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Commit a4c3f909 authored by Balbir Singh's avatar Balbir Singh Committed by Michael Ellerman
Browse files

powerpc: Fix BUG_ON() reporting in real mode 



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: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarBalbir Singh <bsingharora@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 10d8b148

arch/powerpc/kernel/traps.c

+9 −1
Original line number Diff line number Diff line
@@ -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;

		}