Commit 5a94bcfd authored by Keshavamurthy Anil S's avatar Keshavamurthy Anil S Committed by Tony Luck
Browse files

[IA64] Remove getting break_num by decoding instruction 



break.b always sets cr.iim to 0 and the current code tries to
get the break_num by decoding instruction. However, their
seems to be a race condition while reading the regs->cr_iip,
as on other cpu the break.b at regs->cr_iip might have been
replaced with the original instruction as a result of
unregister_kprobe() and hence decoding instruction to
obtain break_num will result in wrong value in this case.

Also includes changes to kprobes.c which now has to handle
break number zero.

Signed-off-by: default avatarAnil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent b77dae52

arch/ia64/kernel/kprobes.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -740,7 +740,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self, 
	switch(val) {

	switch(val) {

	case DIE_BREAK:

	case DIE_BREAK:

		/* err is break number from ia64_bad_break() */

		/* err is break number from ia64_bad_break() */

		if (args->err == 0x80200 || args->err == 0x80300)

		if (args->err == 0x80200 || args->err == 0x80300 || args->err == 0)

			if (pre_kprobes_handler(args))

			if (pre_kprobes_handler(args))

				ret = NOTIFY_STOP;

				ret = NOTIFY_STOP;

		break;

		break;

arch/ia64/kernel/traps.c

+0 −18
Original line number Original line Diff line number Diff line
@@ -132,24 +132,6 @@ __kprobes ia64_bad_break (unsigned long break_num, struct pt_regs *regs) 
	siginfo_t siginfo;

	siginfo_t siginfo;

	int sig, code;

	int sig, code;





	/* break.b always sets cr.iim to 0, which causes problems for

	 * debuggers.  Get the real break number from the original instruction,

	 * but only for kernel code.  User space break.b is left alone, to

	 * preserve the existing behaviour.  All break codings have the same

	 * format, so there is no need to check the slot type.

	 */

	if (break_num == 0 && !user_mode(regs)) {

		struct ia64_psr *ipsr = ia64_psr(regs);

		unsigned long *bundle = (unsigned long *)regs->cr_iip;

		unsigned long slot;

		switch (ipsr->ri) {

		      case 0:  slot = (bundle[0] >>  5); break;

		      case 1:  slot = (bundle[0] >> 46) | (bundle[1] << 18); break;

		      default: slot = (bundle[1] >> 23); break;

		}

		break_num = ((slot >> 36 & 1) << 20) | (slot >> 6 & 0xfffff);

	}



	/* SIGILL, SIGFPE, SIGSEGV, and SIGBUS want these field initialized: */

	/* SIGILL, SIGFPE, SIGSEGV, and SIGBUS want these field initialized: */

	siginfo.si_addr = (void __user *) (regs->cr_iip + ia64_psr(regs)->ri);

	siginfo.si_addr = (void __user *) (regs->cr_iip + ia64_psr(regs)->ri);

	siginfo.si_imm = break_num;

	siginfo.si_imm = break_num;

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