On Thu, 29 Jun 2017 17:24:14 +0530
"Naveen N. Rao" [off-list ref] wrote:

On 2017/06/29 09:01PM, Nicholas Piggin wrote:

quoted

On Thu, 29 Jun 2017 16:11:10 +0530
"Naveen N. Rao" [off-list ref] wrote:
  

quoted

We can't take traps with relocation off, so blacklist enter_rtas() and
rtas_return_loc(). However, instead of blacklisting all of enter_rtas(),
introduce a new symbol __enter_rtas from where on we can't take a trap
and blacklist that.

Signed-off-by: Naveen N. Rao <redacted>
---
 arch/powerpc/kernel/entry_64.S | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 0c27084800b6..16f4c4a1a294 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S

@@ -1082,6 +1082,7 @@ _GLOBAL(enter_rtas)
 	sync				/* disable interrupts so SRR0/1 */
 	mtmsrd	r0			/* don't get trashed */
 
+__enter_rtas:  

Hmm, am I missing something, or is there a reason to put these labels
after the mtmsr? Even if kprobes does the right thing, I think it's
easier to read the code if you cover the mtmsr as well.  

I thought you asked for this, per your previous review comment:
https://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg119667.html

Or, did I get that wrong?

No you're right, I'm contradicting myself. Let me start again.

I think we'd like to put the label before the mtmsrd if possible. So
in that case, should we adjust the system call code instead (then you
wouldn't have to add a comment for it).

And then you could move this label back above the mtmsrd. Sorry for
the confusion.

Thanks,
Nick