in the air to deal with it.
Basically, following a kernel fault (eg. dereferencing a NULL pointer
in kernel mode) a DDB 'trace' did not show the function where the
fault occurred. For example:
db> trace
_Debugger()
_panic()
_trap()
faultstkadj()
_pool_drain()
_uvm_pageout()
_start_pagedaemon()
_proc_trampoline()
db>
The 'faultstkadj()' line here is bogus. It is shown because the return
address to 'trap()' happens to point there, and since faultstkadj() has
no stack frame, DDB assumes it was the faulting function. In this example,
the _real_ function was pool_reclaim(), but you would have to look at
the program counter at the time of the fault to figure that one out.
This fix makes the trace command do the dirty work for you by grubbing
around in 'trap()'s argument list to find the *real* PC value at the
time of the fault, replacing the 'faultstkadj()' line with the real
function's name.
* Map the message buffer with access_type = VM_PROT_READ|VM_PROT_WRITE `just
because'.
* Map the file system buffers with access_type = VM_PROT_READ|VM_PROT_WRITE to
avoid possible problems with pagemove().
* Do not use VM_PROT_EXEC with either of the above.
* Map pages for /dev/mem with access_type = prot. Also, DO NOT use
pmap_kenter() for this, as we DO NOT want to lose modification information.
* Map pages in dumpsys() with VM_PROT_READ.
* Map pages in m68k mappedcopyin()/mappedcopyout() and writeback() with
access_type = prot.
* For now, bus_dma*(), pmap_map(), vmapbuf(), and similar functions still use
access_type = 0. This should probably be revisited.
minor of libc and the major of libutil). For little-endian architectures
merge the bnswap() assembly versions with nto* and hton* using symbols
aliasing. Use symbol renaming for the bswap function in this case to avoid
namespace pollution.
Declare bswap* in machine/bswap.h, not machine/endian.h. For little-endian
machines, common code for inline macros go in machine/byte_swap.h
Sync libkern with libc.
Adjust #include in kernel sources for machine/bswap.h.
non-standard way of invoking sigreturn, specifically a side-effect that I
overlooked. Thus, longjmp's return value was getting clobbered.
Sigh, so burn trap #3 just as sigreturn.
XXX We need an SVR4-style {get,set}context(2) to avoid wasting new
XXX trap vectors in the future.
Makes the sigcode grow by 4 bytes.
Note that we are no longer able to use the HP-UX breakpoint "sigcodetrap"
hack here, as a result. This means that BSD programs can no longer be
debugged by HP-UX debuggers. *Sniff* Don't break my heart...
