[libj6] Change to a more SysV style process init args

Pull out the old linked list of args structures in favor of doing things
the SysV ABI-specified way.

src/libraries/j6/include/j6/init.h

@@ -12,39 +12,42 @@
 extern "C" {
 #endif
 
-#ifdef __cplusplus
-#define add_header(name) \
-    static constexpr j6_arg_type type_id = j6_arg_type_ ## name; \
-    j6_arg_header header;
-#else
-#define add_header(name) \
-    j6_arg_header header;
-#endif
+enum j6_aux_type {
+    // The SysV ABI-specified aux vector types
+    j6_aux_null,        // AT_NULL
+    j6_aux_ignore,      // AT_IGNORE
+    j6_aux_execfd,      // AD_EXECFD - File descriptor of the exe to load
+    j6_aux_phdr,        // AD_PHDR   - Program headers pointer for the exe to load
+    j6_aux_phent,       // AD_PHENT  - Size of a program header entry
+    j6_aux_phnum,       // AD_PHNUM  - Number of program header entries
+    j6_aux_pagesz,      // AD_PAGESZ - System page size
+    j6_aux_base,        // AD_BASE   - Base address of dynamic loader
+    j6_aux_flags,       // AD_FLAGS  - Flags
+    j6_aux_entry,       // AD_ENTRY  - Entrypoint for the exe to load
+    j6_aux_notelf,      // AD_NOTELF - If non-zero, this program is not ELF
+    j6_aux_uid,         // AD_UID    - User ID
+    j6_aux_euid,        // AD_EUID   - Effective User ID
+    j6_aux_gid,         // AD_GID    - Group ID
+    j6_aux_egid,        // AD_EGID   - Effective Group ID
 
-enum j6_arg_type {
-    j6_arg_type_none,
-    j6_arg_type_sysv_init,
-    j6_arg_type_loader,
-    j6_arg_type_driver,
-    j6_arg_type_handles,
+    j6_aux_start = 0xf000,
+    j6_aux_handles,     // Pointer to a j6_arg_handles structure
+    j6_aux_device,      // Pointer to a j6_arg_driver structure
+    j6_aux_loader,      // Pointer to a j6_arg_loader structure
 };
 
-struct j6_arg_header
+struct j6_aux
 {
-    uint32_t size;
-    uint16_t type;
-    uint16_t reserved;
-    j6_arg_header *next;
-};
-
-struct j6_arg_none
-{
-    add_header(none);
+    uint64_t type;
+    union {
+        uint64_t value;
+        void *pointer;
+        void (*func)();
+    };
 };
 
 struct j6_arg_loader
 {
-    add_header(loader);
     uintptr_t loader_base;
     uintptr_t image_base;
     uintptr_t *got;
@@ -54,8 +57,8 @@ struct j6_arg_loader
 
 struct j6_arg_driver
 {
-    add_header(driver);
     uint64_t device;
+    uint32_t size;
     uint8_t data [0];
 };
 
@@ -67,32 +70,13 @@ struct j6_arg_handle_entry
 
 struct j6_arg_handles
 {
-    add_header(handles);
     size_t nhandles;
     j6_arg_handle_entry handles[0];
 };
 
-struct j6_init_args
-{
-    uint64_t argv[2];
-    j6_arg_header *args;
-};
-
-
-/// Find the first handle of the given type held by this process
-j6_handle_t API j6_find_first_handle(j6_object_type obj_type);
-
 /// Find the first handle tagged with the given proto in the process init args
 j6_handle_t API j6_find_init_handle(uint64_t proto);
 
-/// Get the init args
-const j6_init_args * j6_get_init_args();
-
-/// Drivers may use driver_main instead of main
-int driver_main(unsigned, const char **, const char **, const j6_init_args *);
-
 #ifdef __cplusplus
 } // extern "C"
 #endif
-
-#undef add_header

src/libraries/j6/init.cpp

@@ -1,5 +1,7 @@
 // The kernel depends on libj6 for some shared code,
 // but should not include the user-specific code.
+#include "j6/init.h"
+#include "j6/types.h"
 #ifndef __j6kernel
 
 #include <stddef.h>
@@ -10,65 +12,45 @@
 #include <j6/types.h>
 
 namespace {
-    constexpr size_t static_arr_count = 32;
-    j6_handle_descriptor handle_array[static_arr_count];
-    j6_init_args init_args = { 0, 0, 0 };
-} // namespace
+    char const * const *envp = nullptr;
+    const j6_aux *aux = nullptr;
 
-j6_handle_t
-j6_find_first_handle(j6_object_type obj_type)
-{
-    size_t count = static_arr_count;
-    j6_handle_descriptor *handles = handle_array;
-    j6_status_t s = j6_handle_list(handles, &count);
-
-    if (s != j6_err_insufficient && s != j6_status_ok)
-        return j6_handle_invalid;
-
-    if (count > static_arr_count)
-        count = static_arr_count;
-
-    for (size_t i = 0; i < count; ++i) {
-        j6_handle_descriptor &desc = handle_array[i];
-        if (desc.type == obj_type) return desc.handle;
+    const j6_aux * find_aux(uint64_t type) {
+        if (!aux) return nullptr;
+        for (j6_aux const *p = aux; p->type; ++p)
+            if (p->type == type) return p;
+        return nullptr;
     }
-
-    return j6_handle_invalid;
-}
+} // namespace
 
 j6_handle_t
 j6_find_init_handle(uint64_t proto)
 {
-    j6_arg_header *arg = init_args.args;
-    while (arg) {
-        if (arg->type == j6_arg_type_handles) {
-            j6_arg_handles *harg = reinterpret_cast<j6_arg_handles*>(arg);
-            for (unsigned i = 0; i < harg->nhandles; ++i) {
-                j6_arg_handle_entry &ent = harg->handles[i];
-                if (ent.proto == proto)
-                    return ent.handle;
-            }
-        }
-        arg = arg->next;
+    const j6_aux *aux_handles = find_aux(j6_aux_handles);
+    if (!aux_handles)
+        return j6_handle_invalid;
+
+    const j6_arg_handles *arg = reinterpret_cast<const j6_arg_handles*>(aux_handles->pointer);
+    for (unsigned i = 0; i < arg->nhandles; ++i) {
+        const j6_arg_handle_entry &ent = arg->handles[i];
+        if (ent.proto == proto)
+            return ent.handle;
     }
 
     return j6_handle_invalid;
 }
 
-
-const j6_init_args * API
-j6_get_init_args()
-{
-    return &init_args;
-}
-
 extern "C" void API
-__init_libj6(uint64_t argv0, uint64_t argv1, j6_arg_header *args)
+__init_libj6(const uint64_t *stack)
 {
-    init_args.argv[0] = argv0;
-    init_args.argv[1] = argv1;
-    init_args.args = args;
-}
+    // Walk the stack to get the aux vector
+    uint64_t argc = *stack++;
+    stack += argc + 1; // Skip argv's and sentinel
 
+    envp = reinterpret_cast<char const * const *>(stack);
+    while (*stack++); // Skip envp's and sentinel
+
+    aux = reinterpret_cast<const j6_aux*>(stack);
+}
 
 #endif // __j6kernel

src/libraries/j6/init.s

@@ -1,6 +0,0 @@
-extern driver_main
-global main:function weak (main.end - main)
-main:
-    jmp driver_main
-main.end:
-