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 01e2b70f95272a3f2273c9bbc9ddf77c1d495e97..6996d0fac00accfeec0b941447de89ee6930a5f1 100644 (file)
--- a/src/runtime/arch1_ppc64.go
+++ b/src/runtime/arch1_ppc64.go
@@ -8,7 +8,7 @@ const (
        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 6580732a3711537a10267f229ad40221709975b5..7d5dac46a07c6ae851a53c7970c406d570797164 100644 (file)
--- a/src/runtime/arch1_ppc64le.go
+++ b/src/runtime/arch1_ppc64le.go
@@ -8,7 +8,7 @@ const (
        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 8ec051d5dd5052d0408acbf50a91f119795301cf..a2aba632e9b5bf000bdf8c59f9cc7e3804decd5e 100644 (file)
--- 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·gosave(SB), NOSPLIT, $-8-8
 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 @@ TEXT runtime·mcall(SB), NOSPLIT, $-8-8
        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:
 
        // 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     $8, R3
@@ -206,6 +212,7 @@ switch:
        // switch back to g
        MOVD    g_m(g), R3
        MOVD    m_curg(R3), g
+       BL      runtime·save_g(SB)
        MOVD    (g_sched+gobuf_sp)(g), R1
        MOVD    R0, (g_sched+gobuf_sp)(g)
        RETURN
@@ -259,6 +266,7 @@ TEXT runtime·morestack(SB),NOSPLIT,$-8-0
 
        // 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 a3b3cea0b52ae9ccb83ce5558b722029aa4bc387..dda29ab3a0977045912c8591a06f4ad8f80cbd6d 100644 (file)
--- a/src/runtime/rt0_linux_ppc64le.s
+++ b/src/runtime/rt0_linux_ppc64le.s
@@ -6,6 +6,8 @@ TEXT _rt0_ppc64le_linux(SB),NOSPLIT,$0
 TEXT _main<>(SB),NOSPLIT,$-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 (file)
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