From: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx> In most testcases, we enter problem state (userspace) just to test if a privileged instruction causes a fault. In some cases, though, we need to test if an instruction works properly in userspace. This means that we do not expect a fault, and we need an orderly way to leave problem state afterwards. This patch introduces a simple system based on the SVC instruction. Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx> Link: https://lore.kernel.org/kvm/20210302114107.501837-2-imbrenda@xxxxxxxxxxxxx/ Acked-by: David Hildenbrand <david@xxxxxxxxxx> Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx> Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx> Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx> --- lib/s390x/asm/arch_def.h | 7 +++++++ lib/s390x/interrupt.c | 12 ++++++++++-- 2 files changed, 17 insertions(+), 2 deletions(-) diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h index 76cb7b33..7e2c5e62 100644 --- a/lib/s390x/asm/arch_def.h +++ b/lib/s390x/asm/arch_def.h @@ -190,6 +190,8 @@ struct cpuid { uint64_t reserved : 15; }; +#define SVC_LEAVE_PSTATE 1 + static inline unsigned short stap(void) { unsigned short cpu_address; @@ -293,6 +295,11 @@ static inline void enter_pstate(void) load_psw_mask(mask); } +static inline void leave_pstate(void) +{ + asm volatile(" svc %0\n" : : "i" (SVC_LEAVE_PSTATE)); +} + static inline int stsi(void *addr, int fc, int sel1, int sel2) { register int r0 asm("0") = (fc << 28) | sel1; diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c index d9832bc0..ce0003de 100644 --- a/lib/s390x/interrupt.c +++ b/lib/s390x/interrupt.c @@ -223,6 +223,14 @@ int unregister_io_int_func(void (*f)(void)) void handle_svc_int(void) { - report_abort("Unexpected supervisor call interrupt: on cpu %d at %#lx", - stap(), lc->svc_old_psw.addr); + uint16_t code = lc->svc_int_code; + + switch (code) { + case SVC_LEAVE_PSTATE: + lc->svc_old_psw.mask &= ~PSW_MASK_PSTATE; + break; + default: + report_abort("Unexpected supervisor call interrupt: code %#x on cpu %d at %#lx", + code, stap(), lc->svc_old_psw.addr); + } } -- 2.29.2
