Added support for global constructors and destructors

diff --git a/Makefile b/Makefile
index 7c6c8c090546cb8720f3d57bb8e5809122cc39bf..cb116a3a0221186738b3d8484c7d863548da15a9 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -12,12 +12,17 @@ CXXFLAGS := $(CXXFLAGS) -Wall -Wextra -Werror -std=c++20 \
 
 LDFLAGS ?= -O2
 LDFLAGS := $(LDFLAGS) -Wall -Wextra -Werror -std=c++20 \
-       -ffreestanding -T linker.ld -z max-page-size=0x1000
+       -ffreestanding -T linker.ld -z max-page-size=0x1000 \
+       -mno-red-zone -mcmodel=large # Normally has no effect, but is used to change the multilib libgcc, to use mcmodel=large and be able to use global constructors and destructors.
 LDLIBS := $(LDLIBS) -nostdlib -lgcc
 
 CPPOBJS := $(patsubst $(SRC_DIR)%,$(OUT_DIR)%.o,$(shell find $(SRC_DIR) -name '*.cpp'))
-ASMOBJS := $(patsubst $(SRC_DIR)%,$(OUT_DIR)%.o,$(shell find $(SRC_DIR) -name '*.S'))
+ASMOBJS := $(patsubst $(SRC_DIR)%,$(OUT_DIR)%.o,$(shell find $(SRC_DIR) -name '*.S' -and -not -name 'crti.S' -and -not -name 'crtn.S'))
 OBJECTS := $(CPPOBJS) $(ASMOBJS)
+CRTI_OBJ := $(OUT_DIR)crti.S.o
+CRTBEGIN_OBJ := $(shell $(CXX) $(LDFLAGS) -print-file-name=crtbegin.o)
+CRTEND_OBJ := $(shell $(CXX) $(LDFLAGS) -print-file-name=crtend.o)
+CRTN_OBJ := $(OUT_DIR)crtn.S.o
 
 build: $(OUT_DIR)amycros.iso
 qemu: build
@@ -33,9 +38,9 @@ clean:
        -rm -rf $(OUT_DIR) $(DEPS_DIR) isodir
 
 
-$(OUT_DIR)kernel.elf64: $(OBJECTS) linker.ld
+$(OUT_DIR)kernel.elf64: $(OBJECTS) $(CRTI_OBJ) $(CRTBEGIN_OBJ) $(CRTEND_OBJ) $(CRTN_OBJ) linker.ld
        mkdir -p $(OUT_DIR)
-       $(CXX) $(LDFLAGS) -o "$@" $(OBJECTS) $(LDLIBS)
+       $(CXX) $(LDFLAGS) -o "$@" $(CRTI_OBJ) $(CRTBEGIN_OBJ) $(OBJECTS) $(CRTEND_OBJ) $(CRTN_OBJ) $(LDLIBS)
 
 $(OUT_DIR)%.o: $(SRC_DIR)%
        mkdir -p $(@D)

diff --git a/linker.ld b/linker.ld
index 7b57d1eab9d2e3743c3ed73e3526c838a6fc3528..4c35e4128717acc81713958e2e99af62694113d1 100644 (file)
--- a/linker.ld
+++ b/linker.ld
@@ -17,19 +17,35 @@ SECTIONS {
 
        .text ALIGN(4K) : AT(ADDR(.text) - KERNEL_VMA) {
                *(.text)
+               *(.text*)
+               *(.gnu.linkonce.t*)
+               . = ALIGN(8);
+               *(.init)
+               . = ALIGN(8);
+               *(.fini)
+               . = ALIGN(8);
+               *(.ctors)
+               . = ALIGN(8);
+               *(.dtors)
        }
        .rodata ALIGN(4K) : AT(ADDR(.rodata) - KERNEL_VMA) {
+               *(.rodata)
                *(.rodata*)
-       }
-       .data ALIGN(4K) : AT(ADDR(.data) - KERNEL_VMA) {
-               *(.data)
+               *(.gnu.linkonce.r*)
        }
        .eh_frame ALIGN(4K) : AT(ADDR(.eh_frame) - KERNEL_VMA) {
                *(.eh_frame)
        }
+       .data ALIGN(4K) : AT(ADDR(.data) - KERNEL_VMA) {
+               *(.data)
+               *(.data*)
+               *(.gnu.linkonce.d*)
+       }
        .bss ALIGN(4K) : AT(ADDR(.bss) - KERNEL_VMA) {
                *(.bss)
                *(COMMON)
+               *(.bss*)
+               *(.gnu.linkonce.b*)
        }
        . = ALIGN(4K);
        _kernel_phys_end = . - KERNEL_VMA;

diff --git a/src/boot.S b/src/boot.S
index ec6a75f563c815730b16f0722030bff76c6015e6..1bdfdba0c54c916129cb40ec695ae7b3def9b8dd 100644 (file)
--- a/src/boot.S
+++ b/src/boot.S
@@ -237,6 +237,15 @@ _start:
        mov $PML4T - KERNEL_VMA, %rax
        mov %rax, %cr3
 
+       call _init
+
        mov %r14, %rsi
        mov %r15, %rdi
        call kmain # With the two arguments popped earlier.
+
+       # Should never reach that point, but, oh well.
+       call _fini
+
+       cli
+1:     hlt
+       jmp 1b

diff --git a/src/crti.S b/src/crti.S
new file mode 100644 (file)
index 0000000..7d0c60b
--- /dev/null
+++ b/src/crti.S
@@ -0,0 +1,15 @@
+.section .init
+.global _init
+.type _init, @function
+_init:
+       push %rbp
+       movq %rsp, %rbp
+       /* gcc will nicely put the contents of crtbegin.o's .init section here. */
+
+.section .fini
+.global _fini
+.type _fini, @function
+_fini:
+       push %rbp
+       movq %rsp, %rbp
+       /* gcc will nicely put the contents of crtbegin.o's .fini section here. */

diff --git a/src/crtn.S b/src/crtn.S
new file mode 100644 (file)
index 0000000..2880ebb
--- /dev/null
+++ b/src/crtn.S
@@ -0,0 +1,9 @@
+.section .init
+       /* gcc will nicely put the contents of crtend.o's .init section here. */
+       popq %rbp
+       ret
+
+.section .fini
+       /* gcc will nicely put the contents of crtend.o's .fini section here. */
+       popq %rbp
+       ret