linux-kernel - [PATCH v2 00/16] powerpc: Add KUAP support for BOOKE and 40x

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Date:   Fri,  8 Oct 2021 17:40:28 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v2 00/16] powerpc: Add KUAP support for BOOKE and 40x

On booke/40x we don't have segments like book3s/32.
On booke/40x we don't have access protection groups like 8xx.

Use the PID register to provide user access protection.
Kernel address space can be accessed with any PID.
User address space has to be accessed with the PID of the user.
User PID is always not null.

Everytime the kernel is entered, set PID register to 0 and
restore PID register when returning to user.

Everytime kernel needs to access user data, PID is restored
for the access.

In TLB miss handlers, check the PID and bail out to data storage
exception when PID is 0 and accessed address is in user space.

Note that also forbids execution of user text by kernel except
when user access is unlocked. But this shouldn't be a problem
as the kernel is not supposed to ever run user text.

This series has:
- Two first patches have already been submitted and are not directly related to KUAP but would conflict otherwise
- Following patches aim at refactoring the KUAP interface to reduce redundant platform specific code.
- Then comes patches 9 and 10 that add generic support frame for booke type processors
- Followed by the assembly modification for each of the 4 booke family types 
- Last patch removes CONFIG_PPC_HAVE_KUAP now that all powerpc platforms have KUAP.

Changes in v2:
- Rebased on top of today's merge (trivial conflict with d93f9e23744b ("powerpc/32s: Fix kuap_kernel_restore()"))
- Fix missing check in bad_kuap_fault() which led to KUAP fault on platforms where KUAP was disabled (CI g5_defconfig)
- New patch to fix PPC_KUAP_DEBUG dependency

Christophe Leroy (16):
  powerpc/32s: Do kuep_lock() and kuep_unlock() in assembly
  powerpc/32s: Save content of sr0 to avoid 'mfsr'
  powerpc/kuap: Add a generic intermediate layer
  powerpc/kuap: Check KUAP activation in generic functions
  powerpc/kuap: Remove __kuap_assert_locked()
  powerpc/kuap: Add kuap_lock()
  powerpc/nohash: Move setup_kuap out of 8xx.c
  powerpc/config: Add CONFIG_BOOKE_OR_40x
  powerpc/kuap: Prepare for supporting KUAP on BOOK3E/64
  powerpc/kuap: Make PPC_KUAP_DEBUG depend on PPC_KUAP only
  powerpc: Add KUAP support for BOOKE and 40x
  powerpc/kuap: Wire-up KUAP on 44x
  powerpc/kuap: Wire-up KUAP on 40x
  powerpc/kuap: Wire-up KUAP on 85xx in 32 bits mode.
  powerpc/kuap: Wire-up KUAP on book3e/64
  powerpc: Remove CONFIG_PPC_HAVE_KUAP

 arch/powerpc/include/asm/book3s/32/kup.h      | 103 ++++-----------
 arch/powerpc/include/asm/book3s/32/mmu-hash.h |  78 +++++++++++-
 arch/powerpc/include/asm/book3s/64/kup.h      |  56 ++++-----
 arch/powerpc/include/asm/hw_irq.h             |   8 +-
 arch/powerpc/include/asm/interrupt.h          |  13 +-
 arch/powerpc/include/asm/irq.h                |   2 +-
 arch/powerpc/include/asm/kup.h                | 117 +++++++++++++++---
 arch/powerpc/include/asm/nohash/32/kup-8xx.h  |  50 ++------
 arch/powerpc/include/asm/nohash/kup-booke.h   | 110 ++++++++++++++++
 arch/powerpc/include/asm/processor.h          |   4 +
 arch/powerpc/include/asm/ptrace.h             |   2 +-
 arch/powerpc/include/asm/reg.h                |   4 +-
 arch/powerpc/kernel/asm-offsets.c             |   2 +-
 arch/powerpc/kernel/entry_32.S                |  34 ++++-
 arch/powerpc/kernel/head_32.h                 |   6 +
 arch/powerpc/kernel/head_40x.S                |   8 ++
 arch/powerpc/kernel/head_44x.S                |  16 +++
 arch/powerpc/kernel/head_fsl_booke.S          |  12 ++
 arch/powerpc/kernel/interrupt.c               |   3 +-
 arch/powerpc/kernel/irq.c                     |   2 +-
 arch/powerpc/kernel/kgdb.c                    |   4 +-
 arch/powerpc/kernel/process.c                 |   9 +-
 arch/powerpc/kernel/setup.h                   |   2 +-
 arch/powerpc/kernel/setup_32.c                |   2 +-
 arch/powerpc/kernel/time.c                    |   2 +-
 arch/powerpc/mm/book3s32/kuap.c               |   5 +-
 arch/powerpc/mm/book3s32/kuep.c               |  21 +++-
 arch/powerpc/mm/book3s32/mmu_context.c        |  15 ++-
 arch/powerpc/mm/mmu_context.c                 |   9 ++
 arch/powerpc/mm/nohash/8xx.c                  |  21 ----
 arch/powerpc/mm/nohash/Makefile               |   2 +-
 arch/powerpc/mm/nohash/kup.c                  |  31 +++++
 arch/powerpc/mm/nohash/mmu_context.c          |   6 +-
 arch/powerpc/mm/nohash/tlb_low_64e.S          |  40 +++++-
 arch/powerpc/platforms/Kconfig.cputype        |  14 +--
 35 files changed, 575 insertions(+), 238 deletions(-)
 create mode 100644 arch/powerpc/include/asm/nohash/kup-booke.h
 create mode 100644 arch/powerpc/mm/nohash/kup.c

-- 
2.31.1