[PATCH 0/4] riscv: improve link and support ARCH_WANT_LD_ORPHAN_WARN

[PATCH 0/4] riscv: improve link and support ARCH_WANT_LD_ORPHAN_WARN

[Jisheng Zhang]

This series tries to improve link time handling of riscv:
patch1 adds the missing RUNTIME_DISCARD_EXIT as suggested by Masahiro.

Similar as other architectures such as x86, arm64 and so on, enable
ARCH_WANT_LD_ORPHAN_WARN to enable linker orphan warnings to prevent
from missing any new sections in future. So the following two patches
are preparation patches, and the last patch finally selects
ARCH_WANT_LD_ORPHAN_WARN

Jisheng Zhang (4):
  riscv: lds: define RUNTIME_DISCARD_EXIT
  riscv: vmlinux.lds.S: explicitly catch .rela.dyn symbols
  riscv: vmlinux.lds.S: explicitly catch .riscv.attributes sections
  riscv: select ARCH_WANT_LD_ORPHAN_WARN for !XIP_KERNEL

 arch/riscv/Kconfig              | 1 +
 arch/riscv/kernel/vmlinux.lds.S | 6 ++++++
 2 files changed, 7 insertions(+)

-- 
2.38.1


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[PATCH 1/4] riscv: lds: define RUNTIME_DISCARD_EXIT

[Jisheng Zhang]

riscv discards .exit.* sections at run-time but doesn't define
RUNTIME_DISCARD_EXIT. However, the .exit.* sections are still allocated
and kept even if the generic DISCARDS would discard the sections due
to missing RUNTIME_DISCARD_EXIT, because the DISCARD sits at the end of
the linker script. Add the missing RUNTIME_DISCARD_EXIT define so that
it still works if we move DISCARD up or even at the beginning of the
linker script.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
---
 arch/riscv/kernel/vmlinux.lds.S | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 4e6c88aa4d87..07c19f2a288c 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -5,6 +5,7 @@
  */
 
 #define RO_EXCEPTION_TABLE_ALIGN	4
+#define RUNTIME_DISCARD_EXIT
 
 #ifdef CONFIG_XIP_KERNEL
 #include "vmlinux-xip.lds.S"
-- 
2.38.1


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Re: [PATCH 1/4] riscv: lds: define RUNTIME_DISCARD_EXIT

[Conor Dooley]

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On Mon, Jan 16, 2023 at 11:47:57PM +0800, Jisheng Zhang wrote:
> riscv discards .exit.* sections at run-time but doesn't define
> RUNTIME_DISCARD_EXIT. However, the .exit.* sections are still allocated
> and kept even if the generic DISCARDS would discard the sections due
> to missing RUNTIME_DISCARD_EXIT, because the DISCARD sits at the end of
> the linker script. Add the missing RUNTIME_DISCARD_EXIT define so that
> it still works if we move DISCARD up or even at the beginning of the
> linker script.
> 
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>  arch/riscv/kernel/vmlinux.lds.S | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
> index 4e6c88aa4d87..07c19f2a288c 100644
> --- a/arch/riscv/kernel/vmlinux.lds.S
> +++ b/arch/riscv/kernel/vmlinux.lds.S
> @@ -5,6 +5,7 @@
>   */
>  
>  #define RO_EXCEPTION_TABLE_ALIGN	4
> +#define RUNTIME_DISCARD_EXIT
>  
>  #ifdef CONFIG_XIP_KERNEL
>  #include "vmlinux-xip.lds.S"

Since the diff is identical to:
https://patchwork.kernel.org/project/linux-riscv/patch/20230102124936.1363533-1-conor@kernel.org/
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Your commit message is better anyways.

Thanks,
Conor.


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Re: [PATCH 1/4] riscv: lds: define RUNTIME_DISCARD_EXIT

[Jisheng Zhang]

On Mon, Jan 16, 2023 at 04:43:05PM +0000, Conor Dooley wrote:
> On Mon, Jan 16, 2023 at 11:47:57PM +0800, Jisheng Zhang wrote:
> > riscv discards .exit.* sections at run-time but doesn't define
> > RUNTIME_DISCARD_EXIT. However, the .exit.* sections are still allocated
> > and kept even if the generic DISCARDS would discard the sections due
> > to missing RUNTIME_DISCARD_EXIT, because the DISCARD sits at the end of
> > the linker script. Add the missing RUNTIME_DISCARD_EXIT define so that
> > it still works if we move DISCARD up or even at the beginning of the
> > linker script.
> > 
> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> > Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
> > ---
> >  arch/riscv/kernel/vmlinux.lds.S | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
> > index 4e6c88aa4d87..07c19f2a288c 100644
> > --- a/arch/riscv/kernel/vmlinux.lds.S
> > +++ b/arch/riscv/kernel/vmlinux.lds.S
> > @@ -5,6 +5,7 @@
> >   */
> >  
> >  #define RO_EXCEPTION_TABLE_ALIGN	4
> > +#define RUNTIME_DISCARD_EXIT
> >  
> >  #ifdef CONFIG_XIP_KERNEL
> >  #include "vmlinux-xip.lds.S"
> 
> Since the diff is identical to:
> https://patchwork.kernel.org/project/linux-riscv/patch/20230102124936.1363533-1-conor@kernel.org/

OOPS, I didn't notice you submitted the patch which did similar
about RUNTIME_DISCARD_EXIT, then I'd like to recall patch1. I
expected some review comments for remainning patch2\3\4, I will
send v2 which will both address possible review comments and
remove patch1

> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> Your commit message is better anyways.

