[PATCH] arm: Build with -fno-dwarf2-cfi-asm

[PATCH] arm: Build with -fno-dwarf2-cfi-asm

[Michal Marek]

Commit d0679c7 restricted this workaround to powerpc only, but it turns
out that ARM needs it as well. Fixes
https://bugzilla.kernel.org/show_bug.cgi?id=16310 .

Reported-and-Tested-by: Robert Nelson <robertcnelson@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
---
 arch/arm/Makefile |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 64ba313..862d4ba 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -21,6 +21,11 @@ GZFLAGS		:=-9
 # Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
 KBUILD_CFLAGS	+=$(call cc-option,-marm,)
 
+# FIXME: the module load should be taught about the additional relocs
+# generated by this.
+# revert to pre-gcc-4.4 behaviour of .eh_frame
+KBUILD_CFLAGS	+= $(call cc-option,-fno-dwarf2-cfi-asm)
+
 # Do not use arch/arm/defconfig - it's always outdated.
 # Select a platform tht is kept up-to-date
 KBUILD_DEFCONFIG := versatile_defconfig
-- 
1.7.1

[PATCH] arm: Build with -fno-dwarf2-cfi-asm

[Mikael Pettersson]

Michal Marek writes:
 > Commit d0679c7 restricted this workaround to powerpc only, but it turns
 > out that ARM needs it as well. Fixes
 > https://bugzilla.kernel.org/show_bug.cgi?id=16310 .
 > 
 > Reported-and-Tested-by: Robert Nelson <robertcnelson@gmail.com>
 > Signed-off-by: Michal Marek <mmarek@suse.cz>
 > ---
 >  arch/arm/Makefile |    5 +++++
 >  1 files changed, 5 insertions(+), 0 deletions(-)
 > 
 > diff --git a/arch/arm/Makefile b/arch/arm/Makefile
 > index 64ba313..862d4ba 100644
 > --- a/arch/arm/Makefile
 > +++ b/arch/arm/Makefile
 > @@ -21,6 +21,11 @@ GZFLAGS		:=-9
 >  # Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
 >  KBUILD_CFLAGS	+=$(call cc-option,-marm,)
 >  
 > +# FIXME: the module load should be taught about the additional relocs
 > +# generated by this.
 > +# revert to pre-gcc-4.4 behaviour of .eh_frame
 > +KBUILD_CFLAGS	+= $(call cc-option,-fno-dwarf2-cfi-asm)

Appears related to gcc PR40521, which should be fixed in gcc-4.4.3,
though it may have been re-broken in gcc-4.5.0 for in a corner case
<http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40521#c24> that may or
may not apply to the kernel.  There's also a related binutils issue.

The above fix seems appropriate, but the FIXME comment seems wrong:
this is about getting the right kind of exception unwind tables in
the entire kernel, not just relocs in modules.

The comment should just say:
# Never generate .eh_frame:

So for the fix without the comment part:

Acked-by: Mikael Pettersson <mikpe@it.uu.se>

[PATCH] arm: Build with -fno-dwarf2-cfi-asm

[Michal Marek]

On 10.7.2010 15:02, Mikael Pettersson wrote:
> Michal Marek writes:
>  > Commit d0679c7 restricted this workaround to powerpc only, but it turns
>  > out that ARM needs it as well. Fixes
>  > https://bugzilla.kernel.org/show_bug.cgi?id=16310 .
>  > 
>  > Reported-and-Tested-by: Robert Nelson <robertcnelson@gmail.com>
>  > Signed-off-by: Michal Marek <mmarek@suse.cz>
>  > ---
>  >  arch/arm/Makefile |    5 +++++
>  >  1 files changed, 5 insertions(+), 0 deletions(-)
>  > 
>  > diff --git a/arch/arm/Makefile b/arch/arm/Makefile
>  > index 64ba313..862d4ba 100644
>  > --- a/arch/arm/Makefile
>  > +++ b/arch/arm/Makefile
>  > @@ -21,6 +21,11 @@ GZFLAGS		:=-9
>  >  # Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
>  >  KBUILD_CFLAGS	+=$(call cc-option,-marm,)
>  >  
>  > +# FIXME: the module load should be taught about the additional relocs
>  > +# generated by this.
>  > +# revert to pre-gcc-4.4 behaviour of .eh_frame
>  > +KBUILD_CFLAGS	+= $(call cc-option,-fno-dwarf2-cfi-asm)
> 
> Appears related to gcc PR40521, which should be fixed in gcc-4.4.3,
> though it may have been re-broken in gcc-4.5.0 for in a corner case
> <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40521#c24> that may or
> may not apply to the kernel.  There's also a related binutils issue.
> 
> The above fix seems appropriate, but the FIXME comment seems wrong:
> this is about getting the right kind of exception unwind tables in
> the entire kernel, not just relocs in modules.
> 
> The comment should just say:
> # Never generate .eh_frame:
> 
> So for the fix without the comment part:
> 
> Acked-by: Mikael Pettersson <mikpe@it.uu.se>

