[MIPS] MT: Improved multithreading support.

    
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 449 insertions, 0 deletions

diff --git a/arch/mips/kernel/mips-mt.c b/arch/mips/kernel/mips-mt.c
new file mode 100644
index 00000000000..02237a685ec
--- /dev/null
+++ b/arch/mips/kernel/mips-mt.c
@@ -0,0 +1,449 @@
+/*
+ * General MIPS MT support routines, usable in AP/SP, SMVP, or SMTC kernels
+ * Copyright (C) 2005 Mips Technologies, Inc
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/cpumask.h>
+#include <linux/interrupt.h>
+
+#include <asm/cpu.h>
+#include <asm/processor.h>
+#include <asm/atomic.h>
+#include <asm/system.h>
+#include <asm/hardirq.h>
+#include <asm/mmu_context.h>
+#include <asm/smp.h>
+#include <asm/mipsmtregs.h>
+#include <asm/r4kcache.h>
+#include <asm/cacheflush.h>
+
+/*
+ * CPU mask used to set process affinity for MT VPEs/TCs with FPUs
+ */
+
+cpumask_t mt_fpu_cpumask;
+
+#ifdef CONFIG_MIPS_MT_FPAFF
+
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <asm/uaccess.h>
+
+unsigned long mt_fpemul_threshold = 0;
+
+/*
+ * Replacement functions for the sys_sched_setaffinity() and
+ * sys_sched_getaffinity() system calls, so that we can integrate
+ * FPU affinity with the user's requested processor affinity.
+ * This code is 98% identical with the sys_sched_setaffinity()
+ * and sys_sched_getaffinity() system calls, and should be
+ * updated when kernel/sched.c changes.
+ */
+
+/*
+ * find_process_by_pid - find a process with a matching PID value.
+ * used in sys_sched_set/getaffinity() in kernel/sched.c, so
+ * cloned here.
+ */
+static inline task_t *find_process_by_pid(pid_t pid)
+{
+	return pid ? find_task_by_pid(pid) : current;
+}
+
+
+/*
+ * mipsmt_sys_sched_setaffinity - set the cpu affinity of a process
+ */
+asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
+				      unsigned long __user *user_mask_ptr)
+{
+	cpumask_t new_mask;
+	cpumask_t effective_mask;
+	int retval;
+	task_t *p;
+
+	if (len < sizeof(new_mask))
+		return -EINVAL;
+
+	if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
+		return -EFAULT;
+
+	lock_cpu_hotplug();
+	read_lock(&tasklist_lock);
+
+	p = find_process_by_pid(pid);
+	if (!p) {
+		read_unlock(&tasklist_lock);
+		unlock_cpu_hotplug();
+		return -ESRCH;
+	}
+
+	/*
+	 * It is not safe to call set_cpus_allowed with the
+	 * tasklist_lock held.  We will bump the task_struct's
+	 * usage count and drop tasklist_lock before invoking
+	 * set_cpus_allowed.
