[PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Mingzheng Xing]

When compiling the kernel with the toolchain composed of GCC >= 12.1.0 and
binutils < 2.38, default ISA spec used when building binutils and GCC, the
following build failure will appear because the
CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI is not turned on.
(i.e, gcc-12.1.0 and binutils-2.36, or gcc-12.3.0 and binutils-2.37, use
default ISA spec.)

  CC      arch/riscv/kernel/vdso/vgettimeofday.o
  <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h: Assembler messages:
  <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:79: Error: unrecognized opcode `csrr a5,0xc01'

Binutils has updated the default ISA spec version, and the community has
responded well to this[1][2][3], but it appears that this is not over yet.

We also need to consider the situation of binutils < 2.38 but
GCC >= 12.1.0, since the combination between different versions of GCC and
binutils is not unique, which is to some extent flexible. GCC release
12.1.0 updated the default ISA spec version in GCC commit[4].

For more information, please refer to:

commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")

[1]: https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/aE1ZeHHCYf4
[2]: https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
[3]: https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
[4]: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd

Signed-off-by: Mingzheng Xing <xingmingzheng@iscas.ac.cn>
---
 arch/riscv/Kconfig | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 4c07b9189c86..b49cea30f6cc 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -570,11 +570,15 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
 config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
 	def_bool y
 	# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
-	depends on AS_IS_GNU && AS_VERSION >= 23800
+	# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
+	depends on CC_IS_GCC && GCC_VERSION >= 120100 || \
+		   AS_IS_GNU && AS_VERSION >= 23800
 	help
 	  Newer binutils versions default to ISA spec version 20191213 which
 	  moves some instructions from the I extension to the Zicsr and Zifencei
 	  extensions.
+	  Similarly, GCC release 12.1.0 has changed the default ISA spec version to
+	  20191213, so the above situation requires this option to be enabled.
 
 config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
 	def_bool y
-- 
2.34.1


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Re: [PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Nathan Chancellor]

Hi Mingzheng,

Thanks for the patch!

On Wed, Jul 26, 2023 at 01:04:05AM +0800, Mingzheng Xing wrote:
> When compiling the kernel with the toolchain composed of GCC >= 12.1.0 and
> binutils < 2.38, default ISA spec used when building binutils and GCC, the
> following build failure will appear because the
> CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI is not turned on.
> (i.e, gcc-12.1.0 and binutils-2.36, or gcc-12.3.0 and binutils-2.37, use
> default ISA spec.)
> 
>   CC      arch/riscv/kernel/vdso/vgettimeofday.o
>   <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h: Assembler messages:
>   <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:79: Error: unrecognized opcode `csrr a5,0xc01'

The gift that keeps on giving :/

> Binutils has updated the default ISA spec version, and the community has
> responded well to this[1][2][3], but it appears that this is not over yet.
> 
> We also need to consider the situation of binutils < 2.38 but
> GCC >= 12.1.0, since the combination between different versions of GCC and
> binutils is not unique, which is to some extent flexible. GCC release
> 12.1.0 updated the default ISA spec version in GCC commit[4].

I suspect this combination is not too common because binutils 2.38 came
out before GCC 12.1.0 but as you note, it is obviously possible. What
toolchain has this combination in the wild, which would be helpful for
documentation purposes?

> For more information, please refer to:
> 
> commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
> commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
> 
> [1]: https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/aE1ZeHHCYf4
> [2]: https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
> [3]: https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
> [4]: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
> 
> Signed-off-by: Mingzheng Xing <xingmingzheng@iscas.ac.cn>
> ---
>  arch/riscv/Kconfig | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 4c07b9189c86..b49cea30f6cc 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -570,11 +570,15 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
>  config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
>  	def_bool y
>  	# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
> -	depends on AS_IS_GNU && AS_VERSION >= 23800
> +	# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
> +	depends on CC_IS_GCC && GCC_VERSION >= 120100 || \
> +		   AS_IS_GNU && AS_VERSION >= 23800

GCC_VERSION will be 0 for clang, so you don't need the CC_IS_GCC check.
With that change, this should be able to stay on one line:

    depends on GCC_VERSION >= 120100 || (AS_IS_GNU && AS_VERSION >= 23800)

>  	help
>  	  Newer binutils versions default to ISA spec version 20191213 which
>  	  moves some instructions from the I extension to the Zicsr and Zifencei
>  	  extensions.
> +	  Similarly, GCC release 12.1.0 has changed the default ISA spec version to
> +	  20191213, so the above situation requires this option to be enabled.
>  
>  config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
>  	def_bool y
> -- 
> 2.34.1
> 

Cheers,
Nathan

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Re: [PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Conor Dooley]

