The patch titled
powerpc: FULL_REGS on exec
has been added to the -mm tree. Its filename is
powerpc-full_regs-on-exec.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: powerpc: FULL_REGS on exec
From: Roland McGrath <roland@xxxxxxxxxx>
When PTRACE_O_TRACEEXEC is used, a ptrace call to fetch the registers at the
PTRACE_EVENT_EXEC stop (PTRACE_PEEKUSR) will oops in CHECK_FULL_REGS. With
recent versions, "gdb --args /bin/sh -c 'exec /bin/true'" and "run" at the
(gdb) prompt is sufficient to produce this. I also have written an isolated
test case, see https://bugzilla.redhat.com/show_bug.cgi?id=301791#c15.
This change fixes the problem by clearing the low bit of pt_regs.trap in
start_thread so that FULL_REGS is true again. This is correct since all of
the GPRs that "full" refers to are cleared in start_thread.
Signed-off-by: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN arch/powerpc/kernel/process.c~powerpc-full_regs-on-exec arch/powerpc/kernel/process.c
--- a/arch/powerpc/kernel/process.c~powerpc-full_regs-on-exec
+++ a/arch/powerpc/kernel/process.c
@@ -605,6 +605,13 @@ void start_thread(struct pt_regs *regs,
regs->ccr = 0;
regs->gpr[1] = sp;
+ /*
+ * We have just cleared all the nonvolatile GPRs, so make
+ * FULL_REGS(regs) return true. This is necessary to allow
+ * ptrace to examine the thread immediately after exec.
+ */
+ regs->trap &= ~1UL;
+
#ifdef CONFIG_PPC32
regs->mq = 0;
regs->nip = start;
_
Patches currently in -mm which might be from roland@xxxxxxxxxx are
powerpc-vdso-install-unstripped-copies-on-disk.patch
powerpc-vdso-install-unstripped-copies-on-disk-update.patch
powerpc-ptrace-check_full_regs.patch
powerpc-full_regs-on-exec.patch
x86_64-vdso-linker-script-cleanup.patch
x86_64-vdso-put-vars-in-rodata.patch
clone-flag-clone_parent_tidptr-leaves-invalid-results-in-memory.patch
add-sys-module-name-notes.patch
do_sigaction-remove-now-unneeded-recalc_sigpending.patch
handle-the-multi-threaded-inits-exit-properly.patch
add-linux-elfcore-compath.patch
x86_64-use-linux-elfcore-compath.patch
powerpc-use-linux-elfcore-compath.patch
wait_task_zombie-remove-unneeded-child-signal-check.patch
wait_task_zombie-fix-2-3-races-vs-forget_original_parent.patch
exit_notify-dont-take-tasklist-for-tif_sigpending-re-targeting.patch
zap_other_threads-dont-optimize-thread_group_empty-case.patch
wait_task_zombie-dont-fight-with-non-existing-race-with-a-dying-ptracee.patch
__group_complete_signal-eliminate-unneeded-wakeup-of-group_exit_task.patch
wait_task_stopped-continued-remove-unneeded-p-signal-=-null-check.patch
add-mmf_dump_elf_headers.patch
pie-executable-randomization.patch
pie-executable-randomization-fix.patch
pie-executable-randomization-fix-2.patch
pie-executable-randomization-fix-3.patch
use-erestart_restartblock-if-poll-is-interrupted-by-a-signal.patch
exec-simplify-sighand-switching.patch
exec-simplify-the-new-sighand-allocation.patch
exec-consolidate-2-fast-paths.patch
exec-rt-sub-thread-can-livelock-and-monopolize-cpu-on-exec.patch
do_sigaction-dont-worry-about-signal_pending.patch
increase-at_vector_size-to-terminate-saved_auxv-properly.patch
fix-tsk-exit_state-usage-resend.patch
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