[RFC,2/2] powerpc/kprobes: Move kprobes over to patch_instruction

Submitted by Balbir Singh on May 16, 2017, 3:49 a.m.

Details

Message ID 20170516034913.21163-3-bsingharora@gmail.com
State Superseded
Headers show

Commit Message

Balbir Singh May 16, 2017, 3:49 a.m.
arch_arm/disarm_probe use direct assignment for copying
instructions, replace them with patch_instruction

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/kernel/kprobes.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Naveen N. Rao May 16, 2017, 1:35 p.m.
On 2017/05/16 01:49PM, Balbir Singh wrote:
> arch_arm/disarm_probe use direct assignment for copying
> instructions, replace them with patch_instruction

Thanks for doing this!

We will also have to convert optprobes and ftrace to use 
patch_instruction, but that can be done once the basic infrastructure is 
in.

Regards,
Naveen
Balbir Singh May 17, 2017, 1:40 a.m.
On Tue, 2017-05-16 at 19:05 +0530, Naveen N. Rao wrote:
> On 2017/05/16 01:49PM, Balbir Singh wrote:
> > arch_arm/disarm_probe use direct assignment for copying
> > instructions, replace them with patch_instruction
> 
> Thanks for doing this!
> 
> We will also have to convert optprobes and ftrace to use 
> patch_instruction, but that can be done once the basic infrastructure is 
> in.
>

I think these patches can go in without even patch 1. I looked quickly at
optprobes and ftrace and thought they were already using patch_instruction
(ftrace_modify_code() and arch_optimize_kprobes()), are there other paths
I missed?

Balbir Singh
Naveen N. Rao May 30, 2017, 2:28 p.m.
On 2017/05/17 11:40AM, Balbir Singh wrote:
> On Tue, 2017-05-16 at 19:05 +0530, Naveen N. Rao wrote:
> > On 2017/05/16 01:49PM, Balbir Singh wrote:
> > > arch_arm/disarm_probe use direct assignment for copying
> > > instructions, replace them with patch_instruction
> > 
> > Thanks for doing this!
> > 
> > We will also have to convert optprobes and ftrace to use 
> > patch_instruction, but that can be done once the basic infrastructure is 
> > in.
> >
> 
> I think these patches can go in without even patch 1. I looked quickly at
> optprobes and ftrace and thought they were already using patch_instruction
> (ftrace_modify_code() and arch_optimize_kprobes()), are there other paths
> I missed?

[Sorry for the delay...]

Yes, all the patch_*_insns() functions need to be converted since the 
area they patch comes from .text. There is also a memcpy() where we copy 
the instruction template in, so perhaps a patch_instructions() helper 
may be useful too.

- Naveen

Patch hide | download patch | download mbox

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 160ae0f..5e1fa86 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -158,7 +158,7 @@  NOKPROBE_SYMBOL(arch_prepare_kprobe);
 
 void arch_arm_kprobe(struct kprobe *p)
 {
-	*p->addr = BREAKPOINT_INSTRUCTION;
+	patch_instruction(p->addr, BREAKPOINT_INSTRUCTION);
 	flush_icache_range((unsigned long) p->addr,
 			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
 }
@@ -166,7 +166,7 @@  NOKPROBE_SYMBOL(arch_arm_kprobe);
 
 void arch_disarm_kprobe(struct kprobe *p)
 {
-	*p->addr = p->opcode;
+	patch_instruction(p->addr, BREAKPOINT_INSTRUCTION);
 	flush_icache_range((unsigned long) p->addr,
 			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
 }