Hi Russell,

should I resend the patch with the comment by Mikael?

Thanks,
Michal

[PATCH] arm: Build with -fno-dwarf2-cfi-asm

[Russell King - ARM Linux]

On Mon, Jul 26, 2010 at 03:04:18PM +0200, Michal Marek wrote:
> On 10.7.2010 15:02, Mikael Pettersson wrote:
> > Michal Marek writes:
> >  > Commit d0679c7 restricted this workaround to powerpc only, but it turns
> >  > out that ARM needs it as well. Fixes
> >  > https://bugzilla.kernel.org/show_bug.cgi?id=16310 .
> >  > 
> >  > Reported-and-Tested-by: Robert Nelson <robertcnelson@gmail.com>
> >  > Signed-off-by: Michal Marek <mmarek@suse.cz>
> >  > ---
> >  >  arch/arm/Makefile |    5 +++++
> >  >  1 files changed, 5 insertions(+), 0 deletions(-)
> >  > 
> >  > diff --git a/arch/arm/Makefile b/arch/arm/Makefile
> >  > index 64ba313..862d4ba 100644
> >  > --- a/arch/arm/Makefile
> >  > +++ b/arch/arm/Makefile
> >  > @@ -21,6 +21,11 @@ GZFLAGS		:=-9
> >  >  # Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
> >  >  KBUILD_CFLAGS	+=$(call cc-option,-marm,)
> >  >  
> >  > +# FIXME: the module load should be taught about the additional relocs
> >  > +# generated by this.
> >  > +# revert to pre-gcc-4.4 behaviour of .eh_frame
> >  > +KBUILD_CFLAGS	+= $(call cc-option,-fno-dwarf2-cfi-asm)
> > 
> > Appears related to gcc PR40521, which should be fixed in gcc-4.4.3,
> > though it may have been re-broken in gcc-4.5.0 for in a corner case
> > <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40521#c24> that may or
> > may not apply to the kernel.  There's also a related binutils issue.
> > 
> > The above fix seems appropriate, but the FIXME comment seems wrong:
> > this is about getting the right kind of exception unwind tables in
> > the entire kernel, not just relocs in modules.
> > 
> > The comment should just say:
> > # Never generate .eh_frame:
> > 
> > So for the fix without the comment part:
> > 
> > Acked-by: Mikael Pettersson <mikpe@it.uu.se>
> 
> Hi Russell,
> 
> should I resend the patch with the comment by Mikael?

Yes please - and please put it in the patch system.

[PATCH v2] arm: Build with -fno-dwarf2-cfi-asm

[Michal Marek]

Commit d0679c7 restricted this workaround to powerpc only, but it turns
out that ARM needs it as well. Fixes
https://bugzilla.kernel.org/show_bug.cgi?id=16310 .

Reported-and-Tested-by: Robert Nelson <robertcnelson@gmail.com>
Acked-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Michal Marek <mmarek@suse.cz>
---

v2: changed commend as suggested by Mikael

---
 arch/arm/Makefile |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 64ba313..730d40c 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -21,6 +21,9 @@ GZFLAGS		:=-9
 # Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
 KBUILD_CFLAGS	+=$(call cc-option,-marm,)
 
+# Never generate .eh_frame
+KBUILD_CFLAGS	+= $(call cc-option,-fno-dwarf2-cfi-asm)
+
 # Do not use arch/arm/defconfig - it's always outdated.
 # Select a platform tht is kept up-to-date
 KBUILD_DEFCONFIG := versatile_defconfig
-- 
1.7.1