Add discriminator to MutatorContextStruct and implement MutatorContex…

…tInitFault and MutatorContextInitThread on POSIX/Linux. Copied from Perforce Change: 192577 ServerID: perforce.ravenbrook.com
Ravenbrook · Oct 14, 2016 · 5e70f08 · 5e70f08
1 parent 9edf039
commit 5e70f08
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Showing 7 changed files with 39 additions and 11 deletions.
diff --git a/code/prmcan.c b/code/prmcan.c
@@ -3,10 +3,6 @@
  * $Id$
  * Copyright (c) 2001-2016 Ravenbrook Limited.  See end of file for license.
  *
- * .design: See <design/prot/> for the generic design of the interface
- * which is implemented in this module including the contracts for the
- * functions.
- *
  * .purpose: Implement the mutator context module. See <design/prmc/>.
  * In this ANSI version none of the functions have a useful
  * implementation.
@@ -17,6 +13,14 @@
 SRCID(prmcan, "$Id$");
 
 
+Bool MutatorContextCheck(MutatorContext context)
+{
+  UNUSED(context);
+
+  return TRUE;
+}
+
+
 Bool MutatorContextCanStepInstruction(MutatorContext context)
 {
   UNUSED(context);

diff --git a/code/prmcix.c b/code/prmcix.c
@@ -24,17 +24,22 @@ SRCID(prmcix, "$Id$");
 Bool MutatorContextCheck(MutatorContext context)
 {
   CHECKS(MutatorContext, context);
+  CHECKL(NONNEGATIVE(context->var));
+  CHECKL(context->var < MutatorContextLIMIT);
+  CHECKL((context->var == MutatorContextTHREAD) == (context->info == NULL));
   CHECKL(context->ucontext != NULL);
   return TRUE;
 }
 
 
-void MutatorContextInit(MutatorContext context, siginfo_t *info,
-                        ucontext_t *ucontext)
+void MutatorContextInitFault(MutatorContext context, siginfo_t *info,
+                             ucontext_t *ucontext)
 {
   AVER(context != NULL);
+  AVER(info != NULL);
   AVER(ucontext != NULL);
 
+  context->var = MutatorContextFAULT;
   context->info = info;
   context->ucontext = ucontext;
   context->sig = MutatorContextSig;
@@ -43,6 +48,20 @@ void MutatorContextInit(MutatorContext context, siginfo_t *info,
 }
 
 
+void MutatorContextInitThread(MutatorContext context, ucontext_t *ucontext)
+{
+  AVER(context != NULL);
+  AVER(ucontext != NULL);
+
+  context->var = MutatorContextTHREAD;
+  context->info = NULL;
+  context->ucontext = ucontext;
+  context->sig = MutatorContextSig;
+
+  AVERT(MutatorContext, context);
+}
+
+
 Res MutatorContextScan(ScanState ss, MutatorContext context,
                        mps_area_scan_t scan_area, void *closure)
 {
@@ -63,7 +82,7 @@ Res MutatorContextScan(ScanState ss, MutatorContext context,
 
 /* C. COPYRIGHT AND LICENSE
  *
- * Copyright (C) 2001-2015 Ravenbrook Limited <http://www.ravenbrook.com/>.
+ * Copyright (C) 2001-2016 Ravenbrook Limited <http://www.ravenbrook.com/>.
  * All rights reserved.  This is an open source license.  Contact
  * Ravenbrook for commercial licensing options.
  * 

diff --git a/code/prmcix.h b/code/prmcix.h
@@ -16,11 +16,14 @@
 
 typedef struct MutatorContextStruct {
   Sig sig;                      /* <design/sig/> */
-  siginfo_t *info;
+  MutatorContextVar var;        /* Discriminator. */
+  siginfo_t *info;              /* Signal info, if stopped by protection
+                                 * fault; NULL if stopped by thread manager. */
   ucontext_t *ucontext;
 } MutatorContextStruct;
 
-extern void MutatorContextInit(MutatorContext context, siginfo_t *info, ucontext_t *ucontext);
+extern void MutatorContextInitFault(MutatorContext context, siginfo_t *info, ucontext_t *ucontext);
+extern void MutatorContextInitThread(MutatorContext context, ucontext_t *ucontext);
 
 #endif /* prmcix_h */
 

diff --git a/code/prmclii3.c b/code/prmclii3.c
@@ -79,6 +79,7 @@ void Prmci3DecodeFaultContext(MRef *faultmemReturn,
   AVER(faultmemReturn != NULL);
   AVER(insvecReturn != NULL);
   AVERT(MutatorContext, context);
+  AVER(context->var == MutatorContextFAULT);
 
   /* .source.linux.kernel (linux/arch/i386/mm/fault.c). */
   *faultmemReturn = (MRef)context->info->si_addr;

diff --git a/code/prmclii6.c b/code/prmclii6.c
@@ -83,6 +83,7 @@ void Prmci6DecodeFaultContext(MRef *faultmemReturn,
   AVER(faultmemReturn != NULL);
   AVER(insvecReturn != NULL);
   AVERT(MutatorContext, context);
+  AVER(context->var == MutatorContextFAULT);
 
   /* .source.linux.kernel (linux/arch/x86/mm/fault.c). */
   *faultmemReturn = (MRef)context->info->si_addr;

diff --git a/code/protsgix.c b/code/protsgix.c
@@ -83,7 +83,7 @@ static void sigHandle(int sig, siginfo_t *info, void *uap)  /* .sigh.args */
     Addr base;
     MutatorContextStruct context;
 
-    MutatorContextInit(&context, info, (ucontext_t *)uap);
+    MutatorContextInitFault(&context, info, (ucontext_t *)uap);
 
     mode = AccessREAD | AccessWRITE; /* .sigh.mode */
 

diff --git a/code/pthrdext.c b/code/pthrdext.c
@@ -80,7 +80,7 @@ static void suspendSignalHandler(int sig,
     /* copy the ucontext structure so we definitely have it on our stack,
      * not (e.g.) shared with other threads. */
     ucontext = *(ucontext_t *)uap;
-    MutatorContextInit(&context, NULL, &ucontext);
+    MutatorContextInitThread(&context, &ucontext);
     suspendingVictim->context = &context;
     /* Block all signals except PTHREADEXT_SIGRESUME while suspended. */
     sigfillset(&signal_set);