[v9] Introduce 64b relocatable kernel

[PATCH v9 0/6] Introduce 64b relocatable kernel

Posted by Alexandre Ghiti 2 years, 5 months ago

After multiple attempts, this patchset is now based on the fact that the
64b kernel mapping was moved outside the linear mapping.

The first patch allows to build relocatable kernels but is not selected
by default. That patch is a requirement for KASLR.
The second and third patches take advantage of an already existing powerpc
script that checks relocations at compile-time, and uses it for riscv.

This patchset is rebased on top of:

riscv: Use PUD/P4D/PGD pages for the linear mapping
(https://patchwork.kernel.org/project/linux-riscv/list/?series=733603)
base-commit-tag: v6.3-rc1

Changes in v9:
  * Fix gcc/llvm compilation errors by adding patch 1, thanks to Bjorn
  * Move a patch to move rela.dyn outside of init (patch 2): it is a
    separate patch to clearly explain why
  * To effectively move rela.dyn to init, we need to add patch 6: separate patch since we may be
    able at some point to revert (along with patch 2).
  * Add a lot of orphan sections to the linker script

Changes in v8:
  * Fix UEFI boot by moving rela.dyn section into the data so that PE/COFF
    loader actually copies the relocations too
  * Fix check that used PGDIR instead of PUD which was not correct
    for sv48 and sv57
  * Fix PE/COFF header data size definition as it led to size of 0

Changes in v7:
  * Rebase on top of v5.15
  * Fix LDFLAGS_vmlinux which was overriden when CONFIG_DYNAMIC_FTRACE was
    set
  * Make relocate_kernel static
  * Add Ack from Michael

Changes in v6:
  * Remove the kernel move to vmalloc zone
  * Rebased on top of for-next
  * Remove relocatable property from 32b kernel as the kernel is mapped in
    the linear mapping and would then need to be copied physically too
  * CONFIG_RELOCATABLE depends on !XIP_KERNEL
  * Remove Reviewed-by from first patch as it changed a bit

Changes in v5:
  * Add "static __init" to create_kernel_page_table function as reported by
    Kbuild test robot
  * Add reviewed-by from Zong
  * Rebase onto v5.7

Changes in v4:
  * Fix BPF region that overlapped with kernel's as suggested by Zong
  * Fix end of module region that could be larger than 2GB as suggested by Zong
  * Fix the size of the vm area reserved for the kernel as we could lose
    PMD_SIZE if the size was already aligned on PMD_SIZE
  * Split compile time relocations check patch into 2 patches as suggested by Anup
  * Applied Reviewed-by from Zong and Anup

Changes in v3:
  * Move kernel mapping to vmalloc

Changes in v2:
  * Make RELOCATABLE depend on MMU as suggested by Anup
  * Rename kernel_load_addr into kernel_virt_addr as suggested by Anup
  * Use __pa_symbol instead of __pa, as suggested by Zong
  * Rebased on top of v5.6-rc3
  * Tested with sv48 patchset
  * Add Reviewed/Tested-by from Zong and Anup

Alexandre Ghiti (6):
  riscv: Prepare EFI header for relocatable kernels
  riscv: Move .rela.dyn outside of init to avoid empty relocations
  riscv: Introduce CONFIG_RELOCATABLE
  powerpc: Move script to check relocations at compile time in scripts/
  riscv: Check relocations at compile time
  riscv: Use --emit-relocs in order to move .rela.dyn in init

 arch/powerpc/tools/relocs_check.sh  | 18 ++--------
 arch/riscv/Kconfig                  | 14 ++++++++
 arch/riscv/Makefile                 |  7 ++--
 arch/riscv/Makefile.postlink        | 49 ++++++++++++++++++++++++++
 arch/riscv/boot/Makefile            |  7 ++++
 arch/riscv/include/asm/set_memory.h |  3 ++
 arch/riscv/kernel/efi-header.S      | 19 ++++++++--
 arch/riscv/kernel/vmlinux.lds.S     | 26 ++++++++++----
 arch/riscv/mm/Makefile              |  4 +++
 arch/riscv/mm/init.c                | 54 ++++++++++++++++++++++++++++-
 arch/riscv/tools/relocs_check.sh    | 26 ++++++++++++++
 scripts/relocs_check.sh             | 20 +++++++++++
 12 files changed, 218 insertions(+), 29 deletions(-)
 create mode 100644 arch/riscv/Makefile.postlink
 create mode 100755 arch/riscv/tools/relocs_check.sh
 create mode 100755 scripts/relocs_check.sh

-- 
2.37.2

Re: [PATCH v9 0/6] Introduce 64b relocatable kernel

Posted by Palmer Dabbelt 2 years, 4 months ago

On Tue, 28 Mar 2023 21:53:23 PDT (-0700), alexghiti@rivosinc.com wrote:
> After multiple attempts, this patchset is now based on the fact that the
> 64b kernel mapping was moved outside the linear mapping.
>
> The first patch allows to build relocatable kernels but is not selected
> by default. That patch is a requirement for KASLR.
> The second and third patches take advantage of an already existing powerpc
> script that checks relocations at compile-time, and uses it for riscv.
>
> This patchset is rebased on top of:
>
> riscv: Use PUD/P4D/PGD pages for the linear mapping
> (https://patchwork.kernel.org/project/linux-riscv/list/?series=733603)
> base-commit-tag: v6.3-rc1

The QEMU CI has some way to say "this depends on an un-merged patch set 
sent as $MESSAGE_ID", not sure if that's a b4-ism but it's a bit less 
confusing.