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On Tue, Jul 25, 2023 at 10:23:44AM -0700, Nathan Chancellor wrote:
> Hi Mingzheng,
> 
> Thanks for the patch!
> 
> On Wed, Jul 26, 2023 at 01:04:05AM +0800, Mingzheng Xing wrote:
> > When compiling the kernel with the toolchain composed of GCC >= 12.1.0 and
> > binutils < 2.38, default ISA spec used when building binutils and GCC, the
> > following build failure will appear because the
> > CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI is not turned on.
> > (i.e, gcc-12.1.0 and binutils-2.36, or gcc-12.3.0 and binutils-2.37, use
> > default ISA spec.)
> > 
> >   CC      arch/riscv/kernel/vdso/vgettimeofday.o
> >   <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h: Assembler messages:
> >   <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:79: Error: unrecognized opcode `csrr a5,0xc01'
> 
> The gift that keeps on giving :/
> 
> > Binutils has updated the default ISA spec version, and the community has
> > responded well to this[1][2][3], but it appears that this is not over yet.
> > 
> > We also need to consider the situation of binutils < 2.38 but
> > GCC >= 12.1.0, since the combination between different versions of GCC and
> > binutils is not unique, which is to some extent flexible. GCC release
> > 12.1.0 updated the default ISA spec version in GCC commit[4].
> 
> I suspect this combination is not too common because binutils 2.38 came
> out before GCC 12.1.0 but as you note, it is obviously possible. What
> toolchain has this combination in the wild, which would be helpful for
> documentation purposes?

Yeah, that'd be great to know, at least the other niche stuff that we
are working around had a clear use-case (testing LLVM in debian containers)
whereas there's no clear user for this.
That's doubly interesting, as this patch seems to break things for binutils
< 2.35, and if we have to make a trade-off between those too, then it'd
be good to be able to weigh up the options.
Do we perhaps need the misa-spec workaround instead for this case?
Haven't tested that though, trying to dig myself out of email backlog.

> > For more information, please refer to:
> > 
> > commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
> > commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
> > 
> > [1]: https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/aE1ZeHHCYf4
> > [2]: https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
> > [3]: https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
> > [4]: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd

btw, please make these regular Link: tags (with a [N] at EOL) and drop
the space between them and the sign off. Also, this probably needs to be
CC: stable@vger.kernel.org too.

Cheers,
Conor.

> > 
> > Signed-off-by: Mingzheng Xing <xingmingzheng@iscas.ac.cn>
> > ---
> >  arch/riscv/Kconfig | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 4c07b9189c86..b49cea30f6cc 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -570,11 +570,15 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
> >  config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
> >  	def_bool y
> >  	# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
> > -	depends on AS_IS_GNU && AS_VERSION >= 23800
> > +	# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
> > +	depends on CC_IS_GCC && GCC_VERSION >= 120100 || \
> > +		   AS_IS_GNU && AS_VERSION >= 23800
> 
> GCC_VERSION will be 0 for clang, so you don't need the CC_IS_GCC check.
> With that change, this should be able to stay on one line:
> 
>     depends on GCC_VERSION >= 120100 || (AS_IS_GNU && AS_VERSION >= 23800)
> 
> >  	help
> >  	  Newer binutils versions default to ISA spec version 20191213 which
> >  	  moves some instructions from the I extension to the Zicsr and Zifencei
> >  	  extensions.
> > +	  Similarly, GCC release 12.1.0 has changed the default ISA spec version to
> > +	  20191213, so the above situation requires this option to be enabled.
> >  
> >  config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
> >  	def_bool y
> > -- 
> > 2.34.1
> > 


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Re: [PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Conor Dooley]

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On Tue, Jul 25, 2023 at 07:57:54PM +0100, Conor Dooley wrote:
> On Tue, Jul 25, 2023 at 10:23:44AM -0700, Nathan Chancellor wrote:
> > On Wed, Jul 26, 2023 at 01:04:05AM +0800, Mingzheng Xing wrote:
> > > When compiling the kernel with the toolchain composed of GCC >= 12.1.0 and
> > > binutils < 2.38, default ISA spec used when building binutils and GCC, the
> > > following build failure will appear because the
> > > CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI is not turned on.
> > > (i.e, gcc-12.1.0 and binutils-2.36, or gcc-12.3.0 and binutils-2.37, use
> > > default ISA spec.)
> > > 
> > >   CC      arch/riscv/kernel/vdso/vgettimeofday.o
> > >   <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h: Assembler messages:
> > >   <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:79: Error: unrecognized opcode `csrr a5,0xc01'
> > 
> > The gift that keeps on giving :/
> > 
> > > Binutils has updated the default ISA spec version, and the community has
> > > responded well to this[1][2][3], but it appears that this is not over yet.

Also, I just noticed this comment. I disagree with the wording "well",
and more like "with weeping and gnashing of teeth" ;) This stuff is a
huge pain in the ass, and mixing toolchains between LLVM & GNU stuff (or
using an older binutils with a newer GCC) really makes it a lot worse.
Thanks for submitting a fix for this so that Nathan or I didn't have to!

> > > 
> > > We also need to consider the situation of binutils < 2.38 but
> > > GCC >= 12.1.0, since the combination between different versions of GCC and
> > > binutils is not unique, which is to some extent flexible. GCC release
> > > 12.1.0 updated the default ISA spec version in GCC commit[4].
> > 
> > I suspect this combination is not too common because binutils 2.38 came
> > out before GCC 12.1.0 but as you note, it is obviously possible. What
> > toolchain has this combination in the wild, which would be helpful for
> > documentation purposes?
> 
> Yeah, that'd be great to know, at least the other niche stuff that we
> are working around had a clear use-case (testing LLVM in debian containers)
> whereas there's no clear user for this.
> That's doubly interesting, as this patch seems to break things for binutils
> < 2.35, and if we have to make a trade-off between those too, then it'd
> be good to be able to weigh up the options.
> Do we perhaps need the misa-spec workaround instead for this case?
> Haven't tested that though, trying to dig myself out of email backlog.

