* Re: [SCM] master: Use libunwind cursor to get at CFA.
2007-12-03 16:19 ` [SCM] master: Use libunwind cursor to get at CFA Andrew Cagney
@ 2007-12-03 20:49 ` Mark Wielaard
2007-12-04 14:42 ` Andrew Cagney
0 siblings, 1 reply; 3+ messages in thread
From: Mark Wielaard @ 2007-12-03 20:49 UTC (permalink / raw)
To: Andrew Cagney; +Cc: frysk
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Hi Andrew,
On Mon, 2007-12-03 at 11:19 -0500, Andrew Cagney wrote:
> The confusion comes from what libunwind considers to be the cursor's
> CFA. It returns what you're more likely to recognize as the
> inner-to-cursor's CFA and not the cursor''s CFA. Effectively the
> current frame's SP, in fact:
>
> case UNW_X86_64_CFA:
> case UNW_X86_64_RSP:
> if (write)
> return -UNW_EREADONLYREG;
> *valp = c->dwarf.cfa;
> return 0;
Nice catch. Well that is somewhat of a bummer. Then we must fall back on
the unwind one frame trick and get the SP again.
What is somewhat worrying is that none of the tests caught this. So I
added one that does fail with my change, and passes with that commit
reverted.
frysk-core/frysk/pkglibdir/ChangeLog
2007-12-03 Mark Wielaard <mwielaard@redhat.com>
* funit-stepping-asm.S: Add fifth function and _stepOverPrologue_
marker.
frysk-core/frysk/stepping/ChangeLog
2007-12-03 Mark Wielaard <mwielaard@redhat.com>
* TestStepping.java (testASMFunctionStepOverPrologue): New test.
Cheers,
Mark
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diff --git a/frysk-core/frysk/pkglibdir/funit-stepping-asm.S b/frysk-core/frysk/pkglibdir/funit-stepping-asm.S
index 4af1506..cde2b22 100644
--- a/frysk-core/frysk/pkglibdir/funit-stepping-asm.S
+++ b/frysk-core/frysk/pkglibdir/funit-stepping-asm.S
@@ -40,10 +40,18 @@
#include "frysk-asm.h"
+ FUNCTION_BEGIN(fifth,1)
+ FUNCTION_PROLOGUE(fifth,1) ; NO_OP // _stepOverPrologue_
+ FUNCTION_EPILOGUE(fifth,1)
+ FUNCTION_RETURN(fifth,1)
+ FUNCTION_END(fifth,1)
+
+
FUNCTION_BEGIN(fourth,0)
FUNCTION_PROLOGUE(fourth,0)
NO_OP // _stepAdvanceStart_
NO_OP
+ FUNCTION_CALL(fifth)
FUNCTION_EPILOGUE(fourth,0)
FUNCTION_RETURN(fourth,0)
FUNCTION_END(fourth,0)
diff --git a/frysk-core/frysk/stepping/TestStepping.java b/frysk-core/frysk/stepping/TestStepping.java
index 7f14ea1..cab4480 100644
--- a/frysk-core/frysk/stepping/TestStepping.java
+++ b/frysk-core/frysk/stepping/TestStepping.java
@@ -952,6 +952,52 @@ public class TestStepping extends TestLib {
cleanup();
}
+ /**
+ * Tests that the line stepper steps OK even when stack pointer
+ * changes.
+ */
+ public void testASMFunctionStepOverPrologue() {
+
+ /** Variable setup */
+ String source = Config.getRootSrcDir()
+ + "frysk-core/frysk/pkglibdir/funit-stepping-asm.S";
+
+ this.scanner = new TestfileTokenScanner(new File(source));
+
+ /* The line number where the test begins, prologue of fifth
+ function. */
+ int startLine = this.scanner.findTokenLine("_stepOverPrologue_");
+
+ /* The line number the test should end up at, still the same
+ line (only prologue is stepped over, not the NO_OP) */
+ int endLine = this.scanner.findTokenLine("_stepOverPrologue_");
+
+ /* The test process */
+ dbae = new DaemonBlockedAtEntry(Config
+ .getPkgLibFile("funit-stepping-asm"));
+
+ Task theTask = dbae.getMainTask();
+
+ this.testStarted = false;
+
+ initTaskWithTask(theTask, source, startLine, endLine);
+
+ this.currentTest = new AssertLine(endLine, theTask);
+
+ DebugInfoFrame frame = DebugInfoStackFactory
+ .createDebugInfoStackTrace(theTask);
+ assertTrue("Line information present", frame.getLines().length > 0);
+
+ /** The stepping operation */
+ this.se.stepOver(theTask, frame);
+
+ this.testStarted = true;
+ /** Run to completion */
+ assertRunUntilStop("Running test");
+ cleanup();
+ }
+
+
boolean genericUpdate = false;
public Task initTask(Offspring process, String source, int startLine,
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