runtime: disabling inlining breaks on arm64, ppc64

[mwhudson]

For example:

(vivid)mwh@rugby:~/go/src$ go install -a  -gcflags -l -installsuffix=noinl cmd/pack
(vivid)mwh@rugby:~/go/src$ /home/mwh/go/pkg/tool/linux_arm64/pack tv ../pkg/linux_arm64/runtime.a
runtime: newstack sp=0x4820041b60 stack=[0x4820040000, 0x4820041fc0]
        morebuf={pc:0x45970 sp:0x4820041b60 lr:0x0}
        sched={pc:0x4e3a8 sp:0x4820041b60 lr:0x45970 ctxt:0x0}
syscall.Syscall6(0x38, 0xffffffffffffff9c, 0x482000e160, 0x80000, 0x0, 0x0, 0x0, 0x234cc, 0x1e1c00, 0x30)
        /home/mwh/go/src/syscall/asm_linux_arm64.s:36 +0x8
syscall.openat(0xffffffffffffff9c, 0x7ff883a7a8, 0x1c, 0x80000, 0x0, 0x0, 0x0, 0x0)
        /home/mwh/go/src/syscall/zsyscall_linux_arm64.go:40 +0xa0
syscall.Open(0x7ff883a7a8, 0x1c, 0x80000, 0x0, 0x481ffff5f6, 0x0, 0x0)
        /home/mwh/go/src/syscall/syscall_linux.go:51 +0x58
os.OpenFile(0x7ff883a7a8, 0x1c, 0x0, 0x0, 0x0, 0x0, 0x0)
        /home/mwh/go/src/os/file_unix.go:93 +0x70
os.Open(0x7ff883a7a8, 0x1c, 0x0, 0x0, 0x0)
        /home/mwh/go/src/os/file.go:246 +0x4c
main.existingArchive(0x7ff883a7a8, 0x1c, 0x4820041e18)
        /home/mwh/go/src/cmd/pack/pack.go:181 +0x38
main.archive(0x7ff883a7a8, 0x1c, 0x0, 0x482000a360, 0x0, 0x0, 0x202bd0)
        /home/mwh/go/src/cmd/pack/pack.go:149 +0x34
main.main()
        /home/mwh/go/src/cmd/pack/pack.go:74 +0x83c
fatal error: runtime: stack split at bad time

runtime stack:
runtime.throw(0x1586d0, 0x20)
        /home/mwh/go/src/runtime/panic.go:527 +0x80
runtime.newstack()
        /home/mwh/go/src/runtime/stack1.go:675 +0x4c4
runtime.morestack()
        /home/mwh/go/src/runtime/asm_arm64.s:300 +0x5c

goroutine 1 [syscall]:
runtime.reentersyscall(0xce9b8, 0x4820041bb0)
        /home/mwh/go/src/runtime/proc1.go:1831 +0x140 fp=0x4820041b90 sp=0x4820041b60
runtime.entersyscall(0x0)
        /home/mwh/go/src/runtime/proc1.go:1855 +0x38 fp=0x4820041bb0 sp=0x4820041b90
syscall.Syscall6(0x38, 0xffffffffffffff9c, 0x482000e160, 0x80000, 0x0, 0x0, 0x0, 0x234cc, 0x1e1c00, 0x30)
        /home/mwh/go/src/syscall/asm_linux_arm64.s:36 +0x8 fp=0x4820041bc0 sp=0x4820041bb0
syscall.openat(0xffffffffffffff9c, 0x7ff883a7a8, 0x1c, 0x80000, 0x0, 0x0, 0x0, 0x0)
        /home/mwh/go/src/syscall/zsyscall_linux_arm64.go:40 +0xa0 fp=0x4820041c30 sp=0x4820041bc0
syscall.Open(0x7ff883a7a8, 0x1c, 0x80000, 0x0, 0x481ffff5f6, 0x0, 0x0)
        /home/mwh/go/src/syscall/syscall_linux.go:51 +0x58 fp=0x4820041c80 sp=0x4820041c30
os.OpenFile(0x7ff883a7a8, 0x1c, 0x0, 0x0, 0x0, 0x0, 0x0)
        /home/mwh/go/src/os/file_unix.go:93 +0x70 fp=0x4820041cf0 sp=0x4820041c80
os.Open(0x7ff883a7a8, 0x1c, 0x0, 0x0, 0x0)
        /home/mwh/go/src/os/file.go:246 +0x4c fp=0x4820041d30 sp=0x4820041cf0
main.existingArchive(0x7ff883a7a8, 0x1c, 0x4820041e18)
        /home/mwh/go/src/cmd/pack/pack.go:181 +0x38 fp=0x4820041db0 sp=0x4820041d30
main.archive(0x7ff883a7a8, 0x1c, 0x0, 0x482000a360, 0x0, 0x0, 0x202bd0)
        /home/mwh/go/src/cmd/pack/pack.go:149 +0x34 fp=0x4820041e50 sp=0x4820041db0
main.main()
        /home/mwh/go/src/cmd/pack/pack.go:74 +0x83c fp=0x4820041f40 sp=0x4820041e50
runtime.main()
        /home/mwh/go/src/runtime/proc.go:111 +0x2c0 fp=0x4820041f90 sp=0x4820041f40
runtime.goexit()
        /home/mwh/go/src/runtime/asm_arm64.s:1012 +0x4 fp=0x4820041f90 sp=0x4820041f90
(vivid)mwh@rugby:~/go/src$ 

I guess something that is usually inlined needs to be marked nosplit?

[bradfitz]

Moving to Go 1.6, since arm64 and ppc64 are only preview releases in 1.5.

[mwhudson]

This happens on ppc64 too.

[rsc]

Looks like a missing nosplit. It would be nice to find out what exactly the pc= in the morebuf line corresponds to. That is, the output above says:

morebuf={pc:0x45970 sp:0x4820041b60 lr:0x0}

In that case it would be nice to know what list *0x45970 said in gdb on the appropriate binary. (Or use whatever address currently gets printed.)

[mwhudson]

Ah thanks for the hint -- it was one of the {g,m,p}uintptr methods. Just sent a CL marking them all nosplit.

[gopherbot]

CL https://golang.org/cl/17165 mentions this issue.