runtime: do not generate code during runtime in windows NewCallback
Update #5494
R=golang-dev, minux.ma, rsc, iant
CC=golang-dev
https://golang.org/cl/10368043
diff --git a/src/cmd/dist/a.h b/src/cmd/dist/a.h
index 73c1264..d8a13f9 100644
--- a/src/cmd/dist/a.h
+++ b/src/cmd/dist/a.h
@@ -94,6 +94,7 @@
// buildruntime.c
void mkzasm(char*, char*);
+void mkzsys(char*, char*);
void mkzgoarch(char*, char*);
void mkzgoos(char*, char*);
void mkzruntimedefs(char*, char*);
diff --git a/src/cmd/dist/build.c b/src/cmd/dist/build.c
index cdab81d..ba32d3e 100644
--- a/src/cmd/dist/build.c
+++ b/src/cmd/dist/build.c
@@ -528,6 +528,7 @@
}},
{"pkg/runtime", {
"zasm_$GOOS_$GOARCH.h",
+ "zsys_$GOOS_$GOARCH.s",
"zgoarch_$GOARCH.go",
"zgoos_$GOOS.go",
"zruntime_defs_$GOOS_$GOARCH.go",
@@ -552,6 +553,7 @@
{"opnames.h", gcopnames},
{"enam.c", mkenam},
{"zasm_", mkzasm},
+ {"zsys_", mkzsys},
{"zgoarch_", mkzgoarch},
{"zgoos_", mkzgoos},
{"zruntime_defs_", mkzruntimedefs},
diff --git a/src/cmd/dist/buildruntime.c b/src/cmd/dist/buildruntime.c
index 8f3fc541..2d221eb 100644
--- a/src/cmd/dist/buildruntime.c
+++ b/src/cmd/dist/buildruntime.c
@@ -178,6 +178,8 @@
},
};
+#define MAXWINCB 2000 /* maximum number of windows callbacks allowed */
+
// mkzasm writes zasm_$GOOS_$GOARCH.h,
// which contains struct offsets for use by
// assembly files. It also writes a copy to the work space
@@ -249,6 +251,8 @@
aggr = "gobuf";
else if(streq(fields.p[1], "WinCall"))
aggr = "wincall";
+ else if(streq(fields.p[1], "WinCallbackContext"))
+ aggr = "cbctxt";
else if(streq(fields.p[1], "SEH"))
aggr = "seh";
}
@@ -262,6 +266,11 @@
bwritestr(&out, bprintf(&b, "#define %s_%s %s\n", aggr, fields.p[n-1], fields.p[n-2]));
}
}
+
+ // Some #defines that are used for .c files.
+ if(streq(goos, "windows")) {
+ bwritestr(&out, bprintf(&b, "#define cb_max %d\n", MAXWINCB));
+ }
// Write both to file and to workdir/zasm_GOOS_GOARCH.h.
writefile(&out, file, 0);
@@ -275,6 +284,41 @@
vfree(&fields);
}
+// mkzsys writes zsys_$GOOS_$GOARCH.h,
+// which contains arch or os specific asm code.
+//
+void
+mkzsys(char *dir, char *file)
+{
+ int i;
+ Buf out;
+
+ USED(dir);
+
+ binit(&out);
+
+ bwritestr(&out, "// auto generated by go tool dist\n\n");
+ if(streq(goos, "windows")) {
+ bwritef(&out,
+ "// runtime·callbackasm is called by external code to\n"
+ "// execute Go implemented callback function. It is not\n"
+ "// called from the start, instead runtime·compilecallback\n"
+ "// always returns address into runtime·callbackasm offset\n"
+ "// appropriately so different callbacks start with different\n"
+ "// CALL instruction in runtime·callbackasm. This determines\n"
+ "// which Go callback function is executed later on.\n"
+ "TEXT runtime·callbackasm(SB),7,$0\n");
+ for(i=0; i<MAXWINCB; i++) {
+ bwritef(&out, "\tCALL\truntime·callbackasm1(SB)\n");
+ }
+ bwritef(&out, "\tRET\n");
+ }
+
+ writefile(&out, file, 0);
+
+ bfree(&out);
+}
+
static char *runtimedefs[] = {
"proc.c",
"iface.c",
diff --git a/src/pkg/runtime/callback_windows.c b/src/pkg/runtime/callback_windows.c
new file mode 100644
index 0000000..88ee53b
--- /dev/null
+++ b/src/pkg/runtime/callback_windows.c
@@ -0,0 +1,76 @@
+// Copyright 2009 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.
