bitkeeper revision 1.696 (401a7b30TOUK5wUOTZ_RoVNCXsji4g)

sched.h, config.h, current.h, smpboot.c, setup.c, boot.S:
  Add support for detecting stack overflow within Xen. This is turned on for debug builds.

diff --git a/xen/arch/i386/boot/boot.S b/xen/arch/i386/boot/boot.S
index 621ae879056198657ac361adc5be000e0d3fdd17..f0e5a57c75f2c2f7f721a4c28f2459b914e0470c 100644 (file)
--- a/xen/arch/i386/boot/boot.S
+++ b/xen/arch/i386/boot/boot.S
@@ -214,7 +214,7 @@ bad_cpu:
 /*** STACK LOCATION ***/
         
 ENTRY(stack_start)
-        .long SYMBOL_NAME(cpu0_stack) + 4000 - __PAGE_OFFSET
+        .long SYMBOL_NAME(cpu0_stack) + 8100 - __PAGE_OFFSET
         .long __HYPERVISOR_DS
         
 /*** DESCRIPTOR TABLES ***/
@@ -256,11 +256,10 @@ ENTRY(gdt_table)
         .quad 0x0000000000000000     /* unused                           */
         .fill 2*NR_CPUS,8,0          /* space for TSS and LDT per CPU    */
 
-# The following adds 8-12kB to the kernel file size.
         .org 0x1000
-ENTRY(idle_pg_table)
+ENTRY(idle_pg_table) # Initial page directory is 4kB
         .org 0x2000
-ENTRY(cpu0_stack)
-        .org 0x3000
+ENTRY(cpu0_stack)    # Initial stack is 8kB
+        .org 0x4000
 ENTRY(stext)
 ENTRY(_stext)

diff --git a/xen/arch/i386/setup.c b/xen/arch/i386/setup.c
index 13298f7385ac1207e0f5a1a56574d870cb75f81f..b0f6766b9f926c92b0815f53779f33e012914f87 100644 (file)
--- a/xen/arch/i386/setup.c
+++ b/xen/arch/i386/setup.c
@@ -321,6 +321,30 @@ void __init start_of_day(void)
     extern int do_timer_lists_from_pit;
     unsigned long low_mem_size;
     
+#ifdef STACK_GUARD
+    extern unsigned long cpu0_stack[];
+    l1_pgentry_t *l1;
+    l2_pgentry_t *l2;
+    int i, j;
+
+    /* When stack-guarding, Xen's heap cannot be mapped by super pages. */
+    for ( i = 0; i < (MAX_MONITOR_ADDRESS >> L2_PAGETABLE_SHIFT); i++ )
+    {
+        l1 = (l1_pgentry_t *)get_free_page(GFP_KERNEL);
+        for ( j = 0; j < ENTRIES_PER_L1_PAGETABLE; j++ )
+            l1[j] = mk_l1_pgentry((i << L2_PAGETABLE_SHIFT) |
+                                   (j << L1_PAGETABLE_SHIFT) | 
+                                   PAGE_HYPERVISOR);
+        idle_pg_table[i] = idle_pg_table[i + l2_table_offset(PAGE_OFFSET)] =
+            mk_l2_pgentry(virt_to_phys(l1) | PAGE_HYPERVISOR);
+    }
+
+    /* Unmap the first page of CPU0's stack. */
+    l2  = &idle_pg_table[l2_table_offset(virt_to_phys(cpu0_stack))];
+    l1  = l2_pgentry_to_l1(*l2) + l1_table_offset(virt_to_phys(cpu0_stack));
+    *l1 = mk_l1_pgentry(0);
+#endif
+
     if ( opt_watchdog ) 
         nmi_watchdog = NMI_LOCAL_APIC;
 

diff --git a/xen/arch/i386/smpboot.c b/xen/arch/i386/smpboot.c
index b5a424900380a9bc55029b0e99039cd2c2d26abc..083aa3ce2e998f4260ae9bb6a4dc02f952a19261 100644 (file)
--- a/xen/arch/i386/smpboot.c
+++ b/xen/arch/i386/smpboot.c
@@ -667,7 +667,7 @@ static void __init do_boot_cpu (int apicid)
     struct task_struct *idle;
     unsigned long boot_error = 0;
     int timeout, cpu;
-    unsigned long start_eip;
+    unsigned long start_eip, stack;
 
     cpu = ++cpucount;
 
@@ -687,7 +687,17 @@ static void __init do_boot_cpu (int apicid)
 
     /* So we see what's up. */
     printk("Booting processor %d/%d eip %lx\n", cpu, apicid, start_eip);
-    stack_start.esp = __pa(get_free_page(GFP_KERNEL)) + 4000;
+
+    stack = __pa(__get_free_pages(GFP_KERNEL, 1));
+#ifdef STACK_GUARD
+    {
+        /* Unmap the first page of the new CPU0's stack. */
+        l2_pgentry_t *l2  = &idle_pg_table[l2_table_offset(stack)];
+        l1_pgentry_t *l1  = l2_pgentry_to_l1(*l2) + l1_table_offset(stack);
+        *l1 = mk_l1_pgentry(0);
+    }
+#endif
+    stack_start.esp = stack + STACK_SIZE - STACK_RESERVED;
 
