loader: Map all of RAM in the loader

loader/Makefile

@@ -35,27 +35,33 @@ else
   LD = $(TARGET_TRIPLE)-ld
 endif
 
+RUSTC := rustc
+
 ifeq ($(ARCH),aarch64)
 	CFLAGS_AARCH64 := -mcpu=$(GCC_CPU) -mgeneral-regs-only -mstrict-align -mno-outline-atomics
 	CFLAGS_ARCH := $(CFLAGS_AARCH64) -DARCH_aarch64
 	ASM_FLAGS_ARCH := -mcpu=$(GCC_CPU)
 	ARCH_DIR := aarch64
+	RUST_TARGET_TRIPLE := aarch64-unknown-none
 else ifeq ($(ARCH),riscv64)
 	CFLAGS_RISCV64 := -mcmodel=medany -march=rv64imac_zicsr_zifencei -mabi=lp64
 	CFLAGS_ARCH := $(CFLAGS_RISCV64) -DARCH_riscv64
 	ASM_FLAGS_ARCH := -march=rv64imac_zicsr_zifencei -mabi=lp64
+	RUST_TARGET_TRIPLE := riscv64gc-unknown-none-elf
 	ARCH_DIR := riscv
 endif
 
 CFLAGS := -std=gnu11 -g -O3 -nostdlib -ffreestanding \
 					-MP -MD $(CFLAGS_ARCH) -DBOARD_$(BOARD) -I$(SEL4_SDK)/include \
 					-Wall -Werror -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations \
-					-Wundef -Wno-nonnull -Wnested-externs
+					-Wundef -Wno-nonnull -Wnested-externs -ffunction-sections -fdata-sections
 
 ASM_FLAGS := $(ASM_FLAGS_ARCH) -g -MP -MD -I$(SEL4_SDK)/include
 
+RUSTFLAGS := --target $(RUST_TARGET_TRIPLE) --edition 2024 -g -C opt-level=2
+
 PROGS := loader.elf
-OBJECTS := loader.o crt0.o uart.o cutil.o
+OBJECTS := loader.o crt0.o uart.o cutil.o libpage_tables.a
 
 ifeq ($(ARCH),aarch64)
 	OBJECTS += util64.o el.o exceptions.o init.o mmu.o cpus.o
@@ -80,6 +86,17 @@ $(BUILD_DIR)/%.o : src/$(ARCH_DIR)/%.c
 $(BUILD_DIR)/%.o : src/%.c
 	$(CC) -c $(CFLAGS) $< -o $@
 
+# Note: having multiple libs with staticlib will give duplicate linker symbol
+# issues. Use "--crate-type rlib" instead, but then we need to link a single
+# copy of the rust corelibs. For now this is fine.
+$(BUILD_DIR)/lib%.a : src/%.rs
+	$(RUSTC) $(RUSTFLAGS) \
+		--emit dep-info,metadata,link \
+		--out-dir $(BUILD_DIR) -L dependency=$(BUILD_DIR) \
+		--crate-type staticlib \
+		--crate-name $(patsubst lib%.a,%,$(notdir $@)) \
+		$<
+
 -include $(BUILD_DIR)/*.d
 
 OBJPROG = $(addprefix $(BUILD_DIR)/, $(PROGS))
@@ -89,5 +106,8 @@ all: $(OBJPROG)
 $(LINKSCRIPT): $(LINKSCRIPT_INPUT)
 	$(CPP) -DLINK_ADDRESS=$(LINK_ADDRESS) $< | grep -v "^#" > $@
 
+LDFLAGS := -T$(LINKSCRIPT) --gc-sections
+
 $(OBJPROG): $(addprefix $(BUILD_DIR)/, $(OBJECTS)) $(LINKSCRIPT)
-	$(LD) -T$(LINKSCRIPT) $(addprefix $(BUILD_DIR)/, $(OBJECTS)) -o $@
+	$(LD) $(LDFLAGS) --start-group $(addprefix $(BUILD_DIR)/, $(OBJECTS)) --end-group -o $@
+

loader/aarch64.ld

@@ -8,6 +8,12 @@ PHDRS
     all PT_LOAD AT (LINK_ADDRESS);
 }
 
+
+//    text PT_LOAD FLAGS(5); /* RX */
+//    rodata PT_LOAD FLAGS(4); /* RO */
+//    data PT_LOAD FLAGS(6); /* RW */
+//    bss PT_LOAD FLAGS(6); /* RW */
+
 SECTIONS
 {
     . = LINK_ADDRESS;
@@ -17,27 +23,40 @@ SECTIONS
     .text :
     {
         _text = .;
-        *(.text.start)
-        *(.text*)
-        *(.rodata)
+
+        KEEP(*(.text.start))
+        *(.text .text.*)
+
         _text_end = .;
     } :all
 