+
+#include "runtime.h"
+#include "type.h"
+#include "typekind.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
+#include "zasm_GOOS_GOARCH.h"
+
+typedef struct Callbacks Callbacks;
+struct Callbacks {
+ Lock;
+ WinCallbackContext* ctxt[cb_max];
+ int32 n;
+};
+
+static Callbacks cbs;
+
+WinCallbackContext** runtime·cbctxts; // to simplify access to cbs.ctxt in sys_windows_*.s
+
+// Call back from windows dll into go.
+byte *
+runtime·compilecallback(Eface fn, bool cleanstack)
+{
+ FuncType *ft;
+ Type *t;
+ int32 argsize, i, n;
+ WinCallbackContext *c;
+
+ if(fn.type == nil || fn.type->kind != KindFunc)
+ runtime·panicstring("compilecallback: not a function");
+ ft = (FuncType*)fn.type;
+ if(ft->out.len != 1)
+ runtime·panicstring("compilecallback: function must have one output parameter");
+ if(((Type**)ft->out.array)[0]->size != sizeof(uintptr))
+ runtime·panicstring("compilecallback: output parameter size is wrong");
+ argsize = 0;
+ for(i=0; i<ft->in.len; i++) {
+ t = ((Type**)ft->in.array)[i];
+ if(t->size > sizeof(uintptr))
+ runtime·panicstring("compilecallback: input parameter size is wrong");
+ argsize += sizeof(uintptr);
+ }
+
+ runtime·lock(&cbs);
+ if(runtime·cbctxts == nil)
+ runtime·cbctxts = &(cbs.ctxt[0]);
+ n = cbs.n;
+ for(i=0; i<n; i++) {
+ if(cbs.ctxt[i]->gobody == fn.data) {
+ runtime·unlock(&cbs);
+ // runtime·callbackasm is just a series of CALL instructions
+ // (each is 5 bytes long), and we want callback to arrive at
+ // correspondent call instruction instead of start of
+ // runtime·callbackasm.
+ return (byte*)runtime·callbackasm + i * 5;
+ }
+ }
+ if(n >= cb_max)
+ runtime·throw("too many callback functions");
+ c = runtime·mal(sizeof *c);
+ c->gobody = fn.data;
+ c->argsize = argsize;
+ if(cleanstack && argsize!=0)
+ c->restorestack = argsize;
+ else
+ c->restorestack = 0;
+ cbs.ctxt[n] = c;
+ cbs.n++;
+ runtime·unlock(&cbs);
+
+ // as before
+ return (byte*)runtime·callbackasm + n * 5;
+}
diff --git a/src/pkg/runtime/callback_windows_386.c b/src/pkg/runtime/callback_windows_386.c
deleted file mode 100644
index 880588d..0000000
--- a/src/pkg/runtime/callback_windows_386.c
+++ /dev/null
@@ -1,108 +0,0 @@
-// Copyright 2009 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.
-
-#include "runtime.h"
-#include "type.h"
-#include "typekind.h"
-#include "defs_GOOS_GOARCH.h"
-#include "os_GOOS.h"
-
-// Will keep all callbacks in a linked list, so they don't get garbage collected.
-typedef struct Callback Callback;
-struct Callback {
- Callback* link;
- void* gobody;
- byte asmbody;
-};
-
-typedef struct Callbacks Callbacks;
-struct Callbacks {
- Lock;
- Callback* link;
- int32 n;
-};
-
-static Callbacks cbs;
-
-// Call back from windows dll into go.
-byte *
-runtime·compilecallback(Eface fn, bool cleanstack)
-{
- FuncType *ft;
- Type *t;
- int32 argsize, i, n;
- byte *p;
- Callback *c;
-
- if(fn.type == nil || fn.type->kind != KindFunc)
- runtime·panicstring("compilecallback: not a function");
- ft = (FuncType*)fn.type;
- if(ft->out.len != 1)
- runtime·panicstring("compilecallback: function must have one output parameter");
- if(((Type**)ft->out.array)[0]->size != sizeof(uintptr))
- runtime·panicstring("compilecallback: output parameter size is wrong");
- argsize = 0;
- for(i=0; i<ft->in.len; i++) {
- t = ((Type**)ft->in.array)[i];
- if(t->size > sizeof(uintptr))
- runtime·panicstring("compilecallback: input parameter size is wrong");
- argsize += sizeof(uintptr);
- }
-
- // compute size of new fn.
