Date: Mon, 8 Jan 2001 18:57:09 +1030 From: Greg Lehey <grog@lemis.com> To: Roman Shterenzon <roman@xpert.com> Cc: hackers@freebsd.org Subject: Dump analysis (was: Ideas? (fwd)) Message-ID: <20010108185709.D83353@wantadilla.lemis.com> In-Reply-To: <Pine.LNX.4.30.0101081003520.32287-100000@jamus.xpert.com>; from roman@xpert.com on Mon, Jan 08, 2001 at 10:04:44AM %2B0200 References: <Pine.LNX.4.30.0101081003520.32287-100000@jamus.xpert.com>
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On Monday, 8 January 2001 at 10:04:44 +0200, Roman Shterenzon wrote: > * Roman Shterenzon <roman@xpert.com> [010107 10:24] wrote: >> Hi, >> >> Could you please take a look at : >> http://www.freebsd.org/cgi/query-pr.cgi?pr=24019 >> It's my friend's PR. Can you give me some hints on how can I debug this >> issue. I'm completely puzzled here. >> It panics on "goto out" with page fault. What I understand from it is that >> the block at the address it tries to jmp to isn't present. But it's kernel >> code which is never swapped out. Does it mean that the address was >> rewritten? If it's so, what can rewrite this address? Ideas? My first suspicion here is that the sources are out of sync with the kernel you're debugging. It's very important to ensure that they are absolutely in sync. Here are a couple of incantations to throw at this dump (you may recognize the second one from an earlier mail exchange): (kgdb) x/10i epread (kgdb) x/10i 0xc012a038 The first one should show the beginning of the function; if it's in sync it will look like (modulo addresses): (kgdb) x/10i epread 0xc0165f8c <epread>: push %ebp 0xc0165f8d <epread+1>: mov %esp,%ebp 0xc0165f8f <epread+3>: sub $0x1c,%esp 0xc0165f92 <epread+6>: push %edi 0xc0165f93 <epread+7>: push %esi 0xc0165f94 <epread+8>: push %ebx 0xc0165f95 <epread+9>: mov 0x8(%ebp),%eax 0xc0165f98 <epread+12>: mov %eax,0xfffffff4(%ebp) 0xc0165f9b <epread+15>: mov 0x118(%eax),%edx 0xc0165fa1 <epread+21>: add $0x8,%edx In particular, those first two instructions are at the beginning of just about every function, so if you don't find them, you should check whether your code is in sync. >> P.S. Can it be due to faulty hardware? Or faulty Italian cuisine? In each case, not if it's repeatable. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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