Date: Wed, 25 Dec 2019 19:46:01 -0500 From: "Farhan Khan" <farhan@farhan.codes> To: freebsd-usb@freebsd.org Subject: Page fault at USB attachment code Message-ID: <7b2a53c8-8640-4b0c-8d6e-22a1988a3ebd@www.fastmail.com>
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Hi all,
I am writing a simple USB network device driver skeleton, just to learn the framework. What I think is fairly simple code is having a kernel panic when it hits the attachment code.
The code and kgdb output are below. I apologize, its been some time since I used kgdb, so I am not sure what the next step I should do to debug this.
---------------------
static int
skel_usb_attach(device_t self)
{
struct usb_attach_arg *uaa = device_get_ivars(self);
struct skel_usb_softc *uc = device_get_softc(self);
struct skel_softc *sc = uc->sc_sc;
struct ieee80211com *ic = &sc->sc_ic;
device_set_usb_desc(self);
uc->uc_udev = uaa->device;
sc->sc_dev = self;
ic->ic_name = device_get_nameunit(self);
return 0;
}
---------------------
When I run kgdb, I get the following output.
---------------------
sudo kgdb -n last
GNU gdb (GDB) 8.3.1 [GDB v8.3.1 for FreeBSD]
Copyright (C) 2019 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>;
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-portbld-freebsd13.0".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
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For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /usr/obj/usr/src/amd64.amd64/sys/GENERIC/kernel.full...
Unread portion of the kernel message buffer:
Matched!
skel0 on uhub0
skel0: <ATHEROS USB2.0 WLAN, rev 1.10/ff.ff, addr 2> on usbus0
Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address = 0x7170
fault code = supervisor write data, page not present
instruction pointer = 0x20:0xffffffff8271f094
stack pointer = 0x28:0xfffffe00036f5930
frame pointer = 0x28:0xfffffe00036f5950
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process = 15 (usbus0)
trap number = 12
panic: page fault
cpuid = 0
time = 1577299341
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe00036f5590
vpanic() at vpanic+0x17e/frame 0xfffffe00036f55f0
panic() at panic+0x43/frame 0xfffffe00036f5650
trap_fatal() at trap_fatal+0x386/frame 0xfffffe00036f56b0
trap_pfault() at trap_pfault+0x99/frame 0xfffffe00036f5730
trap() at trap+0x2a3/frame 0xfffffe00036f5860
calltrap() at calltrap+0x8/frame 0xfffffe00036f5860
--- trap 0xc, rip = 0xffffffff8271f094, rsp = 0xfffffe00036f5930, rbp = 0xfffffe00036f5950 ---
skel_usb_attach() at skel_usb_attach+0x34/frame 0xfffffe00036f5950
device_attach() at device_attach+0x3ca/frame 0xfffffe00036f5990
device_probe_and_attach() at device_probe_and_attach+0x70/frame 0xfffffe00036f59c0
usb_probe_and_attach_sub() at usb_probe_and_attach_sub+0x150/frame 0xfffffe00036f5a10
usb_probe_and_attach() at usb_probe_and_attach+0x463/frame 0xfffffe00036f5ae0
uhub_explore() at uhub_explore+0x753/frame 0xfffffe00036f5b50
usb_bus_explore() at usb_bus_explore+0x11a/frame 0xfffffe00036f5b70
usb_process() at usb_process+0x103/frame 0xfffffe00036f5bb0
fork_exit() at fork_exit+0x80/frame 0xfffffe00036f5bf0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe00036f5bf0
--- trap 0, rip = 0, rsp = 0, rbp = 0 ---
KDB: enter: panic
warning: Could not load shared library symbols for if_skel_usb.ko.
Do you need "set solib-search-path" or "set sysroot"?
---------------------
Note: I am testing this with an Atheros USB device.
Thanks!
--
Farhan Khan
PGP Fingerprint: 1312 89CE 663E 1EB2 179C 1C83 C41D 2281 F8DA C0DE
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