IBM AIX Continuous Availability Features - IBM Redbooks

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Load the kernel extension so that a system call can use it form user mode, as shown in Example 3-27. Example 3-27 Loading kernel extension using tool “service” # ./service --load kkey_set64 Preserving 2378 bytes of symbol table [kkey_set64] [kkey_set64] loaded successfully kernel mid=[546676736] Run myprog without any argument, which means it will run the kernel extension (syscall) with the appropriate protection gate {{KKEYSET_KERNEXT}+KKEY_VMM}. Because the private heap of the kernel extension has been protected by KKEY_VMM, you can access it and the system call will return without any DSI/crash. Execute the user-level program that will call the kernel system call with protection gate enabled with KKEY_VMM, as shown in Example 3-28. Example 3-28 First iteration with KKEY_VMM #./myprog Testing Kernel Storage key Current hardware keyset =0008000000000000 hardware keyset after KERNEXT =F00F000000000000 hardware keyset after KKEY_VMM=F00C000000000000 Now execute the user-level program that will call the kernel system call with a protection gate without KKEY_VMM key in its keyset (see Example 3-29 on page 96). This will cause the kernel to crash. Running myprog with argument>2 will do that. Because the private heap of the kernel extension has not been protected by KKEY_VMM, a DSI will result and the kernel will crash. Keep in mind that exception type EXCEPT_SKEY cannot be caught with setjmpx(), so the kernel programmer cannot catch EXCEPT_SKEY using setjmpx(). Note: There are kernel services provided for catching storage-key exceptions. However, their use is not recommended and they are provided only for testing purposes. Example 3-29 Second iteration without KKEY_VMM # ./myprog 1 Current hardware keyset =0008000000000000 hardware keyset after KERNEXT =F00F000000000000 hardware keyset after KKEY_VMM=F00C000000000000 hardware keyset w/o KKEY_VMM =F00F000000000000 Data Storage Interrupt - PROC .kkey_test+0002C8 stb r3,A(r4) r3=000000000000000A,A(r4)=F10006C00134A00A KDB(6)> When you are debugging in kernel mode (see Example 3-30), you can see the value of the AMR (current hardware key or protection gate), the current process which caused the exception, and the exception type. Refer to 3.7.8, “Kernel debugger commands” on page 108 96 IBM AIX Continuous Availability Features
for more information about KDB commands relevant for debugging storage-key exceptions and related issues. Example 3-30 KDB debugging KDB(6)> f pvthread+80B100 STACK: [F1000000908E34C8]kkey_test+0002C8 (0000000100000001) [00014D70].hkey_legacy_gate+00004C () [00003820]ovlya_addr_sc_flih_main+000100 () [kdb_get_virtual_doubleword] no real storage @ FFFFFFFF3FFFE60 KDB(6)> dr amr amr : F00F000000000000 hkey 2 RW PUBLIC hkey 3 RW BLOCK_DEV LVM RAMDISK FILE_SYSTEM NFS CACHEFS AUTOFS KRB5 ... hkey 4 RW COMMO NETM IPSEC USB GRAPHICS hkey 5 RW DMA PCI VDEV TRB IOMAP PRIVATE1 PRIVATE17 PRIVATE9 PRIVATE25 ... KDB(6)> dk 1 @r4 Protection for sid 4000006000000, pno 00C00134, raddr 81C7A000 Hardware Storage Key... 7 Page Protect key....... 0 No-Execute............. 0 KDB(6)> p SLOT NAME STATE PID PPID ADSPACE CL #THS pvproc+100AC00 16427*myprog ACTIVE 002B186 00301C8 00000000A9857590 0 0001 NAME....... myprog STATE...... stat :07 .... xstat :0000 FLAGS...... flag :00200001 LOAD EXECED ........... flag2 :00000001 64BIT ........... flag3 :00000000 ........... atomic :00000000 ........... secflag:0001 ROOT LINKS...... child :0000000000000000 ........... siblings :0000000000000000 ........... uidinfo :000000000256BA78 ........... ganchor :F10008070100AC00 THREAD..... threadlist :F10008071080B100 DISPATCH... synch :FFFFFFFFFFFFFFFF AACCT...... projid :00000000 ........... sprojid :00000000 ........... subproj :0000000000000000 ........... file id :0000000000000000 0000000000000000 00000000 ........... kcid :00000000 ........... flags :0000 (6)> more (^C to quit) ? KDB(6)> mst Machine State Save Area iar : F1000000908E34C8 msr : 8000000000009032 cr : 80243422 lr : F1000000908E34BC ctr : 00000000007CD2A0 xer : 20000001 mq : FFFFFFFF asr : FFFFFFFFFFFFFFFF amr : F00F000000000000 r0 : F1000000908E34BC r1 : F00000002FF47480 r2 : F1000000908E4228 Chapter 3. AIX advanced continuous availability tools and features 97
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Front cover IBM AIX Continuous Avai
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Note: Before using this information
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2.3.7 Minidump . . . . . . . . . .