+    .rodata :
+    {
+        *(.rodata .rodata.* .rodata..Lanon.*)
+    } :all
+
     .data :
     {
         _data = .;
-        *(.data)
+        *(.data .data.*)
+        *(.data.*)
+
+        KEEP(*(.data.uart_addr))
+
         _data_end = .;
     } :all
 
     .bss :
     {
         _bss = .;
         *(.bss)
+        *(.bss.*)
         *(COMMON)
         . = ALIGN(4);
         _bss_end = .;
     } :all
 
+
+
     _loader_end = .;
 }

loader/riscv64.ld

@@ -15,27 +15,32 @@ SECTIONS
     .text :
     {
         _text = .;
-        *(.text.start)
+        KEEP(*(.text.start))
         *(.text*)
+        *(.text.*)
         *(.rodata)
+        *(.rodata.*)
         _text_end = .;
     } :all
 
     .data :
     {
         _data = .;
         *(.data)
+        *(.data.*)
         __global_pointer$ = . + 0x800;
-    *(.srodata)
-    *(.sdata)
+        *(.srodata)
+        *(.sdata)
+        KEEP(*(.data.uart_addr))
        _data_end = .;
     } :all
 
     .bss :
     {
         _bss = .;
-    *(.sbss)
+        *(.sbss)
         *(.bss)
+        *(.bss.*)
         *(COMMON)
         . = ALIGN(4);
         _bss_end = .;

loader/src/aarch64/mmu.c

@@ -12,21 +12,29 @@
 #include "../cutil.h"
 #include "../uart.h"
 
-void el1_mmu_enable(void);
-void el2_mmu_enable(void);
+void el1_mmu_enable(uint64_t aarch64_pt_ttbr0_el1, uint64_t aarch64_pt_ttbr1_el1);
+void el2_mmu_enable(uint64_t aarch64_pt_ttbr0_el2);
 
-/* Paging structures for kernel mapping */
-uint64_t boot_lvl0_upper[1 << 9] ALIGN(1 << 12);
-uint64_t boot_lvl1_upper[1 << 9] ALIGN(1 << 12);
-uint64_t boot_lvl2_upper[1 << 9] ALIGN(1 << 12);
+/* Pointers to the top-level paging structures */
+uint64_t aarch64_pt_ttbr0_el1;
+uint64_t aarch64_pt_ttbr1_el1;
+uint64_t aarch64_pt_ttbr0_el2;
 
-/* Paging structures for identity mapping */
-uint64_t boot_lvl0_lower[1 << 9] ALIGN(1 << 12);
-uint64_t boot_lvl1_lower[1 << 9] ALIGN(1 << 12);
-uint64_t boot_lvl2_lower[1 << 9] ALIGN(1 << 12);
+struct ret {
+    uint64_t a;
+    uint64_t b;
+    uint64_t c;
+};
+
+extern struct ret aarch64_setup_pagetables(uint64_t kernel_first_vaddr, uint64_t kernel_first_paddr, uint64_t page_tables_paddr_start);
 
 int arch_mmu_enable(int logical_cpu)
 {
+    struct ret x = aarch64_setup_pagetables(0, 0, 0);
+    aarch64_pt_ttbr0_el2 = x.a;
+    aarch64_pt_ttbr0_el1 = x.b;
+    aarch64_pt_ttbr1_el1 = x.c;
+
     int r;
     enum el el;
     r = ensure_correct_el(logical_cpu);
@@ -37,9 +45,9 @@ int arch_mmu_enable(int logical_cpu)
     LDR_PRINT("INFO", logical_cpu, "enabling MMU\n");
     el = current_el();
     if (el == EL1) {
-        el1_mmu_enable();
+        el1_mmu_enable(aarch64_pt_ttbr0_el1, aarch64_pt_ttbr1_el1);
     } else if (el == EL2) {
-        el2_mmu_enable();
+        el2_mmu_enable(aarch64_pt_ttbr0_el2);
     } else {
         LDR_PRINT("ERROR", logical_cpu, "unknown EL for MMU enable\n");
     }

loader/src/aarch64/util64.S

@@ -308,7 +308,6 @@ END_FUNC(el1_mmu_disable)
 