+	 */
+	get_task_struct(p);
+
+	retval = -EPERM;
+	if ((current->euid != p->euid) && (current->euid != p->uid) &&
+			!capable(CAP_SYS_NICE)) {
+		read_unlock(&tasklist_lock);
+		goto out_unlock;
+	}
+
+	/* Record new user-specified CPU set for future reference */
+	p->thread.user_cpus_allowed = new_mask;
+
+	/* Unlock the task list */
+	read_unlock(&tasklist_lock);
+
+	/* Compute new global allowed CPU set if necessary */
+	if( (p->thread.mflags & MF_FPUBOUND)
+	&& cpus_intersects(new_mask, mt_fpu_cpumask)) {
+		cpus_and(effective_mask, new_mask, mt_fpu_cpumask);
+		retval = set_cpus_allowed(p, effective_mask);
+	} else {
+		p->thread.mflags &= ~MF_FPUBOUND;
+		retval = set_cpus_allowed(p, new_mask);
+	}
+
+
+out_unlock:
+	put_task_struct(p);
+	unlock_cpu_hotplug();
+	return retval;
+}
+
+/*
+ * mipsmt_sys_sched_getaffinity - get the cpu affinity of a process
+ */
+asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
+				      unsigned long __user *user_mask_ptr)
+{
+	unsigned int real_len;
+	cpumask_t mask;
+	int retval;
+	task_t *p;
+
+	real_len = sizeof(mask);
+	if (len < real_len)
+		return -EINVAL;
+
+	lock_cpu_hotplug();
+	read_lock(&tasklist_lock);
+
+	retval = -ESRCH;
+	p = find_process_by_pid(pid);
+	if (!p)
+		goto out_unlock;
+
+	retval = 0;
+
+	cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map);
+
+out_unlock:
+	read_unlock(&tasklist_lock);
+	unlock_cpu_hotplug();
+	if (retval)
+		return retval;
+	if (copy_to_user(user_mask_ptr, &mask, real_len))
+		return -EFAULT;
+	return real_len;
+}
+
+#endif /* CONFIG_MIPS_MT_FPAFF */
+
+/*
+ * Dump new MIPS MT state for the core. Does not leave TCs halted.
+ * Takes an argument which taken to be a pre-call MVPControl value.
+ */
+
+void mips_mt_regdump(unsigned long mvpctl)
+{
+	unsigned long flags;
+	unsigned long vpflags;
+	unsigned long mvpconf0;
+	int nvpe;
+	int ntc;
+	int i;
+	int tc;
+	unsigned long haltval;
+	unsigned long tcstatval;
+#ifdef CONFIG_MIPS_MT_SMTC
+	void smtc_soft_dump(void);
+#endif /* CONFIG_MIPT_MT_SMTC */
+
+	local_irq_save(flags);
+	vpflags = dvpe();
+	printk("=== MIPS MT State Dump ===\n");
+	printk("-- Global State --\n");
+	printk("   MVPControl Passed: %08lx\n", mvpctl);
+	printk("   MVPControl Read: %08lx\n", vpflags);
+	printk("   MVPConf0 : %08lx\n", (mvpconf0 = read_c0_mvpconf0()));
+	nvpe = ((mvpconf0 & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT) + 1;
+	ntc = ((mvpconf0 & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT) + 1;
+	printk("-- per-VPE State --\n");
+	for(i = 0; i < nvpe; i++) {
+	    for(tc = 0; tc < ntc; tc++) {
+			settc(tc);
+		if((read_tc_c0_tcbind() & TCBIND_CURVPE) == i) {
+		    printk("  VPE %d\n", i);
+		    printk("   VPEControl : %08lx\n", read_vpe_c0_vpecontrol());
+		    printk("   VPEConf0 : %08lx\n", read_vpe_c0_vpeconf0());
+		    printk("   VPE%d.Status : %08lx\n",
+				i, read_vpe_c0_status());
+		    printk("   VPE%d.EPC : %08lx\n", i, read_vpe_c0_epc());
+		    printk("   VPE%d.Cause : %08lx\n", i, read_vpe_c0_cause());
+		    printk("   VPE%d.Config7 : %08lx\n",
+				i, read_vpe_c0_config7());
