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local regs = {
"rax", "rbx",
"rcx", "rdx",
"rdi", "rsi",
"rbp", "rsp",
"r8", "r9",
"r10", "r11",
"r12", "r13",
"r14", "r15",
}
print("global watchdog")
print("extern rand, watchdog_err")
print("section .bss")
print("regs_backup: resq 16")
print("regs_rand: resq 16")
print("section .text")
print("watchdog:")
local function iter_regs(f)
for i, r in ipairs(regs) do
f(i-1, r)
end
end
-- backup registers
iter_regs(function(i, r) print("mov [regs_backup+" .. (8*i) .. "], " .. r) end)
-- populate random table
iter_regs(function(i) print("xor rax, rax\ncall rand\nmov [regs_rand+" .. (8*i) .. "], rax") end)
-- read registers from random table
iter_regs(function(i, r)
if r == "rsp" then
print("mov [regs_rand+" .. (8*i) .. "], rsp")
else
print("mov " .. r .. ", [regs_rand+" .. (8*i) .. "]")
end
end)
print(".loop:")
-- wait for interrupts
print("hlt")
-- check and jump if changed
iter_regs(function(i, r)
print("cmp " .. r .. ", [regs_rand+" .. (8*i) .. "]")
print("jne .ch_" .. r)
end)
print("jmp .loop")
-- write error and return
iter_regs(function(i, r)
print(".ch_" .. r .. ":")
print("mov qword[watchdog_err], " .. i)
print("mov qword[watchdog_err+8], " .. r)
print("mov rax, [regs_rand+" .. (8*i) .. "]")
print("mov qword[watchdog_err+16], rax")
print("jmp .ret")
end)
print(".ret:")
-- restore registers
iter_regs(function(i, r)
if r ~= "rsp" then
print("mov " .. r .. ", [regs_backup+" .. (8*i) .. "]")
end
end)
print("ret")
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