thermosphere: trap refactor WIP

thermosphere/src/cpu/hvisor_cpu_exception_sysregs.hpp

@@ -101,7 +101,7 @@ namespace ams::hvisor::cpu {
 
         constexpr bool HasValidFar()
         {
-            return isv && fnv;
+            return isv && !fnv;
         }
         constexpr size_t GetAccessSize()
         {

thermosphere/src/data_abort.c

@@ -1,68 +0,0 @@
-/*
- * Copyright (c) 2019 Atmosphère-NX
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include <string.h>
-#include <stdio.h>
-#include "data_abort.h"
-#include "sysreg.h"
-#include "debug_log.h"
-#include "irq.h"
-#include "vgic.h"
-
-// Lower el
-
-void dumpUnhandledDataAbort(DataAbortIss dabtIss, u64 far, const char *msg)
-{
-    char s1[64], s2[32], s3[64] = "";
-    (void)s1; (void)s2; (void)s3;
-    sprintf(s1, "Unhandled%s %s", msg , dabtIss.wnr ? "write" : "read");
-    if (dabtIss.fnv) {
-        sprintf(s2, "<unk>");
-    } else {
-        sprintf(s2, "%016lx", far);
-    }
-
-    if (dabtIss.isv) {
-        sprintf(s3, ", size %u Rt=%u", BIT(dabtIss.sas), dabtIss.srt);
-    }
-
-    DEBUG("%s at %s%s\n", s1, s2, s3);
-}
-
-void handleLowerElDataAbortException(ExceptionStackFrame *frame, ExceptionSyndromeRegister esr)
-{
-    DataAbortIss dabtIss;
-    u32 iss = esr.iss;
-    memcpy(&dabtIss, &iss, 4);
-
-    u64 far = GET_SYSREG(far_el2);
-    u64 farpg = far & ~0xFFFull;
-
-    if (!dabtIss.isv || dabtIss.fnv) {
-        dumpUnhandledDataAbort(dabtIss, far, "");
-    }
-
-    if (farpg == MEMORY_MAP_PA_GICD) {
-        handleVgicdMmio(frame, dabtIss, far & 0xFFF);
-    } else if (farpg == MEMORY_MAP_PA_GICH) {
-        dumpUnhandledDataAbort(dabtIss, far, " GICH");
-    } else {
-        dumpUnhandledDataAbort(dabtIss, far, "");
-    }
-
-    // Skip instruction anyway
-    skipFaultingInstruction(frame, esr.il == 0 ? 2 : 4);
-}

thermosphere/src/data_abort.h

@@ -1,42 +0,0 @@
-/*
- * Copyright (c) 2019 Atmosphère-NX
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#pragma once
-
-#include "exceptions.h"
-
-typedef struct DataAbortIss {
-    u32 dfsc        : 6; // Fault status code
-
-    u32 wnr         : 1; // Write, not Read
-    u32 s1ptw       : 1; // Stage1 page table walk fault
-    u32 cm          : 1; // Cache maintenance
-    u32 ea          : 1; // External abort
-    u32 fnv         : 1; // FAR not Valid
-    u32 set         : 2; // Synchronous error type
-    u32 vncr        : 1; // vncr_el2 trap
-
-    u32 ar          : 1; // Acquire/release. Bit 14
-    u32 sf          : 1; // 64-bit register used
-    u32 srt         : 5; // Syndrome register transfer (register used)
-    u32 sse         : 1; // Syndrome sign extend
-    u32 sas         : 2; // Syndrome access size. Bit 23
-
-    u32 isv         : 1; // Instruction syndrome valid (ISS[23:14] valid)
-} DataAbortIss;
-
-void dumpUnhandledDataAbort(DataAbortIss dabtIss, u64 far, const char *msg);
-void handleLowerElDataAbortException(ExceptionStackFrame *frame, ExceptionSyndromeRegister esr);

thermosphere/src/hvisor_exception_dispatcher.cpp

@@ -21,51 +21,6 @@
 
 #include "debug_manager.h"
 