- // must match code laid out below.
- n = 1+4; // MOVL fn, AX
- n += 1+4; // MOVL argsize, DX
- n += 1+4; // MOVL callbackasm, CX
- n += 2; // CALL CX
- n += 1; // RET
- if(cleanstack && argsize!=0)
- n += 2; // ... argsize
-
- runtime·lock(&cbs);
- for(c = cbs.link; c != nil; c = c->link) {
- if(c->gobody == fn.data) {
- runtime·unlock(&cbs);
- return &c->asmbody;
- }
- }
- if(cbs.n >= 2000)
- runtime·throw("too many callback functions");
- c = runtime·mal(sizeof *c + n);
- c->gobody = fn.data;
- c->link = cbs.link;
- cbs.link = c;
- cbs.n++;
- runtime·unlock(&cbs);
-
- p = &c->asmbody;
-
- // MOVL fn, AX
- *p++ = 0xb8;
- *(uint32*)p = (uint32)(fn.data);
- p += 4;
-
- // MOVL argsize, DX
- *p++ = 0xba;
- *(uint32*)p = argsize;
- p += 4;
-
- // MOVL callbackasm, CX
- *p++ = 0xb9;
- *(uint32*)p = (uint32)runtime·callbackasm;
- p += 4;
-
- // CALL CX
- *p++ = 0xff;
- *p++ = 0xd1;
-
- // RET argsize?
- if(cleanstack && argsize!=0) {
- *p++ = 0xc2;
- *(uint16*)p = argsize;
- } else
- *p = 0xc3;
-
- return &c->asmbody;
-}
diff --git a/src/pkg/runtime/callback_windows_amd64.c b/src/pkg/runtime/callback_windows_amd64.c
deleted file mode 100644
index 1a47792..0000000
--- a/src/pkg/runtime/callback_windows_amd64.c
+++ /dev/null
@@ -1,105 +0,0 @@
-// Copyright 2009 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.
-
-#include "runtime.h"
-#include "type.h"
-#include "typekind.h"
-#include "defs_GOOS_GOARCH.h"
-#include "os_GOOS.h"
-
-// Will keep all callbacks in a linked list, so they don't get garbage collected.
-typedef struct Callback Callback;
-struct Callback {
- Callback* link;
- void* gobody;
- byte asmbody;
-};
-
-typedef struct Callbacks Callbacks;
-struct Callbacks {
- Lock;
- Callback* link;
- int32 n;
-};
-
-static Callbacks cbs;
-
-// Call back from windows dll into go.
-byte *
-runtime·compilecallback(Eface fn, bool /*cleanstack*/)
-{
- FuncType *ft;
- Type *t;
- int32 argsize, i, n;
- byte *p;
- Callback *c;
-
- if(fn.type == nil || fn.type->kind != KindFunc)
- runtime·panicstring("compilecallback: not a function");
- ft = (FuncType*)fn.type;
- if(ft->out.len != 1)
- runtime·panicstring("compilecallback: function must have one output parameter");
- if(((Type**)ft->out.array)[0]->size != sizeof(uintptr))
- runtime·panicstring("compilecallback: output parameter size is wrong");
- argsize = 0;
- for(i=0; i<ft->in.len; i++) {
- t = ((Type**)ft->in.array)[i];
- if(t->size > sizeof(uintptr))
- runtime·panicstring("compilecallback: input parameter size is wrong");
- argsize += sizeof(uintptr);
- }
-
- // compute size of new fn.
- // must match code laid out below.
