# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1201516571 0
# Node ID 36a8e6763f3af8938f3c5c60e67cedd8a7ef0120
# Parent c8c91e2e552e3b614d9c3f33bdc3d89c465d09c8
x86: Clarify early_page_fault() handler intent, and improve debug
tracing.
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
xen-unstable changeset: 16887:923f2f7365079861e0e2341de22839376183208e
xen-unstable date: Fri Jan 25 13:42:36 2008 +0000
---
xen/arch/x86/traps.c | 22 ++++++++++++++--------
1 files changed, 14 insertions(+), 8 deletions(-)
diff -r c8c91e2e552e -r 36a8e6763f3a xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c Mon Jan 28 10:35:47 2008 +0000
+++ b/xen/arch/x86/traps.c Mon Jan 28 10:36:11 2008 +0000
@@ -1116,12 +1116,11 @@ asmlinkage void do_page_fault(struct cpu
}
/*
- * Early handler to deal with spurious page faults. For example, consider a
- * routine that uses a mapping immediately after installing it (making it
- * present). The CPU may speculatively execute the memory access before
- * executing the PTE write. The instruction will then be marked to cause a
- * page fault when it is retired, despite the fact that the PTE is present and
- * correct at that point in time.
+ * Early #PF handler to print CR2, error code, and stack.
+ *
+ * We also deal with spurious faults here, even though they should never happen
+ * during early boot (an issue was seen once, but was most likely a hardware
+ * problem).
*/
asmlinkage void do_early_page_fault(struct cpu_user_regs *regs)
{
@@ -1140,8 +1139,15 @@ asmlinkage void do_early_page_fault(stru
}
if ( stuck++ == 1000 )
- panic("Early fatal page fault at %04x:%p (cr2=%p, ec=%04x)\n",
- regs->cs, _p(regs->eip), _p(cr2), regs->error_code);
+ {
+ unsigned long *stk = (unsigned long *)regs;
+ printk("Early fatal page fault at %04x:%p (cr2=%p, ec=%04x)\n",
+ regs->cs, _p(regs->eip), _p(cr2), regs->error_code);
+ printk("Stack dump: ");
+ while ( ((long)stk & ((PAGE_SIZE - 1) & ~(BYTES_PER_LONG - 1))) != 0 )
+ printk("%p ", _p(*stk++));
+ for ( ; ; ) ;
+ }
}
long do_fpu_taskswitch(int set)
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