-namespace {
-
-    void DumpStackFrame(const ams::hvisor::ExceptionStackFrame *frame, bool sameEl)
-    {
-#ifndef NDEBUG
-        uintptr_t stackTop = memoryMapGetStackTop(ams::hvisor::currentCoreCtx->GetCoreId());
-
-        for (u32 i = 0; i < 30; i += 2) {
-            DEBUG("x%u\t\t%016llx\t\tx%u\t\t%016llx\n", i, frame->x[i], i + 1, frame->x[i + 1]);
-        }
-
-        DEBUG("x30\t\t%016llx\n\n", frame->x[30]);
-        DEBUG("elr_el2\t\t%016llx\n", frame->elr_el2);
-        DEBUG("spsr_el2\t%016llx\n", frame->spsr_el2);
-        DEBUG("far_el2\t\t%016llx\n", frame->far_el2);
-        if (sameEl) {
-            DEBUG("sp_el2\t\t%016llx\n", frame->sp_el2);
-        } else {
-            DEBUG("sp_el1\t\t%016llx\n", frame->sp_el1);
-        }
-        DEBUG("sp_el0\t\t%016llx\n", frame->sp_el0);
-        DEBUG("cntpct_el0\t%016llx\n", frame->cntpct_el0);
-        if (frame == ams::hvisor::currentCoreCtx->GetGuestFrame()) {
-            DEBUG("cntp_ctl_el0\t%016llx\n", frame->cntp_ctl_el0);
-            DEBUG("cntv_ctl_el0\t%016llx\n", frame->cntv_ctl_el0);
-        } else if ((frame->sp_el2 & ~0xFFFul) + 0x1000 == stackTop) {
-            // Try to dump the stack (comment if this crashes)
-            u64 *sp = (u64 *)frame->sp_el2;
-            u64 *spEnd = sp + 0x20;
-            u64 *spMax = reinterpret_cast<u64 *>((frame->sp_el2 + 0xFFF) & ~0xFFFul);
-            DEBUG("Stack trace:\n");
-            while (sp < spEnd && sp < spMax) {
-                DEBUG("\t%016lx\n", *sp++);
-            }
-        } else {
-            DEBUG("Stack overflow/double fault detected!\n");
-        }
-#else
-        (void)frame;
-        (void)sameEl;
-#endif
-    }
-
-}
-
 namespace ams::hvisor {
 
     void EnableGeneralTraps(void)
@@ -89,6 +44,47 @@ namespace ams::hvisor {
         EnableGuestTimerTraps();
     }
 
+void DumpStackFrame(ExceptionStackFrame *frame, bool sameEl)
+    {
+#ifndef NDEBUG
+        uintptr_t stackTop = memoryMapGetStackTop(currentCoreCtx->GetCoreId());
+
+        for (u32 i = 0; i < 30; i += 2) {
+            DEBUG("x%u\t\t%016llx\t\tx%u\t\t%016llx\n", i, frame->x[i], i + 1, frame->x[i + 1]);
+        }
+
+        DEBUG("x30\t\t%016llx\n\n", frame->x[30]);
+        DEBUG("elr_el2\t\t%016llx\n", frame->elr_el2);
+        DEBUG("spsr_el2\t%016llx\n", frame->spsr_el2);
+        DEBUG("far_el2\t\t%016llx\n", frame->far_el2);
+        if (sameEl) {
+            DEBUG("sp_el2\t\t%016llx\n", frame->sp_el2);
+        } else {
+            DEBUG("sp_el1\t\t%016llx\n", frame->sp_el1);
+        }
+        DEBUG("sp_el0\t\t%016llx\n", frame->sp_el0);
+        DEBUG("cntpct_el0\t%016llx\n", frame->cntpct_el0);
+        if (frame == currentCoreCtx->GetGuestFrame()) {
+            DEBUG("cntp_ctl_el0\t%016llx\n", frame->cntp_ctl_el0);
+            DEBUG("cntv_ctl_el0\t%016llx\n", frame->cntv_ctl_el0);
+        } else if ((frame->sp_el2 & ~0xFFFul) + 0x1000 == stackTop) {
+            // Try to dump the stack (comment if this crashes)
+            u64 *sp = (u64 *)frame->sp_el2;
+            u64 *spEnd = sp + 0x20;
+            u64 *spMax = reinterpret_cast<u64 *>((frame->sp_el2 + 0xFFF) & ~0xFFFul);
+            DEBUG("Stack trace:\n");
+            while (sp < spEnd && sp < spMax) {
+                DEBUG("\t%016lx\n", *sp++);
+            }
+        } else {
+            DEBUG("Stack overflow/double fault detected!\n");
+        }
+#else
+        (void)frame;
+        (void)sameEl;
+#endif
+    }
+
     void ExceptionEntryPostprocess(ExceptionStackFrame *frame, bool isLowerEl)
     {
         if (frame == currentCoreCtx->GetGuestFrame()) {

thermosphere/src/hvisor_exception_dispatcher.hpp

@@ -23,6 +23,8 @@ namespace ams::hvisor {
 
     void EnableGeneralTraps(void);
 