     /*
      * This grunge runs the startup process for

diff --git a/xen/include/asm-i386/current.h b/xen/include/asm-i386/current.h
index c2d29857889cd0b2de4642433ae2cd1890b6b221..ee5b4b8516d6c208025289d7032cc06ca833b9da 100644 (file)
--- a/xen/include/asm-i386/current.h
+++ b/xen/include/asm-i386/current.h
@@ -3,11 +3,14 @@
 
 struct task_struct;
 
+#define STACK_RESERVED \
+    (sizeof(execution_context_t) + sizeof(struct task_struct *))
+
 static inline struct task_struct * get_current(void)
 {
     struct task_struct *current;
     __asm__ ( "orl %%esp,%0; andl $~3,%0; movl (%0),%0" 
-              : "=r" (current) : "0" (4092UL) );
+              : "=r" (current) : "0" (STACK_SIZE-4) );
     return current;
 }
  
@@ -16,14 +19,15 @@ static inline struct task_struct * get_current(void)
 static inline void set_current(struct task_struct *p)
 {
     __asm__ ( "orl %%esp,%0; andl $~3,%0; movl %1,(%0)" 
-              : : "r" (4092UL), "r" (p) );    
+              : : "r" (STACK_SIZE-4), "r" (p) );    
 }
 
 static inline execution_context_t *get_execution_context(void)
 {
     execution_context_t *execution_context;
-    __asm__ ( "andl %%esp,%0; addl $4096-72,%0"
-              : "=r" (execution_context) : "0" (~4095UL) );
+    __asm__ ( "andl %%esp,%0; addl %2,%0"
+              : "=r" (execution_context) 
+              : "0" (~(STACK_SIZE-1)), "i" (STACK_SIZE-STACK_RESERVED) );
     return execution_context;
 }
 
@@ -31,16 +35,18 @@ static inline unsigned long get_stack_top(void)
 {
     unsigned long p;
     __asm__ ( "orl %%esp,%0; andl $~3,%0" 
-              : "=r" (p) : "0" (4092UL) );
+              : "=r" (p) : "0" (STACK_SIZE-4) );
     return p;
 }
 
 #define schedule_tail(_p)                                         \
     __asm__ __volatile__ (                                        \
-        "andl %%esp,%0; addl $4096-72,%0; movl %0,%%esp; jmp *%1" \
-        : : "r" (~4095UL), "r" (unlikely(is_idle_task((_p))) ?    \
+        "andl %%esp,%0; addl %2,%0; movl %0,%%esp; jmp *%1"       \
+        : : "r" (~(STACK_SIZE-1)),                                \
+            "r" (unlikely(is_idle_task((_p))) ?                   \
                                 continue_cpu_idle_loop :          \
-                                continue_nonidle_task) )
+                                continue_nonidle_task),           \
+            "i" (STACK_SIZE-STACK_RESERVED) )
 
 
 #endif /* !(_I386_CURRENT_H) */

diff --git a/xen/include/xeno/config.h b/xen/include/xeno/config.h
index c88e41d15b31b4ffe5ade2d385046de9b3cb5dd6..6dc740405ddcd08e3d8b7c39e0bb7a098aac4bc1 100644 (file)
--- a/xen/include/xeno/config.h
+++ b/xen/include/xeno/config.h
@@ -148,6 +148,7 @@
 #ifndef NDEBUG
 #define DPRINTK(_f, _a...) printk("(file=%s, line=%d) " _f, \
                            __FILE__, __LINE__, ## _a)
+#define STACK_GUARD
 #else
 #define DPRINTK(_f, _a...) ((void)0)
 #endif

diff --git a/xen/include/xeno/sched.h b/xen/include/xeno/sched.h
index e99bd5786d869c79a22c624048c80a45e11bb125..2e9cd0c563b27d8aae9173f5f12fa9c6d9a13b5b 100644 (file)
--- a/xen/include/xeno/sched.h
+++ b/xen/include/xeno/sched.h
@@ -7,7 +7,6 @@
 #include <asm/ptrace.h>
 #include <xeno/smp.h>
 #include <asm/processor.h>
-#include <asm/current.h>
 #include <hypervisor-ifs/hypervisor-if.h>
 #include <hypervisor-ifs/dom0_ops.h>
 
@@ -17,6 +16,9 @@
 #include <xeno/delay.h>
 #include <xeno/rbtree.h>
 
+#define STACK_SIZE (2*PAGE_SIZE)
+#include <asm/current.h>
+
 #define MAX_DOMAIN_NAME 16
 
 extern unsigned long volatile jiffies;
@@ -190,8 +192,6 @@ extern struct task_struct *idle_task[NR_CPUS];
 #define IDLE_DOMAIN_ID   (~0)
 #define is_idle_task(_p) ((_p)->domain == IDLE_DOMAIN_ID)
 
-#define STACK_SIZE PAGE_SIZE
-
 #include <xeno/slab.h>
 
 extern kmem_cache_t *task_struct_cachep;