target/s390x: Implement s390_cpu_record_sigsegv

Move the masking of the address from cpu_loop into
s390_cpu_record_sigsegv -- this is governed by hw, not linux.
This does mean we have to raise our own exception, rather
than return to the fallback.

Use maperr to choose between PGM_PROTECTION and PGM_ADDRESSING.
Use the appropriate si_code for each in cpu_loop.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

linux-user/s390x/cpu_loop.c

@@ -24,8 +24,6 @@
 #include "cpu_loop-common.h"
 #include "signal-common.h"
 
-/* s390x masks the fault address it reports in si_addr for SIGSEGV and SIGBUS */
-#define S390X_FAIL_ADDR_MASK -4096LL
 
 static int get_pgm_data_si_code(int dxc_code)
 {
@@ -111,12 +109,13 @@ void cpu_loop(CPUS390XState *env)
                 n = TARGET_ILL_ILLOPC;
                 goto do_signal_pc;
             case PGM_PROTECTION:
+                force_sig_fault(TARGET_SIGSEGV, TARGET_SEGV_ACCERR,
+                                env->__excp_addr);
+                break;
             case PGM_ADDRESSING:
-                sig = TARGET_SIGSEGV;
+                force_sig_fault(TARGET_SIGSEGV, TARGET_SEGV_MAPERR,
-                /* XXX: check env->error_code */
+                                env->__excp_addr);
-                n = TARGET_SEGV_MAPERR;
+                break;
-                addr = env->__excp_addr & S390X_FAIL_ADDR_MASK;
-                goto do_signal;
             case PGM_EXECUTE:
             case PGM_SPECIFICATION:
             case PGM_SPECIAL_OP:

target/s390x/cpu.c

@@ -266,9 +266,11 @@ static void s390_cpu_reset_full(DeviceState *dev)
 
 static const struct TCGCPUOps s390_tcg_ops = {
     .initialize = s390x_translate_init,
-    .tlb_fill = s390_cpu_tlb_fill,
 
-#if !defined(CONFIG_USER_ONLY)
+#ifdef CONFIG_USER_ONLY
+    .record_sigsegv = s390_cpu_record_sigsegv,
+#else
+    .tlb_fill = s390_cpu_tlb_fill,
     .cpu_exec_interrupt = s390_cpu_exec_interrupt,
     .do_interrupt = s390_cpu_do_interrupt,
     .debug_excp_handler = s390x_cpu_debug_excp_handler,

target/s390x/s390x-internal.h

@@ -270,13 +270,20 @@ ObjectClass *s390_cpu_class_by_name(const char *name);
 void s390x_cpu_debug_excp_handler(CPUState *cs);
 void s390_cpu_do_interrupt(CPUState *cpu);
 bool s390_cpu_exec_interrupt(CPUState *cpu, int int_req);
-bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
-                       MMUAccessType access_type, int mmu_idx,
-                       bool probe, uintptr_t retaddr);
 void s390x_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
                                    MMUAccessType access_type, int mmu_idx,
                                    uintptr_t retaddr) QEMU_NORETURN;
 
+#ifdef CONFIG_USER_ONLY
+void s390_cpu_record_sigsegv(CPUState *cs, vaddr address,
+                             MMUAccessType access_type,
+                             bool maperr, uintptr_t retaddr);
+#else
+bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
+                       MMUAccessType access_type, int mmu_idx,
+                       bool probe, uintptr_t retaddr);
+#endif
+
 
 /* fpu_helper.c */
 uint32_t set_cc_nz_f32(float32 v);

target/s390x/tcg/excp_helper.c

@@ -89,16 +89,20 @@ void s390_cpu_do_interrupt(CPUState *cs)
     cs->exception_index = -1;
 }
 
-bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
+void s390_cpu_record_sigsegv(CPUState *cs, vaddr address,
-                       MMUAccessType access_type, int mmu_idx,
+                             MMUAccessType access_type,
-                       bool probe, uintptr_t retaddr)
+                             bool maperr, uintptr_t retaddr)
 {
     S390CPU *cpu = S390_CPU(cs);
 
-    trigger_pgm_exception(&cpu->env, PGM_ADDRESSING);
+    trigger_pgm_exception(&cpu->env, maperr ? PGM_ADDRESSING : PGM_PROTECTION);
-    /* On real machines this value is dropped into LowMem.  Since this
+    /*
-       is userland, simply put this someplace that cpu_loop can find it.  */
+     * On real machines this value is dropped into LowMem. Since this
-    cpu->env.__excp_addr = address;
+     * is userland, simply put this someplace that cpu_loop can find it.
+     * S390 only gives the page of the fault, not the exact address.
+     * C.f. the construction of TEC in mmu_translate().
+     */
+    cpu->env.__excp_addr = address & TARGET_PAGE_MASK;
     cpu_loop_exit_restore(cs, retaddr);
 }