/* Verify if there is sufficient libunwind information for the frame to use
libunwind frame unwinding. */
const struct frame_unwind *
libunwind_frame_sniffer (struct frame_info *next_frame)
{
unw_cursor_t cursor;
unw_accessors_t *acc;
unw_addr_space_t as;
struct libunwind_descr *descr;
int i, ret;
/* To test for libunwind unwind support, initialize a cursor to the current frame and try to back
up. We use this same method when setting up the frame cache (see libunwind_frame_cache()).
If libunwind returns success for this operation, it means that it has found sufficient
libunwind unwinding information to do so. */
descr = libunwind_descr (get_frame_arch (next_frame));
acc = descr->accessors;
as = unw_create_addr_space_p (acc,
TARGET_BYTE_ORDER == BFD_ENDIAN_BIG
? __BIG_ENDIAN
: __LITTLE_ENDIAN);
ret = unw_init_remote_p (&cursor, as, next_frame);
if (ret >= 0)
ret = unw_step_p (&cursor);
if (ret < 0)
return NULL;
return &libunwind_frame_unwind;
}
static struct libunwind_frame_cache *
libunwind_frame_cache (struct frame_info *next_frame, void **this_cache)
{
unw_accessors_t *acc;
unw_addr_space_t as;
unw_word_t fp;
unw_regnum_t uw_sp_regnum;
struct libunwind_frame_cache *cache;
struct libunwind_descr *descr;
int i, ret;
if (*this_cache)
return *this_cache;
/* Allocate a new cache. */
cache = FRAME_OBSTACK_ZALLOC (struct libunwind_frame_cache);
cache->func_addr = frame_func_unwind (next_frame);
/* Get a libunwind cursor to the previous frame. We do this by initializing
a cursor. Libunwind treats a new cursor as the top of stack and will get
the current register set via the libunwind register accessor. Now, we
provide the platform-specific accessors and we set up the register accessor to use
the frame register unwinding interfaces so that we properly get the registers for
the current frame rather than the top. We then use the unw_step function to
move the libunwind cursor back one frame. We can later use this cursor to find previous
registers via the unw_get_reg interface which will invoke libunwind's special logic. */
descr = libunwind_descr (get_frame_arch (next_frame));
acc = descr->accessors;
as = unw_create_addr_space_p (acc,
TARGET_BYTE_ORDER == BFD_ENDIAN_BIG
? __BIG_ENDIAN
: __LITTLE_ENDIAN);
unw_init_remote_p (&cache->cursor, as, next_frame);
unw_step_p (&cache->cursor);
/* To get base address, get sp from previous frame. */
uw_sp_regnum = descr->gdb2uw (SP_REGNUM);
ret = unw_get_reg_p (&cache->cursor, uw_sp_regnum, &fp);
if (ret < 0)
error ("Can't get libunwind sp register.");
cache->base = (CORE_ADDR)fp;
*this_cache = cache;
return cache;
}
static struct libunwind_frame_cache *
libunwind_frame_cache (struct frame_info *this_frame, void **this_cache)
{
unw_accessors_t *acc;
unw_addr_space_t as;
unw_word_t fp;
unw_regnum_t uw_sp_regnum;
struct libunwind_frame_cache *cache;
struct libunwind_descr *descr;
struct gdbarch *gdbarch = get_frame_arch (this_frame);
int i, ret;
if (*this_cache)
return (struct libunwind_frame_cache *) *this_cache;
/* Allocate a new cache. */
cache = FRAME_OBSTACK_ZALLOC (struct libunwind_frame_cache);
cache->func_addr = get_frame_func (this_frame);
if (cache->func_addr == 0)
/* This can happen when the frame corresponds to a function for which
there is no debugging information nor any entry in the symbol table.
This is probably a static function for which an entry in the symbol
table was not created when the objfile got linked (observed in
libpthread.so on ia64-hpux).
The best we can do, in that case, is use the frame PC as the function
address. We don't need to give up since we still have the unwind
record to help us perform the unwinding. There is also another
compelling to continue, because abandonning now means stopping
the backtrace, which can never be helpful for the user. */
cache->func_addr = get_frame_pc (this_frame);
/* Get a libunwind cursor to the previous frame.
We do this by initializing a cursor. Libunwind treats a new cursor
as the top of stack and will get the current register set via the
libunwind register accessor. Now, we provide the platform-specific
accessors and we set up the register accessor to use the frame
register unwinding interfaces so that we properly get the registers
for the current frame rather than the top. We then use the unw_step
function to move the libunwind cursor back one frame. We can later
use this cursor to find previous registers via the unw_get_reg
interface which will invoke libunwind's special logic. */
descr = libunwind_descr (gdbarch);
acc = (unw_accessors_t *) descr->accessors;
as = unw_create_addr_space_p (acc,
gdbarch_byte_order (gdbarch)
== BFD_ENDIAN_BIG
? __BIG_ENDIAN
: __LITTLE_ENDIAN);
unw_init_remote_p (&cache->cursor, as, this_frame);
if (unw_step_p (&cache->cursor) < 0)
{
unw_destroy_addr_space_p (as);
return NULL;
}
/* To get base address, get sp from previous frame. */
uw_sp_regnum = descr->gdb2uw (gdbarch_sp_regnum (gdbarch));
ret = unw_get_reg_p (&cache->cursor, uw_sp_regnum, &fp);
if (ret < 0)
{
unw_destroy_addr_space_p (as);
error (_("Can't get libunwind sp register."));
}
cache->base = (CORE_ADDR)fp;
cache->as = as;
*this_cache = cache;
return cache;
}