| Message ID | 1455684191.3089.3.camel@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Wed, Feb 17, 2016 at 03:43:11PM +1100, Balbir Singh wrote: > From: Balbir Singh <bsingharora@gmail.com> > > 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 <paulus@samba.org> > Signed-off-by: Balbir Singh <bsingharora@gmail.com> > --- > arch/powerpc/kernel/traps.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c > index b6becc7..8f28120 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 +1159,13 @@ void __kprobes program_check_exception(struct pt_regs *regs) > == NOTIFY_STOP) > goto bail; > > + if (!(regs->msr & MSR_IR)) > + bugaddr = regs->nip + PAGE_OFFSET; > + else > + bugaddr = regs->nip; It might be a little better to do this: bugaddr = regs->nip; if (REGION_ID(bugaddr) == 0 && !(regs->msr & MSR_IR)) bugaddr += PAGE_OFFSET; It is possible to execute from addresses with the 0xc000... on top in real mode, because the CPU ignores the top 4 address bits in real mode. Paul.
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index b6becc7..8f28120 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 +1159,13 @@ void __kprobes program_check_exception(struct pt_regs *regs) == NOTIFY_STOP) goto bail; + if (!(regs->msr & MSR_IR)) + bugaddr = regs->nip + PAGE_OFFSET; + else + bugaddr = regs->nip; + 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; }