From b917ea283e764c34af6a893591b87685180eca77 Mon Sep 17 00:00:00 2001
From: fincs <fincs@devkitpro.org>
Date: Mon, 10 Aug 2020 21:42:19 +0200
Subject: [PATCH] kern: make GetTargetFirmware a compile-time constant when not
 building for Switch

---
 .../include/mesosphere/kern_common.hpp        |  6 ++++++
 .../kernel/source/arch/arm64/init/start.s     |  4 ++++
 .../kernel_ldr/source/arch/arm64/start.s      |  5 ++++-
 .../kernel_ldr/source/kern_init_loader.cpp    | 20 +++++++++++++++++--
 4 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/libraries/libmesosphere/include/mesosphere/kern_common.hpp b/libraries/libmesosphere/include/mesosphere/kern_common.hpp
index be7c94ab8..091d4ba68 100644
--- a/libraries/libmesosphere/include/mesosphere/kern_common.hpp
+++ b/libraries/libmesosphere/include/mesosphere/kern_common.hpp
@@ -22,6 +22,12 @@ namespace ams::kern {
 
     constexpr size_t PageSize = 4_KB;
 
+#ifdef ATMOSPHERE_BOARD_NINTENDO_NX
     ams::TargetFirmware GetTargetFirmware();
+#else
+    consteval ALWAYS_INLINE ams::TargetFirmware GetTargetFirmware() {
+        return ams::TargetFirmware_Current;
+    }
+#endif
 
 }
diff --git a/mesosphere/kernel/source/arch/arm64/init/start.s b/mesosphere/kernel/source/arch/arm64/init/start.s
index f4a6d1bde..0549679b8 100644
--- a/mesosphere/kernel/source/arch/arm64/init/start.s
+++ b/mesosphere/kernel/source/arch/arm64/init/start.s
@@ -61,12 +61,14 @@ __metadata_kernel_layout:
     .error "Incorrect Mesosphere Metadata"
 .endif
 
+#ifdef ATMOSPHERE_BOARD_NINTENDO_NX
 .global     _ZN3ams4kern17GetTargetFirmwareEv
 .type       _ZN3ams4kern17GetTargetFirmwareEv, %function
 _ZN3ams4kern17GetTargetFirmwareEv:
     adr x0, __metadata_target_firmware
     ldr w0, [x0]
     ret
+#endif
 
 /* ams::kern::init::StartCore0(uintptr_t, uintptr_t) */
 .section    .crt0.text._ZN3ams4kern4init10StartCore0Emm, "ax", %progbits
@@ -94,6 +96,7 @@ core0_el2:
 core0_el1:
     bl _ZN3ams4kern4init19DisableMmuAndCachesEv
 
+#ifdef ATMOSPHERE_BOARD_NINTENDO_NX
     /* Get the target firmware from exosphere. */
     LOAD_IMMEDIATE_32(w0, 0xC3000004)
     mov w1, #65000
@@ -105,6 +108,7 @@ core0_el1:
     /* Store the target firmware. */
     adr x0, __metadata_target_firmware
     str w1, [x0]
+#endif
 
     /* We want to invoke kernel loader. */
     adr x0, _start
diff --git a/mesosphere/kernel_ldr/source/arch/arm64/start.s b/mesosphere/kernel_ldr/source/arch/arm64/start.s
index 29efffa5c..f8610ae72 100644
--- a/mesosphere/kernel_ldr/source/arch/arm64/start.s
+++ b/mesosphere/kernel_ldr/source/arch/arm64/start.s
@@ -56,6 +56,7 @@ _main:
     stp x2, x30, [sp, #0x10]
     stp xzr, xzr, [sp, #0x20]
 
+#ifdef ATMOSPHERE_BOARD_NINTENDO_NX
     /* Get the target firmware from exosphere. */
     LOAD_IMMEDIATE_32(w0, 0xC3000004)
     mov w1, #65000
@@ -67,6 +68,7 @@ _main:
     /* Store the target firmware. */
     adr x0, __metadata_target_firmware
     str w1, [x0]
+#endif
 
     /* Apply relocations and call init array for KernelLdr. */
     adr x0, _start
@@ -121,13 +123,14 @@ _main:
     mov sp, x2
     br  x1
 
-
+#ifdef ATMOSPHERE_BOARD_NINTENDO_NX
 .global     _ZN3ams4kern17GetTargetFirmwareEv
 .type       _ZN3ams4kern17GetTargetFirmwareEv, %function
 _ZN3ams4kern17GetTargetFirmwareEv:
     adr x0, __metadata_target_firmware
     ldr w0, [x0]
     ret
+#endif
 
 .balign 8
 __external_references:
diff --git a/mesosphere/kernel_ldr/source/kern_init_loader.cpp b/mesosphere/kernel_ldr/source/kern_init_loader.cpp
index 658b2a39e..fb25f4890 100644
--- a/mesosphere/kernel_ldr/source/kern_init_loader.cpp
+++ b/mesosphere/kernel_ldr/source/kern_init_loader.cpp
@@ -87,6 +87,22 @@ namespace ams::kern::init::loader {
             cpu::InvalidateEntireTlb();
         }
 
+        #ifdef ATMOSPHERE_BOARD_NINTENDO_NX
+
+        ALWAYS_INLINE bool ShouldPerformCpuSpecificSetup() {
+            /* Perform cpu-specific setup only on < 10.0.0. */
+            return kern::GetTargetFirmware() < ams::TargetFirmware_10_0_0;
+        }
+
+        #else
+
+        consteval ALWAYS_INLINE bool ShouldPerformCpuSpecificSetup() {
+            /* Always perform cpu-specific setup. */
+            return true;
+        }
+
+        #endif
+
         void SetupInitialIdentityMapping(KInitialPageTable &ttbr1_table, uintptr_t base_address, uintptr_t kernel_size, uintptr_t page_table_region, size_t page_table_region_size, KInitialPageTable::IPageAllocator &allocator) {
             /* Make a new page table for TTBR0_EL1. */
             KInitialPageTable ttbr0_table(allocator.Allocate());
@@ -116,8 +132,8 @@ namespace ams::kern::init::loader {
             cpu::MemoryAccessIndirectionRegisterAccessor(MairValue).Store();
             cpu::TranslationControlRegisterAccessor(TcrValue).Store();
 
-            /* Perform cpu-specific setup on < 10.0.0. */
-            if (kern::GetTargetFirmware() < ams::TargetFirmware_10_0_0) {
+            /* Perform cpu-specific setup if needed. */
+            if (ShouldPerformCpuSpecificSetup()) {
                 SavedRegisterState saved_registers;
                 SaveRegistersToTpidrEl1(&saved_registers);
                 ON_SCOPE_EXIT { VerifyAndClearTpidrEl1(&saved_registers); };