I merged this on top of the pre-merge hugepage linear mapping changes, 
it's on for-next.

> Changes in v9:
>   * Fix gcc/llvm compilation errors by adding patch 1, thanks to Bjorn
>   * Move a patch to move rela.dyn outside of init (patch 2): it is a
>     separate patch to clearly explain why
>   * To effectively move rela.dyn to init, we need to add patch 6: separate patch since we may be
>     able at some point to revert (along with patch 2).
>   * Add a lot of orphan sections to the linker script
>
> Changes in v8:
>   * Fix UEFI boot by moving rela.dyn section into the data so that PE/COFF
>     loader actually copies the relocations too
>   * Fix check that used PGDIR instead of PUD which was not correct
>     for sv48 and sv57
>   * Fix PE/COFF header data size definition as it led to size of 0
>
> Changes in v7:
>   * Rebase on top of v5.15
>   * Fix LDFLAGS_vmlinux which was overriden when CONFIG_DYNAMIC_FTRACE was
>     set
>   * Make relocate_kernel static
>   * Add Ack from Michael
>
> Changes in v6:
>   * Remove the kernel move to vmalloc zone
>   * Rebased on top of for-next
>   * Remove relocatable property from 32b kernel as the kernel is mapped in
>     the linear mapping and would then need to be copied physically too
>   * CONFIG_RELOCATABLE depends on !XIP_KERNEL
>   * Remove Reviewed-by from first patch as it changed a bit
>
> Changes in v5:
>   * Add "static __init" to create_kernel_page_table function as reported by
>     Kbuild test robot
>   * Add reviewed-by from Zong
>   * Rebase onto v5.7
>
> Changes in v4:
>   * Fix BPF region that overlapped with kernel's as suggested by Zong
>   * Fix end of module region that could be larger than 2GB as suggested by Zong
>   * Fix the size of the vm area reserved for the kernel as we could lose
>     PMD_SIZE if the size was already aligned on PMD_SIZE
>   * Split compile time relocations check patch into 2 patches as suggested by Anup
>   * Applied Reviewed-by from Zong and Anup
>
> Changes in v3:
>   * Move kernel mapping to vmalloc
>
> Changes in v2:
>   * Make RELOCATABLE depend on MMU as suggested by Anup
>   * Rename kernel_load_addr into kernel_virt_addr as suggested by Anup
>   * Use __pa_symbol instead of __pa, as suggested by Zong
>   * Rebased on top of v5.6-rc3
>   * Tested with sv48 patchset
>   * Add Reviewed/Tested-by from Zong and Anup
>
> Alexandre Ghiti (6):
>   riscv: Prepare EFI header for relocatable kernels
>   riscv: Move .rela.dyn outside of init to avoid empty relocations
>   riscv: Introduce CONFIG_RELOCATABLE
>   powerpc: Move script to check relocations at compile time in scripts/
>   riscv: Check relocations at compile time
>   riscv: Use --emit-relocs in order to move .rela.dyn in init
>
>  arch/powerpc/tools/relocs_check.sh  | 18 ++--------
>  arch/riscv/Kconfig                  | 14 ++++++++
>  arch/riscv/Makefile                 |  7 ++--
>  arch/riscv/Makefile.postlink        | 49 ++++++++++++++++++++++++++
>  arch/riscv/boot/Makefile            |  7 ++++
>  arch/riscv/include/asm/set_memory.h |  3 ++
>  arch/riscv/kernel/efi-header.S      | 19 ++++++++--
>  arch/riscv/kernel/vmlinux.lds.S     | 26 ++++++++++----
>  arch/riscv/mm/Makefile              |  4 +++
>  arch/riscv/mm/init.c                | 54 ++++++++++++++++++++++++++++-
>  arch/riscv/tools/relocs_check.sh    | 26 ++++++++++++++
>  scripts/relocs_check.sh             | 20 +++++++++++
>  12 files changed, 218 insertions(+), 29 deletions(-)
>  create mode 100644 arch/riscv/Makefile.postlink
>  create mode 100755 arch/riscv/tools/relocs_check.sh
>  create mode 100755 scripts/relocs_check.sh

Re: [PATCH v9 0/6] Introduce 64b relocatable kernel

Posted by Konstantin Ryabitsev 2 years, 4 months ago

April 21, 2023 2:59 PM, "Palmer Dabbelt" <palmer@dabbelt.com> wrote:
>> riscv: Use PUD/P4D/PGD pages for the linear mapping
>> (https://patchwork.kernel.org/project/linux-riscv/list/?series=733603)
>> base-commit-tag: v6.3-rc1
> 
> The QEMU CI has some way to say "this depends on an un-merged patch set sent as $MESSAGE_ID", not
> sure if that's a b4-ism but it's a bit less confusing.

