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cmd/go,cmd/link: support buildmode c-shared on ppc64le

This change enables buildmode c-shared on ppc64le.

A bug was fixed in runtime/rt0_linux_ppc64le.s that was necessary to
make this work.  In _rt0_ppc64le_linux_lib, there is code to store
the value of r2 onto the caller's stack.  However, if this file
is compiled using a build mode that maintains the TOC address in
r2, then instructions will be inserted at the beginning of this
function to generate the r2 value for the callee, not the caller.
That means the r2 value for the callee is stored onto the caller's
stack.  If caller and callee don't have the same r2 values, then
the caller will restore the wrong r2 value after it returns.  This
situation can happen when using dlopen since the caller of this
function will be in ld64.so and will definitely have a different
TOC.

Updates #20756

Change-Id: I6e165e0d0716e73721bbbcc520e8302e4856e3ba
Reviewed-on: https://go-review.googlesource.com/53890
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Lynn Boger 2017-08-08 13:45:41 -04:00
parent 53f2d53450
commit 3e7abf82e3
4 changed files with 3 additions and 5 deletions

View File

@ -824,7 +824,7 @@ func (t *tester) supportedBuildmode(mode string) bool {
return false
case "c-shared":
switch pair {
case "linux-386", "linux-amd64", "linux-arm", "linux-arm64",
case "linux-386", "linux-amd64", "linux-arm", "linux-arm64", "linux-ppc64le",
"darwin-amd64", "darwin-386",
"android-arm", "android-arm64", "android-386":
return true

View File

@ -293,7 +293,7 @@ func BuildModeInit() {
codegenArg = "-fPIC"
} else {
switch platform {
case "linux/amd64", "linux/arm", "linux/arm64", "linux/386",
case "linux/amd64", "linux/arm", "linux/arm64", "linux/386", "linux/ppc64le",
"android/amd64", "android/arm", "android/arm64", "android/386":
codegenArg = "-shared"
case "darwin/amd64", "darwin/386":

View File

@ -63,7 +63,7 @@ func (mode *BuildMode) Set(s string) error {
*mode = BuildmodeCArchive
case "c-shared":
switch objabi.GOARCH {
case "386", "amd64", "arm", "arm64":
case "386", "amd64", "arm", "arm64", "ppc64le":
default:
return badmode()
}

View File

@ -10,7 +10,6 @@ TEXT _rt0_ppc64le_linux_lib(SB),NOSPLIT,$-8
MOVD R0, 16(R1) // Save LR in caller's frame.
MOVW CR, R0 // Save CR in caller's frame
MOVD R0, 8(R1)
MOVD R2, 24(R1) // Save TOC in caller's frame.
MOVDU R1, -320(R1) // Allocate frame.
// Preserve callee-save registers.
@ -121,7 +120,6 @@ done:
FMOVD 304(R1), F31
ADD $320, R1
MOVD 24(R1), R2
MOVD 8(R1), R0
MOVFL R0, $0xff
MOVD 16(R1), R0