I don't think the misa-spec stuff is what we need actually. Instead, the
workaround/fix that this patch implements just needs to be constrained to
versions of GAS greater than 2.35.

Thanks,
Conor.

> 
> > > For more information, please refer to:
> > > 
> > > commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
> > > commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
> > > 
> > > [1]: https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/aE1ZeHHCYf4
> > > [2]: https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
> > > [3]: https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
> > > [4]: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
> 
> btw, please make these regular Link: tags (with a [N] at EOL) and drop
> the space between them and the sign off. Also, this probably needs to be
> CC: stable@vger.kernel.org too.

> > > 
> > > Signed-off-by: Mingzheng Xing <xingmingzheng@iscas.ac.cn>
> > > ---
> > >  arch/riscv/Kconfig | 6 +++++-
> > >  1 file changed, 5 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > > index 4c07b9189c86..b49cea30f6cc 100644
> > > --- a/arch/riscv/Kconfig
> > > +++ b/arch/riscv/Kconfig
> > > @@ -570,11 +570,15 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
> > >  config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
> > >  	def_bool y
> > >  	# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
> > > -	depends on AS_IS_GNU && AS_VERSION >= 23800
> > > +	# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
> > > +	depends on CC_IS_GCC && GCC_VERSION >= 120100 || \
> > > +		   AS_IS_GNU && AS_VERSION >= 23800
> > 
> > GCC_VERSION will be 0 for clang, so you don't need the CC_IS_GCC check.
> > With that change, this should be able to stay on one line:
> > 
> >     depends on GCC_VERSION >= 120100 || (AS_IS_GNU && AS_VERSION >= 23800)
> > 
> > >  	help
> > >  	  Newer binutils versions default to ISA spec version 20191213 which
> > >  	  moves some instructions from the I extension to the Zicsr and Zifencei
> > >  	  extensions.
> > > +	  Similarly, GCC release 12.1.0 has changed the default ISA spec version to
> > > +	  20191213, so the above situation requires this option to be enabled.
> > >  
> > >  config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
> > >  	def_bool y
> > > -- 
> > > 2.34.1
> > > 
> 



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Re: [PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Mingzheng Xing]

On 7/26/23 01:23, Nathan Chancellor wrote:
> Hi Mingzheng,
>
> Thanks for the patch!
>
> On Wed, Jul 26, 2023 at 01:04:05AM +0800, Mingzheng Xing wrote:
>> When compiling the kernel with the toolchain composed of GCC >= 12.1.0 and
>> binutils < 2.38, default ISA spec used when building binutils and GCC, the
>> following build failure will appear because the
>> CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI is not turned on.
>> (i.e, gcc-12.1.0 and binutils-2.36, or gcc-12.3.0 and binutils-2.37, use
>> default ISA spec.)
>>
>>    CC      arch/riscv/kernel/vdso/vgettimeofday.o
>>    <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h: Assembler messages:
>>    <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:79: Error: unrecognized opcode `csrr a5,0xc01'
> The gift that keeps on giving :/
Yeah, but things will get better :)
>> Binutils has updated the default ISA spec version, and the community has
>> responded well to this[1][2][3], but it appears that this is not over yet.
>>
>> We also need to consider the situation of binutils < 2.38 but
>> GCC >= 12.1.0, since the combination between different versions of GCC and
>> binutils is not unique, which is to some extent flexible. GCC release
>> 12.1.0 updated the default ISA spec version in GCC commit[4].
> I suspect this combination is not too common because binutils 2.38 came
> out before GCC 12.1.0 but as you note, it is obviously possible. What
> toolchain has this combination in the wild, which would be helpful for
> documentation purposes?
Actually, this issue was discovered during the upgrade of the distribution
openEuler for RISC-V. It is a temporary phenomenon caused by
inconsistent upgrade speeds of packages such as GCC and binutils.
 From my limited understanding, GCC and binutils are not strictly
version-bound in some other distributions, so I can't rule out this issue
happening in other scenarios. But once it happens it can cause problems
with compiling the kernel.
>> For more information, please refer to:
>>
>> commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
>> commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
>>
>> [1]:https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/aE1ZeHHCYf4
>> [2]:https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
>> [3]:https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
>> [4]:https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
>>
>> Signed-off-by: Mingzheng Xing<xingmingzheng@iscas.ac.cn>
>> ---
>>   arch/riscv/Kconfig | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index 4c07b9189c86..b49cea30f6cc 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -570,11 +570,15 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
>>   config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
>>   	def_bool y
>>   	#https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
>> -	depends on AS_IS_GNU && AS_VERSION >= 23800
>> +	#https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
>> +	depends on CC_IS_GCC && GCC_VERSION >= 120100 || \
>> +		   AS_IS_GNU && AS_VERSION >= 23800
> GCC_VERSION will be 0 for clang, so you don't need the CC_IS_GCC check.
> With that change, this should be able to stay on one line:
>
>      depends on GCC_VERSION >= 120100 || (AS_IS_GNU && AS_VERSION >= 23800)
OK, I'll change it in v2.

