unwind_for_each_frame stops after the first frame if regs->gprs[15] <=
sp.
The reason is that in case regs are specified, the first frame should be
regs->psw.addr and the second frame should be sp->gprs[8]. However,
currently the second frame is regs->gprs[15], which confuses
outside_of_stack().
Fix by introducing a flag to distinguish this special case from
unwinding the interrupt handler, for which the current behavior is
appropriate.
Fixes: 78c98f9074 ("s390/unwind: introduce stack unwind API")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: stable@vger.kernel.org # v5.2+
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
When current task is interrupted in-between stack frame allocation
and backchain write instructions new stack frame backchain pointer
is left uninitialized. That invalid backchain value is passed into
outside_of_stack for sanity check. Make sure int overflow does not happen
by subtracting stack_frame size from the stack "end" rather than adding
it to "random" backchain value.
Fixes: 41b0474c1b1c ("s390/unwind: introduce stack unwind API")
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Avoid kasan false positive when current task is interrupted in-between
stack frame allocation and backchain write instructions leaving new stack
frame backchain invalid. In particular if backchain is 0 the unwinder
tries to read pt_regs from the stack and might hit kasan poisoned bytes,
leading to kasan "stack-out-of-bounds" report.
Disable kasan instrumentation of unwinder stack reads, since this
limitation couldn't be handled otherwise with current backchain unwinder
implementation.
Fixes: 78c98f9074 ("s390/unwind: introduce stack unwind API")
Reported-by: Julian Wiedmann <jwi@linux.ibm.com>
Tested-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Make the call chain more reliable by tagging the ftrace stack entries
with the stack pointer that is associated with the return address.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Rework the dump_trace() stack unwinder interface to support different
unwinding algorithms. The new interface looks like this:
struct unwind_state state;
unwind_for_each_frame(&state, task, regs, start_stack)
do_something(state.sp, state.ip, state.reliable);
The unwind_bc.c file contains the implementation for the classic
back-chain unwinder.
One positive side effect of the new code is it now handles ftraced
functions gracefully. It prints the real name of the return function
instead of 'return_to_handler'.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
