Re: [PATCH 7/8] ia64-hpux: unwinding bsp value from system call

[Pedro Alves <pedro@codesourcery.com>]

On Wednesday 29 December 2010 03:28:48, Joel Brobecker wrote:
> > What is the underlying object you're getting those values from?
> > I understood it to be whatever object TT_LWP_RUREGS accesses?
> > You seem to call it save_state_t?  Why not TARGET_OBJECT_HPUX_RUREGS
> > or TARGET_OBJECT_HPUX_SAVE_STATE, or something along those lines?
> > Then, the offset, and length passed to target_xfer would the
> > the offset and length you're currently passing to
> > ia64_hpux_read_register_from_save_state_t.  This would allow
> > (if useful) exporting this object similarly to the $_siginfo and
> > $_tlb objects.
> 
> I cannot determine the offset from the tdep code.  The offset is
> is a obtained by including one of the system hearders.

Before you dismiss this completely on that
ground, looking at hppa-hpux-tdep.c, I see:

 /* Bit in the `ss_flag' member of `struct save_state' that indicates
    that the 64-bit register values are live.  From
    <machine/save_state.h>.  */
 #define HPPA_HPUX_SS_WIDEREGS		0x40

 /* Offsets of various parts of `struct save_state'.  From
    <machine/save_state.h>.  */
 #define HPPA_HPUX_SS_FLAGS_OFFSET	0
 #define HPPA_HPUX_SS_NARROW_OFFSET	4
 #define HPPA_HPUX_SS_FPBLOCK_OFFSET 	256
 #define HPPA_HPUX_SS_WIDE_OFFSET        640

 /* The size of `struct save_state.  */
 #define HPPA_HPUX_SAVE_STATE_SIZE	1152

 /* The size of `struct pa89_save_state', which corresponds to PA-RISC
    1.1, the lowest common denominator that we support.  */
 #define HPPA_HPUX_PA89_SAVE_STATE_SIZE	512

...

 * Bit in the `ss_flag' member of `struct save_state' that indicates
    the state was saved from a system call.  From
    <machine/save_state.h>.  */
 #define HPPA_HPUX_SS_INSYSCALL	0x02


And e.g., see hppa_hpux_supply_save_state.

When you implement core support for ia64-hpux, if done
right (in tdep code, host-independent, supporting cross core
debugging), you'll need to hardcode these offsets anyway.  It
looks like HPUX dumps each LWP's save_save in the cores.  These
offset are usually practically part of the ABI.

Just adding this as a data point.

-- 
Pedro Alves