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runtime/debug: add SetPanicOnFault

SetPanicOnFault allows recovery from unexpected memory faults.
This can be useful if you are using a memory-mapped file
or probing the address space of the current program.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/66590044
This commit is contained in:
Russ Cox 2014-02-20 16:18:05 -05:00
parent 67c83db60d
commit e56c6e7535
14 changed files with 52 additions and 15 deletions

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@ -8,3 +8,4 @@ testing: add b.RunParallel function (CL 57270043)
misc/benchcmp has been replaced by go tool benchcmp (CL 47980043)
cmd/go, go/build: support .m files (CL 60590044)
unicode: upgrade from Unicode 6.2.0 to 6.3.0 (CL 65400044)
runtime/debug: add SetPanicOnFault (CL 66590044)

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@ -135,3 +135,14 @@ func SetMaxStack(bytes int) int {
func SetMaxThreads(threads int) int {
return setMaxThreads(threads)
}
// SetPanicOnFault controls the runtime's behavior when a program faults
// at an unexpected (non-nil) address. Such faults are typically caused by
// bugs such as runtime memory corruption, so the default response is to crash
// the program. Programs working with memory-mapped files or unsafe
// manipulation of memory may cause faults at non-nil addresses in less
// dramatic situations; SetPanicOnFault allows such programs to request
// that the runtime trigger only a panic, not a crash.
// SetPanicOnFault applies only to the current goroutine.
// It returns the previous setting.
func SetPanicOnFault(enabled bool) bool

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@ -436,7 +436,7 @@ runtime·sigpanic(void)
{
switch(g->sig) {
case SIGBUS:
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");
@ -444,7 +444,7 @@ runtime·sigpanic(void)
runtime·printf("unexpected fault address %p\n", g->sigcode1);
runtime·throw("fault");
case SIGSEGV:
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");

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@ -171,7 +171,7 @@ runtime·sigpanic(void)
{
switch(g->sig) {
case SIGBUS:
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");
@ -179,7 +179,7 @@ runtime·sigpanic(void)
runtime·printf("unexpected fault address %p\n", g->sigcode1);
runtime·throw("fault");
case SIGSEGV:
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");

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@ -179,7 +179,7 @@ runtime·sigpanic(void)
{
switch(g->sig) {
case SIGBUS:
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");
@ -187,7 +187,7 @@ runtime·sigpanic(void)
runtime·printf("unexpected fault address %p\n", g->sigcode1);
runtime·throw("fault");
case SIGSEGV:
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");

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@ -220,7 +220,7 @@ runtime·sigpanic(void)
{
switch(g->sig) {
case SIGBUS:
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");
@ -228,7 +228,7 @@ runtime·sigpanic(void)
runtime·printf("unexpected fault address %p\n", g->sigcode1);
runtime·throw("fault");
case SIGSEGV:
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");

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@ -239,7 +239,7 @@ runtime·sigpanic(void)
{
switch(g->sig) {
case SIGBUS:
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");
@ -247,7 +247,7 @@ runtime·sigpanic(void)
runtime·printf("unexpected fault address %p\n", g->sigcode1);
runtime·throw("fault");
case SIGSEGV:
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");

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@ -216,7 +216,7 @@ runtime·sigpanic(void)
{
switch(g->sig) {
case SIGBUS:
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");
@ -224,7 +224,7 @@ runtime·sigpanic(void)
runtime·printf("unexpected fault address %p\n", g->sigcode1);
runtime·throw("fault");
case SIGSEGV:
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");

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@ -211,7 +211,7 @@ runtime·sigpanic(void)
{
switch(g->sig) {
case SIGBUS:
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");
@ -219,7 +219,7 @@ runtime·sigpanic(void)
runtime·printf("unexpected fault address %p\n", g->sigcode1);
runtime·throw("fault");
case SIGSEGV:
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");

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@ -348,7 +348,7 @@ runtime·sigpanic(void)
{
switch(g->sig) {
case EXCEPTION_ACCESS_VIOLATION:
if(g->sigcode1 < 0x1000) {
if(g->sigcode1 < 0x1000 || g->paniconfault) {
if(g->sigpc == 0)
runtime·panicstring("call of nil func value");
runtime·panicstring("invalid memory address or nil pointer dereference");

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@ -1449,6 +1449,7 @@ goexit0(G *gp)
gp->status = Gdead;
gp->m = nil;
gp->lockedm = nil;
gp->paniconfault = 0;
m->curg = nil;
m->lockedg = nil;
if(m->locked & ~LockExternal) {

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@ -20,3 +20,8 @@ func setGCPercent(in int) (out int) {
func setMaxThreads(in int) (out int) {
out = runtime·setmaxthreads(in);
}
func SetPanicOnFault(enabled bool) (old bool) {
old = g->paniconfault;
g->paniconfault = enabled;
}

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@ -273,6 +273,7 @@ struct G
bool issystem; // do not output in stack dump
bool isbackground; // ignore in deadlock detector
bool preempt; // preemption signal, duplicates stackguard0 = StackPreempt
bool paniconfault; // panic (instead of crash) on unexpected fault address
int8 raceignore; // ignore race detection events
M* m; // for debuggers, but offset not hard-coded
M* lockedm;

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@ -10,9 +10,11 @@ import (
"os"
"os/exec"
. "runtime"
"runtime/debug"
"strconv"
"strings"
"testing"
"unsafe"
)
var errf error
@ -131,3 +133,19 @@ func TestRuntimeGogoBytes(t *testing.T) {
func TestStopCPUProfilingWithProfilerOff(t *testing.T) {
SetCPUProfileRate(0)
}
func TestSetPanicOnFault(t *testing.T) {
old := debug.SetPanicOnFault(true)
defer debug.SetPanicOnFault(old)
defer func() {
if err := recover(); err == nil {
t.Fatalf("did not find error in recover")
}
}()
var p *int
p = (*int)(unsafe.Pointer(^uintptr(0)))
println(*p)
t.Fatalf("still here - should have faulted")
}