| Message ID | 20190802170300.20662-6-cristian.marussi@arm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add arm64/signal initial kselftest support | expand |
On Fri, Aug 02, 2019 at 06:02:54PM +0100, Cristian Marussi wrote: > Added a simple mangle testcase which messes with the ucontext_t Add > from within the sig_handler, trying to toggle PSTATE SSBS bit. signal handler > Expect SIGILL if SSBS feature unsupported or that the value set in > PSTATE.SSBS is preserved on test PASS. The test doesn't set PSTATE.SSBS directly. Maybe something like: "Expect SIGILL if the SSBS feature is unsupported. Otherwise, expect sigreturn to set PSTATE.SSBS from the corresponding bit in pstate in the signal frame." > This commit also introduces a new common utility function: > get_current_context() which can be used to grab a ucontext without > the help of libc, and detect if such ucontext has been actively used > to jump back into it. > > Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> > --- > .../selftests/arm64/signal/test_signals.h | 4 + > .../arm64/signal/test_signals_utils.c | 93 +++++++++++++++++++ > .../arm64/signal/test_signals_utils.h | 2 + > .../arm64/signal/testcases/.gitignore | 1 + > .../testcases/mangle_pstate_ssbs_regs.c | 56 +++++++++++ > 5 files changed, 156 insertions(+) > create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c > > diff --git a/tools/testing/selftests/arm64/signal/test_signals.h b/tools/testing/selftests/arm64/signal/test_signals.h > index 85db3ac44b32..37bed0590226 100644 > --- a/tools/testing/selftests/arm64/signal/test_signals.h > +++ b/tools/testing/selftests/arm64/signal/test_signals.h > @@ -116,6 +116,10 @@ struct tdescr { > /* optional sa_flags for the installed handler */ > int sa_flags; > ucontext_t saved_uc; > + /* used by get_current_ctx() */ > + size_t live_sz; > + ucontext_t *live_uc; > + volatile bool live_uc_valid; > > /* a setup function to be called before test starts */ > int (*setup)(struct tdescr *td); > diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.c b/tools/testing/selftests/arm64/signal/test_signals_utils.c > index ac0055f6340b..faf55ba99d58 100644 > --- a/tools/testing/selftests/arm64/signal/test_signals_utils.c > +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.c > @@ -11,12 +11,16 @@ > #include <linux/auxvec.h> > #include <ucontext.h> > > +#include <asm/unistd.h> > + > #include "test_signals.h" > #include "test_signals_utils.h" > #include "testcases/testcases.h" > > extern struct tdescr *current; > > +static int sig_copyctx = SIGUSR2; > + > static char *feats_store[FMAX_END] = { > "SSBS", > "PAN", > @@ -37,6 +41,85 @@ static inline char *feats_to_string(unsigned long feats) > return feats_string; > } > > +/* > + * Obtaining a valid and full-blown ucontext_t from userspace is tricky: > + * libc getcontext does() not save all the regs and messes with some of > + * them (pstate value in particular is not reliable). > + * Here we use a service signal to grab the ucontext_t from inside a > + * dedicated signal handler, since there, it is populated by Kernel > + * itself in setup_sigframe(). The grabbed context is then stored and > + * made available in td->live_uc. > + * > + * Anyway this function really serves a dual purpose: > + * > + * 1. grab a valid sigcontext into td->live_uc for result analysis: in > + * such case it returns 1. > + * > + * 2. detect if somehow a previously grabbed live_uc context has been > + * used actively with a sigreturn: in such a case the execution would have > + * magically resumed in the middle of the function itself (seen_already==1): > + * in such a case return 0, since in fact we have not just simply grabbed > + * the context. > + * > + * This latter case is useful to detect when a fake_sigreturn test-case has > + * unexpectedly survived without hittig a SEGV. > + */ > +bool get_current_context(struct tdescr *td, ucontext_t *dest_uc) > +{ > + static volatile sig_atomic_t seen_already; > + > + if (!td || !dest_uc) { > + fprintf(stdout, "Signal-based Context dumping NOT available\n"); Should this ever happen inless there is a test bug? Maybe this should just be an assert. > + return 0; > + } > + > + /* it's a genuine invokation..reinit */ > + seen_already = 0; > + td->live_uc_valid = 0; > + td->live_sz = sizeof(*dest_uc); > + memset(dest_uc, 0x00, td->live_sz); Eventually we will need to examine the signal frame to determine its size, but for now this is fine. It will start to matter for SVE. > + td->live_uc = dest_uc; > + /* > + * Grab ucontext_t triggering a signal... > + * ASM equivalent of raise(sig_copyctx); > + * > + * Note that: > + * - live_uc_valid is declared volatile in struct tdescr > + * since it will be changed inside the sig_copyctx handler. > + * - the kill() syscall invocation returns only after any possible > + * registered sig_handler for the invoked signal has returned, sig_handler looks like the name of some function of variable, but I can't find it. Did I miss something? > + * so that live_uc_valid flag is surely up to date when this > + * function return it. > + * - the additional 'memory' clobber is there to avoid possible > + * compiler's assumption on the content pointed by dest_uc, which > + * is changed inside the handler, but not referenced here anyway. > + */ > + asm volatile ("mov x8, %0\n\t" > + "svc #0\n\t" > + "mov x1, %1\n\t" > + "mov x8, %2\n\t" > + "svc #0" > + : > + : "i" (__NR_getpid), > + "r" (sig_copyctx), > + "i" (__NR_kill) > + : "x1","x8","x0","memory"); > + /* > + * If we get here with seen_already==1 it implies the td->live_uc > + * context has been used to get back here....this probably means > + * a test has failed to cause a SEGV...anyway the live_uc has not > + * just been acquired...so return 0 > + */ > + if (seen_already) { > + fprintf(stdout, > + "Successful sigreturn detected: live_uc is stale !\n"); > + return 0; > + } > + seen_already = 1; > + > + return td->live_uc_valid; > +} > + > static void unblock_signal(int signum) > { > sigset_t sset; > @@ -112,6 +195,12 @@ static void default_handler(int signum, siginfo_t *si, void *uc) > * to terminate immediately exiting straight away > */ > default_result(current, 1); > + } else if (signum == sig_copyctx && current->live_uc) { > + memcpy(current->live_uc, uc, current->live_sz); > + ASSERT_GOOD_CONTEXT(current->live_uc); > + current->live_uc_valid = 1; > + fprintf(stderr, > + "GOOD CONTEXT grabbed from sig_copyctx handler\n"); > } else { > if (signum == current->sig_unsupp && !are_feats_ok(current)) { > fprintf(stderr, "-- RX SIG_UNSUPP on unsupported feature...OK\n"); > @@ -214,6 +303,10 @@ static int test_init(struct tdescr *td) > !feats_ok ? "NOT " : ""); > } > > + if (td->sig_trig == sig_copyctx) > + sig_copyctx = SIGUSR1; What's this for? What if we have the same signal for sig_trig and sig_copyctx? > + unblock_signal(sig_copyctx); > + > td->initialized = 1; > return 1; > } > diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h > index 8658d1a7d4b9..ce35be8ebc8e 100644 > --- a/tools/testing/selftests/arm64/signal/test_signals_utils.h > +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h > @@ -10,4 +10,6 @@ int test_setup(struct tdescr *td); > void test_cleanup(struct tdescr *td); > int test_run(struct tdescr *td); > void test_result(struct tdescr *td); > + > +bool get_current_context(struct tdescr *td, ucontext_t *dest_uc); > #endif > diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore > index 226bb179b673..a48a118b1a1a 100644 > --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore > +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore > @@ -3,3 +3,4 @@ mangle_pstate_invalid_daif_bits > mangle_pstate_invalid_mode_el1 > mangle_pstate_invalid_mode_el2 > mangle_pstate_invalid_mode_el3 > +mangle_pstate_ssbs_regs > diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c > new file mode 100644 > index 000000000000..a399d9aa40d5 > --- /dev/null > +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c > @@ -0,0 +1,56 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* Copyright (C) 2019 ARM Limited */ > + > +#include <stdio.h> > +#include <ucontext.h> > + > +#include "test_signals_utils.h" > +#include "testcases.h" > + > +static int mangle_invalid_pstate_ssbs_run(struct tdescr *td, > + siginfo_t *si, ucontext_t *uc) > +{ > + ASSERT_GOOD_CONTEXT(uc); > + > + /* set bit value */ Should we clear SSBS in the test setup (using MSR), to make sure that sigreturn really succeeds in _changing_ the bit to 1? > + uc->uc_mcontext.pstate |= PSR_SSBS_BIT; > + fprintf(stderr, "SSBS set to 1 -- PSTATE: 0x%016lX\n", > + uc->uc_mcontext.pstate); > + /* Save after mangling...it should be preserved */ > + td->saved_uc = *uc; > + > + return 1; > +} [...] Cheers ---Dave
Hi On 13/08/2019 17:25, Dave Martin wrote: > On Fri, Aug 02, 2019 at 06:02:54PM +0100, Cristian Marussi wrote: >> Added a simple mangle testcase which messes with the ucontext_t > > Add > >> from within the sig_handler, trying to toggle PSTATE SSBS bit. > > signal handler > Ok. >> Expect SIGILL if SSBS feature unsupported or that the value set in >> PSTATE.SSBS is preserved on test PASS. > > The test doesn't set PSTATE.SSBS directly. > > Maybe something like: "Expect SIGILL if the SSBS feature is unsupported. > Otherwise, expect sigreturn to set PSTATE.SSBS from the corresponding > bit in pstate in the signal frame." > Ok >> This commit also introduces a new common utility function: >> get_current_context() which can be used to grab a ucontext without >> the help of libc, and detect if such ucontext has been actively used >> to jump back into it. >> >> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> >> --- >> .../selftests/arm64/signal/test_signals.h | 4 + >> .../arm64/signal/test_signals_utils.c | 93 +++++++++++++++++++ >> .../arm64/signal/test_signals_utils.h | 2 + >> .../arm64/signal/testcases/.gitignore | 1 + >> .../testcases/mangle_pstate_ssbs_regs.c | 56 +++++++++++ >> 5 files changed, 156 insertions(+) >> create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c >> >> diff --git a/tools/testing/selftests/arm64/signal/test_signals.h b/tools/testing/selftests/arm64/signal/test_signals.h >> index 85db3ac44b32..37bed0590226 100644 >> --- a/tools/testing/selftests/arm64/signal/test_signals.h >> +++ b/tools/testing/selftests/arm64/signal/test_signals.h >> @@ -116,6 +116,10 @@ struct tdescr { >> /* optional sa_flags for the installed handler */ >> int sa_flags; >> ucontext_t saved_uc; >> + /* used by get_current_ctx() */ >> + size_t live_sz; >> + ucontext_t *live_uc; >> + volatile bool live_uc_valid; >> >> /* a setup function to be called before test starts */ >> int (*setup)(struct tdescr *td); >> diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.c b/tools/testing/selftests/arm64/signal/test_signals_utils.c >> index ac0055f6340b..faf55ba99d58 100644 >> --- a/tools/testing/selftests/arm64/signal/test_signals_utils.c >> +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.c >> @@ -11,12 +11,16 @@ >> #include <linux/auxvec.h> >> #include <ucontext.h> >> >> +#include <asm/unistd.h> >> + >> #include "test_signals.h" >> #include "test_signals_utils.h" >> #include "testcases/testcases.h" >> >> extern struct tdescr *current; >> >> +static int sig_copyctx = SIGUSR2; >> + >> static char *feats_store[FMAX_END] = { >> "SSBS", >> "PAN", >> @@ -37,6 +41,85 @@ static inline char *feats_to_string(unsigned long feats) >> return feats_string; >> } >> >> +/* >> + * Obtaining a valid and full-blown ucontext_t from userspace is tricky: >> + * libc