func nacladdr(ctxt *liblink.Link, p *liblink.Prog, a *liblink.Addr) {
if p.As == ALEAL || p.As == ALEAQ {
return
}
if a.Typ == D_BP || a.Typ == D_INDIR+D_BP {
ctxt.Diag("invalid address: %P", p)
return
}
if a.Typ == D_INDIR+D_TLS {
a.Typ = D_INDIR + D_BP
} else if a.Typ == D_TLS {
a.Typ = D_BP
}
if D_INDIR <= a.Typ && a.Typ <= D_INDIR+D_INDIR {
switch a.Typ {
// all ok
case D_INDIR + D_BP,
D_INDIR + D_SP,
D_INDIR + D_R15:
break
default:
if a.Index != D_NONE {
ctxt.Diag("invalid address %P", p)
}
a.Index = a.Typ - D_INDIR
if a.Index != D_NONE {
a.Scale = 1
}
a.Typ = D_INDIR + D_R15
break
}
}
}
// Append code to p to check for stack split.
// Appends to (does not overwrite) p.
// Assumes g is in CX.
// Returns last new instruction.
// On return, *jmpok is the instruction that should jump
// to the stack frame allocation if no split is needed.
func stacksplit(ctxt *liblink.Link, p *liblink.Prog, framesize int64, noctxt int, jmpok **liblink.Prog) *liblink.Prog {
var q *liblink.Prog
var q1 *liblink.Prog
var arg int
if ctxt.Debugstack != 0 {
// 8l -K means check not only for stack
// overflow but stack underflow.
// On underflow, INT 3 (breakpoint).
// Underflow itself is rare but this also
// catches out-of-sync stack guard info.
p = liblink.Appendp(ctxt, p)
p.As = ACMPL
p.From.Typ = D_INDIR + D_CX
p.From.Offset = 4
p.To.Typ = D_SP
p = liblink.Appendp(ctxt, p)
p.As = AJCC
p.To.Typ = D_BRANCH
p.To.Offset = 4
q1 = p
p = liblink.Appendp(ctxt, p)
p.As = AINT
p.From.Typ = D_CONST
p.From.Offset = 3
p = liblink.Appendp(ctxt, p)
p.As = ANOP
q1.Pcond = p
}
q1 = nil
if framesize <= liblink.StackSmall {
// small stack: SP <= stackguard
// CMPL SP, stackguard
p = liblink.Appendp(ctxt, p)
p.As = ACMPL
p.From.Typ = D_SP
p.To.Typ = D_INDIR + D_CX
} else if framesize <= liblink.StackBig {
// large stack: SP-framesize <= stackguard-StackSmall
// LEAL -(framesize-StackSmall)(SP), AX
// CMPL AX, stackguard
p = liblink.Appendp(ctxt, p)
p.As = ALEAL
p.From.Typ = D_INDIR + D_SP
p.From.Offset = -(framesize - liblink.StackSmall)
p.To.Typ = D_AX
p = liblink.Appendp(ctxt, p)
p.As = ACMPL
p.From.Typ = D_AX
p.To.Typ = D_INDIR + D_CX
} else {
// Such a large stack we need to protect against wraparound
// if SP is close to zero.
// SP-stackguard+StackGuard <= framesize + (StackGuard-StackSmall)
// The +StackGuard on both sides is required to keep the left side positive:
// SP is allowed to be slightly below stackguard. See stack.h.
//
// Preemption sets stackguard to StackPreempt, a very large value.
// That breaks the math above, so we have to check for that explicitly.
