.o crtbeginT.o crtend.o crtendS.o"
> -+  if test x$enable_vtable_verify = xyes; then
> -+    extra_parts="$extra_parts vtv_start.o vtv_end.o vtv_start_preinit.o vtv_end_preinit.o"
> -+  fi
> -+  ;;
> - *-*-linux* | frv-*-*linux* | *-*-kfreebsd*-gnu | *-*-knetbsd*-gnu | *-*-gnu* | *-*-kopensolaris*-gnu)
> -   tmake_file="$tmake_file t-crtstuff-pic t-libgcc-pic t-eh-dw2-dip t-slibgcc t-slibgcc-gld t-slibgcc-elf-ver t-linux"
> -   extra_parts="crtbegin.o crtbeginS.o crtbeginT.o crtend.o crtendS.o"
> diff --git a/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch b/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch
> new file mode 100644
> index 0000000..315b406
> --- /dev/null
> +++ b/package/gcc/6.1.0/892-fix-dwarf-fdpic.patch
> @@ -0,0 +1,37 @@
> +Fix DWARF compilation for FDPIC targets
> +
> +Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
> +
> +diff -Nur gcc-6.1.0.orig/libgcc/unwind-dw2-fde-dip.c gcc-6.1.0/libgcc/unwind-dw2-fde-dip.c
> +--- gcc-6.1.0.orig/libgcc/unwind-dw2-fde-dip.c	2016-01-04 15:30:50.000000000 +0100
> ++++ gcc-6.1.0/libgcc/unwind-dw2-fde-dip.c	2016-08-05 02:17:40.424195128 +0200
> +@@ -124,7 +124,11 @@
> + {
> +   _Unwind_Ptr pc_low;
> +   _Unwind_Ptr pc_high;
> ++#if defined __FRV_FDPIC__ || defined __BFIN_FDPIC__
> ++  struct elf32_fdpic_loadaddr load_base;
> ++#else
> +   _Unwind_Ptr load_base;
> ++#endif
> +   const ElfW(Phdr) *p_eh_frame_hdr;
> +   const ElfW(Phdr) *p_dynamic;
> +   struct frame_hdr_cache_element *link;
> +@@ -163,7 +167,7 @@
> +   struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr;
> +   const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic;
> +   long n, match;
> +-#ifdef __FRV_FDPIC__
> ++#if defined __FRV_FDPIC__ || defined __BFIN_FDPIC__
> +   struct elf32_fdpic_loadaddr load_base;
> + #else
> +   _Unwind_Ptr load_base;
> +@@ -347,7 +351,7 @@
> + 	    break;
> + 	  }
> +     }
> +-# elif defined __FRV_FDPIC__ && defined __linux__
> ++# elif (defined __FRV_FDPIC__ || defined __BFIN_FDPIC__) && defined __linux__
> +   data->dbase = load_base.got_value;
> + # else
> + #  error What is DW_EH_PE_datarel base on this platform?
> diff --git a/package/gcc/6.1.0/893-bfin-add-libgcc-linker-script.patch b/package/gcc/6.1.0/893-bfin-add-libgcc-linker-script.patch
> new file mode 100644
> index 0000000..88548fc
> --- /dev/null
> +++ b/package/gcc/6.1.0/893-bfin-add-libgcc-linker-script.patch
> @@ -0,0 +1,20 @@
> +Add libgcc linker script for Blackfin FDPIC.
> +
> +Solves following linking error:
> +# bfin-openadk-linux-uclibc-g++ -o foo t.c
> +bfin-openadk-linux-uclibc/bin/ld: foo: hidden symbol `___udivsi3' in libgcc.a(_udivsi3.o) is referenced by DSO
> +
> +Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
> +
> +diff -Nur gcc-6.1.0.orig/libgcc/config.host gcc-6.1.0/libgcc/config.host
> +--- gcc-6.1.0.orig/libgcc/config.host	2016-02-26 21:02:28.000000000 +0100
> ++++ gcc-6.1.0/libgcc/config.host	2016-07-25 02:47:05.818797217 +0200
> +@@ -444,7 +444,7 @@
> + 	md_unwind_header=bfin/linux-unwind.h
> +         ;;
> + bfin*-linux-uclibc*)
> +-	tmake_file="$tmake_file bfin/t-bfin bfin/t-crtstuff t-libgcc-pic t-fdpbit bfin/t-linux"
> ++	tmake_file="$tmake_file bfin/t-bfin bfin/t-crtstuff t-libgcc-pic t-slibgcc-libgcc t-fdpbit bfin/t-linux"
> + 	# No need to build crtbeginT.o on uClibc systems.  Should probably
> + 	# be moved to the OS specific section above.
> + 	extra_parts="crtbegin.o crtbeginS.o crtend.o crtendS.o"
> -- 
> 1.7.10.4
> 
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