From f72c22e45e8f8fe78c7f793d983bee5bed63497e Mon Sep 17 00:00:00 2001 From: Richard Weinberger Date: Mon, 23 Sep 2013 17:38:02 +0200 Subject: um: Make stack trace reliable against kernel mode faults As UML uses an alternative signal stack we cannot use the current stack pointer for stack dumping if UML itself dies by SIGSEGV. To bypass this issue we save regs taken from mcontext in our segv handler into thread_struct and use these regs to obtain the stack pointer in show_stack(). Signed-off-by: Richard Weinberger --- arch/um/os-Linux/signal.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch/um/os-Linux/signal.c') diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c index 905924b773d3..7b605e4dfffa 100644 --- a/arch/um/os-Linux/signal.c +++ b/arch/um/os-Linux/signal.c @@ -304,3 +304,11 @@ int set_signals(int enable) return ret; } + +int os_is_signal_stack(void) +{ + stack_t ss; + sigaltstack(NULL, &ss); + + return ss.ss_flags & SS_ONSTACK; +} -- cgit v1.2.3