| Message ID | 20200918085122.26132-1-david@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] s390x/tcg: Implement MONITOR CALL | expand |
On 9/18/20 1:51 AM, David Hildenbrand wrote: > Recent upstream Linux uses the MONITOR CALL instruction for things like > BUG_ON() and WARN_ON(). We currently inject an operation exception when > we hit a MONITOR CALL instruction - which is wrong, as the instruction > is not glued to specific CPU features. > > Doing a simple WARN_ON_ONCE() currently results in a panic: > [ 18.162801] illegal operation: 0001 ilc:2 [#1] SMP > [ 18.162889] Modules linked in: > [...] > [ 18.165476] Kernel panic - not syncing: Fatal exception: panic_on_oops > > With a proper implementation, we now get: > [ 18.242754] ------------[ cut here ]------------ > [ 18.242855] WARNING: CPU: 7 PID: 1 at init/main.c:1534 [...] > [ 18.242919] Modules linked in: > [...] > [ 18.246262] ---[ end trace a420477d71dc97b4 ]--- > [ 18.259014] Freeing unused kernel memory: 4220K > > Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> > Signed-off-by: David Hildenbrand <david@redhat.com> > --- Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
On Fri, 18 Sep 2020 10:51:22 +0200 David Hildenbrand <david@redhat.com> wrote: > Recent upstream Linux uses the MONITOR CALL instruction for things like > BUG_ON() and WARN_ON(). We currently inject an operation exception when > we hit a MONITOR CALL instruction - which is wrong, as the instruction > is not glued to specific CPU features. > > Doing a simple WARN_ON_ONCE() currently results in a panic: > [ 18.162801] illegal operation: 0001 ilc:2 [#1] SMP > [ 18.162889] Modules linked in: > [...] > [ 18.165476] Kernel panic - not syncing: Fatal exception: panic_on_oops > > With a proper implementation, we now get: > [ 18.242754] ------------[ cut here ]------------ > [ 18.242855] WARNING: CPU: 7 PID: 1 at init/main.c:1534 [...] > [ 18.242919] Modules linked in: > [...] > [ 18.246262] ---[ end trace a420477d71dc97b4 ]--- > [ 18.259014] Freeing unused kernel memory: 4220K > > Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > > v1 -> v2: > - Simplify by not using the tb flags, always calling the helper. > > I looked into monitor-event counting, which looks easy at first glance > - but proper DAT/access exception handling is tricky. Leaving that for > a cold winter evening :) Fortunately, this is covered by a facility bit, so no need to do this now :) > > --- > target/s390x/excp_helper.c | 23 +++++++++++++++++++++++ > target/s390x/helper.h | 1 + > target/s390x/insn-data.def | 3 +++ > target/s390x/translate.c | 21 +++++++++++++++++++++ > 4 files changed, 48 insertions(+) Thanks, applied.
