Re: [PATCH v3 6/6] powerpc/64s: Blacklist rtas entry/exit from kprobes
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2017-06-22 03:49:11
On Thu, 22 Jun 2017 00:08:42 +0530 "Naveen N. Rao" [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 | 4 ++++ 1 file changed, 4 insertions(+)diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index d376f07153d7..49c35450f399 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S@@ -1076,6 +1076,8 @@ _GLOBAL(enter_rtas) rldicr r9,r9,MSR_SF_LG,(63-MSR_SF_LG) ori r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI|MSR_LE andc r6,r0,r9 + +__enter_rtas: sync /* disable interrupts so SRR0/1 */ mtmsrd r0 /* don't get trashed */
Along the lines of the system call patch... For consistency, could we put the __enter_rtas right after mtmsrd? And I wonder if we shoul come up with a common prefix or postfix naming convention for these such labels used to control probing? How do opal calls avoid tracing? Thanks, Nick