getcontext does() not save all the regs and messes with some of >> + * them (pstate value in particular is not reliable). >> + * Here we use a service signal to grab the ucontext_t from inside a >> + * dedicated signal handler, since there, it is populated by Kernel >> + * itself in setup_sigframe(). The grabbed context is then stored and >> + * made available in td->live_uc. >> + * >> + * Anyway this function really serves a dual purpose: >> + * >> + * 1. grab a valid sigcontext into td->live_uc for result analysis: in >> + * such case it returns 1. >> + * >> + * 2. detect if somehow a previously grabbed live_uc context has been >> + * used actively with a sigreturn: in such a case the execution would have >> + * magically resumed in the middle of the function itself (seen_already==1): >> + * in such a case return 0, since in fact we have not just simply grabbed >> + * the context. >> + * >> + * This latter case is useful to detect when a fake_sigreturn test-case has >> + * unexpectedly survived without hittig a SEGV. >> + */ >> +bool get_current_context(struct tdescr *td, ucontext_t *dest_uc) >> +{ >> + static volatile sig_atomic_t seen_already; >> + >> + if (!td || !dest_uc) { >> + fprintf(stdout, "Signal-based Context dumping NOT available\n"); > > Should this ever happen inless there is a test bug? > > Maybe this should just be an assert. Yes definitely better. > >> + return 0; >> + } >> + >> + /* it's a genuine invokation..reinit */ >> + seen_already = 0; >> + td->live_uc_valid = 0; >> + td->live_sz = sizeof(*dest_uc); >> + memset(dest_uc, 0x00, td->live_sz); > > Eventually we will need to examine the signal frame to determine its > size, but for now this is fine. > > It will start to matter for SVE. Yes this function has been reworked in the SVE signal frame patches to dynamically detect runtime signal frame and be able to optionally grab a sigframe containing SVE material (avoiding the kill() syscall to trigger a signal in favour of a brk instruction to cause a SIGTRAP without passing via the syscall machinery which would zero the SVE sigframe stuff) Such patch, which depends on this series, is still not published. > >> + td->live_uc = dest_uc; >> + /* >> + * Grab ucontext_t triggering a signal... >> + * ASM equivalent of raise(sig_copyctx); >> + * >> + * Note that: >> + * - live_uc_valid is declared volatile in struct tdescr >> + * since it will be changed inside the sig_copyctx handler. >> + * - the kill() syscall invocation returns only after any possible >> + * registered sig_handler for the invoked signal has returned, > > sig_handler looks like the name of some function of variable, but I > can't find it. Did I miss something? No I'll replace the comment with "signal handler" > >> + * so that live_uc_valid flag is surely up to date when this >> + * function return it. >> + * - the additional 'memory' clobber is there to avoid possible >> + * compiler's assumption on the content pointed by dest_uc, which >> + * is changed inside the handler, but not referenced here anyway. >> + */ >> + asm volatile ("mov x8, %0\n\t" >> + "svc #0\n\t" >> + "mov x1, %1\n\t" >> + "mov x8, %2\n\t" >> + "svc #0" >> + : >> + : "i" (__NR_getpid), >> + "r" (sig_copyctx), >> + "i" (__NR_kill) >> + : "x1","x8","x0","memory"); >> + /* >> + * If we get here with seen_already==1 it implies the td->live_uc >> + * context has been used to get back here....this probably means >> + * a test has failed to cause a SEGV...anyway the live_uc has not >> + * just been acquired...so return 0 >> + */ >> + if (seen_already) { >> + fprintf(stdout, >> + "Successful sigreturn detected: live_uc is stale !