From: Oleg Nesterov <oleg@redhat.com>
To: Yonghong Song <yhs@fb.com>
Cc: mingo@kernel.org, tglx@linutronix.de, peterz@infradead.org,
linux-kernel@vger.kernel.org, x86@kernel.org,
netdev@vger.kernel.org, ast@fb.com, kernel-team@fb.com
Subject: Re: [PATCH][v2] uprobes/x86: emulate push insns for uprobe on x86
Date: Tue, 14 Nov 2017 16:34:24 +0100 [thread overview]
Message-ID: <20171114153424.GA17667@redhat.com> (raw)
In-Reply-To: <6fdd9773-a0d0-7598-35d4-959bb3701d1b@fb.com>
On 11/13, Yonghong Song wrote:
>
> On 11/13/17 4:59 AM, Oleg Nesterov wrote:
> >>+ switch (opc1) {
> >>+ case 0x50:
> >>+ reg_offset = offsetof(struct pt_regs, r8);
> >>+ break;
> >>+ case 0x51:
> >>+ reg_offset = offsetof(struct pt_regs, r9);
> >>+ break;
> >>+ case 0x52:
> >>+ reg_offset = offsetof(struct pt_regs, r10);
> >>+ break;
> >>+ case 0x53:
> >>+ reg_offset = offsetof(struct pt_regs, r11);
> >>+ break;
> >>+ case 0x54:
> >>+ reg_offset = offsetof(struct pt_regs, r12);
> >>+ break;
> >>+ case 0x55:
> >>+ reg_offset = offsetof(struct pt_regs, r13);
> >>+ break;
> >>+ case 0x56:
> >>+ reg_offset = offsetof(struct pt_regs, r14);
> >>+ break;
> >>+ case 0x57:
> >>+ reg_offset = offsetof(struct pt_regs, r15);
> >>+ break;
> >>+ }
> >>+#else
> >>+ return -ENOSYS;
> >>+#endif
> >
> >OK, but shouldn't we also return ENOSYS if CONFIG_X86_64=y but the probed task is 32bit?
>
> Just tested with a 32bit app on x86 box and segfaults.
Hmm. How did you verify this?
Your v3 doesn't look right and it seems you misunderstood me...
> Yes, we would need to
> return ENOSYS if the app is 32bit on 64bit system.
Only if insn->length == 2. "push bp" and other valid 32bit push'es should be
emulated correctly or your patch is wrong. Confused...
> >Or in this case uprobe_init_insn(x86_64 => false) should fail and push_setup_xol_ops()
> >won't be called?
So it doesn't fail?
Oleg.
next prev parent reply other threads:[~2017-11-14 15:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-10 17:25 [PATCH][v2] uprobes/x86: emulate push insns for uprobe on x86 Yonghong Song
2017-11-13 12:59 ` Oleg Nesterov
2017-11-13 20:32 ` Yonghong Song
2017-11-14 15:34 ` Oleg Nesterov [this message]
2017-11-14 22:22 ` Yonghong Song
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