Thanks,
Mingzheng.
>>   	help
>>   	  Newer binutils versions default to ISA spec version 20191213 which
>>   	  moves some instructions from the I extension to the Zicsr and Zifencei
>>   	  extensions.
>> +	  Similarly, GCC release 12.1.0 has changed the default ISA spec version to
>> +	  20191213, so the above situation requires this option to be enabled.
>>   
>>   config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
>>   	def_bool y
>> -- 
>> 2.34.1
>>
> Cheers,
> Nathan
>
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Re: [PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Mingzheng Xing]

On 7/26/23 02:57, Conor Dooley wrote:
> On Tue, Jul 25, 2023 at 10:23:44AM -0700, Nathan Chancellor wrote:
>> Hi Mingzheng,
>>
>> Thanks for the patch!
>>
>> On Wed, Jul 26, 2023 at 01:04:05AM +0800, Mingzheng Xing wrote:
>>> When compiling the kernel with the toolchain composed of GCC >= 12.1.0 and
>>> binutils < 2.38, default ISA spec used when building binutils and GCC, the
>>> following build failure will appear because the
>>> CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI is not turned on.
>>> (i.e, gcc-12.1.0 and binutils-2.36, or gcc-12.3.0 and binutils-2.37, use
>>> default ISA spec.)
>>>
>>>    CC      arch/riscv/kernel/vdso/vgettimeofday.o
>>>    <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h: Assembler messages:
>>>    <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:79: Error: unrecognized opcode `csrr a5,0xc01'
>> The gift that keeps on giving :/
>>
>>> Binutils has updated the default ISA spec version, and the community has
>>> responded well to this[1][2][3], but it appears that this is not over yet.
>>>
>>> We also need to consider the situation of binutils < 2.38 but
>>> GCC >= 12.1.0, since the combination between different versions of GCC and
>>> binutils is not unique, which is to some extent flexible. GCC release
>>> 12.1.0 updated the default ISA spec version in GCC commit[4].
>> I suspect this combination is not too common because binutils 2.38 came
>> out before GCC 12.1.0 but as you note, it is obviously possible. What
>> toolchain has this combination in the wild, which would be helpful for
>> documentation purposes?
> Yeah, that'd be great to know, at least the other niche stuff that we
> are working around had a clear use-case (testing LLVM in debian containers)
> whereas there's no clear user for this.
> That's doubly interesting, as this patch seems to break things for binutils
> < 2.35, and if we have to make a trade-off between those too, then it'd
> be good to be able to weigh up the options.
> Do we perhaps need the misa-spec workaround instead for this case?
> Haven't tested that though, trying to dig myself out of email backlog.
Well, what I encountered use-case was a temporary thing caused by the
inconsistent pace of distro package upgrades, but it really happened and
took quite a bit of time to explore why. There are sites like [1] that count
the "Successful Builds" between different GCC and binutils releases,
(Though they don't seem to be updated much...), but it seems to indicate
that all kinds of available pairings are possible.

Before replying to the e-mail, I tested some "extreme" cases and things
seemed to be a little clearer.

1. binutils-2.38 and GCC-12.1.0 each changed default ISA spec version,
     updating from 2.2 to 20191213.

2. binutils>=2.38 or GCC>=12.1.0
     when meet any of these it is recommended to turn on
     TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI, the good outweighs
     the bad. (My personal understanding.)

3. (Extreme case) binutils>=2.38 AND GCC<11.1.0
     GCC-11.1.0 starts to support zicsr and zifencei extension for 
-march[2].
     In this case just turn on TOOLCHAIN_NEEDS_OLD_ISA_SPEC.
     (Otherwise compiling the kernel will report an error whether
     TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI is turned on or not.)

4. (Extreme case) GCC>=12.1.0, binutils<2.36
     I tested GCC-12.1.0 + binutils-2.36 and it compiles the kernel 
fine(after
     hitting this patch). Also tested GCC-12.1.0 + binutils2.35 and
     GCC-12.1.0 + binutils-2.34.0, but both pairings gave errors and failed
     to produce a usable toolchain (Default ISA versions used). It seems 
safe
     to assume that GCC-12.1.0 + binutils<2.35 is almost non-existent.

I'm no expert on toolchains, so thanks for correcting me if I'm wrong 
somewhere...

[1] https://wiki.osdev.org/Cross-Compiler_Successful_Builds
[2] 
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b03be74bad08c382da47e048007a78fa3fb4ef49
>>> For more information, please refer to:
>>>
>>> commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
>>> commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
>>>
>>> [1]:https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/aE1ZeHHCYf4
>>> [2]:https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
>>> [3]:https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
>>> [4]:https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
> btw, please make these regular Link: tags (with a [N] at EOL) and drop
> the space between them and the sign off. Also, this probably needs to be
> CC:stable@vger.kernel.org  too.
OK, I'll fix it.

