Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ba797b28 authored by Jason Wessel's avatar Jason Wessel
Browse files

powerpc,kgdb: Introduce low level trap catching 



The only way the debugger can handle a trap in inside rcu_lock,
notify_die, or atomic_notifier_call_chain without a recursive fault is
to allow the kernel debugger to handle the exception first in
program_check_exception().

The other change here is to make sure that kgdb_handle_exception() is
called with correct parameters when catching an oops, because kdb
needs to know if the entry was an oops, single step, or breakpoint
exception.

[benh@kernel.crashing.org: move debugger_bpt instead of #ifdef]

CC: Paul Mackerras <paulus@samba.org>
Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
Acked-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent f503b5ae

arch/powerpc/kernel/kgdb.c

+4 −2
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/smp.h>

#include <linux/signal.h>

#include <linux/ptrace.h>

#include <linux/kdebug.h>

#include <asm/current.h>

#include <asm/processor.h>

#include <asm/machdep.h>
@@ -115,7 +116,8 @@ void kgdb_roundup_cpus(unsigned long flags) 
/* KGDB functions to use existing PowerPC64 hooks. */

static int kgdb_debugger(struct pt_regs *regs)

{

	return kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs);

	return !kgdb_handle_exception(1, computeSignal(TRAP(regs)),

				      DIE_OOPS, regs);

}



static int kgdb_handle_breakpoint(struct pt_regs *regs)
@@ -123,7 +125,7 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs) 
	if (user_mode(regs))

		return 0;



	if (kgdb_handle_exception(0, SIGTRAP, 0, regs) != 0)

	if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0)

		return 0;



	if (*(u32 *) (regs->nip) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr))

arch/powerpc/kernel/traps.c

+5 −2
Original line number Diff line number Diff line
@@ -815,12 +815,15 @@ void __kprobes program_check_exception(struct pt_regs *regs) 
		return;

	}

	if (reason & REASON_TRAP) {

		/* Debugger is first in line to stop recursive faults in

		 * rcu_lock, notify_die, or atomic_notifier_call_chain */

		if (debugger_bpt(regs))

			return;



		/* trap exception */

		if (notify_die(DIE_BPT, "breakpoint", regs, 5, 5, SIGTRAP)

				== NOTIFY_STOP)

			return;

		if (debugger_bpt(regs))

			return;



		if (!(regs->msr & MSR_PR) &&  /* not user-mode */

		    report_bug(regs->nip, regs) == BUG_TRAP_TYPE_WARN) {