// MOVL stackguard, CX
// CMPL CX, $StackPreempt
// JEQ label-of-call-to-morestack
// LEAL StackGuard(SP), AX
// SUBL stackguard, AX
// CMPL AX, $(framesize+(StackGuard-StackSmall))
p = liblink.Appendp(ctxt, p)
p.As = AMOVL
p.From.Typ = D_INDIR + D_CX
p.From.Offset = 0
p.To.Typ = D_SI
p = liblink.Appendp(ctxt, p)
p.As = ACMPL
p.From.Typ = D_SI
p.To.Typ = D_CONST
p.To.Offset = int64(uint32(liblink.StackPreempt & 0xFFFFFFFF))
p = liblink.Appendp(ctxt, p)
p.As = AJEQ
p.To.Typ = D_BRANCH
q1 = p
p = liblink.Appendp(ctxt, p)
p.As = ALEAL
p.From.Typ = D_INDIR + D_SP
p.From.Offset = liblink.StackGuard
p.To.Typ = D_AX
p = liblink.Appendp(ctxt, p)
p.As = ASUBL
p.From.Typ = D_SI
p.From.Offset = 0
p.To.Typ = D_AX
p = liblink.Appendp(ctxt, p)
p.As = ACMPL
p.From.Typ = D_AX
p.To.Typ = D_CONST
p.To.Offset = framesize + (liblink.StackGuard - liblink.StackSmall)
}
// common
p = liblink.Appendp(ctxt, p)
p.As = AJHI
p.To.Typ = D_BRANCH
p.To.Offset = 4
q = p
p = liblink.Appendp(ctxt, p) // save frame size in DI
p.As = AMOVL
p.To.Typ = D_DI
p.From.Typ = D_CONST
// If we ask for more stack, we'll get a minimum of StackMin bytes.
// We need a stack frame large enough to hold the top-of-stack data,
// the function arguments+results, our caller's PC, our frame,
// a word for the return PC of the next call, and then the StackLimit bytes
// that must be available on entry to any function called from a function
// that did a stack check. If StackMin is enough, don't ask for a specific
// amount: then we can use the custom functions and save a few
// instructions.
if int64(liblink.StackTop+ctxt.Cursym.Text.To.Offset2)+ctxt.Arch.Ptrsize+framesize+ctxt.Arch.Ptrsize+liblink.StackLimit >= liblink.StackMin {
p.From.Offset = (framesize + 7) &^ 7
}
arg = ctxt.Cursym.Text.To.Offset2
if arg == 1 { // special marker for known 0
arg = 0
}
if arg&3 != 0 {
ctxt.Diag("misaligned argument size in stack split")
}
p = liblink.Appendp(ctxt, p) // save arg size in AX
p.As = AMOVL
p.To.Typ = D_AX
p.From.Typ = D_CONST
p.From.Offset = int64(arg)
p = liblink.Appendp(ctxt, p)
p.As = ACALL
p.To.Typ = D_BRANCH
p.To.Sym = ctxt.Symmorestack[noctxt]
p = liblink.Appendp(ctxt, p)
p.As = AJMP
p.To.Typ = D_BRANCH
p.Pcond = ctxt.Cursym.Text.Link
if q != nil {
q.Pcond = p.Link
}
if q1 != nil {
q1.Pcond = q.Link
}
*jmpok = q
return p
}
func stacksplit(ctxt *liblink.Link, p *liblink.Prog, framesize int64, noctxt int) *liblink.Prog {
var arg int
// MOVW g_stackguard(g), R1
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.From.Typ = D_OREG
p.From.Reg = REGG
p.To.Typ = D_REG
p.To.Reg = 1
if framesize <= liblink.StackSmall {
// small stack: SP < stackguard
// CMP stackguard, SP
p = liblink.Appendp(ctxt, p)
p.As = ACMP
p.From.Typ = D_REG
p.From.Reg = 1
p.Reg = REGSP
} else if framesize <= liblink.StackBig {
// large stack: SP-framesize < stackguard-StackSmall
// MOVW $-framesize(SP), R2
// CMP stackguard, R2
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.From.Typ = D_CONST
p.From.Reg = REGSP
p.From.Offset = -framesize
p.To.Typ = D_REG
p.To.Reg = 2
p = liblink.Appendp(ctxt, p)
p.As = ACMP
p.From.Typ = D_REG
p.From.Reg = 1
p.Reg = 2
} else {
// Such a large stack we need to protect against wraparound
// if SP is close to zero.
// SP-stackguard+StackGuard < framesize + (StackGuard-StackSmall)
// The +StackGuard on both sides is required to keep the left side positive:
// SP is allowed to be slightly below stackguard. See stack.h.
