[kernel] Add debug names to processes

To make debugging easier, add names to processes. These are arbitrary
and supplied by the caller of process_create. The max is 31 characters
in debug configuration, and 0 in release.

src/kernel/kernel_main.cpp

@@ -86,7 +86,7 @@ load_init_server(bootproto::program &program, uintptr_t modules_address)
     using bootproto::section_flags;
     using obj::vm_flags;
 
-    obj::process *p = new obj::process;
+    obj::process *p = new obj::process {"srv.init"};
 
     j6_handle_t sys_handle =
         g_cap_table.create(&obj::system::get(), obj::system::init_caps);

src/kernel/objects/process.cpp

@@ -1,3 +1,4 @@
+#include <j6/memutils.h>
 #include <util/no_construct.h>
 
 #include "kassert.h"
@@ -18,10 +19,18 @@ obj::process &g_kernel_process = __g_kernel_process_storage.value;
 
 namespace obj {
 
-process::process() :
+process::process(const char *name) :
     kobject {kobject::type::process},
     m_state {state::running}
 {
+    if constexpr(__use_process_names) {
+        memset(m_name, 0, sizeof(m_name));
+        if (name) {
+            static constexpr size_t charlen = sizeof(m_name) - 1;
+            for (size_t i = 0; i < charlen && name[i]; ++i)
+                m_name[i] = name[i];
+        }
+    }
 }
 
 // The "kernel process"-only constructor
@@ -30,6 +39,11 @@ process::process(page_table *kpml4) :
     m_space {kpml4},
     m_state {state::running}
 {
+    if constexpr(__use_process_names) {
+        static constexpr char kernel[] = "KERNEL";
+        memcpy(m_name, kernel, sizeof(kernel));
+        memset(m_name + sizeof(kernel), 0, sizeof(m_name) - sizeof(kernel));
+    }
 }
 
 process::~process()

src/kernel/objects/process.h

@@ -13,6 +13,14 @@
 
 namespace obj {
 
+static constexpr bool __use_process_names =
+#ifdef __jsix_config_debug
+    true;
+#else
+    false;
+#endif
+
+
 class process :
     public kobject
 {
@@ -32,7 +40,7 @@ public:
     static constexpr kobject::type type = kobject::type::process;
 
     /// Constructor.
-    process();
+    process(const char *name);
 
     /// Destructor.
     virtual ~process();
@@ -47,6 +55,9 @@ public:
     /// Get the process' virtual memory space
     vm_space & space() { return m_space; }
 
+    /// Get the debugging name of the process
+    const char *name() { if constexpr(__use_process_names) return m_name; else return nullptr; }
+
     /// Create a new thread in this process
     /// \args rsp3      If non-zero, sets the ring3 stack pointer to this value
     /// \args priority  The new thread's scheduling priority
@@ -107,6 +118,15 @@ private:
 
     enum class state : uint8_t { running, exited };
     state m_state;
+
+    static constexpr size_t max_name_len =
+#ifdef __jsix_config_debug
+        32;
+#else
+        0;
+#endif
+
+    char m_name[max_name_len];
 };
 
 } // namespace obj

src/kernel/panic.serial/display.cpp

@@ -2,6 +2,7 @@
 
 #include "cpu.h"
 #include "display.h"
+#include "kernel.dir/memory.h"
 #include "objects/process.h"
 #include "objects/thread.h"
 #include "serial.h"
@@ -9,6 +10,44 @@
 
 namespace panicking {
 
+template <typename T> inline bool
+check_pointer(T p)
+{
+    static constexpr uint64_t large_flag = (1<<7);
+    static constexpr uint64_t pointer_mask = 0x0000fffffffff000;
+    static constexpr uintptr_t canon_mask = 0xffff800000000000;
+
+    uintptr_t addr = reinterpret_cast<uintptr_t>(p);
+
+    uintptr_t canon_bits = addr & canon_mask;
+    if (canon_bits && canon_bits != canon_mask)
+        return false;
+
+    uintptr_t pml4 = 0;
+    asm volatile ( "mov %%cr3, %0" : "=r" (pml4) );
+    pml4 += mem::linear_offset;
+
+    uint64_t *table = reinterpret_cast<uint64_t*>(pml4);
+    unsigned shift = 39;
+
+    while (table) {
+        unsigned index = (addr >> shift) & 0x1ffull;
+        uint64_t entry = table[index];
+
+        if ((entry & 0x1) == 0)
+            return false;
+
+        if ((entry & large_flag) || shift <= 12)
+            return true;
+
+        uint64_t next = (entry & pointer_mask) + mem::linear_offset;
+        table = reinterpret_cast<uint64_t*>(next);
+        shift -= 9;
+    }
+
+    return false;
+}
+
 const char *clear = "\e[0m\n";
 
