diff mbox series

[v3,1/2] target/s390x: Fix SIGILL psw.addr reporting

Message ID 20210602002210.3144559-2-iii@linux.ibm.com
State New
Headers show
Series target/s390x: Fix SIGILL psw.addr reporting | expand

Commit Message

Ilya Leoshkevich June 2, 2021, 12:22 a.m. UTC
When a s390x CPU attempts to execute an illegal instruction, an
operation exception is recognized. This is a suppressing exception,
which means that the PSW is advanced by the length of the illegal
instruction.

On the real hardware or in qemu-system-s390x the kernel then raises
SIGILL with si_addr pointing to the suppressed instruction and
psw.addr containing the updated PSW.

Unfortunately qemu-s390x sets both to the address of the suppressed
instruction at the moment. Fix by sharing the PSW advancement logic
with qemu-system-s390x and setting si_addr to the address of the
instruction that raised the exception.

Sharing the PSW advancement logic means, however, that now the helpers
and the CPU loop must follow the hardware and the kernel a little bit
more strictly. In particular:

* Unmapped memory accesses should result in a translation rather than
  in an addressing exception.
* Protection exception must rewind psw.addr.
* Translation exception must cause a SIGSEGV.

While at it, also fix the handling of addressing and privileged
operation exceptions.

Buglink: https://gitlab.com/qemu-project/qemu/-/issues/319
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 linux-user/s390x/cpu_loop.c | 23 ++++++++++--
 target/s390x/excp_helper.c  | 71 ++++++++++++++++++++-----------------
 target/s390x/internal.h     |  1 +
 target/s390x/mem_helper.c   |  2 +-
 4 files changed, 60 insertions(+), 37 deletions(-)
diff mbox series

Patch

diff --git a/linux-user/s390x/cpu_loop.c b/linux-user/s390x/cpu_loop.c
index f2d1215fb1..72ba9170ed 100644
--- a/linux-user/s390x/cpu_loop.c
+++ b/linux-user/s390x/cpu_loop.c
@@ -21,6 +21,7 @@ 
 #include "qemu-common.h"
 #include "qemu.h"
 #include "cpu_loop-common.h"
+#include "internal.h"
 
 /* s390x masks the fault address it reports in si_addr for SIGSEGV and SIGBUS */
 #define S390X_FAIL_ADDR_MASK -4096LL
@@ -29,6 +30,7 @@  void cpu_loop(CPUS390XState *env)
 {
     CPUState *cs = env_cpu(env);
     int trapnr, n, sig;
+    target_ulong excp_psw_addr;
     target_siginfo_t info;
     target_ulong addr;
     abi_long ret;
@@ -38,6 +40,7 @@  void cpu_loop(CPUS390XState *env)
         trapnr = cpu_exec(cs);
         cpu_exec_end(cs);
         process_queued_cpu_work(cs);
+        excp_psw_addr = env->psw.addr;
 
         switch (trapnr) {
         case EXCP_INTERRUPT:
@@ -66,15 +69,29 @@  void cpu_loop(CPUS390XState *env)
             n = TARGET_TRAP_BRKPT;
             goto do_signal_pc;
         case EXCP_PGM:
+            s390_cpu_program_interrupt_advance_psw(env);
             n = env->int_pgm_code;
             switch (n) {
             case PGM_OPERATION:
-            case PGM_PRIVILEGED:
                 sig = TARGET_SIGILL;
                 n = TARGET_ILL_ILLOPC;
                 goto do_signal_pc;
-            case PGM_PROTECTION:
+            case PGM_PRIVILEGED:
+                sig = TARGET_SIGILL;
+                n = TARGET_ILL_PRVOPC;
+                goto do_signal_pc;
             case PGM_ADDRESSING:
+                sig = TARGET_SIGILL;
+                n = TARGET_ILL_ILLADR;
+                goto do_signal_pc;
+            case PGM_PROTECTION:
+                /*
+                 * Protection exception handler is special: it is the only one
+                 * that rewinds psw.addr.
+                 */
+                env->psw.addr = excp_psw_addr;
+                /* FALL THROUGH */
+            case PGM_PAGE_TRANS:
                 sig = TARGET_SIGSEGV;
                 /* XXX: check env->error_code */
                 n = TARGET_SEGV_MAPERR;
@@ -131,7 +148,7 @@  void cpu_loop(CPUS390XState *env)
             break;
 
         do_signal_pc:
-            addr = env->psw.addr;
+            addr = excp_psw_addr;
         do_signal:
             info.si_signo = sig;
             info.si_errno = 0;
diff --git a/target/s390x/excp_helper.c b/target/s390x/excp_helper.c
index 20625c2c8f..4133e93978 100644
--- a/target/s390x/excp_helper.c
+++ b/target/s390x/excp_helper.c
@@ -82,6 +82,42 @@  void HELPER(data_exception)(CPUS390XState *env, uint32_t dxc)
     tcg_s390_data_exception(env, dxc, GETPC());
 }
 