Thanks,
Mingzheng.
> Cheers,
> Conor.
>
>>> Signed-off-by: Mingzheng Xing<xingmingzheng@iscas.ac.cn>
>>> ---
>>>   arch/riscv/Kconfig | 6 +++++-
>>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>> index 4c07b9189c86..b49cea30f6cc 100644
>>> --- a/arch/riscv/Kconfig
>>> +++ b/arch/riscv/Kconfig
>>> @@ -570,11 +570,15 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
>>>   config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
>>>   	def_bool y
>>>   	#https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
>>> -	depends on AS_IS_GNU && AS_VERSION >= 23800
>>> +	#https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
>>> +	depends on CC_IS_GCC && GCC_VERSION >= 120100 || \
>>> +		   AS_IS_GNU && AS_VERSION >= 23800
>> GCC_VERSION will be 0 for clang, so you don't need the CC_IS_GCC check.
>> With that change, this should be able to stay on one line:
>>
>>      depends on GCC_VERSION >= 120100 || (AS_IS_GNU && AS_VERSION >= 23800)
>>
>>>   	help
>>>   	  Newer binutils versions default to ISA spec version 20191213 which
>>>   	  moves some instructions from the I extension to the Zicsr and Zifencei
>>>   	  extensions.
>>> +	  Similarly, GCC release 12.1.0 has changed the default ISA spec version to
>>> +	  20191213, so the above situation requires this option to be enabled.
>>>   
>>>   config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
>>>   	def_bool y
>>> -- 
>>> 2.34.1
>>>


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Re: [PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Mingzheng Xing]

On 7/26/23 06:17, Conor Dooley wrote:
> On Tue, Jul 25, 2023 at 07:57:54PM +0100, Conor Dooley wrote:
>> On Tue, Jul 25, 2023 at 10:23:44AM -0700, Nathan Chancellor wrote:
>>> On Wed, Jul 26, 2023 at 01:04:05AM +0800, Mingzheng Xing wrote:
>>>> When compiling the kernel with the toolchain composed of GCC >= 12.1.0 and
>>>> binutils < 2.38, default ISA spec used when building binutils and GCC, the
>>>> following build failure will appear because the
>>>> CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI is not turned on.
>>>> (i.e, gcc-12.1.0 and binutils-2.36, or gcc-12.3.0 and binutils-2.37, use
>>>> default ISA spec.)
>>>>
>>>>    CC      arch/riscv/kernel/vdso/vgettimeofday.o
>>>>    <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h: Assembler messages:
>>>>    <<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:79: Error: unrecognized opcode `csrr a5,0xc01'
>>> The gift that keeps on giving :/
>>>
>>>> Binutils has updated the default ISA spec version, and the community has
>>>> responded well to this[1][2][3], but it appears that this is not over yet.
> Also, I just noticed this comment. I disagree with the wording "well",
> and more like "with weeping and gnashing of teeth" ;) This stuff is a
> huge pain in the ass, and mixing toolchains between LLVM & GNU stuff (or
> using an older binutils with a newer GCC) really makes it a lot worse.
At least in the usual way , except in my unusual case...
> Thanks for submitting a fix for this so that Nathan or I didn't have to!
Hopefully this patch will make things better.
>>>> We also need to consider the situation of binutils < 2.38 but
>>>> GCC >= 12.1.0, since the combination between different versions of GCC and
>>>> binutils is not unique, which is to some extent flexible. GCC release
>>>> 12.1.0 updated the default ISA spec version in GCC commit[4].
>>> I suspect this combination is not too common because binutils 2.38 came
>>> out before GCC 12.1.0 but as you note, it is obviously possible. What
>>> toolchain has this combination in the wild, which would be helpful for
>>> documentation purposes?
>> Yeah, that'd be great to know, at least the other niche stuff that we
>> are working around had a clear use-case (testing LLVM in debian containers)
>> whereas there's no clear user for this.
>> That's doubly interesting, as this patch seems to break things for binutils
>> < 2.35, and if we have to make a trade-off between those too, then it'd
>> be good to be able to weigh up the options.
>> Do we perhaps need the misa-spec workaround instead for this case?
>> Haven't tested that though, trying to dig myself out of email backlog.
> I don't think the misa-spec stuff is what we need actually. Instead, the
> workaround/fix that this patch implements just needs to be constrained to
> versions of GAS greater than 2.35.
I'm sorry, I didn't quite understand this, could you provide some more
information, thank you very much!
I'll change the handling in v2. After testing it myself, it seems to 
work fine.

