KernelModule/source/main.c

#include <whb/log.h>
#include <whb/log_udp.h>
#include <coreinit/memorymap.h>

#include <wums.h>
#include <coreinit/cache.h>

WUMS_MODULE_EXPORT_NAME("homebrew_kernel");

#define KERN_SYSCALL_TBL1 0xFFE84C70 //Unknown
#define KERN_SYSCALL_TBL2 0xFFE85070 //Games
#define KERN_SYSCALL_TBL3 0xFFE85470 //Loader
#define KERN_SYSCALL_TBL4 0xFFEAAA60 //Home menu
#define KERN_SYSCALL_TBL5 0xFFEAAE60 //Browser

extern void SCKernelCopyData(uint32_t dst, uint32_t src, uint32_t len);
extern void KernelCopyDataInternal(uint32_t dst, uint32_t src, uint32_t len);

void kernelInitialize();

extern void  KernelCopyData(uint32_t dst, uint32_t src, uint32_t len){
    KernelCopyDataInternal(dst, src, len);
}
WUMS_EXPORT_FUNCTION(KernelCopyData);

/* Write a 32-bit word with kernel permissions */
void __attribute__ ((noinline)) kern_write(void *addr, uint32_t value) {
    asm volatile (
    "li 3,1\n"
    "li 4,0\n"
    "mr 5,%1\n"
    "li 6,0\n"
    "li 7,0\n"
    "lis 8,1\n"
    "mr 9,%0\n"
    "mr %1,1\n"
    "li 0,0x3500\n"
    "sc\n"
    "nop\n"
    "mr 1,%1\n"
    :
    :    "r"(addr), "r"(value)
    :    "memory", "ctr", "lr", "0", "3", "4", "5", "6", "7", "8", "9", "10",
    "11", "12"
    );
}

/* Read a 32-bit word with kernel permissions */
uint32_t __attribute__ ((noinline)) kern_read(const void *addr) {
    uint32_t result;
    asm volatile (
    "li 3,1\n"
    "li 4,0\n"
    "li 5,0\n"
    "li 6,0\n"
    "li 7,0\n"
    "lis 8,1\n"
    "mr 9,%1\n"
    "li 0,0x3400\n"
    "mr %0,1\n"
    "sc\n"
    "nop\n"
    "mr 1,%0\n"
    "mr %0,3\n"
    :    "=r"(result)
    :    "b"(addr)
    :    "memory", "ctr", "lr", "0", "3", "4", "5", "6", "7", "8", "9", "10",
    "11", "12"
    );

    return result;
}

void PatchSyscall(int index, uint32_t addr) {
    kern_write((void *) (KERN_SYSCALL_TBL1 + index * 4), addr);
    kern_write((void *) (KERN_SYSCALL_TBL2 + index * 4), addr);
    kern_write((void *) (KERN_SYSCALL_TBL3 + index * 4), addr);
    kern_write((void *) (KERN_SYSCALL_TBL4 + index * 4), addr);
    kern_write((void *) (KERN_SYSCALL_TBL5 + index * 4), addr);
}

void kernelInitialize() {
    static uint8_t ucSyscallsSetupRequired = 1;
    if (!ucSyscallsSetupRequired){
        return;
    }
    ucSyscallsSetupRequired = 0;

    PatchSyscall(0x25, (uint32_t) SCKernelCopyData);
WUMS_INITIALIZE(){
    kernelInitialize();
}

int main(int argc, char **argv) {
    return 0;
}