+void s390_cpu_program_interrupt_advance_psw(CPUS390XState *env)
+{
+    switch (env->int_pgm_code) {
+    case PGM_PER:
+        if (env->per_perc_atmid & PER_CODE_EVENT_NULLIFICATION) {
+            break;
+        }
+        /* FALL THROUGH */
+    case PGM_OPERATION:
+    case PGM_PRIVILEGED:
+    case PGM_EXECUTE:
+    case PGM_PROTECTION:
+    case PGM_ADDRESSING:
+    case PGM_SPECIFICATION:
+    case PGM_DATA:
+    case PGM_FIXPT_OVERFLOW:
+    case PGM_FIXPT_DIVIDE:
+    case PGM_DEC_OVERFLOW:
+    case PGM_DEC_DIVIDE:
+    case PGM_HFP_EXP_OVERFLOW:
+    case PGM_HFP_EXP_UNDERFLOW:
+    case PGM_HFP_SIGNIFICANCE:
+    case PGM_HFP_DIVIDE:
+    case PGM_TRANS_SPEC:
+    case PGM_SPECIAL_OP:
+    case PGM_OPERAND:
+    case PGM_HFP_SQRT:
+    case PGM_PC_TRANS_SPEC:
+    case PGM_ALET_SPEC:
+    case PGM_MONITOR:
+        /* advance the PSW if our exception is not nullifying */
+        env->psw.addr += env->int_pgm_ilen;
+        break;
+    }
+}
+
 #if defined(CONFIG_USER_ONLY)
 
 void s390_cpu_do_interrupt(CPUState *cs)
@@ -95,7 +131,7 @@  bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
 {
     S390CPU *cpu = S390_CPU(cs);
 
-    trigger_pgm_exception(&cpu->env, PGM_ADDRESSING);
+    trigger_pgm_exception(&cpu->env, PGM_PAGE_TRANS);
     /* On real machines this value is dropped into LowMem.  Since this
        is userland, simply put this someplace that cpu_loop can find it.  */
     cpu->env.__excp_addr = address;
@@ -202,38 +238,7 @@  static void do_program_interrupt(CPUS390XState *env)
 
     assert(ilen == 2 || ilen == 4 || ilen == 6);
 
-    switch (env->int_pgm_code) {
-    case PGM_PER:
-        if (env->per_perc_atmid & PER_CODE_EVENT_NULLIFICATION) {
-            break;
-        }
-        /* FALL THROUGH */
-    case PGM_OPERATION:
-    case PGM_PRIVILEGED:
-    case PGM_EXECUTE:
-    case PGM_PROTECTION:
-    case PGM_ADDRESSING:
-    case PGM_SPECIFICATION:
-    case PGM_DATA:
-    case PGM_FIXPT_OVERFLOW:
-    case PGM_FIXPT_DIVIDE:
-    case PGM_DEC_OVERFLOW:
-    case PGM_DEC_DIVIDE:
-    case PGM_HFP_EXP_OVERFLOW:
-    case PGM_HFP_EXP_UNDERFLOW:
-    case PGM_HFP_SIGNIFICANCE:
-    case PGM_HFP_DIVIDE:
-    case PGM_TRANS_SPEC:
-    case PGM_SPECIAL_OP:
-    case PGM_OPERAND:
-    case PGM_HFP_SQRT:
-    case PGM_PC_TRANS_SPEC:
-    case PGM_ALET_SPEC:
-    case PGM_MONITOR:
-        /* advance the PSW if our exception is not nullifying */
-        env->psw.addr += ilen;
-        break;
-    }
+    s390_cpu_program_interrupt_advance_psw(env);
 
     qemu_log_mask(CPU_LOG_INT,
                   "%s: code=0x%x ilen=%d psw: %" PRIx64 " %" PRIx64 "\n",
diff --git a/target/s390x/internal.h b/target/s390x/internal.h
index 11515bb617..9f1665ccbf 100644
--- a/target/s390x/internal.h
+++ b/target/s390x/internal.h
@@ -272,6 +272,7 @@  bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
 void s390x_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
                                    MMUAccessType access_type,
                                    int mmu_idx, uintptr_t retaddr);
+void s390_cpu_program_interrupt_advance_psw(CPUS390XState *cpu);
 
 
 /* fpu_helper.c */
diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index f6a7d29273..dff19cba60 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -147,7 +147,7 @@  static int s390_probe_access(CPUArchState *env, target_ulong addr, int size,
     flags = page_get_flags(addr);
     if (!(flags & (access_type == MMU_DATA_LOAD ?  PAGE_READ : PAGE_WRITE_ORG))) {
         env->__excp_addr = addr;
-        flags = (flags & PAGE_VALID) ? PGM_PROTECTION : PGM_ADDRESSING;
+        flags = (flags & PAGE_VALID) ? PGM_PROTECTION : PGM_PAGE_TRANS;
         if (nonfault) {
             return flags;
         }