On Fri, 7 Dec 2007 17:11:52 -0800 (PST) Roland McGrath <roland@xxxxxxxxxx> wrote: > > This adds support to allow asm/ptrace.h to define two new macros, > arch_ptrace_stop_needed and arch_ptrace_stop. These control special > machine-specific actions to be done before a ptrace stop. The new > code compiles away to nothing when the new macros are not defined. > This is the case on all machines to begin with. > > On ia64, these macros will be defined to solve the long-standing > issue of ptrace vs register backing store. > > Signed-off-by: Roland McGrath <roland@xxxxxxxxxx> > CC: Petr Tesarik <ptesarik@xxxxxxx> > CC: Tony Luck <tony.luck@xxxxxxxxx> > --- > include/linux/ptrace.h | 35 +++++++++++++++++++++++++++++++++++ > kernel/signal.c | 33 ++++++++++++++++++++++++++++++++- > 2 files changed, 67 insertions(+), 1 deletions(-) > > diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h > index ae8146a..7168757 100644 > --- a/include/linux/ptrace.h > +++ b/include/linux/ptrace.h > @@ -128,6 +128,41 @@ int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data); > #define force_successful_syscall_return() do { } while (0) > #endif > > +#ifndef arch_ptrace_stop_needed > +/** > + * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called > + * @code: current->exit_code value ptrace will stop with > + * @info: siginfo_t pointer (or %NULL) for signal ptrace will stop with > + * > + * This is called with the siglock held, to decide whether or not it's > + * necessary to release the siglock and call arch_ptrace_stop() with the > + * same @code and @info arguments. It can be defined to a constant if > + * arch_ptrace_stop() is never required, or always is. On machines where > + * this makes sense, it should be defined to a quick test to optimize out > + * calling arch_ptrace_stop() when it would be superfluous. For example, > + * if the thread has not been back to user mode since the last stop, the > + * thread state might indicate that nothing needs to be done. > + */ > +#define arch_ptrace_stop_needed(code, info) (0) > +#endif > + > +#ifndef arch_ptrace_stop > +/** > + * arch_ptrace_stop - Do machine-specific work before stopping for ptrace > + * @code: current->exit_code value ptrace will stop with > + * @info: siginfo_t pointer (or %NULL) for signal ptrace will stop with > + * > + * This is called with no locks held when arch_ptrace_stop_needed() has > + * just returned nonzero. It is allowed to block, e.g. for user memory > + * access. The arch can have machine-specific work to be done before > + * ptrace stops. On ia64, register backing store gets written back to user > + * memory here. Since this can be costly (requires dropping the siglock), > + * we only do it when the arch requires it for this particular stop, as > + * indicated by arch_ptrace_stop_needed(). > + */ > +#define arch_ptrace_stop(code, info) do { } while (0) Mutter. These would be better as static inlines. A macro just invites variable-unused warnings on non-ia64 and outright compilation errors on ia64. Speaking from experience... static inline void arch_ptrace_stop(int exit_code, siginfo_t *info) { } #define arch_ptrace_stop arch_ptrace_stop should work? > /* > + * Return nonzero if there is a SIGKILL that should be waking us up. > + * Called with the siglock held. > + */ > +static int sigkill_pending(struct task_struct *tsk) > +{ > + return ((sigismember(&tsk->pending.signal, SIGKILL) || > + sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) && > + !unlikely(sigismember(&tsk->blocked, SIGKILL))); > +} Could you please take a peek at the infrastructure added by ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.24-rc4/2.6.24-rc4-mm1/broken-out/add-lock_page_killable.patch and see if there is exploitable commonality? - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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