runtime: set up C TLS and save g to it on ppc64
Cgo will need this for calls from C to Go and for handling signals
that may occur in C code.
Change-Id: I50cc4caf17cd142bff501e7180a1e27721463ada
Reviewed-on: https://go-review.googlesource.com/2008
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/src/runtime/arch1_ppc64.go b/src/runtime/arch1_ppc64.go
index 01e2b70..6996d0f 100644
--- a/src/runtime/arch1_ppc64.go
+++ b/src/runtime/arch1_ppc64.go
@@ -8,7 +8,7 @@
thechar = '9'
_BigEndian = 1
_CacheLineSize = 64
- _RuntimeGogoBytes = 64
+ _RuntimeGogoBytes = 72
_PhysPageSize = 65536
_PCQuantum = 4
_Int64Align = 8
diff --git a/src/runtime/arch1_ppc64le.go b/src/runtime/arch1_ppc64le.go
index 6580732..7d5dac4 100644
--- a/src/runtime/arch1_ppc64le.go
+++ b/src/runtime/arch1_ppc64le.go
@@ -8,7 +8,7 @@
thechar = '9'
_BigEndian = 0
_CacheLineSize = 64
- _RuntimeGogoBytes = 64
+ _RuntimeGogoBytes = 72
_PhysPageSize = 65536
_PCQuantum = 4
_Int64Align = 8
diff --git a/src/runtime/asm_ppc64x.s b/src/runtime/asm_ppc64x.s
index 8ec051d..a2aba63 100644
--- a/src/runtime/asm_ppc64x.s
+++ b/src/runtime/asm_ppc64x.s
@@ -10,6 +10,8 @@
#include "textflag.h"
TEXT runtime·rt0_go(SB),NOSPLIT,$0
+ // R1 = stack; R3 = argc; R4 = argv; R13 = C TLS base pointer
+
// initialize essential registers
BL runtime·reginit(SB)
@@ -102,6 +104,8 @@
TEXT runtime·gogo(SB), NOSPLIT, $-8-8
MOVD buf+0(FP), R5
MOVD gobuf_g(R5), g // make sure g is not nil
+ BL runtime·save_g(SB)
+
MOVD 0(g), R4
MOVD gobuf_sp(R5), R1
MOVD gobuf_lr(R5), R31
@@ -133,6 +137,7 @@
MOVD g, R3
MOVD g_m(g), R8
MOVD m_g0(R8), g
+ BL runtime·save_g(SB)
CMP g, R3
BNE 2(PC)
BR runtime·badmcall(SB)
@@ -191,6 +196,7 @@
// switch to g0
MOVD R5, g
+ BL runtime·save_g(SB)
MOVD (g_sched+gobuf_sp)(g), R3
// make it look like mstart called systemstack on g0, to stop traceback
SUB $8, R3
@@ -206,6 +212,7 @@
// switch back to g
MOVD g_m(g), R3
MOVD m_curg(R3), g
+ BL runtime·save_g(SB)
MOVD (g_sched+gobuf_sp)(g), R1
MOVD R0, (g_sched+gobuf_sp)(g)
RETURN
@@ -259,6 +266,7 @@
// Call newstack on m->g0's stack.
MOVD m_g0(R7), g
+ BL runtime·save_g(SB)
MOVD (g_sched+gobuf_sp)(g), R1
BL runtime·newstack(SB)
diff --git a/src/runtime/rt0_linux_ppc64le.s b/src/runtime/rt0_linux_ppc64le.s
index a3b3cea..dda29ab 100644
--- a/src/runtime/rt0_linux_ppc64le.s
+++ b/src/runtime/rt0_linux_ppc64le.s
@@ -6,6 +6,8 @@
TEXT _main<>(SB),NOSPLIT,$-8
MOVD 0(R1), R3 // argc
ADD $8, R1, R4 // argv
+ MOVD $runtime·tls0(SB), R13 // TLS
+ ADD $0x7000, R13
BR main(SB)
TEXT main(SB),NOSPLIT,$-8
diff --git a/src/runtime/tls_ppc64x.s b/src/runtime/tls_ppc64x.s
new file mode 100644
index 0000000..fa1f9ac
--- /dev/null
+++ b/src/runtime/tls_ppc64x.s
@@ -0,0 +1,56 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ppc64 ppc64le
+
+#include "go_asm.h"
+#include "go_tls.h"
+#include "funcdata.h"
+#include "textflag.h"
+
+// We have to resort to TLS variable to save g (R30).
+// One reason is that external code might trigger
+// SIGSEGV, and our runtime.sigtramp don't even know we
+// are in external code, and will continue to use R30,
+// this might well result in another SIGSEGV.
+
+// save_g saves the g register into pthread-provided
+// thread-local memory, so that we can call externally compiled
+// ppc64 code that will overwrite this register.
+//
+// If !iscgo, this is a no-op.
+TEXT runtime·save_g(SB),NOSPLIT,$-8-0
+ MOVB runtime·iscgo(SB), R31
+ CMP R31, $0
+ BEQ nocgo
+
+ // $runtime.tlsg(SB) is a special linker symbol.
+ // It is the offset from the start of TLS to our
+ // thread-local storage for g.
+ MOVD $runtime·tlsg(SB), R31
+ ADD R13, R31
+ // The actual TLS base is 0x7000 below R13
+ SUB $0x7000, R31
+
+ // Store g in TLS
+ MOVD g, 0(R31)
+
+nocgo:
+ RET
+
+// load_g loads the g register from pthread-provided
+// thread-local memory, for use after calling externally compiled
+// ppc64 code that overwrote those registers.
+//
+// This is never called directly from C code (it doesn't have to
+// follow the C ABI), but it may be called from a C context, where the
+// usual Go registers aren't set up.
+TEXT runtime·load_g(SB),NOSPLIT,$-8-0
+ MOVD $runtime·tlsg(SB), R31
+ // R13 is the C ABI TLS base pointer + 0x7000
+ ADD R13, R31
+ SUB $0x7000, R31
+
+ MOVD 0(R31), g
+ RET
