[PATCH v5 0/4] Enable orphan-handling=warn for VDSO

[PATCH v5 0/4] Enable orphan-handling=warn for VDSO

[Joey Gouly]

Hi all,

This small series enables the orphan-handling linker flag for the VDSO.
This could catch subtle errors if features that use special sections are
introduced into the VDSO implementation.

Tested by running the VDSO self tests.
Tested building with LLVM LLD and Binutils LD linkers.

Changes from v4 [1]:
  - Add more sections that showed up when using binutils ld

Thanks,
Joey

[1]: https://lore.kernel.org/linux-arm-kernel/20220414104611.17748-1-joey.gouly@arm.com/

Joey Gouly (4):
  arm64: vdso: put ELF related sections in the linker script
  arm64: vdso: enable orphan handling for VDSO
  arm64: vdso32: put ELF related sections in the linker script
  arm64: vdso32: enable orphan handling for VDSO

 arch/arm64/kernel/vdso/Makefile     |  8 +++++++-
 arch/arm64/kernel/vdso/vdso.lds.S   | 16 ++++++++++++++++
 arch/arm64/kernel/vdso32/Makefile   |  1 +
 arch/arm64/kernel/vdso32/vdso.lds.S | 22 +++++++++++++++++++++-
 4 files changed, 45 insertions(+), 2 deletions(-)

-- 
2.17.1


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[PATCH v5 1/4] arm64: vdso: put ELF related sections in the linker script

[Joey Gouly]

Use macros from vmlinux.lds.h to explicitly name sections that are included
in the VDSO output.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 arch/arm64/kernel/vdso/vdso.lds.S | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S
index a5e61e09ea92..1cd85258c079 100644
--- a/arch/arm64/kernel/vdso/vdso.lds.S
+++ b/arch/arm64/kernel/vdso/vdso.lds.S
@@ -11,6 +11,7 @@
 #include <linux/const.h>
 #include <asm/page.h>
 #include <asm/vdso.h>
+#include <asm-generic/vmlinux.lds.h>
 
 OUTPUT_FORMAT("elf64-littleaarch64", "elf64-bigaarch64", "elf64-littleaarch64")
 OUTPUT_ARCH(aarch64)
@@ -49,11 +50,26 @@ SECTIONS
 
 	.dynamic	: { *(.dynamic) }		:text	:dynamic
 
+	.rela.dyn	: ALIGN(8) { *(.rela .rela*) }
+
+	.plt		: {
+		*(.plt)
+		*(.plt.*)
+		*(.iplt)
+		*(.igot .igot.plt)
+	}
+
+	.got		: { *(.got) }
+	.got.plt	: { *(.got.plt) }
+
 	.rodata		: { *(.rodata*) }		:text
 
 	_end = .;
 	PROVIDE(end = .);
 
+	DWARF_DEBUG
+	ELF_DETAILS
+
 	/DISCARD/	: {
 		*(.data .data.* .gnu.linkonce.d.* .sdata*)
 		*(.bss .sbss .dynbss .dynsbss)
-- 
2.17.1


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Re: [PATCH v5 1/4] arm64: vdso: put ELF related sections in the linker script

[Vincenzo Frascino]

Hi Joey,

On 5/10/22 10:58, Joey Gouly wrote:
> Use macros from vmlinux.lds.h to explicitly name sections that are included
> in the VDSO output.
> 
> Signed-off-by: Joey Gouly <joey.gouly@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Masahiro Yamada <masahiroy@kernel.org>
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Cc: Kees Cook <keescook@chromium.org>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>

As a general rule, when you make a consistent change to a patch that was
previously reviewed you should drop the "Reviewed-by:" tag as an indication that
the patch needs to be reviewed again.

> ---
>  arch/arm64/kernel/vdso/vdso.lds.S | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S
> index a5e61e09ea92..1cd85258c079 100644
> --- a/arch/arm64/kernel/vdso/vdso.lds.S
> +++ b/arch/arm64/kernel/vdso/vdso.lds.S
> @@ -11,6 +11,7 @@
>  #include <linux/const.h>
>  #include <asm/page.h>
>  #include <asm/vdso.h>
> +#include <asm-generic/vmlinux.lds.h>
>  
>  OUTPUT_FORMAT("elf64-littleaarch64", "elf64-bigaarch64", "elf64-littleaarch64")
>  OUTPUT_ARCH(aarch64)
> @@ -49,11 +50,26 @@ SECTIONS
>  
>  	.dynamic	: { *(.dynamic) }		:text	:dynamic
>  
> +	.rela.dyn	: ALIGN(8) { *(.rela .rela*) }
> +
> +	.plt		: {
> +		*(.plt)
> +		*(.plt.*)
> +		*(.iplt)
> +		*(.igot .igot.plt)
> +	}
> +
> +	.got		: { *(.got) }
> +	.got.plt	: { *(.got.plt) }
> +

The vDSO library does not contain absolute relocations. Is there any specific
reason why these sections are not part of ".rodata"?

