[Crash-utility] vmlist initialize fix

[Kazuo Moriwaka]

Hi Dave, 

> The problem is that the return vmalloc address of zero eventually
> gets stored in vt->vmalloc_start, which, among a few other places,
> is used here:
> 
>   #define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
> 
> Can you verify that setting it to zero will not cause problems in
> the macro above, and the other places that it's used directly?

Thank you for your advice.  I rushed..

> Upon a quick examination, it does looks safe enough in the relevant
> vtop routines, but for example, the search command's use of next_kpage()
> looks like it might fail.
> 
> Perhaps IS_VMALLOC_ADDRESS() itself should also verify
> that vt->vmalloc_start is non-zero, and the other places that
> use vt->vmalloc_start directly should be verified.  (Of course
> we don't need to do this kind of check for the processors
> that have hardwired vmalloc addresses).

I checked all places which use vt->vmalloc_start directory, 
and fixing IS_VMALLOC_ADDRESS looks enough.

All places are:
1. IS_VMALLOC_ADDRESS
2. in memory.c: they looks work fine with zero.
3. each architectures .c: just check if(!vt->vmalloc_start). They'll work.

thanks,
-- 
Kazuo Moriwaka <moriwaka at valinux.co.jp>


diff -ru crash-4.0-2.31.orig/defs.h crash-4.0-2.31/defs.h
--- crash-4.0-2.31.orig/defs.h	2006-06-27 23:15:32.000000000 +0900
+++ crash-4.0-2.31/defs.h	2006-07-11 11:17:31.000000000 +0900
@@ -1813,7 +1813,7 @@
 #define MACHINE_TYPE       "X86"
 #define PTOV(X)            ((unsigned long)(X)+(machdep->kvbase))
 #define VTOP(X)            ((unsigned long)(X)-(machdep->kvbase))
-#define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
+#define IS_VMALLOC_ADDR(X) (vt->vmalloc_start && (ulong)(X) >= vt->vmalloc_start)
 #define KVBASE_MASK        (0x7fffff)
 
 #define PGDIR_SHIFT_2LEVEL   (22)
@@ -2011,7 +2011,7 @@
 
 #define PTOV(X)            ((unsigned long)(X)+(machdep->kvbase))
 #define VTOP(X)            ((unsigned long)(X)-(machdep->kvbase))
-#define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
+#define IS_VMALLOC_ADDR(X) (vt->vmalloc_start && (ulong)(X) >= vt->vmalloc_start)
 #define KSEG_BASE_48_BIT   (0xffff800000000000)
 #define KSEG_BASE          (0xfffffc0000000000)
 #define _PFN_MASK          (0xFFFFFFFF00000000)
@@ -2056,7 +2056,7 @@
 
 #define PTOV(X)            ((unsigned long)(X)+(machdep->kvbase))
 #define VTOP(X)            ((unsigned long)(X)-(machdep->kvbase))
-#define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
+#define IS_VMALLOC_ADDR(X) (vt->vmalloc_start && (ulong)(X) >= vt->vmalloc_start)
 
 #define PGDIR_SHIFT   (22)
 #define PTRS_PER_PTE  (1024)
@@ -2240,7 +2240,7 @@
 
 #define PTOV(X)            ((unsigned long)(X)+(machdep->kvbase))
 #define VTOP(X)            ((unsigned long)(X)-(machdep->kvbase))
-#define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
+#define IS_VMALLOC_ADDR(X) (vt->vmalloc_start && (ulong)(X) >= vt->vmalloc_start)
 #define KERNELBASE      machdep->pageoffset
 
 #define PGDIR_SHIFT     (machdep->pageshift + (machdep->pageshift -3) + (machdep->pageshift - 2))
@@ -2343,7 +2343,7 @@
 
 #define PTOV(X)            ((unsigned long)(X)+(machdep->kvbase))
 #define VTOP(X)            ((unsigned long)(X)-(machdep->kvbase))
-#define IS_VMALLOC_ADDR(X) ((ulong)(X) >= vt->vmalloc_start)
+#define IS_VMALLOC_ADDR(X) (vt->vmalloc_start && (ulong)(X) >= vt->vmalloc_start)
 #define PTRS_PER_PTE    512
 #define PTRS_PER_PMD    1024
 #define PTRS_PER_PGD    2048
diff -ru crash-4.0-2.31.orig/memory.c crash-4.0-2.31/memory.c
--- crash-4.0-2.31.orig/memory.c	2006-06-27 23:15:32.000000000 +0900
+++ crash-4.0-2.31/memory.c	2006-07-11 11:20:12.000000000 +0900
@@ -11049,10 +11049,13 @@
         ulong vmlist, addr;
 
         get_symbol_data("vmlist", sizeof(void *), &vmlist);
-
-        if (!readmem(vmlist+OFFSET(vm_struct_addr), KVADDR, &addr, 
-	    sizeof(void *), "first vmlist addr", RETURN_ON_ERROR)) 
-		non_matching_kernel();
+        if (vmlist != 0x0) {
+            if (!readmem(vmlist+OFFSET(vm_struct_addr), KVADDR, &addr, 
+	        sizeof(void *), "first vmlist addr", RETURN_ON_ERROR)) 
+	       	    non_matching_kernel();
+        } else {
+            addr = 0;
+        }
 
         return addr;
 }