runtime: remove 104 byte stack guard

The number 104 appears to date back to the
first implementation of split stacks in
https://go.googlesource.com/go/+/b987f7a757f53f460973622a36eebb696f9b5060.
That change introduces a 104 byte stack guard.
it doesn't makes any sense today.

Change-Id: I73069f6d1a827653af63e616f0119fbac809882e
GitHub-Last-Rev: bcf900059047548c1709c6d4cf4649a96ad85e57
GitHub-Pull-Request: golang/go#56594
Reviewed-on: https://go-review.googlesource.com/c/go/+/448036
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>

diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s
index 13c8de499e7d62a5a0501c5b6e99758735cdec97..5d163da132c0a05bb936fa2fd8f6dd88ac33c825 100644 (file)
--- a/src/runtime/asm_amd64.s
+++ b/src/runtime/asm_amd64.s
@@ -168,7 +168,7 @@ TEXT runtime·rt0_go(SB),NOSPLIT|TOPFRAME,$0
        // create istack out of the given (operating system) stack.
        // _cgo_init may update stackguard.
        MOVQ    $runtime·g0(SB), DI
-       LEAQ    (-64*1024+104)(SP), BX
+       LEAQ    (-64*1024)(SP), BX
        MOVQ    BX, g_stackguard0(DI)
        MOVQ    BX, g_stackguard1(DI)
        MOVQ    BX, (g_stack+stack_lo)(DI)