Commit 83662461 authored by Paul Mundt's avatar Paul Mundt
Browse files

sh: Conditionalize gUSA support. 



This conditionalizes gUSA support. gUSA is not supported on
SMP configurations, and it's not necessary there anyways due
to having other atomicity options (ie, movli.l/movco.l).

Anything implementing the LL/SC semantics (all SH-4A CPUs)
can switch to userspace atomicity implementations without
requiring gUSA. This is left default-enabled on all UP so
that glibc doesn't break.

Those that know what they are doing can disable this explicitly.

Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 995bb781

arch/sh/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -570,6 +570,20 @@ config NR_CPUS 


source "kernel/Kconfig.preempt"



config GUSA

	def_bool y

	depends on !SMP

	help

	  This enables support for gUSA (general UserSpace Atomicity).

	  This is the default implementation for both UP and non-ll/sc

	  CPUs, and is used by the libc, amongst others.



	  For additional information, design information can be found 

	  in <http://lc.linux.or.jp/lc2002/papers/niibe0919p.pdf>.



	  This should only be disabled for special cases where alternate

	  atomicity implementations exist.



endmenu



menu "Boot options"

arch/sh/kernel/entry-common.S

+1 −1
Original line number Diff line number Diff line
@@ -176,7 +176,7 @@ work_notifysig: 
	jmp	@r1

	 lds	r0, pr

work_resched:

#ifndef CONFIG_PREEMPT

#if defined(CONFIG_GUSA) && !defined(CONFIG_PREEMPT)

	! gUSA handling

	mov.l	@(OFF_SP,r15), r0	! get user space stack pointer

	mov	r0, r1

arch/sh/kernel/process.c

+1 −1
Original line number Diff line number Diff line
@@ -350,7 +350,7 @@ struct task_struct *__switch_to(struct task_struct *prev, 
	unlazy_fpu(prev, task_pt_regs(prev));

#endif



#ifdef CONFIG_PREEMPT

#if defined(CONFIG_GUSA) && defined(CONFIG_PREEMPT)

	{

		struct pt_regs *regs;

arch/sh/kernel/signal.c

+2 −0
Original line number Diff line number Diff line
@@ -507,6 +507,7 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info, 
						ctrl_inw(regs->pc - 4));

				break;

		}

#ifdef CONFIG_GUSA

	} else {

		/* gUSA handling */

		preempt_disable();
@@ -523,6 +524,7 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info, 
		}



		preempt_enable_no_resched();

#endif

	}



	/* Set up the stack frame */