+		    break; /* Next VPE */
+		}
+	    }
+	}
+	printk("-- per-TC State --\n");
+	for(tc = 0; tc < ntc; tc++) {
+		settc(tc);
+		if(read_tc_c0_tcbind() == read_c0_tcbind()) {
+			/* Are we dumping ourself?  */
+			haltval = 0; /* Then we're not halted, and mustn't be */
+			tcstatval = flags; /* And pre-dump TCStatus is flags */
+			printk("  TC %d (current TC with VPE EPC above)\n", tc);
+		} else {
+			haltval = read_tc_c0_tchalt();
+			write_tc_c0_tchalt(1);
+			tcstatval = read_tc_c0_tcstatus();
+			printk("  TC %d\n", tc);
+		}
+		printk("   TCStatus : %08lx\n", tcstatval);
+		printk("   TCBind : %08lx\n", read_tc_c0_tcbind());
+		printk("   TCRestart : %08lx\n", read_tc_c0_tcrestart());
+		printk("   TCHalt : %08lx\n", haltval);
+		printk("   TCContext : %08lx\n", read_tc_c0_tccontext());
+		if (!haltval)
+			write_tc_c0_tchalt(0);
+	}
+#ifdef CONFIG_MIPS_MT_SMTC
+	smtc_soft_dump();
+#endif /* CONFIG_MIPT_MT_SMTC */
+	printk("===========================\n");
+	evpe(vpflags);
+	local_irq_restore(flags);
+}
+
+static int mt_opt_norps = 0;
+static int mt_opt_rpsctl = -1;
+static int mt_opt_nblsu = -1;
+static int mt_opt_forceconfig7 = 0;
+static int mt_opt_config7 = -1;
+
+static int __init rps_disable(char *s)
+{
+	mt_opt_norps = 1;
+	return 1;
+}
+__setup("norps", rps_disable);
+
+static int __init rpsctl_set(char *str)
+{
+	get_option(&str, &mt_opt_rpsctl);
+	return 1;
+}
+__setup("rpsctl=", rpsctl_set);
+
+static int __init nblsu_set(char *str)
+{
+	get_option(&str, &mt_opt_nblsu);
+	return 1;
+}
+__setup("nblsu=", nblsu_set);
+
+static int __init config7_set(char *str)
+{
+	get_option(&str, &mt_opt_config7);
+	mt_opt_forceconfig7 = 1;
+	return 1;
+}
+__setup("config7=", config7_set);
+
+/* Experimental cache flush control parameters that should go away some day */
+int mt_protiflush = 0;
+int mt_protdflush = 0;
+int mt_n_iflushes = 1;
+int mt_n_dflushes = 1;
+
+static int __init set_protiflush(char *s)
+{
+	mt_protiflush = 1;
+	return 1;
+}
+__setup("protiflush", set_protiflush);
+
+static int __init set_protdflush(char *s)
+{
+	mt_protdflush = 1;
+	return 1;
+}
+__setup("protdflush", set_protdflush);
+
+static int __init niflush(char *s)
+{
+	get_option(&s, &mt_n_iflushes);
+	return 1;
+}
+__setup("niflush=", niflush);
+
+static int __init ndflush(char *s)
+{
+	get_option(&s, &mt_n_dflushes);
+	return 1;
+}
+__setup("ndflush=", ndflush);
+#ifdef CONFIG_MIPS_MT_FPAFF
+static int fpaff_threshold = -1;
+
+static int __init fpaff_thresh(char *str)
+{
+	get_option(&str, &fpaff_threshold);
+	return 1;
+}
+
+__setup("fpaff=", fpaff_thresh);
+#endif /* CONFIG_MIPS_MT_FPAFF */
+
+static unsigned int itc_base = 0;
+
+static int __init set_itc_base(char *str)
+{
+	get_option(&str, &itc_base);
+	return 1;
+}
+
+__setup("itcbase=", set_itc_base);
+
+void mips_mt_set_cpuoptions(void)
+{
+	unsigned int oconfig7 = read_c0_config7();
+	unsigned int nconfig7 = oconfig7;
+
+	if (mt_opt_norps) {
+		printk("\"norps\" option deprectated: use \"rpsctl=\"\n");
+	}
+	if (mt_opt_rpsctl >= 0) {
+		printk("34K return prediction stack override set to %d.\n",
+			mt_opt_rpsctl);