- n = 2+8+1; // MOVQ fn, AX / PUSHQ AX
- n += 2+8+1; // MOVQ argsize, AX / PUSHQ AX
- n += 2+8; // MOVQ callbackasm, AX
- n += 2; // JMP AX
-
- runtime·lock(&cbs);
- for(c = cbs.link; c != nil; c = c->link) {
- if(c->gobody == fn.data) {
- runtime·unlock(&cbs);
- return &c->asmbody;
- }
- }
- if(cbs.n >= 2000)
- runtime·throw("too many callback functions");
- c = runtime·mal(sizeof *c + n);
- c->gobody = fn.data;
- c->link = cbs.link;
- cbs.link = c;
- cbs.n++;
- runtime·unlock(&cbs);
-
- p = &c->asmbody;
-
- // MOVQ fn, AX
- *p++ = 0x48;
- *p++ = 0xb8;
- *(uint64*)p = (uint64)(fn.data);
- p += 8;
- // PUSH AX
- *p++ = 0x50;
-
- // MOVQ argsize, AX
- *p++ = 0x48;
- *p++ = 0xb8;
- *(uint64*)p = argsize;
- p += 8;
- // PUSH AX
- *p++ = 0x50;
-
- // MOVQ callbackasm, AX
- *p++ = 0x48;
- *p++ = 0xb8;
- *(uint64*)p = (uint64)runtime·callbackasm;
- p += 8;
-
- // JMP AX
- *p++ = 0xFF;
- *p = 0xE0;
-
- return &c->asmbody;
-}
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index f62ee81..f5da54a 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -78,6 +78,7 @@
typedef struct Complex128 Complex128;
typedef struct WinCall WinCall;
typedef struct SEH SEH;
+typedef struct WinCallbackContext WinCallbackContext;
typedef struct Timers Timers;
typedef struct Timer Timer;
typedef struct GCStats GCStats;
@@ -444,6 +445,13 @@
void* prev;
void* handler;
};
+// describes how to handle callback
+struct WinCallbackContext
+{
+ void* gobody; // Go function to call
+ uintptr argsize; // callback arguments size (in bytes)
+ uintptr restorestack; // adjust stack on return by (in bytes) (386 only)
+};
#ifdef GOOS_windows
enum {
diff --git a/src/pkg/runtime/sys_windows_386.s b/src/pkg/runtime/sys_windows_386.s
index 2c63b33..728fb99 100644
--- a/src/pkg/runtime/sys_windows_386.s
+++ b/src/pkg/runtime/sys_windows_386.s
@@ -164,19 +164,16 @@
POPL BP
RET
-// Called from dynamic function created by ../thread.c compilecallback,
-// running on Windows stack (not Go stack).
-// BX, BP, SI, DI registers and DF flag are preserved
-// as required by windows callback convention.
-// AX = address of go func we need to call
-// DX = total size of arguments
-//
-TEXT runtime·callbackasm+0(SB),7,$0
- // preserve whatever's at the memory location that
- // the callback will use to store the return value
- LEAL 8(SP), CX
- PUSHL 0(CX)(DX*1)
- ADDL $4, DX // extend argsize by size of return value
+GLOBL runtime·cbctxts(SB), $4
+
+TEXT runtime·callbackasm1+0(SB),7,$0
+ MOVL 0(SP), AX // will use to find our callback context
+
+ // remove return address from stack, we are not returning there
+ ADDL $4, SP
+
+ // address to callback parameters into CX
+ LEAL 4(SP), CX
// save registers as required for windows callback
PUSHL DI
@@ -189,19 +186,51 @@
PUSHL 0(FS)
MOVL SP, 0(FS)
- // callback parameters
- PUSHL DX
- PUSHL CX
- PUSHL AX
+ // determine index into runtime·cbctxts table
+ SUBL $runtime·callbackasm(SB), AX
+ MOVL $0, DX
+ MOVL $5, BX // divide by 5 because each call instruction in runtime·callbacks is 5 bytes long
+ DIVL BX,
+ // find correspondent runtime·cbctxts table entry
+ MOVL runtime·cbctxts(SB), BX
+ MOVL -4(BX)(AX*4), BX
+
+ // extract callback context
+ MOVL cbctxt_gobody(BX), AX
+ MOVL cbctxt_argsize(BX), DX
+
+ // preserve whatever's at the memory location that
+ // the callback will use to store the return value
+ PUSHL 0(CX)(DX*1)
+
+ // extend argsize by size of return value
+ ADDL $4, DX
+
+ // remember how to restore stack on return
+ MOVL cbctxt_restorestack(BX), BX
+ PUSHL BX
+
+ // call target Go function
+ PUSHL DX // argsize (including return value)
+ PUSHL CX // callback parameters
+ PUSHL AX // address of target Go function
CLD
-
CALL runtime·cgocallback_gofunc(SB)
-
POPL AX
POPL CX
POPL DX
+ // how to restore stack on return
+ POPL BX
+
+ // return value into AX (as per Windows spec)
+ // and restore previously preserved value
+ MOVL -4(CX)(DX*1), AX
+ POPL -4(CX)(DX*1)
+
+ MOVL BX, CX // cannot use BX anymore
+
// pop SEH frame
POPL 0(FS)
POPL BX
@@ -212,10 +241,13 @@
POPL SI
POPL DI
+ // remove callback parameters before return (as per Windows spec)
+ POPL DX
+ ADDL CX, SP
+ PUSHL DX
+
CLD
- MOVL -4(CX)(DX*1), AX
- POPL -4(CX)(DX*1)
RET
// void tstart(M *newm);
diff --git a/src/pkg/runtime/sys_windows_amd64.s b/src/pkg/runtime/sys_windows_amd64.s
index b9eaec6..ca07f57 100644
--- a/src/pkg/runtime/sys_windows_amd64.s
+++ b/src/pkg/runtime/sys_windows_amd64.s
@@ -196,32 +196,37 @@
POPQ BP
RET
-// Continuation of thunk function created for each callback by ../thread.c compilecallback,
-// runs on Windows stack (not Go stack).
