diff options
| -rw-r--r-- | Makefile | 6 | ||||
| -rw-r--r-- | PL0_test.c | 27 | ||||
| -rw-r--r-- | PL0_utils.c | 27 | ||||
| -rw-r--r-- | PL0_utils.h | 10 | ||||
| -rw-r--r-- | interrupts.c | 22 | ||||
| -rw-r--r-- | svc.S | 5 | ||||
| -rw-r--r-- | svc_interface.h | 11 |
7 files changed, 88 insertions, 20 deletions
@@ -5,6 +5,8 @@ ARM_OBJECTS=kernel.o paging.o demo_functionality.o PL0_test.o uart.o loader_stag KERNEL_STAGE2_OBJECTS=setup.o interrupt_vector.o interrupts.o uart.o demo_functionality.o paging.o ramfs_embeddable.o ramfs.o +PL_0_TEST_OBJECTS=PL0_utils.o svc.o PL0_test.o uart.o + RAMFS_FILES=PL_0_test.img all : kernel.img @@ -21,8 +23,8 @@ all : kernel.img %_embeddable.o : %.img arm-none-eabi-objcopy -I binary -O elf32-littlearm -B arm $^ $@ -PL_0_test.elf : PL0_test.ld PL0_test.o uart.o - arm-none-eabi-gcc -T $< -o $@ $(ELFFLAGS) PL0_test.o uart.o +PL_0_test.elf : PL0_test.ld $(PL_0_TEST_OBJECTS) + arm-none-eabi-gcc -T $< -o $@ $(ELFFLAGS) $(PL_0_TEST_OBJECTS) kernel_stage1.o : kernel_stage1.S kernel_stage2.img arm-none-eabi-as -mcpu=cortex-a7 $< -o $@ @@ -1,34 +1,29 @@ -#include "uart.h" -#include "psr.h" +#include "PL0_utils.h" // entry point - must remain the only function in the file! void PL0_main(void) { - // If all went correct, Success! gets printed - uart_puts("Success!\n\r"); - - uart_puts("calling supervisor\n\r"); - - asm volatile("svc #0"); - - uart_puts("back from supervisor call\n\r"); + // If loading program to userspace and handling of svc are + // implemented correctly, this shall get printed + puts("Hello userspace!"); - // if we're indeed in PL0, we should crash now, when trying to access - // memory we're not allowed to + // if we're indeed in PL0, we should trigger the abort handler now, + // when trying to access memory we're not allowed to + puts("Attempting to meddle with kernel memory from userspace :d"); char first_kernel_byte[2]; - first_kernel_byte[0] = *(char*) ((uint32_t) 0x0); + first_kernel_byte[0] = *(char*) 0x0; first_kernel_byte[1] = '\0'; uart_puts(first_kernel_byte); while (1) { - char c = uart_getc(); + char c = getchar(); - uart_putc(c); + putchar(c); if (c == '\r') - uart_putc('\n'); + putchar('\n'); } } diff --git a/PL0_utils.c b/PL0_utils.c new file mode 100644 index 0000000..2cede90 --- /dev/null +++ b/PL0_utils.c @@ -0,0 +1,27 @@ +#include <stddef.h> +#include <stdint.h> + +#include "svc_interface.h" + +// most generic definition possible +// the actual function defined in svc.S +uint32_t svc(enum svc_type, ...); + +void putchar(int character) +{ + svc(UART_PUTCHAR, character); +} + +int getchar(void) +{ + return svc(UART_GETCHAR); +} + +void puts(char *string) +{ + for (size_t i = 0; string[i]; i++) + putchar(string[i]); + + putchar('\n'); + putchar('\r'); +} diff --git a/PL0_utils.h b/PL0_utils.h new file mode 100644 index 0000000..ba72fd3 --- /dev/null +++ b/PL0_utils.h @@ -0,0 +1,10 @@ +#ifndef PL0_UTILS_H +#define PL0_UTILS_H + +void putchar(int character); + +int getchar(void); + +void puts(char *string); + +#endif // PL0_UTILS_H diff --git a/interrupts.c b/interrupts.c index 7932d23..f47bc1d 100644 --- a/interrupts.c +++ b/interrupts.c @@ -1,4 +1,5 @@ #include "uart.h" +#include "svc_interface.h" void setup(void); @@ -24,9 +25,26 @@ void undefined_instruction_vector(void) } } -void supervisor_call_handler(void) +uint32_t supervisor_call_handler(enum svc_type request, uint32_t arg1, + uint32_t arg2, uint32_t arg3) { - uart_puts("something svc happened\n\r"); + (void) arg2; (void) arg3; // unused for now + + switch(request) { + case UART_PUTCHAR: + uart_putc(arg1); + break; + case UART_GETCHAR: + return uart_getc(); + case UART_WRITE: + uart_puts("UART_WRITE not implemented!!!!!\n\r"); + break; + default: + // perhaps we should kill the process now? + uart_puts("unknown supervisor call type!!!!!\n\r"); + } + + return 0; // a dummy value } void abort_handler(void) @@ -0,0 +1,5 @@ +.global svc + +svc: + svc #0 + mov pc, lr diff --git a/svc_interface.h b/svc_interface.h new file mode 100644 index 0000000..aa478ce --- /dev/null +++ b/svc_interface.h @@ -0,0 +1,11 @@ +#ifndef SVC_INTERFACE_H +#define SVC_INTERFACE_H + +enum svc_type + { + UART_PUTCHAR, + UART_GETCHAR, + UART_WRITE + }; + +#endif // SVC_INTERFACE_H |