Commit 2538c2d0 authored Jun 15, 2010 by K.Prasad Committed by Paul Mackerras Jun 22, 2010

powerpc, hw_breakpoint: Handle concurrent alignment interrupts



If an alignment interrupt occurs on an instruction that is being
single-stepped, the alignment interrupt handler currently handles
the single-step condition by unconditionally sending a SIGTRAP to
the process.  Other synchronous interrupts that result in the
instruction being emulated do likewise.

With hw_breakpoint support, the hw_breakpoint code needs to be able
to intercept these single-step events as well as those where the
instruction executes normally and a trace interrupt happens.

Fix this by making emulate_single_step() use the existing
single_step_exception() function instead of calling _exception()
directly.  We then make single_step_exception() use the abstracted
clear_single_step() rather than clearing bits in the MSR image
directly so that emulate_single_step() will continue to work
correctly on Book 3E processors.

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

parent 5aae8a53

arch/powerpc/kernel/traps.c

+3 −5

Original line number	Diff line number	Diff line
		@@ -688,7 +688,7 @@ void RunModeException(struct pt_regs *regs)

		void __kprobes single_step_exception(struct pt_regs *regs)
		{
		regs->msr &= ~(MSR_SE \| MSR_BE); /* Turn off 'trace' bits */
		clear_single_step(regs);

		if (notify_die(DIE_SSTEP, "single_step", regs, 5,
		5, SIGTRAP) == NOTIFY_STOP)
		@@ -707,10 +707,8 @@ void __kprobes single_step_exception(struct pt_regs *regs)
		*/
		static void emulate_single_step(struct pt_regs *regs)
		{
		if (single_stepping(regs)) {
		clear_single_step(regs);
		_exception(SIGTRAP, regs, TRAP_TRACE, 0);
		}
		if (single_stepping(regs))
		single_step_exception(regs);
		}

		static inline int __parse_fpscr(unsigned long fpscr)