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authorPaul Mundt <lethal@linux-sh.org>2007-09-28 16:04:49 +0900
committerPaul Mundt <lethal@linux-sh.org>2007-09-28 16:04:49 +0900
commit836624619b98535079053920a29a7e474ac17cbc (patch)
treebeb3b4fc1b893b6a422be3645c3611b1c7adb456 /arch/sh
parent995bb781d42441ed48517bc7ea6414c3df3386ef (diff)
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: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'arch/sh')
-rw-r--r--arch/sh/Kconfig14
-rw-r--r--arch/sh/kernel/entry-common.S2
-rw-r--r--arch/sh/kernel/process.c2
-rw-r--r--arch/sh/kernel/signal.c2
4 files changed, 18 insertions, 2 deletions
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index a8693edd4f4..44982c1dfa2 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -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"
diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S
index b4672802719..e0317ed080c 100644
--- a/arch/sh/kernel/entry-common.S
+++ b/arch/sh/kernel/entry-common.S
@@ -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
diff --git a/arch/sh/kernel/process.c b/arch/sh/kernel/process.c
index cd8dae16e94..b4469992d6b 100644
--- a/arch/sh/kernel/process.c
+++ b/arch/sh/kernel/process.c
@@ -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;
diff --git a/arch/sh/kernel/signal.c b/arch/sh/kernel/signal.c
index 0f657d32ceb..2f42442cf16 100644
--- a/arch/sh/kernel/signal.c
+++ b/arch/sh/kernel/signal.c
@@ -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 */