Add m1n1 boot support

Entry ABI:

x0 = Kernel Boot args
CurrentEL = Highest EL
Entry point is 0x800 into the image.

Link: https://github.com/asdfugil/m1n1-idevice

Author: asdfugil

src/kernel/entry.c

@@ -245,6 +245,7 @@ __attribute__((noinline)) void pongo_entry_cached()
     {
         default: // >4
         case BOOT_FLAG_RAW: // 4
+        case BOOT_FLAG_M1N1: // 3
             break;
 
         case BOOT_FLAG_HOOK: // 2
@@ -291,7 +292,7 @@ __attribute__((noinline)) void pongo_entry_cached()
 */
 extern void set_exception_stack_core0();
 extern void lowlevel_set_identity(void);
-extern _Noreturn void jump_to_image_extended(uint64_t image, uint64_t args, uint64_t tramp, uint64_t original_image);
+extern _Noreturn void jump_to_image_extended(void *image, void *args, void *tramp, void *original_image);
 extern uint64_t gPongoSlide;
 
 _Noreturn void pongo_entry(uint64_t *kernel_args, void *entryp, void (*exit_to_el1_image)(void *boot_args, void *boot_entry_point, void *trampoline))
@@ -308,23 +309,32 @@ _Noreturn void pongo_entry(uint64_t *kernel_args, void *entryp, void (*exit_to_e
     set_exception_stack_core0();
     gFramebuffer = (uint32_t*)gBootArgs->Video.v_baseAddr;
     lowlevel_cleanup();
-    if(gBootFlag == BOOT_FLAG_RAW)
+
+    // Unused space above kernel static area
+    void *boot_tramp = (void*)((gTopOfKernelData + 0x3fffULL) & ~0x3fffULL);
+    if(gBootFlag == BOOT_FLAG_RAW || gBootFlag == BOOT_FLAG_M1N1)
     {
         // We're in EL1 here, but we might need to go back to EL3
-        uint64_t pfr0;
-        __asm__ volatile("mrs %0, id_aa64pfr0_el1" : "=r"(pfr0));
-        if((pfr0 & 0xf000) != 0)
+        if((__builtin_arm_rsr64("id_aa64pfr0_el1") & 0xf000) != 0)
         {
             __asm__ volatile("smc 0"); // elevate to EL3
         }
+        uint64_t entryOff = 0x800;
+        if(gBootFlag == BOOT_FLAG_RAW)
+        {
+            boot_tramp = NULL;
+            entryOff = 0;
+        }
         // XXX: We should really replace loader_xfer_recv_data with something dedicated here.
-        jump_to_image_extended(((uint64_t)loader_xfer_recv_data) - kCacheableView + 0x800000000, (uint64_t)gBootArgs, 0, (uint64_t)gEntryPoint);
+        void *image = (void*)((uint64_t)loader_xfer_recv_data - kCacheableView + 0x800000000 + entryOff);
+        jump_to_image_extended(image, gBootArgs, boot_tramp, gEntryPoint);
     }
     else
     {
         xnu_boot();
-        exit_to_el1_image(gBootArgs, gEntryPoint, (void*)((gTopOfKernelData + 0x3fffULL) & ~0x3fffULL));
+        exit_to_el1_image(gBootArgs, gEntryPoint, boot_tramp);
     }
+
     screen_puts("didn't boot?!");
     while(1)
     {}

src/kernel/main_task.c

@@ -38,6 +38,7 @@ void shell_main();
 */
 
 uint64_t gBootTimeTicks;
+char gFWVersion[256];
 void pongo_main_task() {
     gBootTimeTicks = get_ticks();
 
@@ -87,6 +88,7 @@ void pongo_main_task() {
 
     char *fwversion = dt_get_prop("/chosen", "firmware-version", NULL);
     iprintf("Booted by: %s\n", fwversion);
+    strlcpy(gFWVersion, fwversion, 256);
     strcpy(fwversion, "pongoOS-" PONGO_VERSION);
 #ifdef __clang__
     iprintf("Built with: Clang %s\n", __clang_version__);

src/kernel/pongo.h

@@ -110,7 +110,7 @@ extern volatile char gBootFlag;
 #define BOOT_FLAG_DEFAULT 0
 #define BOOT_FLAG_HARD 1
 #define BOOT_FLAG_HOOK 2
-// 3: Reserved
+#define BOOT_FLAG_M1N1 3
 #define BOOT_FLAG_RAW 4
 
 typedef uint64_t lock;

src/shell/main.c

@@ -46,6 +46,21 @@ void pongo_boot_raw() {
     task_yield();
 }
 
+extern char gFWVersion[256];
+void pongo_boot_m1n1() {
+    if (!loader_xfer_recv_count) {
+        iprintf("please upload a raw m1n1.bin before issuing this command\n");
+        return;
+    }
+
+    loader_xfer_recv_count = 0;
+    char *fwversion = dt_get_prop("/chosen", "firmware-version", NULL);
+    strlcpy(fwversion, gFWVersion, 256);
+
+    gBootFlag = BOOT_FLAG_M1N1;
+    task_yield();
+}
+
 void* ramdisk_buf;
 uint32_t ramdisk_size;
 
@@ -251,6 +266,7 @@ void shell_main() {
     command_register("ps", "lists current tasks and irq handlers", task_list);
     command_register("ramdisk", "loads a ramdisk for xnu", ramdisk_cmd);
     command_register("bootr", "boot raw image", pongo_boot_raw);
+    command_register("bootm", "boots m1n1", pongo_boot_m1n1);
     command_register("spin", "spins 1 second", pongo_spin);
     command_register("md8", "memory dump", md8_cmd);
     command_register("peek", "32bit mem read", peek_cmd);