+    void DumpStackFrame(const ExceptionStackFrame *frame, bool sameEl);
+
     // Called on exception entry (avoids overflowing a vector section)
     void ExceptionEntryPostprocess(ExceptionStackFrame *frame, bool isLowerEl);
 

thermosphere/src/hvisor_virtual_gic.hpp

@@ -369,6 +369,9 @@ namespace ams::hvisor {
             private:
                 constexpr VirtualGic() = default;
 
+            public:
+                // For convenience (when trapping lower-el data aborts):
+                static constexpr uintptr_t gicdPhysicalAddress = 0; // fixme pls MEMORY_MAP_PA_GICD;
             public:
                 static bool ValidateGicdRegisterAccess(size_t offset, size_t sz);
             public:

thermosphere/src/single_step.c

@@ -1,78 +0,0 @@
-/*
- * Copyright (c) 2019 Atmosphère-NX
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include "single_step.h"
-#include "core_ctx.h"
-#include "sysreg.h"
-#include "debug_manager.h"
-
-SingleStepState singleStepGetNextState(ExceptionStackFrame *frame)
-{
-    u64 mdscr = GET_SYSREG(mdscr_el1);
-    bool mdscrSS = (mdscr & MDSCR_SS) != 0;
-    bool pstateSS = (frame->spsr_el2 & PSTATE_SS) != 0;
-
-    if (!mdscrSS) {
-        return SingleStepState_Inactive;
-    } else {
-        return pstateSS ? SingleStepState_ActiveNotPending : SingleStepState_ActivePending;
-    }
-}
-
-void singleStepSetNextState(ExceptionStackFrame *frame, SingleStepState state)
-{
-    u64 mdscr = GET_SYSREG(mdscr_el1);
-
-    switch (state) {
-        case SingleStepState_Inactive:
-            // Unset mdscr_el1.ss
-            mdscr &= ~MDSCR_SS;
-            break;
-        case SingleStepState_ActiveNotPending:
-            // Set mdscr_el1.ss and pstate.ss
-            mdscr |= MDSCR_SS;
-            frame->spsr_el2 |= PSTATE_SS;
-            break;
-        case SingleStepState_ActivePending:
-            // We never use this because pstate.ss is 0 by default...
-            // Set mdscr_el1.ss and unset pstate.ss
-            mdscr |= MDSCR_SS;
-            frame->spsr_el2 &= ~PSTATE_SS;
-            break;
-        default:
-            break;
-    }
-
-    SET_SYSREG(mdscr_el1, mdscr);
-    __isb(); // TRM-mandated
-}
-
-void handleSingleStep(ExceptionStackFrame *frame, ExceptionSyndromeRegister esr)
-{
-    uintptr_t addr = frame->elr_el2;
-
-    // Stepping range support;
-    if (addr >= currentCoreCtx->steppingRangeStartAddr && addr < currentCoreCtx->steppingRangeEndAddr) {
-        // Reactivate single-step
-        singleStepSetNextState(frame, SingleStepState_ActiveNotPending);
-    } else {
-        // Disable single-step
-        singleStepSetNextState(frame, SingleStepState_Inactive);
-        debugManagerReportEvent(DBGEVENT_EXCEPTION);
-    }
-
-    DEBUG("Single-step exeception ELR = 0x%016llx, ISV = %u, EX = %u\n", frame->elr_el2, (esr.iss >> 24) & 1, (esr.iss >> 6) & 1);
-}

thermosphere/src/single_step.h

@@ -1,34 +0,0 @@
-/*
- * Copyright (c) 2019 Atmosphère-NX
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#pragma once
-
-#include "utils.h"
-#include "exceptions.h"
-
-typedef enum SingleStepState {
-    SingleStepState_Inactive            = 0, // Single step disabled OR in the debugger
-    SingleStepState_ActiveNotPending    = 1, // Instruction not yet executed
-    SingleStepState_ActivePending       = 2, // Instruction executed or return-from-trap, single-step exception is going to be generated soon
-} SingleStepState;
-
-/// Get the single-step state machine state (state after eret)
-SingleStepState singleStepGetNextState(ExceptionStackFrame *frame);
-
-/// Set the single-step state machine state (state after eret). Frame can be NULL iff new state is "inactive"
-void singleStepSetNextState(ExceptionStackFrame *frame, SingleStepState state);
-
-void handleSingleStep(ExceptionStackFrame *frame, ExceptionSyndromeRegister esr);

