* Ingo Molnar <[email protected]> wrote:

> >  tools/testing/selftests/x86/test_syscall_vdso.c | 401 
> > ++++++++++++++++++++++++
> >  tools/testing/selftests/x86/thunks_32.S         |  55 ++++
> >  2 files changed, 456 insertions(+)
> >  create mode 100644 tools/testing/selftests/x86/test_syscall_vdso.c
> >  create mode 100644 tools/testing/selftests/x86/thunks_32.S
> 
> Hm, what I don't see is any Makefile integration. How am I supposed to build 
> this 
> test, and how will automated tests pick this testcase up?

Note that I prettied up its changelog (attached below), please use this for the 
next submission.

Thanks,

        Ingo


=======================>
Subject: x86/asm/entry/32, selftests: Add 'test_syscall_vdso' test
From: Denys Vlasenko <[email protected]>
Date: Fri, 3 Jul 2015 22:02:52 +0200

This new test checks that all x86 registers are preserved across
32-bit syscalls. It tests syscalls through VDSO (if available)
and through INT 0x80, normally and under ptrace.

If kernel is a 64-bit one, high registers (r8..r15) are poisoned
before the syscall is called and are checked afterwards.

They must be either preserved, or cleared to zero (but r11 is special);
r12..15 must be preserved for INT 0x80.

EFLAGS is checked for changes too, but change there is not
considered to be a bug (paravirt kernels do not preserve
arithmetic flags).

Run-tested on 64-bit kernel:

        $ ./test_syscall_vdso_32
        [RUN]   Executing 6-argument 32-bit syscall via VDSO
        [OK]    Arguments are preserved across syscall
        [NOTE]  R11 has changed:0000000000200ed7 - assuming clobbered by SYSRET 
insn
        [OK]    R8..R15 did not leak kernel data
        [RUN]   Executing 6-argument 32-bit syscall via INT 80
        [OK]    Arguments are preserved across syscall
        [OK]    R8..R15 did not leak kernel data
        [RUN]   Running tests under ptrace
        [RUN]   Executing 6-argument 32-bit syscall via VDSO
        [OK]    Arguments are preserved across syscall
        [OK]    R8..R15 did not leak kernel data
        [RUN]   Executing 6-argument 32-bit syscall via INT 80
        [OK]    Arguments are preserved across syscall
        [OK]    R8..R15 did not leak kernel data

On 32-bit paravirt kernel:

        $ ./test_syscall_vdso_32
        [NOTE]  Not a 64-bit kernel, won't test R8..R15 leaks
        [RUN]   Executing 6-argument 32-bit syscall via VDSO
        [WARN]  Flags before=0000000000200ed7 id 0 00 o d i s z 0 a 0 p 1 c
        [WARN]  Flags  after=0000000000200246 id 0 00 i z 0 0 p 1
        [WARN]  Flags change=0000000000000c91 0 00 o d s 0 a 0 0 c
        [OK]    Arguments are preserved across syscall
        [RUN]   Executing 6-argument 32-bit syscall via INT 80
        [OK]    Arguments are preserved across syscall
        [RUN]   Running tests under ptrace
        [RUN]   Executing 6-argument 32-bit syscall via VDSO
        [OK]    Arguments are preserved across syscall
        [RUN]   Executing 6-argument 32-bit syscall via INT 80
        [OK]    Arguments are preserved across syscall
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