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#include "uart.h"
#include "psr.h"
#include "memory.h"
#include "translation_table_descriptors.h"
#include "ramfs.h"
void demo_paging_support(void)
{
uint32_t ID_MMFR0;
// get contents of coprocessor register to check for paging support
asm("mrc p15, 0, %0, c0, c1, 4" : "=r" (ID_MMFR0));
char *paging;
switch(ID_MMFR0 & 0xf) /* lowest 4 bits indicate VMSA support */
{
case 0 : paging = "no paging\n\r"; break;
case 1 : paging = "implementation defined paging\n\r"; break;
case 2 : paging = "VMSAv6, with cache and TLB type registers\n\r"; break;
case 3 : paging = "VMSAv7, with support for remapping and access flag\n\r"; break;
case 4 : paging = "VMSAv7 with PXN bit supported\n\r"; break;
case 5 : paging = "VMSAv7, PXN and long format descriptors. EPAE is supported.\n\r"; break;
default : paging = "?_? unknown paging ?_?\n\r";
}
uart_puts(paging);
}
void demo_current_mode(void)
{
// get content of current program status register to check the current
// processor mode (should be system, as we set it in boot.S)
PSR_t CPSR = read_CPSR();
char *mode_name;
switch(CPSR.fields.PSR_MODE_4_0)
{
case MODE_USER : mode_name = "User (PL0)\r\n"; break;
case MODE_FIQ : mode_name = "FIQ (PL1)\r\n"; break;
case MODE_IRQ : mode_name = "IRQ (PL1)\r\n"; break;
case MODE_SUPERVISOR : mode_name = "Supervisor (PL1)\r\n"; break;
case MODE_MONITOR : mode_name = "Monitor (PL1)\r\n"; break;
case MODE_ABORT : mode_name = "Abort (PL1)\r\n"; break;
case MODE_HYPERVISOR : mode_name = "Hyp (PL2)\r\n"; break;
case MODE_UNDEFINED : mode_name = "Undefined (PL1)\r\n"; break;
case MODE_SYSTEM : mode_name = "System (PL1)\r\n"; break;
default : mode_name = "Unknown mode\r\n"; break;
}
uart_puts("current mode: ");
uart_puts(mode_name);
}
#define TRANSLATION_TABLE \
((short_section_descriptor_t volatile*) TRANSLATION_TABLE_BASE)
extern char
_binary_ramfs_img_start,
_binary_ramfs_img_end,
_binary_ramfs_img_size;
void demo_setup_PL0(void)
{
// find PL_0_test.img im ramfs
struct ramfile PL_0_test_img;
if (find_file(&_binary_ramfs_img_start, "PL_0_test.img",
&PL_0_test_img))
{
uart_puts("PL_0_test.img not found :(\r\n");
asm volatile ("wfi");
}
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
PL0_section = *PL0_section_entry,
UART_memory_section = *UART_memory_section_entry;
// set up address of PL0 section
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 =
AP_2_0_MODEL_RW_ALL >> 2;
PL0_section.ACCESS_PERMISSIONS_1_0 =
AP_2_0_MODEL_RW_ALL & 0b011;
UART_memory_section.ACCESS_PERMISSIONS_2 =
AP_2_0_MODEL_RW_ALL >> 2;
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"
"isb" :: "r" (0) : "memory");
// check that translation works... by copying a string using one
// mapping and reading it using other :D
char message[] = "mapped sections for PL0 code\n\r";
unsigned int i;
for (i = 0; i < sizeof(message); i++)
((volatile char*) UNPRIVILEGED_MEMORY_START)[i] = message[i];
uart_puts((char*) VIRTUAL_PL0_MEMORY_START);
// now paste a userspace program to that section
for (uint32_t i = 0; i < PL_0_test_img.file_size; i++)
((volatile char*) VIRTUAL_PL0_MEMORY_START)[i] =
PL_0_test_img.file_contents[i];
uart_puts("copied PL0 code to it's section\n\r");
}
// needed for array initialization in demo_go_unprivileged()
void *memset(void *s, int c, size_t n)
{
char *mem = s;
for (size_t i = 0; i < n; i++)
mem[i] = c;
return s;
}
void demo_go_unprivileged(void)
{
uint32_t PL0_regs[16] = {0};
PL0_regs[15] = VIRTUAL_PL0_MEMORY_START; // the new pc
PL0_regs[13] = (PL0_SECTION_NUMBER + 1) << 20; // the new sp
PSR_t new_SPSR = read_CPSR();
new_SPSR.fields.PSR_MODE_4_0 = MODE_USER;
write_SPSR(new_SPSR);
uart_puts("All ready, jumping to PL0 code\n\r");
asm volatile("ldm %0, {r0 - r15} ^" ::
"r" (PL0_regs));
}
extern char
__interrupts_start,
__interrupts_end,
__interrupts_size;
extern void (*volatile system_reentry_point)(void);
void system_reentry(void)
{
uart_puts("re-entered system");
while(1);
}
void demo_setup_interrupts(void)
{
system_reentry_point = system_reentry;
for (size_t i = 0; i < (size_t) &__interrupts_size; i++)
((volatile char*) 0)[i] =
(&__interrupts_start)[i];
}
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