diff --git a/target/s390x/excp_helper.c b/target/s390x/excp_helper.c index 3b58d10df3..0adfbbda27 100644 --- a/target/s390x/excp_helper.c +++ b/target/s390x/excp_helper.c @@ -610,4 +610,27 @@ void s390x_cpu_do_unaligned_access(CPUState *cs, vaddr addr, tcg_s390_program_interrupt(env, PGM_SPECIFICATION, retaddr); } +static void QEMU_NORETURN monitor_event(CPUS390XState *env, + uint64_t monitor_code, + uint8_t monitor_class, uintptr_t ra) +{ + /* Store the Monitor Code and the Monitor Class Number into the lowcore */ + stq_phys(env_cpu(env)->as, + env->psa + offsetof(LowCore, monitor_code), monitor_code); + stw_phys(env_cpu(env)->as, + env->psa + offsetof(LowCore, mon_class_num), monitor_class); + + tcg_s390_program_interrupt(env, PGM_MONITOR, ra); +} + +void HELPER(monitor_call)(CPUS390XState *env, uint64_t monitor_code, + uint32_t monitor_class) +{ + g_assert(monitor_class <= 0xff); + + if (env->cregs[8] & (0x8000 >> monitor_class)) { + monitor_event(env, monitor_code, monitor_class, GETPC()); + } +} + #endif /* CONFIG_USER_ONLY */ diff --git a/target/s390x/helper.h b/target/s390x/helper.h index b7887b552b..55bd1551e6 100644 --- a/target/s390x/helper.h +++ b/target/s390x/helper.h @@ -349,4 +349,5 @@ DEF_HELPER_3(sic, void, env, i64, i64) DEF_HELPER_3(rpcit, void, env, i32, i32) DEF_HELPER_5(pcistb, void, env, i32, i32, i64, i32) DEF_HELPER_4(mpcifc, void, env, i32, i64, i32) +DEF_HELPER_3(monitor_call, void, env, i64, i32) #endif diff --git a/target/s390x/insn-data.def b/target/s390x/insn-data.def index d79ae9e3f1..e14cbd63fa 100644 --- a/target/s390x/insn-data.def +++ b/target/s390x/insn-data.def @@ -617,6 +617,9 @@ C(0x9a00, LAM, RS_a, Z, 0, a2, 0, 0, lam, 0) C(0xeb9a, LAMY, RSY_a, LD, 0, a2, 0, 0, lam, 0) +/* MONITOR CALL */ + C(0xaf00, MC, SI, Z, la1, 0, 0, 0, mc, 0) + /* MOVE */ C(0xd200, MVC, SS_a, Z, la1, a2, 0, 0, mvc, 0) C(0xe544, MVHHI, SIL, GIE, la1, i2, 0, m1_16, mov2, 0) diff --git a/target/s390x/translate.c b/target/s390x/translate.c index a777343821..90dc1740e7 100644 --- a/target/s390x/translate.c +++ b/target/s390x/translate.c @@ -3302,6 +3302,27 @@ static DisasJumpType op_lcbb(DisasContext *s, DisasOps *o) return DISAS_NEXT; } +static DisasJumpType op_mc(DisasContext *s, DisasOps *o) +{ +#if !defined(CONFIG_USER_ONLY) + TCGv_i32 i2; +#endif + const uint16_t monitor_class = get_field(s, i2); + + if (monitor_class & 0xff00) { + gen_program_exception(s, PGM_SPECIFICATION); + return DISAS_NORETURN; + } + +#if !defined(CONFIG_USER_ONLY) + i2 = tcg_const_i32(monitor_class); + gen_helper_monitor_call(cpu_env, o->addr1, i2); + tcg_temp_free_i32(i2); +#endif + /* Defaults to a NOP. */ + return DISAS_NEXT; +} + static DisasJumpType op_mov2(DisasContext *s, DisasOps *o) { o->out = o->in2;
Recent upstream Linux uses the MONITOR CALL instruction for things like BUG_ON() and WARN_ON(). We currently inject an operation exception when we hit a MONITOR CALL instruction - which is wrong, as the instruction is not glued to specific CPU features. Doing a simple WARN_ON_ONCE() currently results in a panic: [ 18.162801] illegal operation: 0001 ilc:2 [#1] SMP [ 18.162889] Modules linked in: [...] [ 18.165476] Kernel panic - not syncing: Fatal exception: panic_on_oops With a proper implementation, we now get: [ 18.242754] ------------[ cut here ]------------ [ 18.242855] WARNING: CPU: 7 PID: 1 at init/main.c:1534 [...] [ 18.242919] Modules linked in: [...] [ 18.246262] ---[ end trace a420477d71dc97b4 ]--- [ 18.259014] Freeing unused kernel memory: 4220K Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- v1 -> v2: - Simplify by not using the tb flags, always calling the helper. I looked into monitor-event counting, which looks easy at first glance - but proper DAT/access exception handling is tricky. Leaving that for a cold winter evening :) --- target/s390x/excp_helper.c | 23 +++++++++++++++++++++++ target/s390x/helper.h | 1 + target/s390x/insn-data.def | 3 +++ target/s390x/translate.c | 21 +++++++++++++++++++++ 4 files changed, 48 insertions(+)