thermosphere/src/traps/hvisor_traps_data_abort.cpp

@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2019-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "hvisor_traps_data_abort.hpp"
+
+#include "../hvisor_virtual_gic.hpp"
+
+/*
+#include "../hvisor_core_context.hpp"
+#include "../cpu/hvisor_cpu_sysreg_general.hpp"
+#include "../cpu/hvisor_cpu_instructions.hpp"
+*/
+
+// Lower el
+
+namespace ams::hvisor::traps {
+
+    void DumpUnhandledDataAbort(cpu::DataAbortIss dabtIss, u64 far, const char *msg)
+    {
+        char s1[64], s2[32], s3[64] = "";
+        static_cast<void>(s1);
+        static_cast<void>(s2);
+        static_cast<void>(s3);
+        sprintf(s1, "Unhandled%s %s", msg , dabtIss.wnr ? "write" : "read");
+        if (dabtIss.fnv) {
+            sprintf(s2, "<unk>");
+        } else {
+            sprintf(s2, "%016lx", far);
+        }
+
+        if (dabtIss.isv) {
+            sprintf(s3, ", size %u Rt=%u", BIT(dabtIss.sas), dabtIss.srt);
+        }
+
+        DEBUG("%s at %s%s\n", s1, s2, s3);
+    }
+
+    void HandleLowerElDataAbortException(ExceptionStackFrame *frame, cpu::ExceptionSyndromeRegister esr)
+    {
+        cpu::DataAbortIss dabtIss;
+        u32 iss = esr.iss;
+        std::memcpy(&iss, &dabtIss, 4);
+
+        u64 far = frame->far_el2;
+        u64 farpg = far & ~0xFFFull;
+        size_t off = far & 0xFFF;
+        size_t sz = dabtIss.GetAccessSize();
+
+        // We don't support 8-byte writes for MMIO
+        if (!dabtIss.HasValidFar() || sz > 4) {
+            DumpUnhandledDataAbort(dabtIss, far, "");
+        }
+
+        if (farpg == VirtualGic::gicdPhysicalAddress) {
+            if (VirtualGic::ValidateGicdRegisterAccess(off, sz)) {
+                if (dabtIss.wnr) {
+                    // Register write
+                    u32 reg = frame->ReadFrameRegister<u32>(dabtIss.srt);
+                    VirtualGic::GetInstance().WriteGicdRegister(reg, off, sz);
+                } else {
+                    // Reigster read
+                    frame->WriteFrameRegister(dabtIss.srt, VirtualGic::GetInstance().ReadGicdRegister(off, sz));
+                }
+            } else {
+                // Invalid GICD access
+                DumpUnhandledDataAbort(dabtIss, far, "GICD");
+            }
+        } else {
+            DumpUnhandledDataAbort(dabtIss, far, "");
+        }
+
+        // Skip instruction anyway
+        frame->SkipInstruction(esr.il == 0 ? 2 : 4);
+    }
+
+}

thermosphere/src/traps/hvisor_traps_data_abort.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019 Atmosphère-NX
+ * Copyright (c) 2019-2020 Atmosphère-NX
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -14,16 +14,13 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "hvc.h"
+#pragma once
-#include "debug_log.h"
 
-void handleHypercall(ExceptionStackFrame *frame, ExceptionSyndromeRegister esr)
+#include "../hvisor_exception_stack_frame.hpp"
-{
+
-    u32 id = esr.iss;
+namespace ams::hvisor::traps {
-    switch (id) {
+
-        default:
+    void DumpUnhandledDataAbort(cpu::DataAbortIss dabtIss, u64 far, const char *msg);
-            DEBUG("Unhandled hypercall: 0x%x.\n");
+    void HandleLowerElDataAbort(ExceptionStackFrame *frame, cpu::ExceptionSyndromeRegister esr);
-            dumpStackFrame(frame, false);
+
-            break;
+}
-    }
-}

thermosphere/src/traps/hvisor_traps_hvc.cpp

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2019-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "hvisor_traps_hvc.hpp"
+#include "../hvisor_exception_dispatcher.hpp"
+
+namespace ams::hvisor::traps {
+
+    void HandleHypercall(ExceptionStackFrame *frame, cpu::ExceptionSyndromeRegister esr)
+    {
+        u32 id = esr.iss;
+        switch (id) {
+            default:
+                DEBUG("Unhandled hypercall: 0x%x.\n");
+                DumpStackFrame(frame, false);
+                break;
+        }
+    }
+
+}

thermosphere/src/traps/hvisor_traps_hvc.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019 Atmosphère-NX
+ * Copyright (c) 2019-2020 Atmosphère-NX
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -15,6 +15,11 @@
  */
 
