[0/4] A new selftests/ directory for arm compatibility testing

Message

Dev Jain April 5, 2024, 8:44 a.m. UTC

This series introduces the selftests/arm directory, which tests 32 and 64-bit
kernel compatibility with 32-bit ELFs running on the Aarch platform.
The need for this bucket of tests is that 32 bit applications built on legacy
ARM architecture must not break on the new Aarch64 platforms and the 64-bit
kernel. The kernel must emulate the data structures, system calls and the
registers according to Aarch32, when running a 32-bit process; this directory
fills that testing requirement.

One may find similarity between this directory and selftests/arm64; it is
advisable to refer to that since a lot has been copied from there itself.

The mm directory includes a test for checking 4GB limit of the virtual
address space of a process.

The signal directory contains two tests, following a common theme: mangle
with arm_cpsr, dumped by the kernel to user space while invoking the signal
handler; kernel must spot this illegal attempt and terminate the program by
SEGV.

The elf directory includes a test for checking the 32-bit status of the ELF.

The series has been tested on 6.9.0-rc2, on Aarch64 platform. Testing remains
to be done on Aaarch32.

Dev Jain (4):
  selftests/arm: Add mm test
  selftests/arm: Add signal tests
  selftests/arm: Add elf test
  selftests: Add build infrastructure along with README

 tools/testing/selftests/Makefile              |   1 +
 tools/testing/selftests/arm/Makefile          |  57 ++++
 tools/testing/selftests/arm/README            |  31 +++
 tools/testing/selftests/arm/elf/Makefile      |   6 +
 tools/testing/selftests/arm/elf/parse_elf.c   |  75 +++++
 tools/testing/selftests/arm/mm/Makefile       |   6 +
 tools/testing/selftests/arm/mm/compat_va.c    |  94 +++++++
 tools/testing/selftests/arm/signal/Makefile   |  30 ++
 .../selftests/arm/signal/test_signals.c       |  27 ++
 .../selftests/arm/signal/test_signals.h       |  74 +++++
 .../selftests/arm/signal/test_signals_utils.c | 257 ++++++++++++++++++
 .../selftests/arm/signal/test_signals_utils.h | 128 +++++++++
 .../signal/testcases/mangle_cpsr_aif_bits.c   |  33 +++
 .../mangle_cpsr_invalid_compat_toggle.c       |  29 ++
 14 files changed, 848 insertions(+)
 create mode 100644 tools/testing/selftests/arm/Makefile
 create mode 100644 tools/testing/selftests/arm/README
 create mode 100644 tools/testing/selftests/arm/elf/Makefile
 create mode 100644 tools/testing/selftests/arm/elf/parse_elf.c
 create mode 100644 tools/testing/selftests/arm/mm/Makefile
 create mode 100644 tools/testing/selftests/arm/mm/compat_va.c
 create mode 100644 tools/testing/selftests/arm/signal/Makefile
 create mode 100644 tools/testing/selftests/arm/signal/test_signals.c
 create mode 100644 tools/testing/selftests/arm/signal/test_signals.h
 create mode 100644 tools/testing/selftests/arm/signal/test_signals_utils.c
 create mode 100644 tools/testing/selftests/arm/signal/test_signals_utils.h
 create mode 100644 tools/testing/selftests/arm/signal/testcases/mangle_cpsr_aif_bits.c
 create mode 100644 tools/testing/selftests/arm/signal/testcases/mangle_cpsr_invalid_compat_toggle.c

Comments

Mark Brown April 5, 2024, 5:37 p.m. UTC | #1

On Fri, Apr 05, 2024 at 02:14:06PM +0530, Dev Jain wrote:
> This series introduces the selftests/arm directory, which tests 32 and 64-bit
> kernel compatibility with 32-bit ELFs running on the Aarch platform.
> The need for this bucket of tests is that 32 bit applications built on legacy
> ARM architecture must not break on the new Aarch64 platforms and the 64-bit
> kernel. The kernel must emulate the data structures, system calls and the
> registers according to Aarch32, when running a 32-bit process; this directory
> fills that testing requirement.

You should copy Russell King, the 32 bit architeture maintainer, on this
- I've added him here.

FWIW it was me who suggested this work, like Dev says having some
coverage of the corners of the 32 bit ABI feels especially sensible for
arm64 since compat mode could relatively easily get accidentally broken
making changes for 64 bit.