diff options
-rw-r--r-- | Makefile | 12 | ||||
-rw-r--r-- | PL0_test.c | 3 | ||||
-rw-r--r-- | PL0_test.ld | 5 | ||||
-rw-r--r-- | demo_functionality.c | 96 | ||||
-rw-r--r-- | demo_functionality.h | 4 | ||||
-rw-r--r-- | kernel.c | 6 | ||||
-rw-r--r-- | linker.ld | 41 | ||||
-rw-r--r-- | memory.h | 28 |
8 files changed, 33 insertions, 162 deletions
@@ -3,10 +3,6 @@ ELFFLAGS=-ffreestanding -O2 -nostdlib -lgcc -I. ARM_OBJECTS=kernel.o paging.o demo_functionality.o PL0_test.o uart.o loader_stage1.o loader_stage2.o -EMBEDDABLE_OBJECTS=PL_0_test_embeddable.o loader_stage2_embeddable.o - -RENAME_FLAGS=--rename-section .data=.renamed_data --rename-section .rodata=.renamed_rodata --rename-section .text=.renamed_text --rename-section .bss=.renamed_bss - all : kernel7.img %.o : %.c @@ -21,16 +17,10 @@ all : kernel7.img %_embeddable.o : %.img arm-none-eabi-objcopy -I binary -O elf32-littlearm -B arm --rename-section .data=.rodata $^ $@ -libkernel.o : libkernel.c - arm-none-eabi-gcc $(CFLAGS) -fPIC -c $^ -o $@ - -libkernel_renamed.o : libkernel.o - arm-none-eabi-objcopy $(RENAME_FLAGS) $^ $@ - PL_0_test.elf : PL0_test.o uart.o arm-none-eabi-gcc -T PL0_test.ld -o $@ $(ELFFLAGS) $^ -kernel.elf : boot.o kernel.o uart.o PL_0_test_embeddable.o demo_functionality.o paging.o libkernel_renamed.o +kernel.elf : boot.o kernel.o uart.o PL_0_test_embeddable.o demo_functionality.o paging.o arm-none-eabi-gcc -T linker.ld -o $@ $(ELFFLAGS) $^ loader_stage2.elf : loader_stage2.o uart.o @@ -5,6 +5,9 @@ void PL0_main(void) { uart_puts("hello PL0! Switching to user mode!\n\r"); + asm("cps #0b10000\n\r" + "isb" ::: "memory"); + // if all went correct, Success! gets printed uart_puts("Success!\n\r"); diff --git a/PL0_test.ld b/PL0_test.ld index 45bee5e..430e098 100644 --- a/PL0_test.ld +++ b/PL0_test.ld @@ -4,11 +4,6 @@ SECTIONS { /* 0b10101010101000000000000000000000 */ . = 0xaaa00000; - - /* For some reason ld warns when _start is not defined. */ - /* Other .elf files link ok - only PL0_test.elf seems to */ - /* expect _start to be deifned. */ - _start = .; __start = .; __text_start = .; .text : diff --git a/demo_functionality.c b/demo_functionality.c index fbf5eb4..7bba6a6 100644 --- a/demo_functionality.c +++ b/demo_functionality.c @@ -2,7 +2,6 @@ #include "psr.h" #include "memory.h" #include "translation_table_descriptors.h" -#include "libkernel.h" void demo_paging_support(void) { @@ -56,73 +55,35 @@ void demo_mode_to_system(void) set_system_mode(); } -#define TRANSLATION_TABLE \ - ((short_section_descriptor_t volatile*) TRANSLATION_TABLE_BASE) - -extern char - __renamed_start, - __renamed_end, - __renamed_size; - -void demo_setup_libkernel(void) { - short_section_descriptor_t volatile *libkernel_section_entry = - &TRANSLATION_TABLE[LIBKERNEL_SECTION_NUMBER]; - - short_section_descriptor_t - libkernel_section = *libkernel_section_entry; - - // make libkernel section executable and read-only for - // unprivileged code - libkernel_section.ACCESS_PERMISSIONS_2 = - AP_2_0_MODEL_RW_PL1_RO_PL0 >> 2; - libkernel_section.ACCESS_PERMISSIONS_1_0 = - AP_2_0_MODEL_RW_PL1_RO_PL0 & 0b011; - - *libkernel_section_entry = libkernel_section; - - // invalidate main Translation Lookup Buffer (just