Thanks,
Mingzheng.
> Thanks,
> Conor.
>
>>>> For more information, please refer to:
>>>>
>>>> commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
>>>> commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
>>>>
>>>> [1]:https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/aE1ZeHHCYf4
>>>> [2]:https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
>>>> [3]:https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
>>>> [4]:https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
>> btw, please make these regular Link: tags (with a [N] at EOL) and drop
>> the space between them and the sign off. Also, this probably needs to be
>> CC:stable@vger.kernel.org  too.
>>>> Signed-off-by: Mingzheng Xing<xingmingzheng@iscas.ac.cn>
>>>> ---
>>>>   arch/riscv/Kconfig | 6 +++++-
>>>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>>> index 4c07b9189c86..b49cea30f6cc 100644
>>>> --- a/arch/riscv/Kconfig
>>>> +++ b/arch/riscv/Kconfig
>>>> @@ -570,11 +570,15 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
>>>>   config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
>>>>   	def_bool y
>>>>   	#https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
>>>> -	depends on AS_IS_GNU && AS_VERSION >= 23800
>>>> +	#https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
>>>> +	depends on CC_IS_GCC && GCC_VERSION >= 120100 || \
>>>> +		   AS_IS_GNU && AS_VERSION >= 23800
>>> GCC_VERSION will be 0 for clang, so you don't need the CC_IS_GCC check.
>>> With that change, this should be able to stay on one line:
>>>
>>>      depends on GCC_VERSION >= 120100 || (AS_IS_GNU && AS_VERSION >= 23800)
>>>
>>>>   	help
>>>>   	  Newer binutils versions default to ISA spec version 20191213 which
>>>>   	  moves some instructions from the I extension to the Zicsr and Zifencei
>>>>   	  extensions.
>>>> +	  Similarly, GCC release 12.1.0 has changed the default ISA spec version to
>>>> +	  20191213, so the above situation requires this option to be enabled.
>>>>   
>>>>   config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
>>>>   	def_bool y
>>>> -- 
>>>> 2.34.1
>>>>


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[PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Mingzheng Xing]

Binutils-2.38 and GCC-12.1.0 bumped[0][1] the default ISA spec to the newer
20191213 version which moves some instructions from the I extension to the
Zicsr and Zifencei extensions. So if one of the binutils and GCC exceeds
that version, we should explicitly specifying Zicsr and Zifencei via -march
to cope with the new changes. but this only occurs when binutils >= 2.36
and GCC >= 11.1.0. It's a different story when binutils < 2.36.

binutils-2.36 supports the Zifencei extension[2] and splits Zifencei and
Zicsr from I[3]. GCC-11.1.0 is particular[4] because it add support Zicsr
and Zifencei extension for -march. binutils-2.35 does not support the
Zifencei extension, and does not need to specify Zicsr and Zifencei when
working with GCC >= 12.1.0.

To make our lives easier, let's relax the check to binutils >= 2.36 in
CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. For the other two cases,
where clang < 17 or GCC < 11.1.0, we will deal with them in
CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC.

For more information, please refer to:
commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc [0]
Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd [1]
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=5a1b31e1e1cee6e9f1c92abff59cdcfff0dddf30 [2]
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=729a53530e86972d1143553a415db34e6e01d5d2 [3]
Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b03be74bad08c382da47e048007a78fa3fb4ef49 [4]
Link: https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
Link: https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
Cc: <stable@vger.kernel.org>
Signed-off-by: Mingzheng Xing <xingmingzheng@iscas.ac.cn>
---
 arch/riscv/Kconfig                     | 32 +++++++++++++++-----------
 arch/riscv/kernel/compat_vdso/Makefile |  8 ++++++-
 2 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 4c07b9189c86..10e7a7ad175a 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -570,24 +570,30 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
 config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
 	def_bool y
 	# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
-	depends on AS_IS_GNU && AS_VERSION >= 23800
-	help
-	  Newer binutils versions default to ISA spec version 20191213 which
-	  moves some instructions from the I extension to the Zicsr and Zifencei
-	  extensions.
+	# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
+	depends on AS_IS_GNU && AS_VERSION >= 23600
+	help
+	  Binutils-2.38 and GCC-12.1.0 bumped the default ISA spec to the newer
+	  20191213 version, which moves some instructions from the I extension to
+	  the Zicsr and Zifencei extensions. This requires explicitly specifying
+	  Zicsr and Zifencei when binutils >= 2.38 or GCC >= 12.1.0. Zicsr
+	  and Zifencei are supported in binutils from version 2.36 onwards.
+	  To make life easier, and avoid forcing toolchains that default to a
+	  newer ISA spec to version 2.2, relax the check to binutils >= 2.36.
+	  For clang < 17 or GCC < 11.1.0, for which this is not possible, this is
+	  dealt with in CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC.
 
 config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
 	def_bool y
 	depends on TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
 	# https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16
-	depends on CC_IS_CLANG && CLANG_VERSION < 170000
-	help
-	  Certain versions of clang do not support zicsr and zifencei via -march
-	  but newer versions of binutils require it for the reasons noted in the
-	  help text of CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. This
-	  option causes an older ISA spec compatible with these older versions
-	  of clang to be passed to GAS, which has the same result as passing zicsr
-	  and zifencei to -march.
+	# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b03be74bad08c382da47e048007a78fa3fb4ef49
+	depends on (CC_IS_CLANG && CLANG_VERSION < 170000) || (CC_IS_GCC && GCC_VERSION < 110100)
+	help
+	  Certain versions of clang and GCC do not support zicsr and zifencei via
+	  -march. This option causes an older ISA spec compatible with these older
+	  versions of clang and GCC to be passed to GAS, which has the same result
+	  as passing zicsr and zifencei to -march.
 