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vi IBM AIX Continuous Availability
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Trademarks The following terms are
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Engineering degree in Computer Scie
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Find out more about the residency p
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1.1 Overview In May 2007, IBM intro
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1.5 Continuous operations Continuou
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1.6.2 Availability 1.6.3 Serviceabi
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IBM has tried to enhance FFDC featu
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10 IBM AIX Continuous Availability
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2.1 System availability AIX is buil
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On AIX 5.3, the only way to persist
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When used on a standalone server (s
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mirrored volume group on the client
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2.2.1 Error checking Run-Time Error
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The PowerPC hardware gives software
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System dumps can also be user-initi
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Live dumps are small dumps that do
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Trace is a valuable tool for observ
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Component Trace uses mechanisms sim
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2.3.14 syslog To display the boot l
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Logging can be added to many of the
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compression: on path specification:
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2.4.4 EtherChannel network traffic
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2.4.6 2-Port Adapter-based Ethernet
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operations) without affecting produ
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Quorum A quorum is a vote of the nu
Page 60 and 61: 2.5.8 Journaled File System-related
Page 62 and 63: Fast I/O failure is controlled by a
Page 64 and 65: display its output in a format suit
Page 66 and 67: For more detailed information about
Page 68 and 69: 54 IBM AIX Continuous Availability
Page 70 and 71: 3.1 AIX Reliability, Availability,
Page 72 and 73: This means that traditional AIX sys
Page 74 and 75: used by IBM service personnel, so t
Page 76 and 77: also be used to obtain a snapshot o
Page 78 and 79: 3.5 Live dump and component dump Li
Page 80 and 81: lfs filesystem ._0 | NO | ON/3 | OF
Page 82 and 83: .vmker | YES | ON/3 | OFF/3 .vmpool
Page 84 and 85: The output of Start a Live Dump is
Page 86 and 87: Table 3-3 Concurrent update termino
Page 88 and 89: We tested the installation of an ef
Page 90 and 91: Setting efix state to: STABLE +----
Page 92 and 93: mode, storage keys are called user
Page 94 and 95: Example 3-19 shows the SMIT menu fo
Page 96 and 97: might share a given hardware key. M
Page 98 and 99: KKEY_UPUBLIC, KKEY_FILE_DATA KKEY_U
Page 100 and 101: Note: Kernel keys and keysets, whic
Page 102 and 103: extension key-aware is determining
Page 104 and 105: added a protection gate for the int
Page 106 and 107: } printf("hardware keyset after KER
Page 108 and 109: } param=atoi(*(argv+1)); printf("Te
Page 112 and 113: 3 : 000000000000000A r4 : F10006C00
Page 114 and 115: 3.7.7 User mode protection keys Use
Page 116 and 117: ► The APIs provided by the system
Page 118 and 119: if (!strcmp(*(argv+1),"read")){ if
Page 120 and 121: strlen() at 0xd010da00 _doprnt(??,
Page 122 and 123: int pthread_attr_setukeyset_np (pth
Page 124 and 125: Machine State Save Area iar : 00000
Page 126 and 127: As a consequence, determining the r
Page 128 and 129: A Vue script or Vue program is a pr
Page 130 and 131: ► An optional predicate The predi
Page 132 and 133: 3. Interval probe manager The inter
Page 134 and 135: { int count; count = count +1; prin
Page 136 and 137: ► Errno names ► Signal names
Page 138 and 139: * will result in error out of read(
Page 140 and 141: This places a large part of the bur
Page 142 and 143: Note: The frequency of checks made
Page 144 and 145: Non-fragments 00000066 Promotions 0
Page 146 and 147: immediately after the returned stor
Page 148 and 149: This option should be used with car
Page 150 and 151: 3.9.6 KDB commands for XMDBG ► xm
Page 154 and 155: Name AIX version Hardware required
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Online resources These Web sites ar
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sysdumpdev 27 tprof 28 trace 28 trc
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subsequent reboot 71, 133 SUE 18 Sy
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