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#!/usr/bin/env python3
"""Does the PSP actually WRITE the fence value to a host-chosen address?
Pass 118 showed a command with fence_addr inside the TMR still returns 0x0. Before claiming a
confused-deputy write, verify the mechanics on a target we CAN read: point fence_addr at a
scratch buffer pre-filled with a known pattern and see whether the fence value appears there.
If it does, the host controls both the destination address (fence_addr) and the value
(fence_value) of a 4-byte write performed by the PSP.
"""
import ctypes, glob, struct, sys, time
sys.path.insert(0,'/root/psp/hw')
from tinygrad import Device
from tinygrad.helpers import wait_cond
import tinygrad.runtime.autogen.am.am as am
adev=Device["AMD"].iface.dev_impl; psp=adev.psp
def alloc(n):
pa=adev.mm.palloc(n,align=0x1000,zero=True,boot=False); return pa,adev.paddr2mc(pa)
frame_sz=ctypes.sizeof(am.struct_psp_gfx_rb_frame); step=frame_sz//4
PAT=0xEEEEEEEE
scratch,smc=alloc(0x1000)
blob=open(glob.glob('/root/psp/contall/ta_42-0-0-6_1c874c3c*')[0],'rb').read()
ap_,amc=alloc(0x80000); cp,cmc=alloc(0x8000)
n=(len(blob)+3)&~3
adev.vram.view(ap_,n)[:]=blob+b'\x00'*(n-len(blob)); adev.gmc.flush_hdp()
def mk():
c=am.struct_psp_gfx_cmd_resp(cmd_id=am.GFX_CMD_ID_LOAD_TA); t=c.cmd.cmd_load_ta
t.app_phy_addr_lo,t.app_phy_addr_hi=amc&0xFFFFFFFF,amc>>32; t.app_len=len(blob)
t.cmd_buf_phy_addr_lo,t.cmd_buf_phy_addr_hi=cmc&0xFFFFFFFF,cmc>>32; t.cmd_buf_len=0x4000
return c
def go(fence_mc, fence_val, tag):
adev.vram.view(scratch,0x1000)[:]=bytes(struct.pack('<I',PAT)*(0x1000//4)); adev.gmc.flush_hdp()
wmax=psp.ring_size//4
prev=adev.reg(f"{psp.reg_pref}_67").read()%wmax
msg=am.struct_psp_gfx_rb_frame(fence_value=fence_val,
cmd_buf_addr_lo=adev.paddr2mc(psp.cmd_paddr)&0xFFFFFFFF,
cmd_buf_addr_hi=adev.paddr2mc(psp.cmd_paddr)>>32,
fence_addr_lo=fence_mc&0xFFFFFFFF, fence_addr_hi=fence_mc>>32)
c=mk()
adev.vram.view(psp.cmd_paddr, ctypes.sizeof(c))[:]=memoryview(c).cast('B')
adev.vram.view(psp.ring_paddr+prev*4, ctypes.sizeof(msg))[:]=memoryview(msg).cast('B')
adev.reg(f"{psp.reg_pref}_67").write((prev+step)%wmax)
time.sleep(1.0)
adev.gmc.flush_hdp()
out=bytes(adev.vram.view(scratch,0x40)[:])
vals=[struct.unpack_from('<I',out,o)[0] for o in range(0,0x20,4)]
hit=[hex(v) for v in vals if v!=PAT]
print(' %-40s fence_val=%#-10x scratch[0:8]=%s changed=%s'
%(tag,fence_val,[hex(v) for v in vals[:4]], hit[:4] or 'NONE'), flush=True)
go(smc, 0xDEADBEEF, 'fence_addr -> our scratch buffer')
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