in case) - asm("mcr p15, 0, %0, c8, c7, 0\n\r" - "isb" :: "r" (0) : "memory"); - - // copy libkernel code to libkernel section - for (size_t i = 0; i < (size_t) &__renamed_size; i++) - ((volatile char*) LIBKERNEL_SECTION_START)[i] = - (&__renamed_start)[i]; -} - extern char _binary_PL_0_test_img_start, _binary_PL_0_test_img_end, _binary_PL_0_test_img_size; -void demo_setup_PL0(void) +void demo_go_unprivileged(void) { - short_section_descriptor_t volatile *PL0_section_entry = - &TRANSLATION_TABLE[PL0_SECTION_NUMBER]; - short_section_descriptor_t volatile *UART_memory_section_entry = - &TRANSLATION_TABLE[((uint32_t) GPIO_BASE) >> 20]; + short_section_descriptor_t *translation_table = + (short_section_descriptor_t*) TRANSLATION_TABLE_BASE; - short_section_descriptor_t - PL0_section = *PL0_section_entry, - UART_memory_section = *UART_memory_section_entry; + volatile short_section_descriptor_t *PL0_section = + &translation_table[PL0_SECTION_NUMBER]; + volatile short_section_descriptor_t *UART_memory_section = + &translation_table[((uint32_t) GPIO_BASE) >> 20]; - // set up address of PL0 section - PL0_section.SECTION_BASE_ADDRESS_31_20 = + PL0_section->SECTION_BASE_ADDRESS_31_20 = UNPRIVILEGED_MEMORY_START >> 20; // make the selected section and uart section available for PL0 - PL0_section.ACCESS_PERMISSIONS_2 = + PL0_section->ACCESS_PERMISSIONS_2 = AP_2_0_MODEL_RW_ALL >> 2; - PL0_section.ACCESS_PERMISSIONS_1_0 = + PL0_section->ACCESS_PERMISSIONS_1_0 = AP_2_0_MODEL_RW_ALL & 0b011; - UART_memory_section.ACCESS_PERMISSIONS_2 = + UART_memory_section->ACCESS_PERMISSIONS_2 = AP_2_0_MODEL_RW_ALL >> 2; - UART_memory_section.ACCESS_PERMISSIONS_1_0 = + UART_memory_section->ACCESS_PERMISSIONS_1_0 = AP_2_0_MODEL_RW_ALL & 0b011; - - *PL0_section_entry = PL0_section; - *UART_memory_section_entry = UART_memory_section; + // invalidate main Translation Lookup Buffer (just in case) asm("mcr p15, 0, %0, c8, c7, 0\n\r" @@ -138,30 +99,17 @@ void demo_setup_PL0(void) uart_puts((char*) VIRTUAL_PL0_MEMORY_START); - // now paste a userspace program to that section + // now paste a userspace program to that section, jump to it and + // switch to PL0 for (size_t i = 0; i < (size_t) &_binary_PL_0_test_img_size; i++) ((volatile char*) VIRTUAL_PL0_MEMORY_START)[i] = (&_binary_PL_0_test_img_start)[i]; - uart_puts("copied PL0 and libkernel code to their sections"); -} - -void demo_go_unprivileged(void) -{ - size_t call_unprivileged_offset = - (size_t) &call_unprivileged - (size_t) &__renamed_start; - - void *call_unprivileged_new_location = - (void*) (LIBKERNEL_SECTION_START + call_unprivileged_offset); - - // call call_unprivileged from libkernel - asm volatile("mov r5, %0\n\r" - "mov r0, %1\n\r" - "mov r4, #0\n\r" - "movt r4, #"PL0_SECTION_NUMBER_STR"1111\n\r" - "mov sp, r4\n\r" // setting stack is important :D - "blx r5\n\r" :: - "r" (call_unprivileged_new_location), - "r" (VIRTUAL_PL0_MEMORY_START) - : "memory", "r4", "r5", "r0"); + // jump to that copied code (switch to PL0 is done by that code) + asm volatile("mov r5, #0\n\r" + "movt r5, #"PL0_SECTION_NUMBER_STR"1111\n\r" + "mov sp, r5\n\r" // setting stack is important :D + "mov r5, #0\n\r" + "movt r5, #"PL0_SECTION_NUMBER_STR"0000\n\r" + "blx