From 3eddddcf239c89bbd3c50d1440001a3d384ed40a Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Fri, 16 Sep 2005 19:27:46 -0700 Subject: [PATCH] uml: breakpoint an arbitrary thread This patch implements a stack trace for a thread, not unlike sysrq-t does. The advantage to this is that a break point can be placed on showreqs, so that upon showing the stack, you jump immediately into the debugger. While sysrq-t does the same thing, sysrq-t shows *all* threads stacks. It also doesn't work right now. In the future, I thought it might be acceptable to make this show all pids stacks, but perhaps leaving well enough alone and just using sysrq-t would be okay. For now, upon receiving the stack command, UML switches context to that thread, dumps its registers, and then switches context back to the original thread. Since UML compacts all threads into one of 4 host threads, this sort of mechanism could be expanded in the future to include other debugging helpers that sysrq does not cover. Note by jdike - The main benefit to this is that it brings an arbitrary thread back into context, where it can be examined by gdb. The fact that it dumps it stack is secondary. This provides the capability to examine a sleeping thread, which has existed in tt mode, but not in skas mode until now. Also, the other threads, that sysrq doesn't cover, can be gdb-ed directly anyway. Signed-off-by: Allan Graves Signed-off-by: Jeff Dike Cc: Paolo Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-um/processor-generic.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/asm-um') diff --git a/include/asm-um/processor-generic.h b/include/asm-um/processor-generic.h index b2fc94fbc2d..2d242360c3d 100644 --- a/include/asm-um/processor-generic.h +++ b/include/asm-um/processor-generic.h @@ -21,6 +21,7 @@ struct thread_struct { * copy_thread) to mark that we are begin called from userspace (fork / * vfork / clone), and reset to 0 after. It is left to 0 when called * from kernelspace (i.e. kernel_thread() or fork_idle(), as of 2.6.11). */ + struct task_struct *saved_task; int forking; int nsyscalls; struct pt_regs regs; -- cgit v1.2.3