From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "olsajiri@gmail.com" <olsajiri@gmail.com>,
"oleg@redhat.com" <oleg@redhat.com>
Cc: "songliubraving@fb.com" <songliubraving@fb.com>,
"luto@kernel.org" <luto@kernel.org>,
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Subject: Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
Date: Wed, 15 May 2024 15:13:59 +0000 [thread overview]
Message-ID: <0fa9634e9ac0d30d513eefe6099f5d8d354d93c1.camel@intel.com> (raw)
In-Reply-To: <20240515113525.GB6821@redhat.com>
On Wed, 2024-05-15 at 13:35 +0200, Oleg Nesterov wrote:
> Let me repeat I know nothing about shadow stacks, only tried to
> read Documentation/arch/x86/shstk.rst few minutes ago ;)
>
> On 05/13, Jiri Olsa wrote:
> >
> > 1) current uretprobe which are not working at the moment and we change
> > the top value of shadow stack with shstk_push_frame
> > 2) optimized uretprobe which needs to push new frame on shadow stack
> > with shstk_update_last_frame
> >
> > I think we should do 1) and have current uretprobe working with shadow
> > stack, which is broken at the moment
>
> Agreed,
>
> > I'm ok with not using optimized uretprobe when shadow stack is detected
> > as enabled and we go with current uretprobe in that case
>
> But how can we detect it? Again, suppose userspace does
the rdssp instruction returns the value of the shadow stack pointer. On non-
shadow stack it is a nop. So you could check if the SSP is non-zero to find if
shadow stack is enabled. This would catch most cases, but I guess there is the
possibility of it getting enabled in a signal that hit between checking and the
rest of operation. Is this uretprobe stuff signal safe in general?
next prev parent reply other threads:[~2024-05-15 15:14 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-07 10:53 [PATCHv5 bpf-next 0/8] uprobe: uretprobe speed up Jiri Olsa
2024-05-07 10:53 ` [PATCHv5 bpf-next 1/8] uprobe: Wire up uretprobe system call Jiri Olsa
2024-05-07 10:53 ` [PATCHv5 bpf-next 2/8] uprobe: Add uretprobe syscall to speed up return probe Jiri Olsa
2024-05-07 10:53 ` [PATCHv5 bpf-next 3/8] selftests/bpf: Add uretprobe syscall test for regs integrity Jiri Olsa
2024-05-07 10:53 ` [PATCHv5 bpf-next 4/8] selftests/bpf: Add uretprobe syscall test for regs changes Jiri Olsa
2024-05-07 10:53 ` [PATCHv5 bpf-next 5/8] selftests/bpf: Add uretprobe syscall call from user space test Jiri Olsa
2024-05-07 16:57 ` Andrii Nakryiko
2024-05-07 10:53 ` [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support Jiri Olsa
2024-05-07 17:35 ` Edgecombe, Rick P
2024-05-09 8:30 ` Jiri Olsa
2024-05-09 16:24 ` Edgecombe, Rick P
2024-05-11 21:09 ` Jiri Olsa
2024-05-13 9:50 ` Masami Hiramatsu
2024-05-13 17:12 ` Edgecombe, Rick P
2024-05-13 21:23 ` Jiri Olsa
2024-05-15 1:10 ` Edgecombe, Rick P
2024-05-15 1:44 ` Deepak Gupta
2024-05-15 11:19 ` Oleg Nesterov
2024-05-15 14:36 ` Jiri Olsa
2024-05-15 15:18 ` Edgecombe, Rick P
2024-05-15 15:26 ` Oleg Nesterov
2024-05-15 15:31 ` Edgecombe, Rick P
2024-05-15 11:35 ` Oleg Nesterov
2024-05-15 15:13 ` Edgecombe, Rick P [this message]
2024-05-15 15:42 ` Oleg Nesterov
2024-05-19 22:18 ` Jiri Olsa
2024-05-21 1:31 ` Edgecombe, Rick P
2024-05-21 10:11 ` Jiri Olsa
2024-05-07 10:53 ` [PATCHv5 bpf-next 7/8] selftests/x86: Add return uprobe shadow stack test Jiri Olsa
2024-05-13 9:45 ` Masami Hiramatsu
2024-05-13 21:28 ` Jiri Olsa
2024-05-07 10:53 ` [PATCHv5 8/8] man2: Add uretprobe syscall page Jiri Olsa
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