r5\n\r"); } diff --git a/demo_functionality.h b/demo_functionality.h index 5d6e659..c8b163f 100644 --- a/demo_functionality.h +++ b/demo_functionality.h @@ -5,10 +5,6 @@ void demo_paging_support(void); void demo_mode_to_system(void); -void demo_setup_libkernel(void); - -void demo_setup_PL0(void); - void demo_go_unprivileged(void); #endif // DEMO_FUNCTIONALITY_H @@ -29,12 +29,6 @@ void kernel_main(uint32_t r0, uint32_t r1, uint32_t atags) // prints some info and sets upp translation table, turns on MMU setup_flat_map(); - demo_setup_libkernel(); - - demo_setup_PL0(); - - demo_go_unprivileged(); - // prints some info and sets up a section for PL0 code, loads a blob // there and jumps to it... never, ever, ever returns demo_go_unprivileged(); @@ -49,46 +49,5 @@ SECTIONS . = ALIGN(4096); /* align to page size */ __bss_end = .; __bss_size = __bss_end - __bss_start; - - - - /* Here come the definitions for renamed sections */ - __renamed_start = .; - __renamed_text_start = .; - .renamed_text : - { - *(.renamed_text) - } - . = ALIGN(4096); /* align to page size */ - __renamed_text_end = .; - - __renamed_rodata_start = .; - .renamed_rodata : - { - *(.renamed_rodata) - } - . = ALIGN(4096); /* align to page size */ - __renamed_rodata_end = .; - - __renamed_data_start = .; - .renamed_data : - { - *(.renamed_data) - } - . = ALIGN(4096); /* align to page size */ - __renamed_data_end = .; - - __renamed_bss_start = .; - .renamed_bss : - { - renamed_bss = .; - *(.renamed_bss) - } - . = ALIGN(4096); /* align to page size */ - __renamed_bss_end = .; - __renamed_bss_size = __renamed_bss_end - __renamed_bss_start; - __renamed_end = .; - __renamed_size = __renamed_end - __renamed_start; - __end = .; } @@ -1,17 +1,13 @@ #ifndef MEMORY_H #define MEMORY_H -#include "paging.h" - -#define SECTION_SIZE (((uint32_t) 1) << 20) - #define INTERRUPT_VECTOR_TABLE_START ((uint32_t) 0x0) #define STACK_START ((uint32_t) 0x4000) #define STACK_END ((uint32_t) 0x8000) -extern const char __end; -extern const char __start; +extern char __end; +extern char __start; #define KERNEL_START ((uint32_t) &__start) #define KERNEL_END ((uint32_t) &__end) @@ -24,21 +20,11 @@ extern const char __start; #define TRANSLATION_TABLE_END \ (TRANSLATION_TABLE_BASE + (uint32_t) (4096 * 4)) -#define LIBKERNEL_SECTION_START \ - (((TRANSLATION_TABLE_END - (uint32_t) 1) & ~((uint32_t) 0xfffff)) \ - + SECTION_SIZE) - -#define LIBKERNEL_SECTION_END \ - (LIBKERNEL_SECTION_START + SECTION_SIZE) +#define PRIVILEGED_MEMORY_END TRANSLATION_TABLE_END -// section for libkernel is flat-mapped -#define LIBKERNEL_SECTION_NUMBER (LIBKERNEL_SECTION_START >> 20) - -#define PRIVILEGED_MEMORY_END LIBKERNEL_SECTION_END - -#define UNPRIVILEGED_MEMORY_START PRIVILEGED_MEMORY_END -#define UNPRIVILEGED_MEMORY_END \ - (UNPRIVILEGED_MEMORY_START + SECTION_SIZE) +#define UNPRIVILEGED_MEMORY_START \ + (((PRIVILEGED_MEMORY_END - (uint32_t) 1) & ~((uint32_t) 0xfffff)) \ + + (uint32_t) 0x100000) #define PL0_SECTION_NUMBER ((uint32_t) 0b101010101010) #define PL0_SECTION_NUMBER_STR "0b101010101010" @@ -46,4 +32,4 @@ extern const char __start; #define VIRTUAL_PL0_MEMORY_START (PL0_SECTION_NUMBER << 20) #endif // MEMORY_H - + |