@ -452,6 +452,38 @@ i386_get_frame_setup (CORE_ADDR pc)
return ( - 1 ) ;
}
/* Signal trampolines don't have a meaningful frame. The frame
pointer value we use is actually the frame pointer of the calling
frame - - that is , the frame which was in progress when the signal
trampoline was entered . GDB mostly treats this frame pointer value
as a magic cookie . We detect the case of a signal trampoline by
looking at the SIGNAL_HANDLER_CALLER field , which is set based on
PC_IN_SIGTRAMP .
When a signal trampoline is invoked from a frameless function , we
essentially have two frameless functions in a row . In this case ,
we use the same magic cookie for three frames in a row . We detect
this case by seeing whether the next frame has
SIGNAL_HANDLER_CALLER set , and , if it does , checking whether the
current frame is actually frameless . In this case , we need to get
the PC by looking at the SP register value stored in the signal
context .
This should work in most cases except in horrible situations where
a signal occurs just as we enter a function but before the frame
has been set up . */
/* Return non-zero if we're dealing with a frameless signal, that is,
a signal trampoline invoked from a frameless function . */
static int
i386_frameless_signal_p ( struct frame_info * frame )
{
return ( frame - > next
& & frame - > next - > signal_handler_caller
& & frameless_look_for_prologue ) ;
}
/* Return the chain-pointer for FRAME. In the case of the i386, the
frame ' s nominal address is the address of a 4 - byte word containing
the calling frame ' s address . */
@ -459,7 +491,8 @@ i386_get_frame_setup (CORE_ADDR pc)
static CORE_ADDR
i386_frame_chain ( struct frame_info * frame )
{
if ( frame - > signal_handler_caller )
if ( frame - > signal_handler_caller
| | i386_frameless_signal_p ( frame ) )
return frame - > frame ;
if ( ! inside_entry_file ( frame - > pc ) )
@ -494,6 +527,19 @@ i386_sigtramp_saved_pc (struct frame_info *frame)
return read_memory_unsigned_integer ( addr + tdep - > sc_pc_offset , 4 ) ;
}
/* Assuming FRAME is for a sigtramp routine, return the saved stack
pointer . */
static CORE_ADDR
i386_sigtramp_saved_sp ( struct frame_info * frame )
{
struct gdbarch_tdep * tdep = gdbarch_tdep ( current_gdbarch ) ;
CORE_ADDR addr ;
addr = tdep - > sigcontext_addr ( frame ) ;
return read_memory_unsigned_integer ( addr + tdep - > sc_sp_offset , 4 ) ;
}
/* Return the saved program counter for FRAME. */
static CORE_ADDR
@ -502,6 +548,12 @@ i386_frame_saved_pc (struct frame_info *frame)
if ( frame - > signal_handler_caller )
return i386_sigtramp_saved_pc ( frame ) ;
if ( i386_frameless_signal_p ( frame ) )
{
CORE_ADDR sp = i386_sigtramp_saved_sp ( frame - > next ) ;
return read_memory_unsigned_integer ( sp , 4 ) ;
}
return read_memory_unsigned_integer ( frame - > frame + 4 , 4 ) ;
}
@ -510,6 +562,9 @@ i386_frame_saved_pc (struct frame_info *frame)
static CORE_ADDR
i386_saved_pc_after_call ( struct frame_info * frame )
{
if ( frame - > signal_handler_caller )
return i386_sigtramp_saved_pc ( frame ) ;
return read_memory_unsigned_integer ( read_register ( SP_REGNUM ) , 4 ) ;
}
Mark Kettenis
24 years ago