\n"); >> + return 0; >> + } >> + seen_already = 1; >> + >> + return td->live_uc_valid; >> +} >> + >> static void unblock_signal(int signum) >> { >> sigset_t sset; >> @@ -112,6 +195,12 @@ static void default_handler(int signum, siginfo_t *si, void *uc) >> * to terminate immediately exiting straight away >> */ >> default_result(current, 1); >> + } else if (signum == sig_copyctx && current->live_uc) { >> + memcpy(current->live_uc, uc, current->live_sz); >> + ASSERT_GOOD_CONTEXT(current->live_uc); >> + current->live_uc_valid = 1; >> + fprintf(stderr, >> + "GOOD CONTEXT grabbed from sig_copyctx handler\n"); >> } else { >> if (signum == current->sig_unsupp && !are_feats_ok(current)) { >> fprintf(stderr, "-- RX SIG_UNSUPP on unsupported feature...OK\n"); >> @@ -214,6 +303,10 @@ static int test_init(struct tdescr *td) >> !feats_ok ? "NOT " : ""); >> } >> >> + if (td->sig_trig == sig_copyctx) >> + sig_copyctx = SIGUSR1; > > What's this for? What if we have the same signal for sig_trig and > sig_copyctx? > To avoid that a user defined sig_trig equal to sig_copyctx can fool this function. In SVE signal frame patch (not in this series), I'll anyway switch to use a distinct SIGTRAP sig_trig. >> + unblock_signal(sig_copyctx); >> + >> td->initialized = 1; >> return 1; >> } >> diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h >> index 8658d1a7d4b9..ce35be8ebc8e 100644 >> --- a/tools/testing/selftests/arm64/signal/test_signals_utils.h >> +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h >> @@ -10,4 +10,6 @@ int test_setup(struct tdescr *td); >> void test_cleanup(struct tdescr *td); >> int test_run(struct tdescr *td); >> void test_result(struct tdescr *td); >> + >> +bool get_current_context(struct tdescr *td, ucontext_t *dest_uc); >> #endif >> diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore >> index 226bb179b673..a48a118b1a1a 100644 >> --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore >> +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore >> @@ -3,3 +3,4 @@ mangle_pstate_invalid_daif_bits >> mangle_pstate_invalid_mode_el1 >> mangle_pstate_invalid_mode_el2 >> mangle_pstate_invalid_mode_el3 >> +mangle_pstate_ssbs_regs >> diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c >> new file mode 100644 >> index 000000000000..a399d9aa40d5 >> --- /dev/null >> +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c >> @@ -0,0 +1,56 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* Copyright (C) 2019 ARM Limited */ >> + >> +#include <stdio.h> >> +#include <ucontext.h> >> + >> +#include "test_signals_utils.h" >> +#include "testcases.h" >> + >> +static int mangle_invalid_pstate_ssbs_run(struct tdescr *td, >> + siginfo_t *si, ucontext_t *uc) >> +{ >> + ASSERT_GOOD_CONTEXT(uc); >> + >> + /* set bit value */ > > Should we clear SSBS in the test setup (using MSR), to make sure that > sigreturn really succeeds in _changing_ the bit to 1? > Yes. I introduced a set_regval() asm helper and added a new .init signal-test framework entry in tdescr to be able to call per-test specific initialization. I took the chance also to remove the remaining volatile qualifiers from signal handling code to please checkpatch, and add a dsb barrier to ensure the writes by the signal handler. >> + uc->uc_mcontext.pstate |= PSR_SSBS_BIT; >> + fprintf(stderr, "SSBS set to 1 -- PSTATE: 0x%016lX\n", >> + uc->uc_mcontext.pstate); >> + /* Save after mangling...it should be preserved */ >> + td->saved_uc = *uc; >> + >> + return 1; >> +} > > [...] > > Cheers > ---Dave > Cheers Cristian
