kernel vm question
Jacques Fourie
jf at trispen.com
Thu Jan 27 06:57:16 PST 2005
Hi,
I have a kernel module with the following entry point :
static int test_modevent(module_t mod, int type, void *unused)
{
int s;
unsigned char *p = NULL;
unsigned char v = 0x55;
switch (type)
{
case MOD_LOAD:
p = (unsigned char *)ip_output;
s = splhigh();
v = p[0]; /* Page fault without this line */
p[0] = v;
printf("val = %02X\n", v);
splx(s);
break;
case MOD_UNLOAD:
break;
default:
break;
}
return 0;
}
If I remove the line "Page fault without this line" line, I get a page
fault when loading this module. This crash seems to be hardware as well
as version specific - I can not reproduce the crash on 4.8 but on one
particular piece of hardware it crashes consistently on 4.9 and 4.10.
Could someone please help me in understanding this behaviour? Attached
is the full kernel module source and a dmesg of the hardware in question.
regards,
jacques
-------------- next part --------------
Copyright (c) 1992-2004 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
The Regents of the University of California. All rights reserved.
FreeBSD 4.10-RELEASE #2: Thu Jan 27 14:36:20 SAST 2005
jacques at fbsd410.trispen.com:/usr/src/sys/compile/MYKERN
Timecounter "i8254" frequency 1193182 Hz
Timecounter "TSC" frequency 2657822812 Hz
CPU: Intel(R) Xeon(TM) CPU 2.66GHz (2657.82-MHz 686-class CPU)
Origin = "GenuineIntel" Id = 0xf29 Stepping = 9
Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
Hyperthreading: 2 logical CPUs
real memory = 4160225280 (4062720K bytes)
avail memory = 4054249472 (3959228K bytes)
Preloaded elf kernel "kernel" at 0xc0353000.
Warning: Pentium 4 CPU: PSE disabled
Pentium Pro MTRR support enabled
md0: Malloc disk
Using $PIR table, 20 entries at 0xc00fde80
npx0: <math processor> on motherboard
npx0: INT 16 interface
pcib0: <Host to PCI bridge> on motherboard
pci0: <PCI bus> on pcib0
pci0: <unknown card> (vendor=0x8086, dev=0x2541) at 0.1
pcib1: <PCI to PCI bridge (vendor=8086 device=2543)> at device 2.0 on pci0
pci1: <PCI bus> on pcib1
pci1: <unknown card> (vendor=0x8086, dev=0x1461) at 28.0
pcib2: <PCI to PCI bridge (vendor=8086 device=1460)> at device 29.0 on pci1
pci2: <PCI bus> on pcib2
pci1: <unknown card> (vendor=0x8086, dev=0x1461) at 30.0
pcib3: <PCI to PCI bridge (vendor=8086 device=1460)> at device 31.0 on pci1
pci3: <PCI bus> on pcib3
em0: <Intel(R) PRO/1000 Network Connection, Version - 1.7.25> port 0x7000-0x703f mem 0xfc200000-0xfc23ffff,0xfc280000-0xfc29ffff irq 10 at device 1.0 on pci3
em0: Speed:N/A Duplex:N/A
em1: <Intel(R) PRO/1000 Network Connection, Version - 1.7.25> port 0x7040-0x707f mem 0xfc240000-0xfc27ffff,0xfc2a0000-0xfc2bffff irq 10 at device 1.1 on pci3
em1: Speed:N/A Duplex:N/A
pci0: <unknown card> (vendor=0x8086, dev=0x2544) at 2.1
pci0: <UHCI USB controller> at 29.0 irq 10
pci0: <UHCI USB controller> at 29.1 irq 5
pci0: <UHCI USB controller> at 29.2 irq 10
pcib4: <Intel 82801BA/BAM (ICH2) Hub to PCI bridge> at device 30.0 on pci0
pci4: <PCI bus> on pcib4
pci4: <ATI Mach64-GR graphics accelerator> at 3.0 irq 11
