From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-x22c.google.com (mail-pa0-x22c.google.com [IPv6:2607:f8b0:400e:c03::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 27F1D1A042E for ; Thu, 18 Feb 2016 13:48:10 +1100 (AEDT) Received: by mail-pa0-x22c.google.com with SMTP id yy13so21968316pab.3 for ; Wed, 17 Feb 2016 18:48:10 -0800 (PST) From: Balbir Singh To: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org Cc: paulus@samba.org, Balbir Singh Subject: [RESEND][PATCH] Fix BUG_ON() reporting in real mode on PPC Date: Thu, 18 Feb 2016 13:48:01 +1100 Message-Id: <1455763681-13663-1-git-send-email-bsingharora@gmail.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Changelog: Don't use REGION_ID, breaks on some platforms Don't blindly add PAGE_OFFSET to bugaddr I ran into this issue while debugging an early boot problem. The system hit a BUG_ON() but report bug failed to print the line number and file name. The reason being that the system was running in real mode and report_bug() searches for addresses in the PAGE_OFFSET+ region Suggested-by: Paul Mackerras Signed-off-by: Balbir Singh --- arch/powerpc/kernel/traps.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index b6becc7..4e5c11d 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -1148,6 +1148,7 @@ void __kprobes program_check_exception(struct pt_regs *regs) goto bail; } if (reason & REASON_TRAP) { + unsigned long bugaddr; /* Debugger is first in line to stop recursive faults in * rcu_lock, notify_die, or atomic_notifier_call_chain */ if (debugger_bpt(regs)) @@ -1158,8 +1159,15 @@ void __kprobes program_check_exception(struct pt_regs *regs) == NOTIFY_STOP) goto bail; + bugaddr = regs->nip; + /* + * Fixup bugaddr for BUG_ON() in real mode + */ + if (!is_kernel_addr(bugaddr) && !(regs->msr & MSR_IR)) + bugaddr += PAGE_OFFSET; + if (!(regs->msr & MSR_PR) && /* not user-mode */ - report_bug(regs->nip, regs) == BUG_TRAP_TYPE_WARN) { + report_bug(bugaddr, regs) == BUG_TRAP_TYPE_WARN) { regs->nip += 4; goto bail; } -- 2.5.0