// CMP $StackPreempt, R1
// MOVW.NE $StackGuard(SP), R2
// SUB.NE R1, R2
// MOVW.NE $(framesize+(StackGuard-StackSmall)), R3
// CMP.NE R3, R2
p = liblink.Appendp(ctxt, p)
p.As = ACMP
p.From.Typ = D_CONST
p.From.Offset = int64(uint32(liblink.StackPreempt & 0xFFFFFFFF))
p.Reg = 1
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.From.Typ = D_CONST
p.From.Reg = REGSP
p.From.Offset = liblink.StackGuard
p.To.Typ = D_REG
p.To.Reg = 2
p.Scond = C_SCOND_NE
p = liblink.Appendp(ctxt, p)
p.As = ASUB
p.From.Typ = D_REG
p.From.Reg = 1
p.To.Typ = D_REG
p.To.Reg = 2
p.Scond = C_SCOND_NE
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.From.Typ = D_CONST
p.From.Offset = framesize + (liblink.StackGuard - liblink.StackSmall)
p.To.Typ = D_REG
p.To.Reg = 3
p.Scond = C_SCOND_NE
p = liblink.Appendp(ctxt, p)
p.As = ACMP
p.From.Typ = D_REG
p.From.Reg = 3
p.Reg = 2
p.Scond = C_SCOND_NE
}
// MOVW.LS $framesize, R1
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.Scond = C_SCOND_LS
p.From.Typ = D_CONST
p.From.Offset = framesize
p.To.Typ = D_REG
p.To.Reg = 1
// MOVW.LS $args, R2
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.Scond = C_SCOND_LS
p.From.Typ = D_CONST
arg = ctxt.Cursym.Text.To.Offset2
if arg == 1 { // special marker for known 0
arg = 0
}
if arg&3 != 0 {
ctxt.Diag("misaligned argument size in stack split")
}
p.From.Offset = int64(arg)
p.To.Typ = D_REG
p.To.Reg = 2
// MOVW.LS R14, R3
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.Scond = C_SCOND_LS
p.From.Typ = D_REG
p.From.Reg = REGLINK
p.To.Typ = D_REG
p.To.Reg = 3
// BL.LS runtime.morestack(SB) // modifies LR, returns with LO still asserted
p = liblink.Appendp(ctxt, p)
p.As = ABL
p.Scond = C_SCOND_LS
p.To.Typ = D_BRANCH
p.To.Sym = ctxt.Symmorestack[noctxt]
// BLS start
p = liblink.Appendp(ctxt, p)
p.As = ABLS
p.To.Typ = D_BRANCH
p.Pcond = ctxt.Cursym.Text.Link
return p
}
func addstacksplit(ctxt *liblink.Link, cursym *liblink.LSym) {
var p *liblink.Prog
var q *liblink.Prog
var autoffset int64
var deltasp int64
var a int
if ctxt.Symmorestack[0] == nil {
ctxt.Symmorestack[0] = liblink.Linklookup(ctxt, "runtime.morestack", 0)
ctxt.Symmorestack[1] = liblink.Linklookup(ctxt, "runtime.morestack_noctxt", 0)
}
if ctxt.Headtype == liblink.Hplan9 && ctxt.Plan9privates == nil {
ctxt.Plan9privates = liblink.Linklookup(ctxt, "_privates", 0)
}
ctxt.Cursym = cursym
if cursym.Text == nil || cursym.Text.Link == nil {
return
}
p = cursym.Text
autoffset = p.To.Offset
if autoffset < 0 {
autoffset = 0
}
cursym.Locals = autoffset
cursym.Args = p.To.Offset2
q = nil
if p.From.Scale&liblink.NOSPLIT == 0 || (p.From.Scale&liblink.WRAPPER != 0) {
p = liblink.Appendp(ctxt, p)
p = load_g_cx(ctxt, p) // load g into CX
}
if cursym.Text.From.Scale&liblink.NOSPLIT == 0 {
p = stacksplit(ctxt, p, autoffset, bool2int(cursym.Text.From.Scale&liblink.NEEDCTXT == 0), &q) // emit split check
}
if autoffset != 0 {
p = liblink.Appendp(ctxt, p)
p.As = AADJSP
p.From.Typ = D_CONST
p.From.Offset = autoffset
p.Spadj = autoffset
} else {
// zero-byte stack adjustment.