 config FPU
 	bool "FPU support"
diff --git a/arch/riscv/kernel/compat_vdso/Makefile b/arch/riscv/kernel/compat_vdso/Makefile
index 189345773e7e..b86e5e2c3aea 100644
--- a/arch/riscv/kernel/compat_vdso/Makefile
+++ b/arch/riscv/kernel/compat_vdso/Makefile
@@ -11,7 +11,13 @@ compat_vdso-syms += flush_icache
 COMPAT_CC := $(CC)
 COMPAT_LD := $(LD)
 
-COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
+# binutils 2.35 does not support the zifencei extension, but in the ISA
+# spec 20191213, G stands for IMAFD_ZICSR_ZIFENCEI.
+ifdef CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
+	COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
+else
+	COMPAT_CC_FLAGS := -march=rv32imafd -mabi=ilp32
+endif
 COMPAT_LD_FLAGS := -melf32lriscv
 
 # Disable attributes, as they're useless and break the build.
-- 
2.34.1


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Re: [PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Conor Dooley]

[-- Attachment #1.1: Type: text/plain, Size: 2298 bytes --]

On Mon, Jul 31, 2023 at 11:05:11PM +0800, Mingzheng Xing wrote:
> Binutils-2.38 and GCC-12.1.0 bumped[0][1] the default ISA spec to the newer
> 20191213 version which moves some instructions from the I extension to the
> Zicsr and Zifencei extensions. So if one of the binutils and GCC exceeds
> that version, we should explicitly specifying Zicsr and Zifencei via -march
> to cope with the new changes. but this only occurs when binutils >= 2.36
> and GCC >= 11.1.0. It's a different story when binutils < 2.36.
> 
> binutils-2.36 supports the Zifencei extension[2] and splits Zifencei and
> Zicsr from I[3]. GCC-11.1.0 is particular[4] because it add support Zicsr
> and Zifencei extension for -march. binutils-2.35 does not support the
> Zifencei extension, and does not need to specify Zicsr and Zifencei when
> working with GCC >= 12.1.0.
> 
> To make our lives easier, let's relax the check to binutils >= 2.36 in
> CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. For the other two cases,
> where clang < 17 or GCC < 11.1.0, we will deal with them in
> CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC.
> 
> For more information, please refer to:
> commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
> commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
> Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc [0]
> Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd [1]
> Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=5a1b31e1e1cee6e9f1c92abff59cdcfff0dddf30 [2]
> Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=729a53530e86972d1143553a415db34e6e01d5d2 [3]
> Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b03be74bad08c382da47e048007a78fa3fb4ef49 [4]
> Link: https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
> Link: https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Mingzheng Xing <xingmingzheng@iscas.ac.cn>

This looks good to me now, thanks! Hopefully the next time we look at
this code is removing support for binutils 2.35 :)
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

Cheers,
Conor.

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Re: [PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Mingzheng Xing]

On 7/31/23 23:24, Conor Dooley wrote:
> On Mon, Jul 31, 2023 at 11:05:11PM +0800, Mingzheng Xing wrote:
>> Binutils-2.38 and GCC-12.1.0 bumped[0][1] the default ISA spec to the newer
>> 20191213 version which moves some instructions from the I extension to the
>> Zicsr and Zifencei extensions. So if one of the binutils and GCC exceeds
>> that version, we should explicitly specifying Zicsr and Zifencei via -march
>> to cope with the new changes. but this only occurs when binutils >= 2.36
>> and GCC >= 11.1.0. It's a different story when binutils < 2.36.
>>
>> binutils-2.36 supports the Zifencei extension[2] and splits Zifencei and
>> Zicsr from I[3]. GCC-11.1.0 is particular[4] because it add support Zicsr
>> and Zifencei extension for -march. binutils-2.35 does not support the
>> Zifencei extension, and does not need to specify Zicsr and Zifencei when
>> working with GCC >= 12.1.0.
>>
>> To make our lives easier, let's relax the check to binutils >= 2.36 in
>> CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. For the other two cases,
>> where clang < 17 or GCC < 11.1.0, we will deal with them in
>> CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC.
>>
>> For more information, please refer to:
>> commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
>> commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
>> Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc [0]
>> Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd [1]
>> Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=5a1b31e1e1cee6e9f1c92abff59cdcfff0dddf30 [2]
>> Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=729a53530e86972d1143553a415db34e6e01d5d2 [3]
>> Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b03be74bad08c382da47e048007a78fa3fb4ef49 [4]
>> Link: https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
>> Link: https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
>> Cc: <stable@vger.kernel.org>
>> Signed-off-by: Mingzheng Xing <xingmingzheng@iscas.ac.cn>
> This looks good to me now, thanks! Hopefully the next time we look at
> this code is removing support for binutils 2.35 :)

Thank you for the quick reply.
Hopefully no more "with weeping and gnashing of teeth". ;

> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
>
> Cheers,
> Conor.


