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-rw-r--r--arch/mips/kernel/cpu-probe.c62
1 files changed, 45 insertions, 17 deletions
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index aa2caa67299..9fbf8430c84 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -38,15 +38,40 @@ static void r3081_wait(void)
static void r39xx_wait(void)
{
- unsigned long cfg = read_c0_conf();
- write_c0_conf(cfg | TX39_CONF_HALT);
+ local_irq_disable();
+ if (!need_resched())
+ write_c0_conf(read_c0_conf() | TX39_CONF_HALT);
+ local_irq_enable();
}
+/*
+ * There is a race when WAIT instruction executed with interrupt
+ * enabled.
+ * But it is implementation-dependent wheter the pipelie restarts when
+ * a non-enabled interrupt is requested.
+ */
static void r4k_wait(void)
{
- __asm__(".set\tmips3\n\t"
- "wait\n\t"
- ".set\tmips0");
+ __asm__(" .set mips3 \n"
+ " wait \n"
+ " .set mips0 \n");
+}
+
+/*
+ * This variant is preferable as it allows testing need_resched and going to
+ * sleep depending on the outcome atomically. Unfortunately the "It is
+ * implementation-dependent whether the pipeline restarts when a non-enabled
+ * interrupt is requested" restriction in the MIPS32/MIPS64 architecture makes
+ * using this version a gamble.
+ */
+static void r4k_wait_irqoff(void)
+{
+ local_irq_disable();
+ if (!need_resched())
+ __asm__(" .set mips3 \n"
+ " wait \n"
+ " .set mips0 \n");
+ local_irq_enable();
}
/* The Au1xxx wait is available only if using 32khz counter or
@@ -56,17 +81,17 @@ int allow_au1k_wait;
static void au1k_wait(void)
{
/* using the wait instruction makes CP0 counter unusable */
- __asm__(".set mips3\n\t"
- "cache 0x14, 0(%0)\n\t"
- "cache 0x14, 32(%0)\n\t"
- "sync\n\t"
- "nop\n\t"
- "wait\n\t"
- "nop\n\t"
- "nop\n\t"
- "nop\n\t"
- "nop\n\t"
- ".set mips0\n\t"
+ __asm__(" .set mips3 \n"
+ " cache 0x14, 0(%0) \n"
+ " cache 0x14, 32(%0) \n"
+ " sync \n"
+ " nop \n"
+ " wait \n"
+ " nop \n"
+ " nop \n"
+ " nop \n"
+ " nop \n"
+ " .set mips0 \n"
: : "r" (au1k_wait));
}
@@ -111,7 +136,6 @@ static inline void check_wait(void)
case CPU_NEVADA:
case CPU_RM7000:
case CPU_RM9000:
- case CPU_TX49XX:
case CPU_4KC:
case CPU_4KEC:
case CPU_4KSC:
@@ -125,6 +149,10 @@ static inline void check_wait(void)
cpu_wait = r4k_wait;
printk(" available.\n");
break;
+ case CPU_TX49XX:
+ cpu_wait = r4k_wait_irqoff;
+ printk(" available.\n");
+ break;
case CPU_AU1000:
case CPU_AU1100:
case CPU_AU1500: