[PATCH 1/10] UML - Improve stub debugging

[Jeff Dike <jdike@addtoit.com>]

Add some more debugging information when a stub does something unexpected,
usually segfaulting.  Now, it dumps out the stub's registers as well as
the signal.

Signed-off-by: Jeff Dike <jdike@addtoit.com>

Index: linux-2.6.14-rc2-mm1/arch/um/kernel/skas/process.c
===================================================================
--- linux-2.6.14-rc2-mm1.orig/arch/um/kernel/skas/process.c	2005-10-05 18:37:51.000000000 -0400
+++ linux-2.6.14-rc2-mm1/arch/um/kernel/skas/process.c	2005-10-05 18:50:23.000000000 -0400
@@ -69,6 +69,17 @@
 
         if((n < 0) || !WIFSTOPPED(status) ||
            (WSTOPSIG(status) != SIGUSR1 && WSTOPSIG(status) != SIGTRAP)){
+		unsigned long regs[FRAME_SIZE];
+		if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
+			printk("Failed to get registers from stub, "
+			       "errno = %d\n", errno);
+		else {
+			int i;
+
+			printk("Stub registers -\n");
+			for(i = 0; i < FRAME_SIZE; i++)
+				printk("\t%d - %lx\n", i, regs[i]);
+		}
                 panic("%s : failed to wait for SIGUSR1/SIGTRAP, "
                       "pid = %d, n = %d, errno = %d, status = 0x%x\n",
                       fname, pid, n, errno, status);

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