kern: Support older SVC ABIs

mesosphere/build_mesosphere.py

@@ -2,19 +2,8 @@
 import sys, os
 from struct import pack as pk, unpack as up
 
-ATMOSPHERE_TARGET_FIRMWARE_100  = 1
-ATMOSPHERE_TARGET_FIRMWARE_200  = 2
-ATMOSPHERE_TARGET_FIRMWARE_300  = 3
-ATMOSPHERE_TARGET_FIRMWARE_400  = 4
-ATMOSPHERE_TARGET_FIRMWARE_500  = 5
-ATMOSPHERE_TARGET_FIRMWARE_600  = 6
-ATMOSPHERE_TARGET_FIRMWARE_620  = 7
-ATMOSPHERE_TARGET_FIRMWARE_700  = 8
-ATMOSPHERE_TARGET_FIRMWARE_800  = 9
-ATMOSPHERE_TARGET_FIRMWARE_810  = 10
-ATMOSPHERE_TARGET_FIRMWARE_900  = 11
-ATMOSPHERE_TARGET_FIRMWARE_910  = 12
-ATMOSPHERE_TARGET_FIRMWARE_1000 = 13
+def atmosphere_target_firmware(major, minor, micro, rev = 0):
+    return (major << 24) | (minor << 16) | (micro << 8) | rev
 
 def align_up(val, algn):
     val += algn - 1
@@ -50,7 +39,7 @@ def main(argc, argv):
 
     with open('mesosphere.bin', 'wb') as f:
         f.write(kernel[:kernel_metadata_offset + 4])
-        f.write(pk('<QQI', embedded_ini_offset, kernel_ldr_offset, ATMOSPHERE_TARGET_FIRMWARE_1000))
+        f.write(pk('<QQI', embedded_ini_offset, kernel_ldr_offset, atmosphere_target_firmware(10, 1, 0)))
         f.write(kernel[kernel_metadata_offset + 0x18:])
         f.seek(embedded_ini_offset)
         f.write(embedded_ini)

mesosphere/kernel_ldr/source/kern_init_loader.cpp

@@ -318,6 +318,8 @@ namespace ams::kern::init::loader {
         Elf::ApplyRelocations(GetInteger(virtual_base_address), kernel_dynamic);
 
         /* Call the kernel's init array functions. */
+        /* NOTE: The kernel does this after reprotecting .rodata, but we do it before. */
+        /* This allows our global constructors to edit .rodata, which is valuable for editing the SVC tables to support older firmwares' ABIs. */
         Elf::CallInitArrayFuncs(GetInteger(virtual_base_address) + init_array_offset, GetInteger(virtual_base_address) + init_array_end_offset);
 
         /* Reprotect .rodata as R-- */