diff --git a/tools/testing/selftests/arm64/signal/test_signals.h b/tools/testing/selftests/arm64/signal/test_signals.h index 85db3ac44b32..37bed0590226 100644 --- a/tools/testing/selftests/arm64/signal/test_signals.h +++ b/tools/testing/selftests/arm64/signal/test_signals.h @@ -116,6 +116,10 @@ struct tdescr { /* optional sa_flags for the installed handler */ int sa_flags; ucontext_t saved_uc; + /* used by get_current_ctx() */ + size_t live_sz; + ucontext_t *live_uc; + volatile bool live_uc_valid; /* a setup function to be called before test starts */ int (*setup)(struct tdescr *td); diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.c b/tools/testing/selftests/arm64/signal/test_signals_utils.c index ac0055f6340b..faf55ba99d58 100644 --- a/tools/testing/selftests/arm64/signal/test_signals_utils.c +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.c @@ -11,12 +11,16 @@ #include <linux/auxvec.h> #include <ucontext.h> +#include <asm/unistd.h> + #include "test_signals.h" #include "test_signals_utils.h" #include "testcases/testcases.h" extern struct tdescr *current; +static int sig_copyctx = SIGUSR2; + static char *feats_store[FMAX_END] = { "SSBS", "PAN", @@ -37,6 +41,85 @@ static inline char *feats_to_string(unsigned long feats) return feats_string; } +/* + * Obtaining a valid and full-blown ucontext_t from userspace is tricky: + * libc getcontext does() not save all the regs and messes with some of + * them (pstate value in particular is not reliable). + * Here we use a service signal to grab the ucontext_t from inside a + * dedicated signal handler, since there, it is populated by Kernel + * itself in setup_sigframe(). The grabbed context is then stored and + * made available in td->live_uc. + * + * Anyway this function really serves a dual purpose: + * + * 1. grab a valid sigcontext into td->live_uc for result analysis: in + * such case it returns 1. + * + * 2. detect if somehow a previously grabbed live_uc context has been + * used actively with a sigreturn: in such a case the execution would have + * magically resumed in the middle of the function itself (seen_already==1): + * in such a case return 0, since in fact we have not just simply grabbed + * the context. + * + * This latter case is useful to detect when a fake_sigreturn test-case has + * unexpectedly survived without hittig a SEGV. + */ +bool get_current_context(struct tdescr *td, ucontext_t *dest_uc) +{ + static volatile sig_atomic_t seen_already; + + if (!td || !dest_uc) { + fprintf(stdout, "Signal-based Context dumping NOT available\n"); + return 0; + } + + /* it's a genuine invokation..reinit */ + seen_already = 0; + td->live_uc_valid = 0; + td->live_sz = sizeof(*dest_uc); + memset(dest_uc, 0x00, td->live_sz); + td->live_uc = dest_uc; + /* + * Grab ucontext_t triggering a signal... + * ASM equivalent of raise(sig_copyctx); + * + * Note that: + * - live_uc_valid is declared volatile in struct tdescr + * since it will be changed inside the sig_copyctx handler. + * - the kill() syscall invocation returns only after any possible + * registered sig_handler for the invoked signal has returned, + * so that live_uc_valid flag is surely up to date when this + * function return it. + * - the additional 'memory' clobber is there to avoid possible + * compiler's assumption on the content pointed by dest_uc, which + * is changed inside the handler, but not referenced here anyway. + */ + asm volatile ("mov x8, %0\n\t" + "svc #0\n\t" + "mov x1, %1\n\t" + "mov x8, %2\n\t" + "svc #0" + : + : "i" (__NR_getpid), + "r" (sig_copyctx), + "i" (__NR_kill) + : "x1","x8","x0","memory"); + /* + * If we get here with seen_already==1 it implies the td->live_uc + * context has been used to get back here....this probably means + * a test has failed to cause a SEGV...anyway the live_uc has not + * just been acquired...so return 0 + */ + if (seen_already) { + fprintf(stdout, + "Successful sigreturn detected: live_uc is stale !