 void
@@ -40,23 +79,17 @@ print_cpu(serial_port &out, cpu_data &cpu)
 {
     uint32_t process = cpu.process ? cpu.process->obj_id() : 0;
     uint32_t thread = cpu.thread ? cpu.thread->obj_id() : 0;
+    const char *name = cpu.process ? cpu.process->name() : "<Unknown>";
 
     out.write("\n \e[0;31m==[ CPU: ");
 
     char buffer[64];
-    util::format({buffer, sizeof(buffer)}, "%4d <%02lx:%02lx>",
-            cpu.id + 1, process, thread);
+    size_t len = util::format({buffer, sizeof(buffer)}, "%4d <%02lx:%02lx> ]: %s ",
+            cpu.id + 1, process, thread, name);
     out.write(buffer);
 
-    out.write(" ]=============================================================\n");
-}
-
-template <typename T> inline bool
-canonical(T p)
-{
-    static constexpr uintptr_t mask = 0xffff800000000000;
-    uintptr_t addr = reinterpret_cast<uintptr_t>(p);
-    return (addr & mask) == mask || (addr & mask) == 0;
+    for (size_t i = 0; i < (74-len); ++i) out.write("=");
+    out.write("\n");
 }
 
 void
@@ -65,18 +98,26 @@ print_callstack(serial_port &out, symbol_table &syms, frame const *fp)
     char message[512];
     unsigned count = 0;
 
-    while (canonical(fp) && fp && fp->return_addr) {
-        char const *name = syms.find_symbol(fp->return_addr);
+    while (fp && check_pointer(fp)) {
+        const uintptr_t ret = fp->return_addr;
+        char const *name = ret ? syms.find_symbol(ret) : "<END>";
         if (!name)
-            name = canonical(fp->return_addr) ? "<unknown>" : "<corrupt>";
+            name = check_pointer(fp->return_addr) ? "<unknown>" : "<unmapped>";
 
         util::format({message, sizeof(message)},
-            " \e[0;33mframe %2d: <0x%016lx> \e[1;33m%s\n",
-            count++, fp->return_addr, name);
+            " \e[0;33mframe %2d: <0x%016lx> <0x%016lx> \e[1;33m%s\n",
+            count++, fp, fp->return_addr, name);
 
         out.write(message);
+
+        if (!ret) return;
         fp = fp->prev;
     }
+
+    const char *result = fp ? " <inaccessible>" : "";
+    util::format({message, sizeof(message)}, " \e[0mfinal     <0x%016lx>%s\n",
+            fp, result);
+    out.write(message);
 }
 
 static void

src/kernel/syscalls/process.cpp

@@ -10,9 +10,9 @@ using namespace obj;
 namespace syscalls {
 
 j6_status_t
-process_create(j6_handle_t *self)
+process_create(j6_handle_t *self, const char *path)
 {
-    process *p = construct_handle<process>(self);
+    process *p = construct_handle<process>(self, path);
     log::info(logs::task, "Process <%02lx> created", p->obj_id());
     return j6_status_ok;
 }

src/kernel/syscalls/system.cpp

@@ -23,9 +23,10 @@ using system = class ::system;
 j6_status_t
 log(uint8_t area, uint8_t severity, const char *message)
 {
+    const char *name = process::current().name();
     thread &th = thread::current();
     log::log(static_cast<logs>(area), static_cast<log::level>(severity),
-        "<%02lx:%02lx>: %s", th.parent().obj_id(), th.obj_id(), message);
+        "<%02lx:%02lx> %s: %s", th.parent().obj_id(), th.obj_id(), name, message);
     return j6_status_ok;
 }