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| author | Cherry Zhang <cherryyz@google.com> | 2019-10-26 22:49:13 -0400 |
|---|---|---|
| committer | Cherry Zhang <cherryyz@google.com> | 2019-11-07 19:18:49 +0000 |
| commit | 69dcdbd2ba54e65faafbb40327e4db41dd255ad7 (patch) | |
| tree | 7dd1f952d7bae2957d52387a07bd2820694477a0 /src/cmd/internal/obj/mips/obj0.go | |
| parent | 1b0b9809046c1862f8ea0240fe016e516c67676f (diff) | |
| download | go-69dcdbd2ba54e65faafbb40327e4db41dd255ad7.tar.xz | |
cmd/internal/obj/mips: mark unsafe points
For async preemption, we will be using REGTMP as a temporary
register in injected call on MIPS, which will clobber it. So any
code that uses REGTMP is not safe for async preemption.
In the assembler backend, we expand a Prog to multiple machine
instructions and use REGTMP as a temporary register if necessary.
These need to be marked unsafe. In fact, most of the
multi-instruction Progs use REGTMP, so we mark all of them,
except ones that are whitelisted.
Change-Id: Ic00ae5589683c2c9525abdaee076d884df6b0d1e
Reviewed-on: https://go-review.googlesource.com/c/go/+/203718
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Diffstat (limited to 'src/cmd/internal/obj/mips/obj0.go')
| -rw-r--r-- | src/cmd/internal/obj/mips/obj0.go | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/cmd/internal/obj/mips/obj0.go b/src/cmd/internal/obj/mips/obj0.go index f096c7ff14..3d8e91ce44 100644 --- a/src/cmd/internal/obj/mips/obj0.go +++ b/src/cmd/internal/obj/mips/obj0.go @@ -339,6 +339,10 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) { // Store link register before decrement SP, so if a signal comes // during the execution of the function prologue, the traceback // code will not see a half-updated stack frame. + // This sequence is not async preemptible, as if we open a frame + // at the current SP, it will clobber the saved LR. + q = c.ctxt.StartUnsafePoint(q, c.newprog) + q = obj.Appendp(q, newprog) q.As = mov q.Pos = p.Pos @@ -356,6 +360,8 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) { q.To.Type = obj.TYPE_REG q.To.Reg = REGSP q.Spadj = +autosize + + q = c.ctxt.EndUnsafePoint(q, c.newprog, -1) } if c.cursym.Func.Text.From.Sym.Wrapper() && c.cursym.Func.Text.Mark&LEAF == 0 { |