Memory Set with tag setting, unprivileged. These instructions perform a memory set using the value in the bottom byte of the source register and store an Allocation Tag to memory for each Tag Granule written. The Allocation Tag is calculated from the Logical Address Tag in the register which holds the first address that the set is made to. The prologue, main, and epilogue instructions are expected to be run in succession and to appear consecutively in memory: SETGPT, then SETGMT, and then SETGET.
SETGPT performs some preconditioning of the arguments suitable for using the SETGMT instruction, and performs an implementation defined amount of the memory set. SETGMT performs an implementation defined amount of the memory set. SETGET performs the last part of the memory set.
The inclusion of implementation defined amounts of memory set allows some optimization of the size that can be performed.
The architecture supports two algorithms for the memory set: option A and option B. Which algorithm is used is implementation defined.
Portable software should not assume that the choice of algorithm is constant.
After execution of SETGPT, option A (which results in encoding PSTATE.C = 0):
After execution of SETGPT, option B (which results in encoding PSTATE.C = 1):
For SETGMT, option A (encoded by PSTATE.C = 0), the format of the arguments is:
For SETGMT, option B (encoded by PSTATE.C = 1), the format of the arguments is:
For SETGET, option A (encoded by PSTATE.C = 0), the format of the arguments is:
For SETGET, option B (encoded by PSTATE.C = 1), the format of the arguments is:
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 |
sz | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | Rs | x | x | 0 | 1 | 0 | 1 | Rn | Rd | |||||||||||||
op2 |
if !HaveFeatMOPS() || !HaveMTEExt() || sz != '00' then UNDEFINED; integer d = UInt(Rd); integer s = UInt(Rs); integer n = UInt(Rn); bits(2) options = op2<1:0>; boolean nontemporal = options<1> == '1'; MOPSStage stage; case op2<3:2> of when '00' stage = MOPSStage_Prologue; when '01' stage = MOPSStage_Main; when '10' stage = MOPSStage_Epilogue; otherwise UNDEFINED; CheckMOPSEnabled(); if s == n || s == d || n == d || d == 31 || n == 31 then Constraint c = ConstrainUnpredictable(Unpredictable_MOPSOVERLAP31); assert c IN {Constraint_UNDEF, Constraint_NOP}; case c of when Constraint_UNDEF UNDEFINED; when Constraint_NOP EndOfInstruction();
For information about the constrained unpredictable behavior of this instruction, see Architectural Constraints on UNPREDICTABLE behaviors, and particularly Memory Copy and Memory Set SET*.
bits(64) toaddress = X[d, 64]; bits(64) setsize = X[n, 64]; bits(8) data = X[s, 8]; bits(4) nzcv = PSTATE.<N,Z,C,V>; boolean is_setg = TRUE; integer B; boolean implements_option_a = SETGOptionA(); boolean privileged = if options<0> == '1' then AArch64.IsUnprivAccessPriv() else PSTATE.EL != EL0; AccessDescriptor accdesc = CreateAccDescSTGMOPS(privileged, nontemporal); if stage == MOPSStage_Prologue then if setsize<63> == '1' then setsize = 0x7FFFFFFFFFFFFFF0<63:0>; if ((!IsZero(setsize) && !IsAligned(toaddress, TAG_GRANULE)) || !IsAligned(setsize, TAG_GRANULE)) then AArch64.Abort(toaddress, AlignmentFault(accdesc)); if implements_option_a then nzcv = '0000'; toaddress = toaddress + setsize; setsize = Zeros(64) - setsize; else nzcv = '0010'; else CheckMemSetParams(stage, implements_option_a, nzcv, options, d, s, n, toaddress, setsize, is_setg); if ((!IsZero(setsize) && !IsAligned(toaddress, TAG_GRANULE)) || !IsAligned(setsize, TAG_GRANULE)) then AArch64.Abort(toaddress, AlignmentFault(accdesc)); bits(64) stagesetsize = MemSetStageSize(stage, toaddress, setsize, is_setg); integer tagstep; bits(4) tag; bits(64) tagaddr; if implements_option_a then while SInt(stagesetsize) < 0 do // IMP DEF selection of the block size that is worked on. While many // implementations might make this constant, that is not assumed. B = SETSizeChoice(toaddress, setsize, 16); assert B <= -1 * SInt(stagesetsize); assert B<3:0> == '0000'; Mem[toaddress+setsize, B, accdesc] = Replicate(data, B); tagstep = B DIV 16; tag = AArch64.AllocationTagFromAddress(toaddress + setsize); while tagstep > 0 do tagaddr = toaddress + setsize + (tagstep - 1) * 16; AArch64.MemTag[tagaddr, accdesc] = tag; tagstep = tagstep - 1; setsize = setsize + B; stagesetsize = stagesetsize + B; if stage != MOPSStage_Prologue then X[n, 64] = setsize; else while UInt(stagesetsize) > 0 do // IMP DEF selection of the block size that is worked on. While many // implementations might make this constant, that is not assumed. B = SETSizeChoice(toaddress, setsize, 16); assert B <= UInt(stagesetsize); assert B<3:0> == '0000'; Mem[toaddress, B, accdesc] = Replicate(data, B); tagstep = B DIV 16; tag = AArch64.AllocationTagFromAddress(toaddress); while tagstep > 0 do tagaddr = toaddress + (tagstep - 1) * 16; AArch64.MemTag[tagaddr, accdesc] = tag; tagstep = tagstep - 1; toaddress = toaddress + B; setsize = setsize - B; stagesetsize = stagesetsize - B; if stage != MOPSStage_Prologue then X[n, 64] = setsize; X[d, 64] = toaddress; if stage == MOPSStage_Prologue then X[n, 64] = setsize; X[d, 64] = toaddress; PSTATE.<N,Z,C,V> = nzcv;
Internal version only: isa v33.64, AdvSIMD v29.12, pseudocode v2023-06_rel, sve v2023-06_rel ; Build timestamp: 2023-07-04T19:42
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