2020-02-24 18:02:38

by Christophe Leroy

Subject: [PATCH] powerpc/kprobes: Use probe_address() to read instructions

In order to avoid Oopses, use probe_address() to read the
instruction at the address where the trap happened.

Signed-off-by: Christophe Leroy <[email protected]>
---
arch/powerpc/kernel/kprobes.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 84567406b53d..a35320b79e16 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -276,14 +276,18 @@ int kprobe_handler(struct pt_regs *regs)

p = get_kprobe(addr);
if (!p) {
- if (*addr != BREAKPOINT_INSTRUCTION) {
+ unsigned int instr;
+
+ if (probe_kernel_address(addr, instr))
+ goto no_kprobe;
+
+ if (instr != BREAKPOINT_INSTRUCTION) {
/*
* PowerPC has multiple variants of the "trap"
* instruction. If the current instruction is a
* trap variant, it could belong to someone else
*/
- kprobe_opcode_t cur_insn = *addr;
- if (is_trap(cur_insn))
+ if (is_trap(instr))
goto no_kprobe;
/*
* The breakpoint instruction was removed right
--
2.25.0

2020-06-09 05:30:50

by Michael Ellerman

Subject: Re: [PATCH] powerpc/kprobes: Use probe_address() to read instructions

On Mon, 24 Feb 2020 18:02:10 +0000 (UTC), Christophe Leroy wrote:
> In order to avoid Oopses, use probe_address() to read the
> instruction at the address where the trap happened.

Applied to powerpc/next.

[1/1] powerpc/kprobes: Use probe_address() to read instructions
https://git.kernel.org/powerpc/c/9ed5df69b79a22b40b20bc2132ba2495708b19c4

cheers

2020-06-09 05:59:28

by Christoph Hellwig

Subject: Re: [PATCH] powerpc/kprobes: Use probe_address() to read instructions

On Tue, Jun 09, 2020 at 03:28:38PM +1000, Michael Ellerman wrote:
> On Mon, 24 Feb 2020 18:02:10 +0000 (UTC), Christophe Leroy wrote:
> > In order to avoid Oopses, use probe_address() to read the
> > instruction at the address where the trap happened.
>
> Applied to powerpc/next.
>
> [1/1] powerpc/kprobes: Use probe_address() to read instructions
> https://git.kernel.org/powerpc/c/9ed5df69b79a22b40b20bc2132ba2495708b19c4

probe_addresss has been renamed to get_kernel_nofault in the -mm
queue that Andrew sent off to Linus last night.

2020-06-10 16:08:23

by Michael Ellerman

Subject: Re: [PATCH] powerpc/kprobes: Use probe_address() to read instructions

Christoph Hellwig <[email protected]> writes:
> On Tue, Jun 09, 2020 at 03:28:38PM +1000, Michael Ellerman wrote:
>> On Mon, 24 Feb 2020 18:02:10 +0000 (UTC), Christophe Leroy wrote:
>> > In order to avoid Oopses, use probe_address() to read the
>> > instruction at the address where the trap happened.
>>
>> Applied to powerpc/next.
>>
>> [1/1] powerpc/kprobes: Use probe_address() to read instructions
>> https://git.kernel.org/powerpc/c/9ed5df69b79a22b40b20bc2132ba2495708b19c4
>
> probe_addresss has been renamed to get_kernel_nofault in the -mm
> queue that Andrew sent off to Linus last night.

That commit above is actually already in mainline, I was just _really_
behind on sending the patch notifications.

cheers