 BEGIN_FUNC(el2_mmu_disable)
     stp     x29, x30, [sp, #-16]!
-    stp     x27, x28, [sp, #-16]!
     mov     x29, sp
 
     /* Disable caches */
@@ -323,14 +322,18 @@ BEGIN_FUNC(el2_mmu_disable)
      */
     bl      invalidate_icache
 
-    ldp     x27, x28, [sp], #16
     ldp     x29, x30, [sp], #16
     ret
 END_FUNC(el2_mmu_disable)
 
+/*
+ * Enables the MMU for EL2.
+ * Takes two arguments the physical address for TTBR0_EL1 (x0) and TTBR1_EL1 (x1).
+ */
 BEGIN_FUNC(el1_mmu_enable)
     stp     x29, x30, [sp, #-16]!
     stp     x27, x28, [sp, #-16]!
+    /* move caller-saved to callee-saved registers */
     mov     x29, sp
     mov     x27, x0
     mov     x28, x1
@@ -358,10 +361,8 @@ BEGIN_FUNC(el1_mmu_enable)
     msr     tcr_el1, x10
 
     /* Setup page tables */
-    adrp    x8, boot_lvl0_lower
-    msr     ttbr0_el1, x8
-    adrp    x8, boot_lvl0_upper
-    msr     ttbr1_el1, x8
+    msr     ttbr0_el1, x27  /* argument 0 */
+    msr     ttbr1_el1, x28  /* argument 1 */
     isb
 
     /* invalidate all TLB entries for EL1 */
@@ -374,12 +375,18 @@ BEGIN_FUNC(el1_mmu_enable)
     ldp     x27, x28, [sp], #16
     ldp     x29, x30, [sp], #16
     ret
-
 END_FUNC(el1_mmu_enable)
 
+/*
+ * Enables the MMU for EL2.
+ * Takes one argument, the physical address for TTBR0_EL2 (x0).
+ */
 BEGIN_FUNC(el2_mmu_enable)
     stp     x29, x30, [sp, #-16]!
+    stp     x27, x28, [sp, #-16]!
+    /* move caller-saved to callee-saved registers */
     mov     x29, sp
+    mov     x28, x0
 
     /* Disable the MMU */
     bl      el2_mmu_disable
@@ -403,8 +410,7 @@ BEGIN_FUNC(el2_mmu_enable)
     isb
 
     /* Setup page tables */
-    adrp    x8, boot_lvl0_lower
-    msr     ttbr0_el2, x8
+    msr     ttbr0_el2, x28  /* argument 0 */
     isb
 
     /* invalidate all TLB entries for EL2 */
@@ -423,9 +429,9 @@ BEGIN_FUNC(el2_mmu_enable)
     dsb     ish
     isb
 
+    ldp     x27, x28, [sp], #16
     ldp     x29, x30, [sp], #16
     ret
-
 END_FUNC(el2_mmu_enable)
 
 .extern arm_secondary_cpu_c_entry

loader/src/loader.c

@@ -100,7 +100,6 @@ static int print_lock = 0;
 
 void start_kernel(int logical_cpu)
 {
-    LDR_PRINT("INFO", logical_cpu, "enabling MMU\n");
     int r = arch_mmu_enable(logical_cpu);
     if (r != 0) {
         LDR_PRINT("ERROR", logical_cpu, "failed to enable MMU: ");

loader/src/loader.h

@@ -7,7 +7,7 @@
 
 #pragma once
 
-#define STACK_SIZE 4096
+#define STACK_SIZE 40960
 
 #define REGION_TYPE_DATA 1
 #define REGION_TYPE_ZERO 2