Please refer to: lib/vdso/Makefile

Note: A similar comment applies to vdso32.

>  	.rodata		: { *(.rodata*) }		:text
>  
>  	_end = .;
>  	PROVIDE(end = .);
>  
> +	DWARF_DEBUG
> +	ELF_DETAILS
> +
>  	/DISCARD/	: {
>  		*(.data .data.* .gnu.linkonce.d.* .sdata*)
>  		*(.bss .sbss .dynbss .dynsbss)

-- 
Regards,
Vincenzo

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[PATCH v5 2/4] arm64: vdso: enable orphan handling for VDSO

[Joey Gouly]

Like vmlinux, enable orphan-handling for the VDSO. This can catch
subtle errors that might arise from unexpected sections being included.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 arch/arm64/kernel/vdso/Makefile | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index 172452f79e46..623d9ad2c717 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -24,7 +24,13 @@ btildflags-$(CONFIG_ARM64_BTI_KERNEL) += -z force-bti
 # routines, as x86 does (see 6f121e548f83 ("x86, vdso: Reimplement vdso.so
 # preparation in build-time C")).
 ldflags-y := -shared -soname=linux-vdso.so.1 --hash-style=sysv	\
-	     -Bsymbolic --build-id=sha1 -n $(btildflags-y) -T
+	     -Bsymbolic --build-id=sha1 -n $(btildflags-y)
+
+ifdef CONFIG_LD_ORPHAN_WARN
+  ldflags-y += --orphan-handling=warn
+endif
+
+ldflags-y += -T
 
 ccflags-y := -fno-common -fno-builtin -fno-stack-protector -ffixed-x18
 ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
-- 
2.17.1


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[PATCH v5 3/4] arm64: vdso32: put ELF related sections in the linker script

[Joey Gouly]

Use macros from vmlinux.lds.h to explicitly name sections that are included
in the compat VDSO32 output.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 arch/arm64/kernel/vdso32/vdso.lds.S | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/vdso32/vdso.lds.S b/arch/arm64/kernel/vdso32/vdso.lds.S
index 3348ce5ea306..120cf422036f 100644
--- a/arch/arm64/kernel/vdso32/vdso.lds.S
+++ b/arch/arm64/kernel/vdso32/vdso.lds.S
@@ -11,6 +11,7 @@
 #include <linux/const.h>
 #include <asm/page.h>
 #include <asm/vdso.h>
+#include <asm-generic/vmlinux.lds.h>
 
 OUTPUT_FORMAT("elf32-littlearm", "elf32-bigarm", "elf32-littlearm")
 OUTPUT_ARCH(arm)
@@ -37,10 +38,29 @@ SECTIONS
 
 	.rodata		: { *(.rodata*) }		:text
 
-	.text		: { *(.text*) }			:text	=0xe7f001f2
+	.text		: {
+		*(.text*)
+		*(.glue_7)
+		*(.glue_7t)
+		*(.vfp11_veneer)
+		*(.v4_bx)
+	}						:text	=0xe7f001f2
+
+	.rel.dyn	: { *(.rel.text) }
 
 	.got		: { *(.got) }
+	.rel.got	: { *(.rel.got) }
+	.got.plt	: { *(.got.plt) }
 	.rel.plt	: { *(.rel.plt) }
+	.plt		: {
+		*(.plt)
+		*(.rel.iplt)
+		*(.iplt)
+		*(.igot.plt)
+	}
+
+	ELF_DETAILS
+	.ARM.attributes 0 : { *(.ARM.attributes) }
 
 	/DISCARD/	: {
 		*(.note.GNU-stack)
-- 
2.17.1


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[PATCH v5 4/4] arm64: vdso32: enable orphan handling for VDSO

[Joey Gouly]

Like vmlinux, enable orphan-handling for the compat VDSO32. This can catch
subtle errors that might arise from unexpected sections being included.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 arch/arm64/kernel/vdso32/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
index ed181bedbffc..1bf0bfb99652 100644
--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -104,6 +104,7 @@ VDSO_AFLAGS += -D__ASSEMBLY__
 VDSO_LDFLAGS += -Bsymbolic --no-undefined -soname=linux-vdso.so.1
 VDSO_LDFLAGS += -z max-page-size=4096 -z common-page-size=4096
 VDSO_LDFLAGS += -shared --hash-style=sysv --build-id=sha1
+VDSO_LDFLAGS += --orphan-handling=warn
 