I think it's patchwork-ism, actually. B4 will eventually learn to be able to include dependent series info and automatically retrieve/apply them in the proper order on "shazam", but it can't do that yet.

-K

Re: [PATCH v9 0/6] Introduce 64b relocatable kernel

Posted by Conor Dooley 2 years, 4 months ago

On Fri, Apr 21, 2023 at 07:10:14PM +0000, Konstantin Ryabitsev wrote:
> April 21, 2023 2:59 PM, "Palmer Dabbelt" <palmer@dabbelt.com> wrote:
> >> riscv: Use PUD/P4D/PGD pages for the linear mapping
> >> (https://patchwork.kernel.org/project/linux-riscv/list/?series=733603)
> >> base-commit-tag: v6.3-rc1
> > 
> > The QEMU CI has some way to say "this depends on an un-merged patch set sent as $MESSAGE_ID", not
> > sure if that's a b4-ism but it's a bit less confusing.
> 
> I think it's patchwork-ism, actually. B4 will eventually learn to be
> able to include dependent series info and automatically retrieve/apply
> them in the proper order on "shazam", but it can't do that yet.

A patchwork-ism or a patchew-ism? Drew Jones was my source for this, but
he had said the thing to do in QEMU-land was put a:
Based-on: $message-id
in your cover letter for each thing that you depend on. I'm not entirely
sure if that meant each series or each patch. I think patchew picks that
up and dumps in it on a patchew github account that the CI might pick up
on. From the QEMU docs:
<quote>
It is also okay to base patches on top of other on-going work that is
not yet part of the git master branch. To aid continuous integration
tools, such as `patchew <http://patchew.org/QEMU/>`__, you should `add a
tag <https://lists.gnu.org/archive/html/qemu-devel/2017-08/msg01288.html>`__
line ``Based-on: $MESSAGE_ID`` to your cover letter to make the series
dependency obvious.
<\quote>

FWIW, my vote is for something with a message-id, rather than those
patchwork series links that you can't dump into b4!

Re: [PATCH v9 0/6] Introduce 64b relocatable kernel

Posted by Palmer Dabbelt 2 years, 4 months ago

On Wed, 29 Mar 2023 06:53:23 +0200, Alexandre Ghiti wrote:
> After multiple attempts, this patchset is now based on the fact that the
> 64b kernel mapping was moved outside the linear mapping.
> 
> The first patch allows to build relocatable kernels but is not selected
> by default. That patch is a requirement for KASLR.
> The second and third patches take advantage of an already existing powerpc
> script that checks relocations at compile-time, and uses it for riscv.
> 
> [...]

Applied, thanks!

[1/6] riscv: Prepare EFI header for relocatable kernels
      https://git.kernel.org/palmer/c/55de1e4ad43b
[2/6] riscv: Move .rela.dyn outside of init to avoid empty relocations
      https://git.kernel.org/palmer/c/69a90d2fe107
[3/6] riscv: Introduce CONFIG_RELOCATABLE
      https://git.kernel.org/palmer/c/39b33072941f
[4/6] powerpc: Move script to check relocations at compile time in scripts/
      https://git.kernel.org/palmer/c/47981b5cc687
[5/6] riscv: Check relocations at compile time
      https://git.kernel.org/palmer/c/c2dea0bc5339
[6/6] riscv: Use --emit-relocs in order to move .rela.dyn in init
      https://git.kernel.org/palmer/c/559d1e45a16d

Best regards,
-- 
Palmer Dabbelt <palmer@rivosinc.com>

Re: [PATCH v9 0/6] Introduce 64b relocatable kernel

Posted by patchwork-bot+linux-riscv@kernel.org 2 years, 4 months ago

Hello:

This series was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Wed, 29 Mar 2023 06:53:23 +0200 you wrote:
> After multiple attempts, this patchset is now based on the fact that the
> 64b kernel mapping was moved outside the linear mapping.
> 
> The first patch allows to build relocatable kernels but is not selected
> by default. That patch is a requirement for KASLR.
> The second and third patches take advantage of an already existing powerpc
> script that checks relocations at compile-time, and uses it for riscv.
> 
> [...]

Here is the summary with links:
  - [v9,1/6] riscv: Prepare EFI header for relocatable kernels
    https://git.kernel.org/riscv/c/55de1e4ad43b
  - [v9,2/6] riscv: Move .rela.dyn outside of init to avoid empty relocations
    https://git.kernel.org/riscv/c/69a90d2fe107
  - [v9,3/6] riscv: Introduce CONFIG_RELOCATABLE
    https://git.kernel.org/riscv/c/39b33072941f
  - [v9,4/6] powerpc: Move script to check relocations at compile time in scripts/
    https://git.kernel.org/riscv/c/47981b5cc687
  - [v9,5/6] riscv: Check relocations at compile time
    https://git.kernel.org/riscv/c/c2dea0bc5339
  - [v9,6/6] riscv: Use --emit-relocs in order to move .rela.dyn in init
    https://git.kernel.org/riscv/c/559d1e45a16d

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
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