Unbreak stack traces across double faults. In a particular edge case

(calling a __dead2 function such as panic() at the end of a function), the
saved %eip on the stack will actually not be part of the function that
executed a call instruction but instead will be the first instruction of
the next function in the text.  This happens with dblfault_handler() and
syscall() for example.  Work around this in the one place it matters by
looking at the saved %eip - 1 to determine the calling function when we
check for "magic" frames.

MFC after:	2 weeks

This commit is contained in:

John Baldwin

2005-01-18 03:48:02 +00:00

parent 9196a9005e

commit bb5d43ae2a

1 changed files with 8 additions and 2 deletions

									
										sys/i386/i386/db_trace.c
									
		+8
		-2
	
												View File
												
				@@ -286,10 +286,16 @@ db_nextframe(struct i386_frame **fp, db_addr_t *ip, struct thread *td)

					ebp = db_get_value((int) &(*fp)->f_frame, 4, FALSE);

					/*

					 * Figure out frame type.

					 * Figure out frame type.  We look at the address just before

					 * the saved instruction pointer as the saved EIP is after the

					 * call function, and if the function being called is marked as

					 * dead (such as panic() at the end of dblfault_handler()), then

					 * the instruction at the saved EIP will be part of a different

					 * function (syscall() in this example) rather than the one that

					 * actually made the call.

					 */

					frame_type = NORMAL;

					sym = db_search_symbol(eip, DB_STGY_ANY, &offset);

					sym = db_search_symbol(eip - 1, DB_STGY_ANY, &offset);

					db_symbol_values(sym, &name, NULL);

					if (name != NULL) {

						if (strcmp(name, "calltrap") == 0 ||