-// Thunk code designed to have minimal size for it is copied many (up to thousands) times.
-//
-// thunk:
-// MOVQ $fn, AX
-// PUSHQ AX
-// MOVQ $argsize, AX
-// PUSHQ AX
-// MOVQ $runtime·callbackasm, AX
-// JMP AX
-TEXT runtime·callbackasm(SB),7,$0
+GLOBL runtime·cbctxts(SB), $8
+
+TEXT runtime·callbackasm1(SB),7,$0
// Construct args vector for cgocallback().
// By windows/amd64 calling convention first 4 args are in CX, DX, R8, R9
// args from the 5th on are on the stack.
// In any case, even if function has 0,1,2,3,4 args, there is reserved
// but uninitialized "shadow space" for the first 4 args.
// The values are in registers.
- MOVQ CX, (24+0)(SP)
- MOVQ DX, (24+8)(SP)
- MOVQ R8, (24+16)(SP)
- MOVQ R9, (24+24)(SP)
- // 6l does not accept writing POPQs here issuing a warning "unbalanced PUSH/POP"
- MOVQ 0(SP), DX // POPQ DX
- MOVQ 8(SP), AX // POPQ AX
- ADDQ $16, SP
+ MOVQ CX, (16+0)(SP)
+ MOVQ DX, (16+8)(SP)
+ MOVQ R8, (16+16)(SP)
+ MOVQ R9, (16+24)(SP)
+
+ // remove return address from stack, we are not returning there
+ MOVQ 0(SP), AX
+ ADDQ $8, SP
+
+ // determine index into runtime·cbctxts table
+ SUBQ $runtime·callbackasm(SB), AX
+ MOVQ $0, DX
+ MOVQ $5, CX // divide by 5 because each call instruction in runtime·callbacks is 5 bytes long
+ DIVL CX,
+
+ // find correspondent runtime·cbctxts table entry
+ MOVQ runtime·cbctxts(SB), CX
+ MOVQ -8(CX)(AX*8), AX
+
+ // extract callback context
+ MOVQ cbctxt_argsize(AX), DX
+ MOVQ cbctxt_gobody(AX), AX
// preserve whatever's at the memory location that
// the callback will use to store the return value
@@ -231,8 +236,6 @@
// DI SI BP BX R12 R13 R14 R15 registers and DF flag are preserved
// as required by windows callback convention.
- // 6l does not allow writing many PUSHQs here issuing a warning "nosplit stack overflow"
- // the warning has no sense as this code uses os thread stack
PUSHFQ
SUBQ $64, SP
MOVQ DI, 56(SP)
@@ -247,18 +250,17 @@
// prepare call stack. use SUBQ to hide from stack frame checks
// cgocallback(Go func, void *frame, uintptr framesize)
SUBQ $24, SP
- MOVQ DX, 16(SP) // uintptr framesize
- MOVQ CX, 8(SP) // void *frame
- MOVQ AX, 0(SP) // Go func
+ MOVQ DX, 16(SP) // argsize (including return value)
+ MOVQ CX, 8(SP) // callback parameters
+ MOVQ AX, 0(SP) // address of target Go function
CLD
- CALL runtime·cgocallback_gofunc(SB)
+ CALL runtime·cgocallback_gofunc(SB)
MOVQ 0(SP), AX
MOVQ 8(SP), CX
MOVQ 16(SP), DX
ADDQ $24, SP
// restore registers as required for windows callback
- // 6l does not allow writing many POPs here issuing a warning "nosplit stack overflow"
MOVQ 0(SP), R15
MOVQ 8(SP), R14
MOVQ 16(SP), R13
