diff options
| -rw-r--r-- | src/cmd/internal/objabi/stack.go | 15 | ||||
| -rw-r--r-- | src/cmd/link/internal/ld/stackcheck.go | 2 | ||||
| -rw-r--r-- | src/internal/abi/stack.go | 8 | ||||
| -rw-r--r-- | src/runtime/preempt.go | 2 | ||||
| -rw-r--r-- | src/runtime/stack.go | 19 | ||||
| -rw-r--r-- | test/nosplit.go | 13 |
6 files changed, 25 insertions, 34 deletions
diff --git a/src/cmd/internal/objabi/stack.go b/src/cmd/internal/objabi/stack.go index 5a2f641a75..7c7ff4e058 100644 --- a/src/cmd/internal/objabi/stack.go +++ b/src/cmd/internal/objabi/stack.go @@ -9,18 +9,9 @@ import ( "internal/buildcfg" ) -// For the linkers. Must match Go definitions. - -const ( - STACKSYSTEM = 0 - StackSystem = STACKSYSTEM -) - -func StackLimit(race bool) int { - // This arithmetic must match that in runtime/stack.go:{_StackGuard,_StackLimit}. - stackGuard := 928*stackGuardMultiplier(race) + StackSystem - stackLimit := stackGuard - StackSystem - abi.StackSmall - return stackLimit +func StackNosplit(race bool) int { + // This arithmetic must match that in runtime/stack.go:stackNosplit. + return abi.StackNosplitBase * stackGuardMultiplier(race) } // stackGuardMultiplier returns a multiplier to apply to the default diff --git a/src/cmd/link/internal/ld/stackcheck.go b/src/cmd/link/internal/ld/stackcheck.go index c82dafe51e..24a96fb996 100644 --- a/src/cmd/link/internal/ld/stackcheck.go +++ b/src/cmd/link/internal/ld/stackcheck.go @@ -61,7 +61,7 @@ func (ctxt *Link) doStackCheck() { // The call to morestack in every splittable function ensures // that there are at least StackLimit bytes available below SP // when morestack returns. - limit := objabi.StackLimit(*flagRace) - sc.callSize + limit := objabi.StackNosplit(*flagRace) - sc.callSize if buildcfg.GOARCH == "arm64" { // Need an extra 8 bytes below SP to save FP. limit -= 8 diff --git a/src/internal/abi/stack.go b/src/internal/abi/stack.go index 9efd21b167..8e3327ee48 100644 --- a/src/internal/abi/stack.go +++ b/src/internal/abi/stack.go @@ -5,6 +5,14 @@ package abi const ( + // StackNosplitBase is the base maximum number of bytes that a chain of + // NOSPLIT functions can use. + // + // This value must be multiplied by the stack guard multiplier, so do not + // use it directly. See runtime/stack.go:stackNosplit and + // cmd/internal/objabi/stack.go:StackNosplit. + StackNosplitBase = 800 + // We have three different sequences for stack bounds checks, depending on // whether the stack frame of a function is small, big, or huge. diff --git a/src/runtime/preempt.go b/src/runtime/preempt.go index a575fbcf11..38114243bb 100644 --- a/src/runtime/preempt.go +++ b/src/runtime/preempt.go @@ -320,7 +320,7 @@ func init() { total += funcMaxSPDelta(f) // Add some overhead for return PCs, etc. asyncPreemptStack = uintptr(total) + 8*goarch.PtrSize - if asyncPreemptStack > _StackLimit { + if asyncPreemptStack > stackNosplit { // We need more than the nosplit limit. This isn't // unsafe, but it may limit asynchronous preemption. // diff --git a/src/runtime/stack.go b/src/runtime/stack.go index 6d75301556..92c2ce3cbf 100644 --- a/src/runtime/stack.go +++ b/src/runtime/stack.go @@ -85,19 +85,18 @@ const ( _FixedStack6 = _FixedStack5 | (_FixedStack5 >> 16) _FixedStack = _FixedStack6 + 1 + // stackNosplit is the maximum number of bytes that a chain of NOSPLIT + // functions can use. + // This arithmetic must match that in cmd/internal/objabi/stack.go:StackNosplit. + stackNosplit = abi.StackNosplitBase * sys.StackGuardMultiplier + // The stack guard is a pointer this many bytes above the // bottom of the stack. // - // The guard leaves enough room for one _StackSmall frame plus - // a _StackLimit chain of NOSPLIT calls plus _StackSystem - // bytes for the OS. - // This arithmetic must match that in cmd/internal/objabi/stack.go:StackLimit. - _StackGuard = 928*sys.StackGuardMultiplier + _StackSystem - - // The maximum number of bytes that a chain of NOSPLIT - // functions can use. + // The guard leaves enough room for a stackNosplit chain of NOSPLIT calls + // plus one stackSmall frame plus stackSystem bytes for the OS. // This arithmetic must match that in cmd/internal/objabi/stack.go:StackLimit. - _StackLimit = _StackGuard - _StackSystem - abi.StackSmall + _StackGuard = stackNosplit + _StackSystem + abi.StackSmall ) const ( @@ -1211,7 +1210,7 @@ func shrinkstack(gp *g) { // down to the SP plus the stack guard space that ensures // there's room for nosplit functions. avail := gp.stack.hi - gp.stack.lo - if used := gp.stack.hi - gp.sched.sp + _StackLimit; used >= avail/4 { + if used := gp.stack.hi - gp.sched.sp + stackNosplit; used >= avail/4 { return } diff --git a/test/nosplit.go b/test/nosplit.go index a695654eaf..2b1bb5492d 100644 --- a/test/nosplit.go +++ b/test/nosplit.go @@ -342,22 +342,15 @@ TestCases: nosplit := m[3] body := m[4] - // The limit was originally 128 but is now 800 (928-128). + // The limit was originally 128 but is now 800. // Instead of rewriting the test cases above, adjust // the first nosplit frame to use up the extra bytes. // This isn't exactly right because we could have // nosplit -> split -> nosplit, but it's good enough. if !adjusted && nosplit != "" { + const stackNosplitBase = 800 // internal/abi.StackNosplitBase adjusted = true - size += (928 - 128) - 128 - // Noopt builds have a larger stackguard. - // See ../src/cmd/dist/buildruntime.go:stackGuardMultiplier - // This increase is included in objabi.StackGuard - for _, s := range strings.Split(os.Getenv("GO_GCFLAGS"), " ") { - if s == "-N" { - size += 928 - } - } + size += stackNosplitBase - 128 } if nosplit != "" { |