If you like it, you can take it into your v2 patch;)

Thanks


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Re: [PATCH 1/4] riscv: lds: define RUNTIME_DISCARD_EXIT

[Conor Dooley]

On 17 January 2023 00:06:06 GMT, Jisheng Zhang <jszhang@kernel.org> wrote:
>On Mon, Jan 16, 2023 at 04:43:05PM +0000, Conor Dooley wrote:
>> On Mon, Jan 16, 2023 at 11:47:57PM +0800, Jisheng Zhang wrote:
>> > riscv discards .exit.* sections at run-time but doesn't define
>> > RUNTIME_DISCARD_EXIT. However, the .exit.* sections are still allocated
>> > and kept even if the generic DISCARDS would discard the sections due
>> > to missing RUNTIME_DISCARD_EXIT, because the DISCARD sits at the end of
>> > the linker script. Add the missing RUNTIME_DISCARD_EXIT define so that
>> > it still works if we move DISCARD up or even at the beginning of the
>> > linker script.
>> > 
>> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
>> > Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
>> > ---
>> >  arch/riscv/kernel/vmlinux.lds.S | 1 +
>> >  1 file changed, 1 insertion(+)
>> > 
>> > diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
>> > index 4e6c88aa4d87..07c19f2a288c 100644
>> > --- a/arch/riscv/kernel/vmlinux.lds.S
>> > +++ b/arch/riscv/kernel/vmlinux.lds.S
>> > @@ -5,6 +5,7 @@
>> >   */
>> >  
>> >  #define RO_EXCEPTION_TABLE_ALIGN	4
>> > +#define RUNTIME_DISCARD_EXIT
>> >  
>> >  #ifdef CONFIG_XIP_KERNEL
>> >  #include "vmlinux-xip.lds.S"
>> 
>> Since the diff is identical to:
>> https://patchwork.kernel.org/project/linux-riscv/patch/20230102124936.1363533-1-conor@kernel.org/
>
>OOPS, I didn't notice you submitted the patch which did similar
>about RUNTIME_DISCARD_EXIT, then I'd like to recall patch1. I
>expected some review comments for remainning patch2\3\4, I will
>send v2 which will both address possible review comments and
>remove patch1

Nah, keep your patch in the series.
I'll mark mine as superseded in patchwork.


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[PATCH 2/4] riscv: vmlinux.lds.S: explicitly catch .rela.dyn symbols

[Jisheng Zhang]

When enabling linker orphan section warning, I got warnings similar as
below:
riscv64-linux-gnu-ld: warning: orphan section `.rela.text' from
`init/main.o' being placed in section `.rela.dyn'

Use the approach similar as ARM64 does and declare it in vmlinux.lds.S

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/riscv/kernel/vmlinux.lds.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 07c19f2a288c..6a250313b752 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -97,6 +97,10 @@ SECTIONS
 		*(.rel.dyn*)
 	}
 
+	.rela.dyn : {
+		*(.rela*)
+	}
+
 	__init_data_end = .;
 
 	. = ALIGN(8);
-- 
2.38.1


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[PATCH 3/4] riscv: vmlinux.lds.S: explicitly catch .riscv.attributes sections

[Jisheng Zhang]

When enabling linker orphan section warning, I got warnings similar as
below:
riscv64-linux-gnu-ld: warning: orphan section `.riscv.attributes' from
`init/main.o' being placed in section `.riscv.attributes'

While I don't see any usage of .riscv.attributes sections' usage in
kernel now, just catch the sections so that we can enable linker orphan
section warning.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/riscv/kernel/vmlinux.lds.S | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 6a250313b752..7eb3d25d0dae 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -146,6 +146,7 @@ SECTIONS
 	STABS_DEBUG
 	DWARF_DEBUG
 	ELF_DETAILS
+	.riscv.attributes 0 : { *(.riscv.attributes) }
 
 	DISCARDS
 }
-- 
2.38.1


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[PATCH 4/4] riscv: select ARCH_WANT_LD_ORPHAN_WARN for !XIP_KERNEL

[Jisheng Zhang]

Now, after that all the sections are explicitly described and
declared in vmlinux.lds.S, we can enable ld orphan warnings for
!XIP_KERNEL to prevent from missing any new sections in future.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index e2b656043abf..335e0c45cced 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -46,6 +46,7 @@ config RISCV
 	select ARCH_WANT_FRAME_POINTERS
 	select ARCH_WANT_GENERAL_HUGETLB
 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
+	select ARCH_WANT_LD_ORPHAN_WARN if !XIP_KERNEL
 	select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
 	select BUILDTIME_TABLE_SORT if MMU
-- 
2.38.1


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Re: [PATCH 4/4] riscv: select ARCH_WANT_LD_ORPHAN_WARN for !XIP_KERNEL

[Conor Dooley]

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Hey Jisheng,

On Mon, Jan 16, 2023 at 11:48:00PM +0800, Jisheng Zhang wrote:
> Now, after that all the sections are explicitly described and
> declared in vmlinux.lds.S, we can enable ld orphan warnings for
> !XIP_KERNEL to prevent from missing any new sections in future.
> 
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  arch/riscv/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index e2b656043abf..335e0c45cced 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -46,6 +46,7 @@ config RISCV
>  	select ARCH_WANT_FRAME_POINTERS
>  	select ARCH_WANT_GENERAL_HUGETLB
>  	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
> +	select ARCH_WANT_LD_ORPHAN_WARN if !XIP_KERNEL

Enabling this points out a bunch of warnings in the efi stub:
https://gist.github.com/conor-pwbot/145c5536268aec641671592a4cced32c

Would you mind sorting those out prior to enabling the warning?

Thanks,
Conor.

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