From 8939c3421c2c01f02e88275e76a3cbbaa5b175a5 Mon Sep 17 00:00:00 2001
From: mintsuki <mintsuki@protonmail.com>
Date: Thu, 4 Mar 2021 23:12:40 +0100
Subject: [PATCH] misc: Compile stage 2 with -Os and stage 3 with -O3

---
 stage23/Makefile           | 10 ++++++++--
 stage23/fs/fat32.s2.c      |  3 +++
 stage23/protos/chainload.c |  5 ++++-
 stage23/protos/linux.c     |  5 ++++-
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/stage23/Makefile b/stage23/Makefile
index 5f928a0a..f0dd8422 100644
--- a/stage23/Makefile
+++ b/stage23/Makefile
@@ -20,7 +20,8 @@ E9_OUTPUT = false
 BUILD_ID := $(shell dd if=/dev/urandom count=8 bs=1 | od -An -t x8 | sed 's/^ /0x/')
 LIMINE_VERSION := $(shell git describe --exact-match --tags `git log -n1 --pretty='%h'` || git log -n1 --pretty='%h')
 WERROR = -Werror
-CFLAGS = -Os -g -pipe -Wall -Wextra $(WERROR)
+CFLAGS = -O3 -g -pipe -Wall -Wextra $(WERROR)
+S2CFLAGS = -Os -g -pipe -Wall -Wextra $(WERROR)
 
 INTERNAL_CFLAGS := \
 	-std=gnu11 \
@@ -54,7 +55,7 @@ ifeq ($(TARGET), uefi)
 		-mno-red-zone
 endif
 
-LDFLAGS = -Os -g
+LDFLAGS = -O3 -g
 
 INTERNAL_LDFLAGS := \
 	-fno-lto \
@@ -133,6 +134,11 @@ limine_efi.elf: $(OBJ) font.o sys/smp_trampoline.o
 %.o: %.c
 	$(CC) $(CFLAGS) $(INTERNAL_CFLAGS) -c $< -o $@
 
+ifeq ($(TARGET), bios)
+%.s2.o: %.s2.c
+	$(CC) $(S2CFLAGS) $(INTERNAL_CFLAGS) -c $< -o $@
+endif
+
 %.o: %.asm
 	nasm $< -F dwarf -g -f elf32 -o $@
 
diff --git a/stage23/fs/fat32.s2.c b/stage23/fs/fat32.s2.c
index 06ffe1d2..d17c8bf4 100644
--- a/stage23/fs/fat32.s2.c
+++ b/stage23/fs/fat32.s2.c
@@ -191,6 +191,9 @@ static int fat32_open_in(struct fat32_context* context, struct fat32_directory_e
     size_t   dir_chain_len;
     uint32_t *directory_cluster_chain = cache_cluster_chain(context, current_cluster_number, &dir_chain_len);
 
+    if (directory_cluster_chain == NULL)
+        return -1;
+
     struct fat32_directory_entry *directory_entries = ext_mem_alloc(dir_chain_len * block_size);
     if (!read_cluster_chain(context, directory_cluster_chain, directory_entries, 0, dir_chain_len * block_size))
         return -1;
diff --git a/stage23/protos/chainload.c b/stage23/protos/chainload.c
index f407e35d..5663f9e1 100644
--- a/stage23/protos/chainload.c
+++ b/stage23/protos/chainload.c
@@ -26,7 +26,10 @@ static void spinup(uint8_t drive) {
         "mov eax, cr0\n\t"
         "and al, 0xfe\n\t"
         "mov cr0, eax\n\t"
-        "jmp 0x0000:1f\n\t"
+        "mov eax, OFFSET 1f\n\t"
+        "push eax\n\t"
+        "push 0\n\t"
+        "retf\n\t"
         "1:\n\t"
         "mov ax, 0\n\t"
         "mov ds, ax\n\t"
diff --git a/stage23/protos/linux.c b/stage23/protos/linux.c
index 5803942e..a54a7672 100644
--- a/stage23/protos/linux.c
+++ b/stage23/protos/linux.c
@@ -34,7 +34,10 @@ static void spinup(uint16_t real_mode_code_seg, uint16_t kernel_entry_seg,
         "mov eax, cr0\n\t"
         "and al, 0xfe\n\t"
         "mov cr0, eax\n\t"
-        "jmp 0x0000:1f\n\t"
+        "mov eax, OFFSET 1f\n\t"
+        "push eax\n\t"
+        "push 0\n\t"
+        "retf\n\t"
         "1:\n\t"
         "mov ds, bx\n\t"
         "mov es, bx\n\t"