 
 # Borrow vdsomunge.c from the arm vDSO
-- 
2.17.1


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Re: [PATCH v5 0/4] Enable orphan-handling=warn for VDSO

[Will Deacon]

Hi Joey,

On Tue, May 10, 2022 at 10:58:30AM +0100, Joey Gouly wrote:
> This small series enables the orphan-handling linker flag for the VDSO.
> This could catch subtle errors if features that use special sections are
> introduced into the VDSO implementation.
> 
> Tested by running the VDSO self tests.
> Tested building with LLVM LLD and Binutils LD linkers.

I've applied this locally, but I'm seeing a warning from LLD when linking
the 32-bit vDSO object:

  | LD32    arch/arm64/kernel/vdso32/vdso.so.raw
  | ld.lld: warning: <internal>:(.ARM.exidx) is being placed in '.ARM.exidx'

Please can you take a look and send an additional patch on top to fix this?

Thanks,

Will

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Re: [PATCH v5 0/4] Enable orphan-handling=warn for VDSO

[Joey Gouly]

Hi Will,

On Thu, Jun 23, 2022 at 06:53:53PM +0100, Will Deacon wrote:
> Hi Joey,
> 
> On Tue, May 10, 2022 at 10:58:30AM +0100, Joey Gouly wrote:
> > This small series enables the orphan-handling linker flag for the VDSO.
> > This could catch subtle errors if features that use special sections are
> > introduced into the VDSO implementation.
> > 
> > Tested by running the VDSO self tests.
> > Tested building with LLVM LLD and Binutils LD linkers.
> 
> I've applied this locally, but I'm seeing a warning from LLD when linking
> the 32-bit vDSO object:
> 
>   | LD32    arch/arm64/kernel/vdso32/vdso.so.raw
>   | ld.lld: warning: <internal>:(.ARM.exidx) is being placed in '.ARM.exidx'
> 
> Please can you take a look and send an additional patch on top to fix this?

I have been meaning to send out a v6, I will try get it out tomorrow or next week.

Thanks,
Joey


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Re: [PATCH v5 0/4] Enable orphan-handling=warn for VDSO

[Will Deacon]

On Thu, Jun 23, 2022 at 07:05:03PM +0100, Joey Gouly wrote:
> Hi Will,
> 
> On Thu, Jun 23, 2022 at 06:53:53PM +0100, Will Deacon wrote:
> > Hi Joey,
> > 
> > On Tue, May 10, 2022 at 10:58:30AM +0100, Joey Gouly wrote:
> > > This small series enables the orphan-handling linker flag for the VDSO.
> > > This could catch subtle errors if features that use special sections are
> > > introduced into the VDSO implementation.
> > > 
> > > Tested by running the VDSO self tests.
> > > Tested building with LLVM LLD and Binutils LD linkers.
> > 
> > I've applied this locally, but I'm seeing a warning from LLD when linking
> > the 32-bit vDSO object:
> > 
> >   | LD32    arch/arm64/kernel/vdso32/vdso.so.raw
> >   | ld.lld: warning: <internal>:(.ARM.exidx) is being placed in '.ARM.exidx'
> > 
> > Please can you take a look and send an additional patch on top to fix this?
> 
> I have been meaning to send out a v6, I will try get it out tomorrow or next week.

I already queued v5, so please just send stuff on top of that.

Will

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Re: [PATCH v5 0/4] Enable orphan-handling=warn for VDSO

[Will Deacon]

On Tue, 10 May 2022 10:58:30 +0100, Joey Gouly wrote:
> This small series enables the orphan-handling linker flag for the VDSO.
> This could catch subtle errors if features that use special sections are
> introduced into the VDSO implementation.
> 
> Tested by running the VDSO self tests.
> Tested building with LLVM LLD and Binutils LD linkers.
> 
> [...]

Applied to arm64 (for-next/vdso), thanks!

[1/4] arm64: vdso: put ELF related sections in the linker script
      https://git.kernel.org/arm64/c/b87d34ca60ce
[2/4] arm64: vdso: enable orphan handling for VDSO
      https://git.kernel.org/arm64/c/e0ab20b20a1b
[3/4] arm64: vdso32: put ELF related sections in the linker script
      https://git.kernel.org/arm64/c/eeec7223b697
[4/4] arm64: vdso32: enable orphan handling for VDSO
      https://git.kernel.org/arm64/c/9d4775b332e1

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev

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