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From gshiman...@apache.org
Subject svn commit: r606790 - in /harmony/enhanced/drlvm/trunk/vm: port/src/encoder/ia32_em64t/dec_base.cpp vmcore/src/jvmti/jvmti_break_intf.cpp
Date Tue, 25 Dec 2007 14:51:30 GMT
Author: gshimansky
Date: Tue Dec 25 06:51:28 2007
New Revision: 606790

URL: http://svn.apache.org/viewvc?rev=606790&view=rev
Log:
Fixed bug HARMONY-5342. The change makes parsing of REX prefixes more flexible. All possible
REX combinations should now be allowed including those not mentioned in instruction opcodes
of encoder tables.

Also patch fixes a bug when a return is made from "noreturn" function
VMBreakPoints::process_native_breakpoint. It cannot return because its return address is
undefined in the stack. Instead it should transfer control back to original register context.


Modified:
    harmony/enhanced/drlvm/trunk/vm/port/src/encoder/ia32_em64t/dec_base.cpp
    harmony/enhanced/drlvm/trunk/vm/vmcore/src/jvmti/jvmti_break_intf.cpp

Modified: harmony/enhanced/drlvm/trunk/vm/port/src/encoder/ia32_em64t/dec_base.cpp
URL: http://svn.apache.org/viewvc/harmony/enhanced/drlvm/trunk/vm/port/src/encoder/ia32_em64t/dec_base.cpp?rev=606790&r1=606789&r2=606790&view=diff
==============================================================================
--- harmony/enhanced/drlvm/trunk/vm/port/src/encoder/ia32_em64t/dec_base.cpp (original)
+++ harmony/enhanced/drlvm/trunk/vm/port/src/encoder/ia32_em64t/dec_base.cpp Tue Dec 25 06:51:28
2007
@@ -255,19 +255,39 @@
 #endif
 
         *pbuf = save_pbuf;
-        if (opcode_len != 0) {
 #ifdef _EM64T_
-            // Match REX prefixes
-            if (((*pbuf)[0] & 0xf0) == 0x40 && opcode_ptr[0] == 0x48)
+        // Match REX prefixes
+        unsigned char rex_byte = (*pbuf)[0];
+        if ((rex_byte & 0xf0) == 0x40)
+        {
+            if ((rex_byte & 0x08) != 0)
+            {
+                // Have REX.W
+                if (opcode_len > 0 && opcode_ptr[0] == 0x48)
+                {
+                    // Have REX.W in opcode. All mnemonics that allow
+                    // REX.W have to have specified it in opcode,
+                    // otherwise it is not allowed
+                    rex = *(Rex *)*pbuf;
+                    prex = &rex;
+                    (*pbuf)++;
+                    opcode_ptr++;
+                    opcode_len--;
+                }
+            }
+            else
             {
+                // No REX.W, so it doesn't have to be in opcode. We
+                // have REX.B, REX.X, REX.R or their combination, but
+                // not in opcode, they may extend any part of the
+                // instruction
                 rex = *(Rex *)*pbuf;
                 prex = &rex;
                 (*pbuf)++;
-                opcode_ptr++;
-                opcode_len--;
             }
+        }
 #endif
-
+        if (opcode_len != 0) {
             if (memcmp(*pbuf, opcode_ptr, opcode_len)) {
                 continue;
             }

Modified: harmony/enhanced/drlvm/trunk/vm/vmcore/src/jvmti/jvmti_break_intf.cpp
URL: http://svn.apache.org/viewvc/harmony/enhanced/drlvm/trunk/vm/vmcore/src/jvmti/jvmti_break_intf.cpp?rev=606790&r1=606789&r2=606790&view=diff
==============================================================================
--- harmony/enhanced/drlvm/trunk/vm/vmcore/src/jvmti/jvmti_break_intf.cpp (original)
+++ harmony/enhanced/drlvm/trunk/vm/vmcore/src/jvmti/jvmti_break_intf.cpp Tue Dec 25 06:51:28
2007
@@ -605,11 +605,21 @@
 
     TRACE2("jvmti.break", "Native breakpoint occured: " << addr);
 
+    M2nFrame* m2nf = m2n_push_suspended_frame(&regs);
+
     VMBreakPoint* bp = find_breakpoint(addr);
     if (NULL == bp) {
         // breakpoint could be deleted by another thread
+        assert(*((unsigned char *)addr) != INSTRUMENTATION_BYTE);
         unlock();
-        return;
+        // Transfer execution back to the original register
+        // context. In case the target location happens to be
+        // instrumented, it means that another breakpoint has been set
+        // there right after unlock was done.
+        StackIterator* si = (StackIterator*) STD_ALLOCA(si_size());
+        si_fill_from_registers(si, &regs, false, m2n_get_previous_frame(m2nf));
+
+        si_transfer_control(si);
     }
     assert(bp->addr == addr);
     TRACE2("jvmti.break", "Process native breakpoint: "
@@ -619,8 +629,6 @@
         << (bp->method ? method_get_name((Method*)bp->method) : "(nil)")
         << (bp->method ? method_get_descriptor((Method*)bp->method) : "")
         << " :" << bp->location << " :" << bp->addr);
-
-    M2nFrame* m2nf = m2n_push_suspended_frame(&regs);
 
     jbyte *instruction_buffer;
     BEGIN_RAISE_AREA;



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