[dev.typeparams] runtime: call cgocallbackg indirectly on ARM64

This is CL 312669, for ARM64.

cgocallback calls cgocallbackg after switching the stack. Call it
indirectly to bypass the linker's nosplit check. In particular,
this avoids a nosplit stack overflow on Windows when register ABI
is enabled.

Change-Id: I7054a750fb0ec2579d46004f94b46b6f7b9e3a21
Reviewed-on: https://go-review.googlesource.com/c/go/+/324734
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

diff --git a/src/runtime/asm_arm64.s b/src/runtime/asm_arm64.s
index 4babcc7fcbc30fdcd88aba8e6082edce8bfd7de7..be4313d35d5b713b33fc8564813ed4aca6858397 100644 (file)
--- a/src/runtime/asm_arm64.s
+++ b/src/runtime/asm_arm64.s
@@ -1196,7 +1196,8 @@ havem:
        MOVD    R1, 8(RSP)
        MOVD    R2, 16(RSP)
        MOVD    R3, 24(RSP)
-       BL      runtime·cgocallbackg(SB)
+       MOVD    $runtime·cgocallbackg(SB), R0
+       CALL    (R0) // indirect call to bypass nosplit check. We're on a different stack now.
 
        // Restore g->sched (== m->curg->sched) from saved values.
        MOVD    0(RSP), R5