// Insert a fake non-zero adjustment so that stkcheck can
// recognize the end of the stack-splitting prolog.
p = liblink.Appendp(ctxt, p)
p.As = ANOP
p.Spadj = -ctxt.Arch.Ptrsize
p = liblink.Appendp(ctxt, p)
p.As = ANOP
p.Spadj = ctxt.Arch.Ptrsize
}
if q != nil {
q.Pcond = p
}
deltasp = autoffset
if cursym.Text.From.Scale&liblink.WRAPPER != 0 {
// g->panicwrap += autoffset + ctxt->arch->ptrsize;
p = liblink.Appendp(ctxt, p)
p.As = AADDL
p.From.Typ = D_CONST
p.From.Offset = autoffset + ctxt.Arch.Ptrsize
p.To.Typ = D_INDIR + D_CX
p.To.Offset = 2 * ctxt.Arch.Ptrsize
}
if ctxt.Debugzerostack != 0 && autoffset != 0 && cursym.Text.From.Scale&liblink.NOSPLIT == 0 {
// 8l -Z means zero the stack frame on entry.
// This slows down function calls but can help avoid
// false positives in garbage collection.
p = liblink.Appendp(ctxt, p)
p.As = AMOVL
p.From.Typ = D_SP
p.To.Typ = D_DI
p = liblink.Appendp(ctxt, p)
p.As = AMOVL
p.From.Typ = D_CONST
p.From.Offset = autoffset / 4
p.To.Typ = D_CX
p = liblink.Appendp(ctxt, p)
p.As = AMOVL
p.From.Typ = D_CONST
p.From.Offset = 0
p.To.Typ = D_AX
p = liblink.Appendp(ctxt, p)
p.As = AREP
p = liblink.Appendp(ctxt, p)
p.As = ASTOSL
}
for ; p != nil; p = p.Link {
a = p.From.Typ
if a == D_AUTO {
p.From.Offset += deltasp
}
if a == D_PARAM {
p.From.Offset += deltasp + 4
}
a = p.To.Typ
if a == D_AUTO {
p.To.Offset += deltasp
}
if a == D_PARAM {
p.To.Offset += deltasp + 4
}
switch p.As {
default:
continue
case APUSHL,
APUSHFL:
deltasp += 4
p.Spadj = 4
continue
case APUSHW,
APUSHFW:
deltasp += 2
p.Spadj = 2
continue
case APOPL,
APOPFL:
deltasp -= 4
p.Spadj = -4
continue
case APOPW,
APOPFW:
deltasp -= 2
p.Spadj = -2
continue
case ARET:
break
}
if autoffset != deltasp {
ctxt.Diag("unbalanced PUSH/POP")
}
if cursym.Text.From.Scale&liblink.WRAPPER != 0 {
p = load_g_cx(ctxt, p)
p = liblink.Appendp(ctxt, p)
// g->panicwrap -= autoffset + ctxt->arch->ptrsize;
p.As = ASUBL
p.From.Typ = D_CONST
p.From.Offset = autoffset + ctxt.Arch.Ptrsize
p.To.Typ = D_INDIR + D_CX
p.To.Offset = 2 * ctxt.Arch.Ptrsize
p = liblink.Appendp(ctxt, p)
p.As = ARET
}
if autoffset != 0 {
p.As = AADJSP
p.From.Typ = D_CONST
p.From.Offset = -autoffset
p.Spadj = -autoffset
p = liblink.Appendp(ctxt, p)
p.As = ARET
// If there are instructions following
// this ARET, they come from a branch
// with the same stackframe, so undo
// the cleanup.
p.Spadj = +autoffset
}
if p.To.Sym != nil { // retjmp
p.As = AJMP
}
}
}