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cmd/{asm,compile,internal/obj}: add "maymorestack" support

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This adds a debugging hook for optionally calling a "maymorestack"
function in the prologue of any function that might call morestack
(whether it does at run time or not). The maymorestack function will
let us improve lock checking and add debugging modes that stress
function preemption and stack growth.

Passes toolstash-check -all (except on js/wasm, where toolstash
appears to be broken)

Fixes #48297.

Change-Id: I27197947482b329af75dafb9971fc0d3a52eaf31
Reviewed-on: https://go-review.googlesource.com/c/go/+/359795
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Austin Clements 2019-08-20 17:39:09 -04:00
parent 1c4cfd8010
commit 3839b60014
14 changed files with 620 additions and 46 deletions
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79
src/cmd/internal/obj/mips/obj0.go
View file

@ -658,6 +658,82 @@ func (c *ctxt0) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
mov = AMOVW
}
if c.ctxt.Flag_maymorestack != "" {
// Save LR and REGCTXT.
frameSize := 2 * c.ctxt.Arch.PtrSize
p = c.ctxt.StartUnsafePoint(p, c.newprog)
// MOV REGLINK, -8/-16(SP)
p = obj.Appendp(p, c.newprog)
p.As = mov
p.From.Type = obj.TYPE_REG
p.From.Reg = REGLINK
p.To.Type = obj.TYPE_MEM
p.To.Offset = int64(-frameSize)
p.To.Reg = REGSP
// MOV REGCTXT, -4/-8(SP)
p = obj.Appendp(p, c.newprog)
p.As = mov
p.From.Type = obj.TYPE_REG
p.From.Reg = REGCTXT
p.To.Type = obj.TYPE_MEM
p.To.Offset = -int64(c.ctxt.Arch.PtrSize)
p.To.Reg = REGSP
// ADD $-8/$-16, SP
p = obj.Appendp(p, c.newprog)
p.As = add
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(-frameSize)
p.To.Type = obj.TYPE_REG
p.To.Reg = REGSP
p.Spadj = int32(frameSize)
// JAL maymorestack
p = obj.Appendp(p, c.newprog)
p.As = AJAL
p.To.Type = obj.TYPE_BRANCH
// See ../x86/obj6.go
p.To.Sym = c.ctxt.LookupABI(c.ctxt.Flag_maymorestack, c.cursym.ABI())
p.Mark |= BRANCH
// Restore LR and REGCTXT.
// MOV 0(SP), REGLINK
p = obj.Appendp(p, c.newprog)
p.As = mov
p.From.Type = obj.TYPE_MEM
p.From.Offset = 0
p.From.Reg = REGSP
p.To.Type = obj.TYPE_REG
p.To.Reg = REGLINK
// MOV 4/8(SP), REGCTXT
p = obj.Appendp(p, c.newprog)
p.As = mov
p.From.Type = obj.TYPE_MEM
p.From.Offset = int64(c.ctxt.Arch.PtrSize)
p.From.Reg = REGSP
p.To.Type = obj.TYPE_REG
p.To.Reg = REGCTXT
// ADD $8/$16, SP
p = obj.Appendp(p, c.newprog)
p.As = add
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(frameSize)
p.To.Type = obj.TYPE_REG
p.To.Reg = REGSP
p.Spadj = int32(-frameSize)
p = c.ctxt.EndUnsafePoint(p, c.newprog, -1)
}
// Jump back to here after morestack returns.
startPred := p
// MOV g_stackguard(g), R1
p = obj.Appendp(p, c.newprog)
@ -787,7 +863,8 @@ func (c *ctxt0) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p.As = AJMP
p.To.Type = obj.TYPE_BRANCH
p.To.SetTarget(c.cursym.Func().Text.Link)
p.To.SetTarget(startPred.Link)
startPred.Link.Mark |= LABEL
p.Mark |= BRANCH
// placeholder for q1's jump target