\n"); + return 0; + } + seen_already = 1; + + return td->live_uc_valid; +} + static void unblock_signal(int signum) { sigset_t sset; @@ -112,6 +195,12 @@ static void default_handler(int signum, siginfo_t *si, void *uc) * to terminate immediately exiting straight away */ default_result(current, 1); + } else if (signum == sig_copyctx && current->live_uc) { + memcpy(current->live_uc, uc, current->live_sz); + ASSERT_GOOD_CONTEXT(current->live_uc); + current->live_uc_valid = 1; + fprintf(stderr, + "GOOD CONTEXT grabbed from sig_copyctx handler\n"); } else { if (signum == current->sig_unsupp && !are_feats_ok(current)) { fprintf(stderr, "-- RX SIG_UNSUPP on unsupported feature...OK\n"); @@ -214,6 +303,10 @@ static int test_init(struct tdescr *td) !feats_ok ? "NOT " : ""); } + if (td->sig_trig == sig_copyctx) + sig_copyctx = SIGUSR1; + unblock_signal(sig_copyctx); + td->initialized = 1; return 1; } diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h index 8658d1a7d4b9..ce35be8ebc8e 100644 --- a/tools/testing/selftests/arm64/signal/test_signals_utils.h +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h @@ -10,4 +10,6 @@ int test_setup(struct tdescr *td); void test_cleanup(struct tdescr *td); int test_run(struct tdescr *td); void test_result(struct tdescr *td); + +bool get_current_context(struct tdescr *td, ucontext_t *dest_uc); #endif diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore index 226bb179b673..a48a118b1a1a 100644 --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore @@ -3,3 +3,4 @@ mangle_pstate_invalid_daif_bits mangle_pstate_invalid_mode_el1 mangle_pstate_invalid_mode_el2 mangle_pstate_invalid_mode_el3 +mangle_pstate_ssbs_regs diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c new file mode 100644 index 000000000000..a399d9aa40d5 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c @@ -0,0 +1,56 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 ARM Limited */ + +#include <stdio.h> +#include <ucontext.h> + +#include "test_signals_utils.h" +#include "testcases.h" + +static int mangle_invalid_pstate_ssbs_run(struct tdescr *td, + siginfo_t *si, ucontext_t *uc) +{ + ASSERT_GOOD_CONTEXT(uc); + + /* set bit value */ + uc->uc_mcontext.pstate |= PSR_SSBS_BIT; + fprintf(stderr, "SSBS set to 1 -- PSTATE: 0x%016lX\n", + uc->uc_mcontext.pstate); + /* Save after mangling...it should be preserved */ + td->saved_uc = *uc; + + return 1; +} + +static void pstate_ssbs_bit_checks(struct tdescr *td) +{ + uint64_t val = 0; + ucontext_t uc; + + /* This check reports some result even if MRS SSBS unsupported */ + if (get_current_context(td, &uc)) + fprintf(stderr, + "INFO: live_uc - got PSTATE: 0x%016lX -> SSBS %s\n", + uc.uc_mcontext.pstate, + (td->saved_uc.uc_mcontext.pstate & PSR_SSBS_BIT) == + (uc.uc_mcontext.pstate & PSR_SSBS_BIT) ? + "PRESERVED" : "CLEARED"); + + fprintf(stderr, "Checking with MRS SSBS...\n"); + get_regval(S3_MRS_SSBS_SYSREG, val); + fprintf(stderr, "INFO: MRS SSBS - got: 0x%016lX\n", val); + /* pass when preserved */ + td->pass = (val & PSR_SSBS_BIT) == + (td->saved_uc.uc_mcontext.pstate & PSR_SSBS_BIT); +} + +struct tdescr tde = { + .sanity_disabled = true, + .name = "MANGLE_PSTATE_SSBS_REGS", + .descr = "Mangling uc_mcontext changing SSBS.(PRESERVE)", + .feats_required = FEAT_SSBS, + .sig_trig = SIGUSR1, + .sig_unsupp = SIGILL, + .run = mangle_invalid_pstate_ssbs_run, + .check_result = pstate_ssbs_bit_checks, +};
Added a simple mangle testcase which messes with the ucontext_t from within the sig_handler, trying to toggle PSTATE SSBS bit. Expect SIGILL if SSBS feature unsupported or that the value set in PSTATE.SSBS is preserved on test PASS. This commit also introduces a new common utility function: get_current_context() which can be used to grab a ucontext without the help of libc, and detect if such ucontext has been actively used to jump back into it. Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> --- .../selftests/arm64/signal/test_signals.h | 4 + .../arm64/signal/test_signals_utils.c | 93 +++++++++++++++++++ .../arm64/signal/test_signals_utils.h | 2 + .../arm64/signal/testcases/.gitignore | 1 + .../testcases/mangle_pstate_ssbs_regs.c | 56 +++++++++++ 5 files changed, 156 insertions(+) create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c