lkml.org 
[lkml]   [2020]   [Aug]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] x86/paravirt: Add missing noinstr to arch_local*() helpers
From
Date
On 05.08.20 16:12, 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.
>

Probably. I have found the following in my kernel:

fffffff81540a5f <arch_local_save_flags>:
ffffffff81540a5f: ff 14 25 40 a4 23 82 callq *0xffffffff8223a440
ffffffff81540a66: c3 retq


Juergen

\
 
 \ /
  Last update: 2020-08-05 18:38    [W:0.469 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site