Index

STZGM

Store Tag and Zero Multiple writes a naturally aligned block of N Allocation Tags and stores zero to the associated data locations, where the size of N is identified in DCZID_EL0.BS, and the Allocation Tag is taken from the source register bits<3:0>.

This instruction is UNDEFINED at EL0.

This instruction generates an Unchecked access.

Integer
(FEAT_MTE2)

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 1 0 1 1 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 Xn Xt

STZGM <Xt>, [<Xn|SP>]

if !IsFeatureImplemented(FEAT_MTE2) then UNDEFINED;
integer t = UInt(Xt);
integer n = UInt(Xn);

Assembler Symbols

<Xt>

Is the 64-bit name of the general-purpose source register, encoded in the "Xt" field.
<Xn|SP>

Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Xn" field.

Operation

if PSTATE.EL == EL0 then
    UNDEFINED;

bits(64) data = X[t, 64];
bits(4) tag = data<3:0>;
bits(64) address;
if n == 31 then
    CheckSPAlignment();
    address = SP[];
else
    address = X[n, 64];

integer size = 4 * (2 ^ (UInt(DCZID_EL0.BS)));
address = Align(address, size);
integer count = size >> LOG2_TAG_GRANULE;
AccessDescriptor accdesc = CreateAccDescLDGSTG(MemOp_STORE);

for i = 0 to count-1
    AArch64.MemTag[address, accdesc] = tag;
    Mem[address, TAG_GRANULE, accdesc] = Zeros(8 * TAG_GRANULE);
    address = GenerateAddress(address, TAG_GRANULE, accdesc);