From 527db5ce1f90fcf6d7e9df427b2ccc85f5444268 Mon Sep 17 00:00:00 2001
From: York Jasper Niebuhr <yjnworkstation@gmail.com>
Date: Mon, 27 Oct 2025 23:06:23 +0100
Subject: [PATCH] Finalizer__spslr_program pointer patch

---
 finalize/finalize.cpp     | 21 ++++++++++++++++++++-
 selfpatch/src/selfpatch.c | 15 ++++++++-------
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/finalize/finalize.cpp b/finalize/finalize.cpp
index 1246bdd..a059c81 100644
--- a/finalize/finalize.cpp
+++ b/finalize/finalize.cpp
@@ -178,7 +178,26 @@ int main(int argc, char** argv) {
 	bin->add(new_seg);
 
 	// Set __spslr_program to (new_vaddr - &__spslr_program)
-	// TODO
+	for (Segment& seg : bin->segments()) {
+		uint64_t start = seg.virtual_address();
+		uint64_t end_mem = start + seg.virtual_size();
+
+		if (spslr_program_ptr_address >= start && spslr_program_ptr_address < end_mem) {
+			uint64_t offset_within_seg = spslr_program_ptr_address - start;
+			uint64_t min_needed = offset_within_seg + sizeof(uint64_t);
+
+			if (min_needed > seg.physical_size())
+				seg.physical_size(min_needed);
+
+			break;
+		}
+	}
+
+	uint64_t relative_new_vaddr = new_vaddr - spslr_program_ptr_address;
+	std::vector<uint8_t> program_ptr_bytes;
+	program_ptr_bytes.resize(8);
+	std::memcpy(program_ptr_bytes.data(), &relative_new_vaddr, 8);
+	bin->patch_address(spslr_program_ptr_address, program_ptr_bytes);
 
 	// Output final program
 	Builder builder{ *bin };
diff --git a/selfpatch/src/selfpatch.c b/selfpatch/src/selfpatch.c
index 795581c..658278f 100644
--- a/selfpatch/src/selfpatch.c
+++ b/selfpatch/src/selfpatch.c
@@ -6,13 +6,6 @@
 #include "targets.h"
 #include "patcher.h"
 
-/*
-TODO
-Postprocessing tool patches the value of __spslr_program to point to the SPSLR program section.
-With ASLR, there are 2 options to make it function correctly:
-	1. Make sure __spslr_program is relocated with program image shift (preferred)
-	2. __spslr_program = spslr_ptr_absolute((uint64_t)__spslr_program) and postprocessor inserts relative value (kinda weird)
-*/
 const uint8_t* __spslr_program = NULL;
 
 static void* spslr_ptr_absolute(uint64_t relative) {
@@ -20,6 +13,12 @@ static void* spslr_ptr_absolute(uint64_t relative) {
 	return ((uint8_t*)&__spslr_program) + relative;
 }
 
+static void spslr_init_program_ptr() {
+	// Finalizer patches __spslr_program to be the relative offset from &__spslr_program to the program
+	uint64_t relative = (uint64_t)__spslr_program;
+	__spslr_program = (const uint8_t*)spslr_ptr_absolute(relative);
+}
+
 static int spslr_do(const struct SPSLR_INST* inst) {
 	if (!inst)
 		return -1;
@@ -65,6 +64,8 @@ void spslr_selfpatch() {
 		return;
 	}
 
+	spslr_init_program_ptr();
+
 	int sz;
 	struct SPSLR_INST inst;
 	while ((sz = spslr_inst_load(&inst, __spslr_program)) > 0) {