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;
}