[v2,0/4] A new selftests/ directory for arm compatibility testing

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-rc5, on Aarch64 platform. Testing remains
to be done on Aaarch32.

Changes in v2:
- Formatting changes
- Add .gitignore files and config file

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/config            |   1 +
 tools/testing/selftests/arm/elf/.gitignore    |   2 +
 tools/testing/selftests/arm/elf/Makefile      |   6 +
 tools/testing/selftests/arm/elf/parse_elf.c   |  74 +++++
 tools/testing/selftests/arm/mm/.gitignore     |   2 +
 tools/testing/selftests/arm/mm/Makefile       |   6 +
 tools/testing/selftests/arm/mm/compat_va.c    |  92 +++++++
 tools/testing/selftests/arm/signal/.gitignore |   3 +
 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 ++
 18 files changed, 853 insertions(+)
 create mode 100644 tools/testing/selftests/arm/Makefile
 create mode 100644 tools/testing/selftests/arm/README
 create mode 100644 tools/testing/selftests/arm/config
 create mode 100644 tools/testing/selftests/arm/elf/.gitignore
 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/.gitignore
 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/.gitignore
 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

On 4/22/24 10:21 PM, Will Deacon wrote:
> On Mon, Apr 22, 2024 at 12:37:13PM +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.
>>
>> 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.
> 
> Isn't this going to be difficult to maintain if we have two divergent copies
> of the same stuff? From a very quick skim, a bunch of the signals stuff is
> idential to what we have on arm64...
Agreed.

Why don't we follow what x86 suite has been doing? Compile tests for both
arm and arm64, and add conditionals in the tests based on architecture.

If someone has objection that the suite name is arm64, just rename it to
arm which would be a generic name.


> 
> Will
>