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Re: [PATCH] riscv: Handle zicsr/zifencei issue between gcc and binutils

[Guo Ren]

On Mon, Jul 31, 2023 at 11:06 PM Mingzheng Xing
<xingmingzheng@iscas.ac.cn> wrote:
>
> Binutils-2.38 and GCC-12.1.0 bumped[0][1] the default ISA spec to the newer
> 20191213 version which moves some instructions from the I extension to the
> Zicsr and Zifencei extensions. So if one of the binutils and GCC exceeds
> that version, we should explicitly specifying Zicsr and Zifencei via -march
> to cope with the new changes. but this only occurs when binutils >= 2.36
> and GCC >= 11.1.0. It's a different story when binutils < 2.36.
>
> binutils-2.36 supports the Zifencei extension[2] and splits Zifencei and
> Zicsr from I[3]. GCC-11.1.0 is particular[4] because it add support Zicsr
> and Zifencei extension for -march. binutils-2.35 does not support the
> Zifencei extension, and does not need to specify Zicsr and Zifencei when
> working with GCC >= 12.1.0.
>
> To make our lives easier, let's relax the check to binutils >= 2.36 in
> CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. For the other two cases,
> where clang < 17 or GCC < 11.1.0, we will deal with them in
> CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC.
>
> For more information, please refer to:
> commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
> commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
> Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc [0]
> Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd [1]
> Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=5a1b31e1e1cee6e9f1c92abff59cdcfff0dddf30 [2]
> Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=729a53530e86972d1143553a415db34e6e01d5d2 [3]
> Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b03be74bad08c382da47e048007a78fa3fb4ef49 [4]
> Link: https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
> Link: https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Mingzheng Xing <xingmingzheng@iscas.ac.cn>
> ---
>  arch/riscv/Kconfig                     | 32 +++++++++++++++-----------
>  arch/riscv/kernel/compat_vdso/Makefile |  8 ++++++-
>  2 files changed, 26 insertions(+), 14 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 4c07b9189c86..10e7a7ad175a 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -570,24 +570,30 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
>  config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
>         def_bool y
>         # https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
> -       depends on AS_IS_GNU && AS_VERSION >= 23800
> -       help
> -         Newer binutils versions default to ISA spec version 20191213 which
> -         moves some instructions from the I extension to the Zicsr and Zifencei
> -         extensions.
> +       # https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
> +       depends on AS_IS_GNU && AS_VERSION >= 23600
> +       help
> +         Binutils-2.38 and GCC-12.1.0 bumped the default ISA spec to the newer
> +         20191213 version, which moves some instructions from the I extension to
> +         the Zicsr and Zifencei extensions. This requires explicitly specifying
> +         Zicsr and Zifencei when binutils >= 2.38 or GCC >= 12.1.0. Zicsr
> +         and Zifencei are supported in binutils from version 2.36 onwards.
> +         To make life easier, and avoid forcing toolchains that default to a
> +         newer ISA spec to version 2.2, relax the check to binutils >= 2.36.
> +         For clang < 17 or GCC < 11.1.0, for which this is not possible, this is
> +         dealt with in CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC.
>
>  config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
>         def_bool y
>         depends on TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
>         # https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16
> -       depends on CC_IS_CLANG && CLANG_VERSION < 170000
> -       help
> -         Certain versions of clang do not support zicsr and zifencei via -march
> -         but newer versions of binutils require it for the reasons noted in the
> -         help text of CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. This
> -         option causes an older ISA spec compatible with these older versions
> -         of clang to be passed to GAS, which has the same result as passing zicsr
> -         and zifencei to -march.
> +       # https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b03be74bad08c382da47e048007a78fa3fb4ef49
> +       depends on (CC_IS_CLANG && CLANG_VERSION < 170000) || (CC_IS_GCC && GCC_VERSION < 110100)
> +       help
> +         Certain versions of clang and GCC do not support zicsr and zifencei via
> +         -march. This option causes an older ISA spec compatible with these older
> +         versions of clang and GCC to be passed to GAS, which has the same result
> +         as passing zicsr and zifencei to -march.
>
>  config FPU
>         bool "FPU support"
> diff --git a/arch/riscv/kernel/compat_vdso/Makefile b/arch/riscv/kernel/compat_vdso/Makefile
> index 189345773e7e..b86e5e2c3aea 100644
> --- a/arch/riscv/kernel/compat_vdso/Makefile
> +++ b/arch/riscv/kernel/compat_vdso/Makefile
> @@ -11,7 +11,13 @@ compat_vdso-syms += flush_icache
>  COMPAT_CC := $(CC)
>  COMPAT_LD := $(LD)
>
> -COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
> +# binutils 2.35 does not support the zifencei extension, but in the ISA
> +# spec 20191213, G stands for IMAFD_ZICSR_ZIFENCEI.
> +ifdef CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
Acked-by: Guo Ren <guoren@kernel.org>

> +       COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
> +else
> +       COMPAT_CC_FLAGS := -march=rv32imafd -mabi=ilp32
> +endif


>  COMPAT_LD_FLAGS := -melf32lriscv
>
>  # Disable attributes, as they're useless and break the build.
> --
> 2.34.1
>


-- 
Best Regards
 Guo Ren

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