Note that we have been passing the incorrect code for most
exception codes: uncategorized (do_el0_undef),
systemregistertrap (do_el0_sys), smetrap (do_sme_acc),
btitrap (do_el0_bti) and illegalstate (bad_el0_sync).
Only pacfail uses ILL_ILLOPN (do_el0_fpac).

Note that EC_MOP (do_el0_mops) ought not signal at all.
For now, preserve existing behavior signalling ILL_ILLOPN.

List all other exception codes and document why they do
not apply to user-only.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/aarch64/cpu_loop.c | 75 ++++++++++++++++++++++++++++++++++-
 1 file changed, 74 insertions(+), 1 deletion(-)

diff --git a/linux-user/aarch64/cpu_loop.c b/linux-user/aarch64/cpu_loop.c
index 3b2782581b..7ad26316de 100644
--- a/linux-user/aarch64/cpu_loop.c
+++ b/linux-user/aarch64/cpu_loop.c
@@ -65,6 +65,79 @@ static void signal_for_exception(CPUARMState *env, vaddr addr)
         si_code = TARGET_BUS_ADRALN;
         break;
 
+    case EC_UNCATEGORIZED:         /* E.g. undefined instruction */
+    case EC_SYSTEMREGISTERTRAP:    /* E.g. inaccessible register */
+    case EC_SMETRAP:               /* E.g. invalid insn in streaming state */
+    case EC_BTITRAP:               /* E.g. invalid guarded branch target */
+    case EC_ILLEGALSTATE:
+        /*
+         * Illegal state happens via an ERET from a privileged mode,
+         * so is not normally possible from user-only.  However, gdbstub
+         * is not prevented from writing CPSR_IL, aka PSTATE.IL, which
+         * would generate a trap from the next translated block.
+         * In the kernel, default case -> el0_inv -> bad_el0_sync.
+         */
+        si_signo = TARGET_SIGILL;
+        si_code = TARGET_ILL_ILLOPC;
+        break;
+
+    case EC_PACFAIL:
+        si_signo = TARGET_SIGILL;
+        si_code = TARGET_ILL_ILLOPN;
+        break;
+
+    case EC_MOP:
+        /*
+         * FIXME: The kernel fixes up wrong-option exceptions.
+         * For QEMU linux-user mode, you can only get these if
+         * the process is doing something silly (not executing
+         * the MOPS instructions in the required P/M/E sequence),
+         * so it is not a problem in practice that we do not.
+         *
+         * We ought ideally to implement the same "rewind to the
+         * start of the sequence" logic that the kernel does in
+         * arm64_mops_reset_regs(). In the meantime, deliver
+         * the guest a SIGILL, with the same ILLOPN si_code
+         * we've always used for this.
+         */
+        si_signo = TARGET_SIGILL;
+        si_code = TARGET_ILL_ILLOPN;
+        break;
+
+    case EC_WFX_TRAP:              /* user-only WFI implemented as NOP */
+    case EC_CP15RTTRAP:            /* AArch32 */
+    case EC_CP15RRTTRAP:           /* AArch32 */
+    case EC_CP14RTTRAP:            /* AArch32 */
+    case EC_CP14DTTRAP:            /* AArch32 */
+    case EC_ADVSIMDFPACCESSTRAP:   /* user-only does not disable fpu */
+    case EC_FPIDTRAP:              /* AArch32 */
+    case EC_PACTRAP:               /* user-only does not disable pac regs */
+    case EC_BXJTRAP:               /* AArch32 */
+    case EC_CP14RRTTRAP:           /* AArch32 */
+    case EC_AA32_SVC:              /* AArch32 */
+    case EC_AA32_HVC:              /* AArch32 */
+    case EC_AA32_SMC:              /* AArch32 */
+    case EC_AA64_SVC:              /* generates EXCP_SWI */
+    case EC_AA64_HVC:              /* user-only generates EC_UNCATEGORIZED */
+    case EC_AA64_SMC:              /* user-only generates EC_UNCATEGORIZED */
+    case EC_SVEACCESSTRAP:         /* user-only does not disable sve */
+    case EC_ERETTRAP:              /* user-only generates EC_UNCATEGORIZED */
+    case EC_GPC:                   /* user-only has no EL3 gpc tables */
+    case EC_INSNABORT_SAME_EL:     /* el0 cannot trap to el0 */
+    case EC_DATAABORT_SAME_EL:     /* el0 cannot trap to el0 */
+    case EC_SPALIGNMENT:           /* sp alignment checks not implemented */
+    case EC_AA32_FPTRAP:           /* fp exceptions not implemented */
+    case EC_AA64_FPTRAP:           /* fp exceptions not implemented */
+    case EC_SERROR:                /* user-only does not have hw faults */
+    case EC_BREAKPOINT:            /* user-only does not have hw debug */
+    case EC_BREAKPOINT_SAME_EL:    /* user-only does not have hw debug */
+    case EC_SOFTWARESTEP:          /* user-only does not have hw debug */
+    case EC_SOFTWARESTEP_SAME_EL:  /* user-only does not have hw debug */
+    case EC_WATCHPOINT:            /* user-only does not have hw debug */
+    case EC_WATCHPOINT_SAME_EL:    /* user-only does not have hw debug */
+    case EC_AA32_BKPT:             /* AArch32 */
+    case EC_VECTORCATCH:           /* AArch32 */
+    case EC_AA64_BKPT:             /* generates EXCP_BKPT */
     default:
         g_assert_not_reached();
     }
@@ -108,7 +181,7 @@ void cpu_loop(CPUARMState *env)
             /* just indicate that signals should be handled asap */
             break;
         case EXCP_UDEF:
-            force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLOPN, env->pc);
+            signal_for_exception(env, env->pc);
             break;
         case EXCP_PREFETCH_ABORT:
         case EXCP_DATA_ABORT:
-- 
2.43.0