patch_user_mem_clear.c

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#include <tamtypes.h>
#include <kernel.h>
 
int sbv_patch_user_mem_clear(void *start)
{
    int ret = -1;
    u32 *p;
 
    DI();
    ee_kmode_enter();
 
    for (p = (unsigned int*)0x80001000; p < (unsigned int*)0x80080000; p++) {
        /*
         * Search for function call and patch $a0
         *  lui  $a0, 0x0008
         *  jal  InitializeUserMemory
         *  ori  $a0, $a0, 0x2000
         */
        if (p[0] == 0x3c040008 && (p[1] & 0xfc000000) == 0x0c000000 && p[2] == 0x34842000) {
            p[0] = 0x3c040000 | ((unsigned int)start >> 16);
            p[2] = 0x34840000 | ((unsigned int)start & 0xffff);
            ret = 0;
            break;
        }
    }
 
    ee_kmode_exit();
    EI();
 
    return ret;
}