path: root/arch/powerpc/kernel/process.c
diff options
authorRoland McGrath <roland@redhat.com>2007-09-24 16:52:44 -0700
committerPaul Mackerras <paulus@samba.org>2007-09-25 20:40:41 +1000
commit474f81967217f3bec2389ae913da72641f2c40e3 (patch)
tree8c9e16b05eeb0f56c49dcf61b145732569010ec8 /arch/powerpc/kernel/process.c
parentLinux 2.6.23-rc8 (diff)
[POWERPC] Ensure FULL_REGS on exec
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@redhat.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to '')
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index e477c9d0498b..8a1b001d0b11 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -605,6 +605,13 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
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;