runtime: make stack frames fixed size by modifying goproc/deferproc.
Calls to goproc/deferproc used to push & pop two extra arguments,
the argument size and the function to call. Now, we allocate space
for those arguments in the outargs section so we don't have to
modify the SP.
Defers now use the stack pointer (instead of the argument pointer)
to identify which frame they are associated with.
A followon CL might simplify funcspdelta and some of the stack
walking code.
Fixes issue #8641
Change-Id: I835ec2f42f0392c5dec7cb0fe6bba6f2aed1dad8
Reviewed-on: https://go-review.googlesource.com/1601
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/src/runtime/panic.go b/src/runtime/panic.go
index 7ec084a..07cdd4e 100644
--- a/src/runtime/panic.go
+++ b/src/runtime/panic.go
@@ -62,13 +62,10 @@
// the arguments of fn are in a perilous state. The stack map
// for deferproc does not describe them. So we can't let garbage
// collection or stack copying trigger until we've copied them out
- // to somewhere safe. deferproc_m does that. Until deferproc_m,
- // we can only call nosplit routines.
- argp := uintptr(unsafe.Pointer(&fn))
- argp += unsafe.Sizeof(fn)
- if GOARCH == "arm" || GOARCH == "ppc64" || GOARCH == "ppc64le" {
- argp += ptrSize // skip caller's saved link register
- }
+ // to somewhere safe. The memmove below does that.
+ // Until the copy completes, we can only call nosplit routines.
+ sp := getcallersp(unsafe.Pointer(&siz))
+ argp := uintptr(unsafe.Pointer(&fn)) + unsafe.Sizeof(fn)
callerpc := getcallerpc(unsafe.Pointer(&siz))
systemstack(func() {
@@ -78,7 +75,7 @@
}
d.fn = fn
d.pc = callerpc
- d.argp = argp
+ d.sp = sp
memmove(add(unsafe.Pointer(d), unsafe.Sizeof(*d)), unsafe.Pointer(argp), uintptr(siz))
})
@@ -240,8 +237,8 @@
if d == nil {
return
}
- argp := uintptr(unsafe.Pointer(&arg0))
- if d.argp != argp {
+ sp := getcallersp(unsafe.Pointer(&arg0))
+ if d.sp != sp {
return
}
@@ -250,13 +247,13 @@
// won't know the form of the arguments until the jmpdefer can
// flip the PC over to fn.
mp := acquirem()
- memmove(unsafe.Pointer(argp), deferArgs(d), uintptr(d.siz))
+ memmove(unsafe.Pointer(&arg0), deferArgs(d), uintptr(d.siz))
fn := d.fn
d.fn = nil
gp._defer = d.link
freedefer(d)
releasem(mp)
- jmpdefer(fn, argp)
+ jmpdefer(fn, uintptr(unsafe.Pointer(&arg0)))
}
// Goexit terminates the goroutine that calls it. No other goroutine is affected.
@@ -403,7 +400,7 @@
//GC()
pc := d.pc
- argp := unsafe.Pointer(d.argp) // must be pointer so it gets adjusted during stack copy
+ sp := unsafe.Pointer(d.sp) // must be pointer so it gets adjusted during stack copy
freedefer(d)
if p.recovered {
gp._panic = p.link
@@ -416,7 +413,7 @@
gp.sig = 0
}
// Pass information about recovering frame to recovery.
- gp.sigcode0 = uintptr(argp)
+ gp.sigcode0 = uintptr(sp)
gp.sigcode1 = pc
mcall(recovery)
gothrow("recovery failed") // mcall should not return