+		if (mt_opt_rpsctl)
+			nconfig7 |= (1 << 2);
+		else
+			nconfig7 &= ~(1 << 2);
+	}
+	if (mt_opt_nblsu >= 0) {
+		printk("34K ALU/LSU sync override set to %d.\n", mt_opt_nblsu);
+		if (mt_opt_nblsu)
+			nconfig7 |= (1 << 5);
+		else
+			nconfig7 &= ~(1 << 5);
+	}
+	if (mt_opt_forceconfig7) {
+		printk("CP0.Config7 forced to 0x%08x.\n", mt_opt_config7);
+		nconfig7 = mt_opt_config7;
+	}
+	if (oconfig7 != nconfig7) {
+		__asm__ __volatile("sync");
+		write_c0_config7(nconfig7);
+		ehb ();
+		printk("Config7: 0x%08x\n", read_c0_config7());
+	}
+
+	/* Report Cache management debug options */
+	if (mt_protiflush)
+		printk("I-cache flushes single-threaded\n");
+	if (mt_protdflush)
+		printk("D-cache flushes single-threaded\n");
+	if (mt_n_iflushes != 1)
+		printk("I-Cache Flushes Repeated %d times\n", mt_n_iflushes);
+	if (mt_n_dflushes != 1)
+		printk("D-Cache Flushes Repeated %d times\n", mt_n_dflushes);
+
+#ifdef CONFIG_MIPS_MT_FPAFF
+	/* FPU Use Factor empirically derived from experiments on 34K */
+#define FPUSEFACTOR 333
+
+	if (fpaff_threshold >= 0) {
+		mt_fpemul_threshold = fpaff_threshold;
+	} else {
+		mt_fpemul_threshold =
+			(FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ;
+	}
+	printk("FPU Affinity set after %ld emulations\n",
+			mt_fpemul_threshold);
+#endif /* CONFIG_MIPS_MT_FPAFF */
+
+	if (itc_base != 0) {
+		/*
+		 * Configure ITC mapping.  This code is very
+		 * specific to the 34K core family, which uses
+		 * a special mode bit ("ITC") in the ErrCtl
+		 * register to enable access to ITC control
+		 * registers via cache "tag" operations.
+		 */
+		unsigned long ectlval;
+		unsigned long itcblkgrn;
+
+		/* ErrCtl register is known as "ecc" to Linux */
+		ectlval = read_c0_ecc();
+		write_c0_ecc(ectlval | (0x1 << 26));
+		ehb();
+#define INDEX_0 (0x80000000)
+#define INDEX_8 (0x80000008)
+		/* Read "cache tag" for Dcache pseudo-index 8 */
+		cache_op(Index_Load_Tag_D, INDEX_8);
+		ehb();
+		itcblkgrn = read_c0_dtaglo();
+		itcblkgrn &= 0xfffe0000;
+		/* Set for 128 byte pitch of ITC cells */
+		itcblkgrn |= 0x00000c00;
+		/* Stage in Tag register */
+		write_c0_dtaglo(itcblkgrn);
+		ehb();
+		/* Write out to ITU with CACHE op */
+		cache_op(Index_Store_Tag_D, INDEX_8);
+		/* Now set base address, and turn ITC on with 0x1 bit */
+		write_c0_dtaglo((itc_base & 0xfffffc00) | 0x1 );
+		ehb();
+		/* Write out to ITU with CACHE op */
+		cache_op(Index_Store_Tag_D, INDEX_0);
+		write_c0_ecc(ectlval);
+		ehb();
+		printk("Mapped %ld ITC cells starting at 0x%08x\n",
+			((itcblkgrn & 0x7fe00000) >> 20), itc_base);
+	}
+}
+
+/*
+ * Function to protect cache flushes from concurrent execution
+ * depends on MP software model chosen.
+ */
+
+void mt_cflush_lockdown(void)
+{
+#ifdef CONFIG_MIPS_MT_SMTC
+	void smtc_cflush_lockdown(void);
+
+	smtc_cflush_lockdown();
+#endif /* CONFIG_MIPS_MT_SMTC */
+	/* FILL IN VSMP and AP/SP VERSIONS HERE */
+}
+
+void mt_cflush_release(void)
+{
+#ifdef CONFIG_MIPS_MT_SMTC
+	void smtc_cflush_release(void);
+
+	smtc_cflush_release();
+#endif /* CONFIG_MIPS_MT_SMTC */
+	/* FILL IN VSMP and AP/SP VERSIONS HERE */
+}