Hi list,
As said by `Understanding linux kernel', all the 255 IDT (Interrupt
Descriptor Table) entries are initialized in system initialization
to the handler ignore_int. ignore_int job is to print "Unkown
interrupt" and return to normal code:
--> arch/i386/kernel/head.S:
int_msg:
.asciz "Unknown interrupt or fault at EIP %p %p %p\n"
[...]
ignore_int:
[...]
pushl $int_msg
call printk
[...]
iret
I've created a small module to test above code (having a doubt about
a line) and I got a BUG and the message above wasn't printed.
Here's the module code:
#include <linux/module.h>
MODULE_LICENSE("GPL");
/* IRQ 25 is reserved as said by Intel documentation, So
* vector 25 is handled by ignore_int */
int init(void) { asm("int $25"); return 0;}
module_init(init);
So Is the problem in in my module code ?.
Here's the BUG() - faulty_int is the above module:
Mar 19 00:42:08 localhost kernel: [ 395.697490] int3: 0000 [#1]
Mar 19 00:42:08 localhost kernel: [ 395.697499] Modules linked in: faulty_int i915 drm cpufreq_stats nls_iso8859_1 nls_cp437 vfat fat arc4 ecb blkcipher ieee80211_crypt_wep usbhid snd_intel8x0 snd_ac97_codec ac97_bus snd_pcm_oss snd_mixer_oss snd_pcm snd_timer serio_raw ipw2100 parport_pc parport ehci_hcd uhci_hcd ieee80211 ieee80211_crypt e100 ohci1394 ieee1394 psmouse rtc pcspkr snd soundcore snd_page_alloc generic usbcore intel_agp agpgart evdev
Mar 19 00:42:08 localhost kernel: [ 395.697584] CPU: 0
Mar 19 00:42:08 localhost kernel: [ 395.697587] EIP: 0060:[<c03ce23d>] Not tainted VLI
Mar 19 00:42:08 localhost kernel: [ 395.697591] EFLAGS: 00000086 (2.6.21-rc4 #27)
Mar 19 00:42:08 localhost kernel: [ 395.697606] EIP is at ignore_int+0x1/0x44
Mar 19 00:42:08 localhost kernel: [ 395.697614] eax: e07d9000 ebx: cb613d80 ecx: 00000000 edx: 00000001
Mar 19 00:42:08 localhost kernel: [ 395.697624] esi: e07d92c0 edi: e07d3ad0 ebp: e07d92c0 esp: ca23dec4
Mar 19 00:42:08 localhost kernel: [ 395.697633] ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068
Mar 19 00:42:08 localhost kernel: [ 395.697643] Process insmod (pid: 3684, ti=ca23c000 task=ce2000b0 task.ti=ca23c000)
Mar 19 00:42:08 localhost kernel: [ 395.697650] Stack: e07d9002 00000060 00000286 c013dd93 00000000 00000000 00000000 c05378b8
Mar 19 00:42:08 localhost kernel: [ 395.697670] 00000000 e07d92cc 00000000 0000001c 00000018 0000001c 00000018 e07d3aa8
Mar 19 00:42:08 localhost kernel: [ 395.697688] e07d37b0 e07d3a80 00000000 d2b60b10 e07d7438 00000018 00000017 00000000
Mar 19 00:42:08 localhost kernel: [ 395.697707] Call Trace:
Mar 19 00:42:08 localhost kernel: [ 395.697714] [<e07d9002>] init_module+0x2/0x10 [faulty_int]
Mar 19 00:42:08 localhost kernel: [ 395.697730] [<c013dd93>] sys_init_module+0x143/0x1590
Mar 19 00:42:08 localhost kernel: [ 395.697782] [<c0103f10>] sysenter_past_esp+0x5d/0x99
Mar 19 00:42:08 localhost kernel: [ 395.697805] =======================
Mar 19 00:42:08 localhost kernel: [ 395.697810] Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc <cc> cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc
Mar 19 00:42:08 localhost kernel: [ 395.697902] EIP: [<c03ce23d>] ignore_int+0x1/0x44 SS:ESP 0068:ca23dec4
Mar 19 00:42:08 localhost kernel: [ 395.697923] BUG: sleeping function called from invalid context at kernel/rwsem.c:20
Mar 19 00:42:08 localhost kernel: [ 395.697931] in_atomic():0, irqs_disabled():1
Mar 19 00:42:08 localhost kernel: [ 395.697938] no locks held by insmod/3684.
Mar 19 00:42:08 localhost kernel: [ 395.697943] irq event stamp: 12668
Mar 19 00:42:08 localhost kernel: [ 395.697949] hardirqs last enabled at (12667): [<c02ed715>] __mutex_unlock_slowpath+0xb5/0x170
Mar 19 00:42:08 localhost kernel: [ 395.697965] hardirqs last disabled at (12668): [<c02ef4d5>] _spin_lock_irqsave+0x15/0x50
Mar 19 00:42:08 localhost kernel: [ 395.697980] softirqs last enabled at (12262): [<c0120285>] do_softirq+0x45/0x50
Mar 19 00:42:08 localhost kernel: [ 395.697996] softirqs last disabled at (12253): [<c0120285>] do_softirq+0x45/0x50
Mar 19 00:42:08 localhost kernel: [ 395.698012] [<c0131b95>] down_read+0x15/0x50
Mar 19 00:42:08 localhost kernel: [ 395.698026] [<c013174f>] hrtimer_try_to_cancel+0x3f/0xa0
Mar 19 00:42:08 localhost kernel: [ 395.698039] [<c0143b62>] acct_collect+0x32/0x150
Mar 19 00:42:08 localhost kernel: [ 395.698052] [<c011d86c>] do_exit+0xec/0x7d0
Mar 19 00:42:08 localhost kernel: [ 395.698065] [<c0117018>] __wake_up+0x38/0x50
Mar 19 00:42:08 localhost kernel: [ 395.698085] [<c010576b>] die+0x21b/0x220
Mar 19 00:42:08 localhost kernel: [ 395.698105] [<c0105aef>] do_int3+0x6f/0x80
Mar 19 00:42:08 localhost kernel: [ 395.698122] [<c02ef87f>] int3+0x27/0x2c
Mar 19 00:42:08 localhost kernel: [ 395.698137] [<e07d9000>] init_module+0x0/0x10 [faulty_int]
Mar 19 00:42:08 localhost kernel: [ 395.698152] [<c03ce23d>] ignore_int+0x1/0x44
Mar 19 00:42:08 localhost kernel: [ 395.698164] [<e07d9002>] init_module+0x2/0x10 [faulty_int]
Mar 19 00:42:08 localhost kernel: [ 395.698176] [<c013dd93>] sys_init_module+0x143/0x1590
Mar 19 00:42:08 localhost kernel: [ 395.698225] [<c0103f10>] sysenter_past_esp+0x5d/0x99
Mar 19 00:42:08 localhost kernel: [ 395.698246] =======================
Thanks,
--
Ahmed S. Darwish
http://darwish.07.googlepages.com
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