runtime: netbsd-arm64 fixes

Add missing declaration of crosscall1. Fix stack alignment for pipe2 return value. Work around kernel clobbering of r28 on aarch64 by reloading from ucontext. https://nxr.netbsd.org/xref/src/sys/arch/aarch64/aarch64/sig_machdep.c#104 Update #30824 Change-Id: I7f9472939f4c02953f8c207308610118f5d3c54c Reviewed-on: https://go-review.googlesource.com/c/go/+/257645 Reviewed-by: Ian Lance Taylor <[email protected]> Trust: Benny Siegert <[email protected]>
cloudflare · Sep 28, 2020 · 8ab020a · 8ab020a
1 parent 72a9dec
commit 8ab020a
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diff --git a/src/runtime/cgo/gcc_netbsd_arm64.c b/src/runtime/cgo/gcc_netbsd_arm64.c
@@ -53,6 +53,8 @@ _cgo_sys_thread_start(ThreadStart *ts)
  }
 }
 
+extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
+
 static void*
 threadentry(void *v)
 {

diff --git a/src/runtime/sys_netbsd_arm64.s b/src/runtime/sys_netbsd_arm64.s
@@ -169,11 +169,12 @@ pipeok:
 
 // func pipe2(flags int32) (r, w int32, errno int32)
 TEXT runtime·pipe2(SB),NOSPLIT|NOFRAME,$0-20
- ADD $8, RSP, R0
+ ADD $16, RSP, R0
  MOVW flags+0(FP), R1
  SVC $SYS_pipe2
- BCC 2(PC)
+ BCC pipe2ok
  NEG R0, R0
+pipe2ok:
  MOVW R0, errno+16(FP)
  RET
 
@@ -319,6 +320,12 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$192
  MOVD R26, 8*11(RSP)
  MOVD R27, 8*12(RSP)
  MOVD g, 8*13(RSP)
+ // Unclobber g for now (kernel uses it as ucontext ptr)
+ // See https://github.com/golang/go/issues/30824#issuecomment-492772426
+ // This is only correct in the non-cgo case.
+ // XXX should use lwp_getprivate as suggested.
+ // 8*36 is ucontext.uc_mcontext.__gregs[_REG_X28]
+ MOVD 8*36(g), g
  MOVD R29, 8*14(RSP)
  FMOVD F8, 8*15(RSP)
  FMOVD F9, 8*16(RSP)