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/include/asm/processor-generic.h | 1 + arch/um/include/shared/os.h | 1 + 2 files changed, 2 insertions(+) (limited to 'arch/um/include') diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h index c03cd5a02364..90469031297b 100644 --- a/arch/um/include/asm/processor-generic.h +++ b/arch/um/include/asm/processor-generic.h @@ -21,6 +21,7 @@ struct mm_struct; struct thread_struct { struct task_struct *saved_task; struct pt_regs regs; + struct pt_regs *segv_regs; int singlestep_syscall; void *fault_addr; jmp_buf *fault_catcher; diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h index 021104d98cb3..75298d3358e7 100644 --- a/arch/um/include/shared/os.h +++ b/arch/um/include/shared/os.h @@ -227,6 +227,7 @@ extern void block_signals(void); extern void unblock_signals(void); extern int get_signals(void); extern int set_signals(int enable); +extern int os_is_signal_stack(void); /* util.c */ extern void stack_protections(unsigned long address); -- cgit v1.2.3