fxp0: <Intel 82550 Pro/100 Ethernet> port 0x8400-0x843f mem 0xfc300000-0xfc31ffff,0xfc341000-0xfc341fff irq 10 at device 4.0 on pci4
fxp0: Ethernet address 00:04:23:ae:8c:1d
inphy0: <i82555 10/100 media interface> on miibus0
inphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
em2: <Intel(R) PRO/1000 Network Connection, Version - 1.7.25> port 0x8440-0x847f mem 0xfc320000-0xfc33ffff irq 11 at device 5.0 on pci4
em2: Speed:N/A Duplex:N/A
isab0: <PCI to ISA bridge (vendor=8086 device=2480)> at device 31.0 on pci0
isa0: <ISA bus> on isab0
atapci0: <Intel ICH3 ATA100 controller> port 0x6c60-0x6c6f,0-0x3,0-0x7,0-0x3,0-0x7 irq 0 at device 31.1 on pci0
ata0: at 0x1f0 irq 14 on atapci0
ata1: at 0x170 irq 15 on atapci0
pci0: <unknown card> (vendor=0x8086, dev=0x2483) at 31.3 irq 0
orm0: <Option ROMs> at iomem 0xc0000-0xc7fff,0xe3000-0xe3fff on isa0
pmtimer0 on isa0
atkbdc0: <Keyboard controller (i8042)> at port 0x60,0x64 on isa0
atkbd0: <AT Keyboard> irq 1 on atkbdc0
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0
sc0: <System console> on isa0
sc0: VGA <16 virtual consoles, flags=0x200>
sio0 at port 0x3f8-0x3ff irq 4 flags 0x80 on isa0
sio0: type 16550A
ppc0: <Parallel port> at port 0x378-0x37f irq 7 on isa0
ppc0: SMC-like chipset (ECP/EPP/PS2/NIBBLE) in COMPATIBLE mode
ppc0: FIFO with 16/16/9 bytes threshold
ipfw2 initialized, divert enabled, rule-based forwarding enabled, default to accept, logging limited to 100 packets/entry by default
DUMMYNET initialized (011031)
ad0: 76319MB <ST380011A> [155061/16/63] at ata0-master UDMA100
acd0: DVD-R <Slimtype DVDRW SOSW-852S> at ata1-master PIO4
Mounting root from ufs:/dev/ad0s1a
WARNING: / was not properly dismounted
uhci0: <Intel 82801CA/CAM (ICH3) USB controller USB-A> port 0x6c00-0x6c1f irq 10 at device 29.0 on pci0
usb0: <Intel 82801CA/CAM (ICH3) USB controller USB-A> on uhci0
usb0: USB revision 1.0
uhub0: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
uhci1: <Intel 82801CA/CAM (ICH3) USB controller USB-B> port 0x6c20-0x6c3f irq 5 at device 29.1 on pci0
usb1: <Intel 82801CA/CAM (ICH3) USB controller USB-B> on uhci1
usb1: USB revision 1.0
uhub1: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub1: 2 ports with 2 removable, self powered
uhci2: <Intel 82801CA/CAM (ICH3) USB controller USB-C> port 0x6c40-0x6c5f irq 10 at device 29.2 on pci0
usb2: <Intel 82801CA/CAM (ICH3) USB controller USB-C> on uhci2
usb2: USB revision 1.0
uhub2: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub2: 2 ports with 2 removable, self powered
-------------- next part --------------
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
static int test_modevent(module_t mod, int type, void *unused)
{
int s;
unsigned char *p = NULL;
unsigned char v = 0x55;
switch (type)
{
case MOD_LOAD:
p = (unsigned char *)ip_output;
s = splhigh();
v = p[0];
p[0] = v;
printf("val = %02X\n", v);
splx(s);
break;
case MOD_UNLOAD:
break;
default:
break;
}
return 0;
}
moduledata_t testmod = {
"test",
test_modevent,
0
};
DECLARE_MODULE(test, testmod, SI_SUB_DRIVERS, SI_ORDER_ANY);
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