 #pragma once
-#include "exceptions.h"
 
-void handleHypercall(ExceptionStackFrame *frame, ExceptionSyndromeRegister esr);
+#include "../hvisor_exception_stack_frame.hpp"
+
+namespace ams::hvisor::traps {
+
+    void HandleHypercall(ExceptionStackFrame *frame, cpu::ExceptionSyndromeRegister esr);
+
+}

thermosphere/src/traps/hvisor_traps_single_step.cpp

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2019-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "hvisor_traps_single_step.hpp"
+
+#include "../hvisor_core_context.hpp"
+#include "../cpu/hvisor_cpu_sysreg_general.hpp"
+#include "../cpu/hvisor_cpu_instructions.hpp"
+
+#include "../debug_manager.h"
+
+namespace ams::hvisor::traps {
+
+    SingleStepState GetNextSingleStepState(ExceptionStackFrame *frame)
+    {
+        u64 mdscr = THERMOSPHERE_GET_SYSREG(mdscr_el1);
+        bool mdscrSS = (mdscr & cpu::MDSCR_SS) != 0;
+        bool pstateSS = (frame->spsr_el2 & cpu::PSR_SS) != 0;
+
+        if (!mdscrSS) {
+            return SingleStepState::Inactive;
+        } else {
+            return pstateSS ? SingleStepState::ActiveNotPending : SingleStepState::ActivePending;
+        }
+
+    }
+
+    void SetNextSingleStepState(ExceptionStackFrame *frame, SingleStepState state)
+    {
+        u64 mdscr = THERMOSPHERE_GET_SYSREG(mdscr_el1);
+
+        switch (state) {
+            case SingleStepState::Inactive:
+                // Unset mdscr_el1.ss
+                mdscr &= ~cpu::MDSCR_SS;
+                break;
+            case SingleStepState::ActiveNotPending:
+                // Set mdscr_el1.ss and pstate.ss
+                mdscr |= cpu::MDSCR_SS;
+                frame->spsr_el2 |= cpu::PSR_SS;
+                break;
+            case SingleStepState::ActivePending:
+                // We never use this because pstate.ss is 0 by default...
+                // Set mdscr_el1.ss and unset pstate.ss
+                mdscr |= cpu::MDSCR_SS;
+                frame->spsr_el2 &= cpu::PSR_SS;
+                break;
+            default:
+                break;
+        }
+
+        THERMOSPHERE_SET_SYSREG(mdscr_el1, mdscr);
+        cpu::isb(); // TRM-mandated
+    }
+
+    void HandleSingleStep(ExceptionStackFrame *frame, cpu::ExceptionSyndromeRegister esr)
+    {
+        uintptr_t addr = frame->elr_el2;
+
+        // Stepping range support;
+        auto [startAddr, endAddr] = currentCoreCtx->GetSteppingRange();
+        if (addr >= startAddr && addr < endAddr) {
+            // Reactivate single-step
+            SetNextSingleStepState(frame, SingleStepState::ActiveNotPending);
+        } else {
+            // Disable single-step
+            SetNextSingleStepState(frame, SingleStepState::Inactive);
+            debugManagerReportEvent(DBGEVENT_EXCEPTION);
+        }
+
+        DEBUG("Single-step exeception ELR = 0x%016llx, ISV = %u, EX = %u\n", frame->elr_el2, (esr.iss >> 24) & 1, (esr.iss >> 6) & 1);
+    }
+
+}

thermosphere/src/traps/hvisor_traps_single_step.hpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2019-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "../hvisor_exception_stack_frame.hpp"
+
+namespace ams::hvisor::traps {
+
+    enum class SingleStepState {
+        Inactive            = 0, /// Single step disabled OR in the debugger
+        ActiveNotPending    = 1, /// Instruction not yet executed
+        ActivePending       = 2, /// Instruction executed or return-from-trap, single-step exception is going to be generated soon
+    };
+
+    /// Get the single-step state machine state (state after eret)
+    SingleStepState GetNextSingleStepState(ExceptionStackFrame *frame);
+
+    /// Set the single-step state machine state (state after eret). Frame can be nullptr iff new state is "inactive"
+    void SetNextSingleStepState(ExceptionStackFrame *frame, SingleStepState state);
+
+    void HandleSingleStep(ExceptionStackFrame *frame, cpu::ExceptionSyndromeRegister esr);
+
+}