linux -/var/log/messages 中的错误编号是什么意思？

Question

/var/log/messages 中的上下文是:

ep 24 16:51:35 12006745D kernel: gdns_processor[5978]: segfault at ffffffffffffffe9 rip 0000003a3349d302 rsp 00000000536044e0 error 4
Sep 24 18:38:34 12006745D kernel: gdns_processor[20452]: segfault at ffffffffffffffe8 rip 0000003a3349d302 rsp 0000000052e834e0 error 4
Sep 25 14:58:01 12006745D auditd[3955]: Audit daemon rotating log files
Sep 25 15:18:50 12006745D yum: Installed: 2:vim-common-7.0.109-7.el5.x86_64
Sep 25 15:18:51 12006745D yum: Installed: 2:vim-enhanced-7.0.109-7.el5.x86_64
Sep 25 15:18:52 12006745D yum: Installed: 2:vim-X11-7.0.109-7.el5.x86_64
Sep 25 15:25:10 12006745D kernel: a.out[1694]: segfault at 0000000000000000 rip 0000000000400458 rsp 00007fffe69073a0 error 6
Sep 25 15:29:33 12006745D kernel: a.out[8132]: segfault at 0000000000000000 rip 0000000000400458 rsp 00007fffa01fbb50 error 6
Sep 25 17:57:29 12006745D kernel: gdns_processor[11504]: segfault at 0000000000594598 rip 0000003a3349d338 rsp 0000000052caf4e0 error 7
Sep 25 18:08:05 12006745D kernel: t1[28050]: segfault at 0000000000000000 rip 0000000000400458 rsp 00007fff5ecb0850 error 6

“Sep 24 18:38:34 12006745D kernel: gdns_processor[20452]: segfault at ffffffffffffffe8 rip 0000003a3349d302 rsp 0000000052e834e0 error 4”中的 4 是什么意思？

关于 6 和 7 同样的问题。

谢谢

Answer 1

来自 /arch/<architecture>/mm/fault.c :

Page fault error code bits:

bit 0 ==    0: no page found   1: protection fault
bit 1 ==    0: read access     1: write access
bit 2 ==    0: kernel-mode access  1: user-mode access
bit 3 ==               1: use of reserved bit detected
bit 4 ==               1: fault was an instruction fetch