- relbranch_fixup(), for non-branches, would end up setting
regs->tnpc incorrectly, in fact it would set it equal to
regs->tpc which would cause that instruction to execute twice
Also, if this is not a PC-relative branch, we should just
leave regs->tnpc as-is. This covers cases like 'jmpl' which
branch to absolute values.
- To be absolutely %100 safe, we need to flush the instruction
cache for all assignments to kprobe->ainsn.insn[], including
cases like add_aggr_kprobe()
- prev_kprobe's status field needs to be 'unsigned long' to match
the type of the value it is saving
- jprobes were totally broken:
= jprobe_return() can run in the stack frame of the jprobe handler,
or in an even deeper stack frame, thus we'll be in the wrong
register window than the one from the original probe state.
So unwind using 'restore' instructions, if necessary, right
before we do the jprobe_return() breakpoint trap.
= There is no reason to save/restore the register window saved
at %sp at jprobe trigger time. Those registers cannot be
modified by the jprobe handler. Also, this code was saving
and restoring "sizeof (struct sparc_stackf)" bytes. Depending
upon the caller, this could clobber unrelated stack frame
pieces if there is only a basic 128-byte register window
stored on the stack, without the argument save area.
So just saving and restoring struct pt_regs is sufficient.
= Kill the "jprobe_saved_esp", totally unused.
Also, delete "jprobe_saved_regs_location", with the stack frame
unwind now done explicitly by jprobe_return(), this check is
superfluous.
Signed-off-by: David S. Miller <davem@davemloft.net>
f088258966