def try_unwinder_init():
"""Try to register the custom unwinder if it hasn't been already, and
return whether the unwinder has been successfully registered."""
global _did_init
if _did_init:
return True
# If we can't successfully call is_jitted(), then gdb startup hasn't
# proceeded to a point where it's safe to set up our unwinder yet, so just
# bail out.
try:
frame.is_jitted(0, 0)
except:
return False
register_unwinder(None, HHVMUnwinder())
_did_init = True
return True
def try_unwinder_init():
"""Try to register the custom unwinder if it hasn't been already, and
return whether the unwinder has been successfully registered."""
global _did_init
if _did_init:
return True
# If we can't successfully call is_jitted(), then gdb startup hasn't
# proceeded to a point where it's safe to set up our unwinder yet, so just
# bail out.
try:
frame.is_jitted(0, 0)
except:
return False
register_unwinder(None, HHVMUnwinder())
_did_init = True
return True
# GDB wants a FrameId to be a pair of (stack pointer, starting PC) for
# a given function frame. Unfortunately, we can't restore the stack
# pointer correctly in the TC, and we don't know our starting IP.
#
# Instead, we just use the stack pointer value for our most recent call
# into native code, along with the current PC. It turns out that this
# is good enough.
#
# GDB expects stack pointers to be monotonically nondecreasing as we
# unwind, so we can't use, e.g., the frame pointer as part of the ID.
unwind_info = pending_frame.create_unwind_info(FrameId(sp, ip))
# Restore the saved frame pointer and instruction pointer.
fp = fp.cast(T('uintptr_t').pointer())
unwind_info.add_saved_register('rbp', fp[0])
unwind_info.add_saved_register('rip', fp[1])
if frame.is_jitted(fp[0], fp[1]):
# Our parent frame is jitted. Again, we are unable to track %rsp
# properly in the TC, so just preserve its value (just as we do in
# the TC's custom .eh_frame section).
unwind_info.add_saved_register('rsp', sp)
else:
# Our parent frame is not jitted, so we're in enterTCHelper, and we
# can restore our parent's %rsp as usual.
unwind_info.add_saved_register('rsp', fp + 16)
return unwind_info
register_unwinder(None, HHVMUnwinder())
# a given function frame. Unfortunately, we can't restore the stack
# pointer correctly in the TC, and we don't know our starting IP.
#
# Instead, we just use the stack pointer value for our most recent call
# into native code, along with the current PC. It turns out that this
# is good enough.
#
# GDB expects stack pointers to be monotonically nondecreasing as we
# unwind, so we can't use, e.g., the frame pointer as part of the ID.
unwind_info = pending_frame.create_unwind_info(FrameId(sp, ip))
# Restore the saved frame pointer and instruction pointer.
fp = fp.cast(T('uintptr_t').pointer())
unwind_info.add_saved_register('rbp', fp[0])
unwind_info.add_saved_register('rip', fp[1])
if frame.is_jitted(fp[0], fp[1]):
# Our parent frame is jitted. Again, we are unable to track %rsp
# properly in the TC, so just preserve its value (just as we do in
# the TC's custom .eh_frame section).
unwind_info.add_saved_register('rsp', sp)
else:
# Our parent frame is not jitted, so we're in enterTCHelper, and we
# can restore our parent's %rsp as usual.
unwind_info.add_saved_register('rsp', fp + 16)
return unwind_info
register_unwinder(None, HHVMUnwinder())
