From: peterz@infradead.org
To: Marco Elver <elver@google.com>
Cc: bp@alien8.de, dave.hansen@linux.intel.com, fenghua.yu@intel.com,
hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@redhat.com,
syzkaller-bugs@googlegroups.com, tglx@linutronix.de,
tony.luck@intel.com, x86@kernel.org, yu-cheng.yu@intel.com,
jgross@suse.com, sdeep@vmware.com,
virtualization@lists.linux-foundation.org,
kasan-dev@googlegroups.com,
syzbot <syzbot+8db9e1ecde74e590a657@syzkaller.appspotmail.com>
Subject: Re: [PATCH] x86/paravirt: Add missing noinstr to arch_local*() helpers
Date: Wed, 5 Aug 2020 16:17:09 +0200 [thread overview]
Message-ID: <20200805141709.GD35926@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200805141237.GS2674@hirez.programming.kicks-ass.net>
On Wed, Aug 05, 2020 at 04:12:37PM +0200, peterz@infradead.org wrote:
> On Wed, Aug 05, 2020 at 03:59:40PM +0200, Marco Elver wrote:
> > On Wed, Aug 05, 2020 at 03:42PM +0200, peterz@infradead.org wrote:
>
> > > Shouldn't we __always_inline those? They're going to be really small.
> >
> > I can send a v2, and you can choose. For reference, though:
> >
> > ffffffff86271ee0 <arch_local_save_flags>:
> > ffffffff86271ee0: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> > ffffffff86271ee5: 48 83 3d 43 87 e4 01 cmpq $0x0,0x1e48743(%rip) # ffffffff880ba630 <pv_ops+0x120>
> > ffffffff86271eec: 00
> > ffffffff86271eed: 74 0d je ffffffff86271efc <arch_local_save_flags+0x1c>
> > ffffffff86271eef: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> > ffffffff86271ef4: ff 14 25 30 a6 0b 88 callq *0xffffffff880ba630
> > ffffffff86271efb: c3 retq
> > ffffffff86271efc: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> > ffffffff86271f01: 0f 0b ud2
>
> > ffffffff86271a90 <arch_local_irq_restore>:
> > ffffffff86271a90: 53 push %rbx
> > ffffffff86271a91: 48 89 fb mov %rdi,%rbx
> > ffffffff86271a94: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> > ffffffff86271a99: 48 83 3d 97 8b e4 01 cmpq $0x0,0x1e48b97(%rip) # ffffffff880ba638 <pv_ops+0x128>
> > ffffffff86271aa0: 00
> > ffffffff86271aa1: 74 11 je ffffffff86271ab4 <arch_local_irq_restore+0x24>
> > ffffffff86271aa3: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> > ffffffff86271aa8: 48 89 df mov %rbx,%rdi
> > ffffffff86271aab: ff 14 25 38 a6 0b 88 callq *0xffffffff880ba638
> > ffffffff86271ab2: 5b pop %rbx
> > ffffffff86271ab3: c3 retq
> > ffffffff86271ab4: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> > ffffffff86271ab9: 0f 0b ud2
>
>
> Blergh, that's abysmall. In part I suspect because you have
> CONFIG_PARAVIRT_DEBUG, let me try and untangle that PV macro maze.
Yeah, look here:
0000 0000000000462149 <arch_local_save_flags>:
0000 462149: ff 14 25 00 00 00 00 callq *0x0
0003 46214c: R_X86_64_32S pv_ops+0x120
0007 462150: c3 retq
That's exactly what I was expecting.
next prev parent reply other threads:[~2020-08-05 19:57 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-05 7:19 upstream test error: WARNING in __local_bh_enable_ip syzbot
2020-08-05 13:26 ` [PATCH] x86/paravirt: Add missing noinstr to arch_local*() helpers Marco Elver
2020-08-05 13:42 ` peterz
2020-08-05 13:59 ` Marco Elver
2020-08-05 14:12 ` peterz
2020-08-05 14:17 ` Jürgen Groß
2020-08-05 14:17 ` peterz [this message]
2020-08-05 14:36 ` Marco Elver
2020-08-05 17:31 ` Marco Elver
2020-08-06 7:47 ` Marco Elver
2020-08-06 11:32 ` peterz
2020-08-06 13:17 ` Marco Elver
2020-08-06 16:06 ` Marco Elver
2020-08-07 9:01 ` Marco Elver
2020-08-07 9:24 ` Jürgen Groß
2020-08-07 9:50 ` Marco Elver
2020-08-07 10:35 ` Jürgen Groß
2020-08-07 11:38 ` Marco Elver
2020-08-07 12:04 ` Jürgen Groß
2020-08-07 12:08 ` Marco Elver
2020-08-07 15:19 ` Marco Elver
2020-08-11 7:00 ` Marco Elver
2020-08-11 7:04 ` Jürgen Groß
2020-08-11 7:41 ` Peter Zijlstra
2020-08-11 7:57 ` Jürgen Groß
2020-08-11 8:12 ` Peter Zijlstra
2020-08-11 8:18 ` Jürgen Groß
2020-08-11 8:38 ` Jürgen Groß
2020-08-11 9:20 ` peterz
2020-08-11 9:46 ` peterz
2020-08-11 20:17 ` peterz
2020-08-12 8:06 ` Marco Elver
2020-08-12 8:18 ` peterz
2020-08-12 8:57 ` peterz
2020-08-06 21:02 ` kernel test robot
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