Atmosphere: improve fatal error context

include/stratosphere/on_crash.hpp

@@ -21,7 +21,7 @@
 
 static constexpr size_t AtmosphereFatalErrorNumGprs = 29;
 
-static constexpr u32 AtmosphereFatalErrorMagic = 0x30454641; /* "AFE0" */
+static constexpr u32 AtmosphereFatalErrorMagic = 0x31454641; /* "AFE1" */
 
 /* Will be called by libstratosphere on crash. */
 void StratosphereCrashHandler(ThreadExceptionDump *ctx);

include/stratosphere/services/bpc_ams.h

@@ -21,6 +21,14 @@
 extern "C" {
 #endif
 
+#define AMS_FATAL_ERROR_MAX_STACKTRACE 0x20
+#define AMS_FATAL_ERROR_MAX_STACKDUMP 0x100
+
+#define STD_ABORT_ADDR_MAGIC   (0x8)
+#define STD_ABORT_VALUE_MAGIC  (0xA55AF00DDEADCAFEul)
+#define DATA_ABORT_ERROR_DESC  (0x101)
+#define STD_ABORT_ERROR_DESC   (0xFFE)
+
 typedef struct {
     u32 magic;
     u32 error_desc;
@@ -35,13 +43,17 @@ typedef struct {
         };
     };
     u64 pc;
-    u64 padding;
+    u64 module_base;
     u32 pstate;
     u32 afsr0;
     u32 afsr1;
     u32 esr;
     u64 far;
     u64 report_identifier; /* Normally just system tick. */
+    u64 stack_trace_size;
+    u64 stack_dump_size;
+    u64 stack_trace[AMS_FATAL_ERROR_MAX_STACKTRACE];
+    u8 stack_dump[AMS_FATAL_ERROR_MAX_STACKDUMP];
 } AtmosphereFatalErrorContext;
 
 Result bpcAmsInitialize(void);

source/on_crash.cpp

@@ -26,6 +26,17 @@ extern "C" {
     void abort();
 };
 
+static inline u64 GetPc() {
+    u64 pc;
+    __asm__ __volatile__ ("adr %[pc], ." : [pc]"=&r"(pc) :: );
+    return pc;
+}
+
+struct StackFrame {
+    u64 fp;
+    u64 lr;
+};
+
 void StratosphereCrashHandler(ThreadExceptionDump *ctx) {
     AtmosphereFatalErrorContext ams_ctx;
     /* Convert thread dump to atmosphere dump. */
@@ -36,6 +47,13 @@ void StratosphereCrashHandler(ThreadExceptionDump *ctx) {
         for (size_t i = 0; i < AtmosphereFatalErrorNumGprs; i++) {
             ams_ctx.gprs[i] = ctx->cpu_gprs[i].x;
         }
+        if (ams_ctx.error_desc == DATA_ABORT_ERROR_DESC &&
+            ams_ctx.gprs[2] == STD_ABORT_ADDR_MAGIC &&
+            ams_ctx.gprs[3] == STD_ABORT_VALUE_MAGIC) {
+            /* Detect std::abort(). */
+            ams_ctx.error_desc = STD_ABORT_ERROR_DESC;
+        }
+
         ams_ctx.fp = ctx->fp.x;
         ams_ctx.lr = ctx->lr.x;
         ams_ctx.sp = ctx->sp.x;
@@ -45,6 +63,55 @@ void StratosphereCrashHandler(ThreadExceptionDump *ctx) {
         ams_ctx.afsr1 = ctx->afsr1;
         ams_ctx.far = ctx->far.x;
         ams_ctx.report_identifier = armGetSystemTick();
+        /* Grab module base. */
+        {
+            MemoryInfo mem_info;
+            u32 page_info;
+            if (R_SUCCEEDED(svcQueryMemory(&mem_info, &page_info, GetPc()))) {
+                ams_ctx.module_base = mem_info.addr;
+            } else {
+                ams_ctx.module_base = 0;
+            }
+        }
+        ams_ctx.stack_trace_size = 0;
+        u64 cur_fp = ams_ctx.fp;
+        for (size_t i = 0; i < AMS_FATAL_ERROR_MAX_STACKTRACE; i++) {
+            /* Validate current frame. */
+            if (cur_fp == 0 || (cur_fp & 0xF)) {
+                break;
+            }
+
+            /* Read a new frame. */
+            StackFrame cur_frame;
+            MemoryInfo mem_info;
+            u32 page_info;
+            if (R_SUCCEEDED(svcQueryMemory(&mem_info, &page_info, cur_fp)) && (mem_info.perm & Perm_R) == Perm_R) {
+                std::memcpy(&cur_frame, reinterpret_cast<void *>(cur_fp), sizeof(cur_frame));
+            } else {
+                break;
+            }
+
+            /* Advance to the next frame. */
+            ams_ctx.stack_trace[ams_ctx.stack_trace_size++] = cur_frame.lr;
+            cur_fp = cur_frame.fp;
+        }
+        /* Clear unused parts of stack trace. */
+        for (size_t i = ams_ctx.stack_trace_size; i < AMS_FATAL_ERROR_MAX_STACKTRACE; i++) {
+            ams_ctx.stack_trace[i] = 0;
+        }
+
+        /* Grab up to 0x100 of stack. */
+        {
+            MemoryInfo mem_info;
+            u32 page_info;
+            if (R_SUCCEEDED(svcQueryMemory(&mem_info, &page_info, ams_ctx.sp)) && (mem_info.perm & Perm_R) == Perm_R) {
+                size_t copy_size = std::min(static_cast<size_t>(AMS_FATAL_ERROR_MAX_STACKDUMP), static_cast<size_t>(mem_info.addr + mem_info.size - ams_ctx.sp));
+                ams_ctx.stack_dump_size = copy_size;
+                std::memcpy(ams_ctx.stack_dump, reinterpret_cast<void *>(ams_ctx.sp), copy_size);
+            } else {
+                ams_ctx.stack_dump_size = 0;
+            }
+        }
     }
 
     /* Just call the user exception handler. */
@@ -67,7 +134,13 @@ void __attribute__((weak)) __libstratosphere_exception_handler(AtmosphereFatalEr
 /* Custom abort handler, so that std::abort will trigger these. */
 void abort() {
     /* Just perform a data abort. */
+    register u64 addr __asm__("x2") = STD_ABORT_ADDR_MAGIC;
+    register u64 val __asm__("x3") = STD_ABORT_VALUE_MAGIC;
     while (true) {
-        *((volatile u64 *)0x8) = 0xCAFEBABE;
+        __asm__ __volatile__ (
+            "str %[val], [%[addr]]"
+            :
+            : [val]"r"(val), [addr]"r"(addr)
+        );
     }
 }