On Thu, Jun 13, 2019 at 12:13:27PM +0100, Cristian Marussi wrote: > Added a simple mangle testcase which messes with the ucontext_t > from within the sig_handler, trying to set PSTATE DAIF bits to an > invalid value (masking everything). > Expects SIGSEGV on test PASS. > > Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx> > --- > .../arm64/signal/testcases/.gitignore | 1 + > .../mangle_pstate_invalid_daif_bits.c | 25 +++++++++++++++++++ > 2 files changed, 26 insertions(+) > create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_daif_bits.c > > diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore > index a87fb0f0d2cf..a609a08b744f 100644 > --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore > +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore > @@ -1,2 +1,3 @@ > mangle_sp_misaligned > mangle_pc_invalid > +mangle_pstate_invalid_daif_bits > diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_daif_bits.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_daif_bits.c > new file mode 100644 > index 000000000000..710681cba59c > --- /dev/null > +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_daif_bits.c > @@ -0,0 +1,25 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* Copyright (C) 2019 ARM Limited */ > + > +#include "test_signals_utils.h" > +#include "testcases.h" > + > +static int mangle_invalid_pstate_run(struct tdescr *td, siginfo_t *si, > + ucontext_t *uc) > +{ > + ASSERT_GOOD_CONTEXT(uc); > + > + /* This config should trigger a SIGSEGV by Kernel */ > + uc->uc_mcontext.pstate |= PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT; It may be worth commenting to mention what we're testing in the kernel here: in this case, we're checking that valid_native_regs() is called to police the new pstate value, and to check that it does the right thing. Is there a way to check that the SIGSEGV comes from the sigreturn and not from something else? It looks like the SIGSEGV should have si_code == SEGV_ACCERR and si_addr == <sigframe base address> in this case. uc_mcontext.pc will also point into sigtramp in the vdso, which we may be able to check somehow. We don't have to have a bulletproof check here, but it would be nice to have some kind of sanity-check at least. [...] Cheers ---Dave