arch/tile: core support for Tilera 32-bit chips.

This change is the core kernel support for TILEPro and TILE64 chips.
No driver support (except the console driver) is included yet.

This includes the relevant Linux headers in asm/; the low-level
low-level "Tile architecture" headers in arch/, which are
shared with the hypervisor, etc., and are build-system agnostic;
and the relevant hypervisor headers in hv/.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reviewed-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 485 insertions, 0 deletions

diff --git a/arch/tile/kernel/stack.c b/arch/tile/kernel/stack.c
new file mode 100644
index 000000000000..382170b4b40a
--- /dev/null
+++ b/arch/tile/kernel/stack.c
@@ -0,0 +1,485 @@
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/pfn.h>
+#include <linux/kallsyms.h>
+#include <linux/stacktrace.h>
+#include <linux/uaccess.h>
+#include <linux/mmzone.h>
+#include <asm/backtrace.h>
+#include <asm/page.h>
+#include <asm/tlbflush.h>
+#include <asm/ucontext.h>
+#include <asm/sigframe.h>
+#include <asm/stack.h>
+#include <arch/abi.h>
+#include <arch/interrupts.h>
+
+
+/* Is address on the specified kernel stack? */
+static int in_kernel_stack(struct KBacktraceIterator *kbt, VirtualAddress sp)
+{
+	ulong kstack_base = (ulong) kbt->task->stack;
+	if (kstack_base == 0)  /* corrupt task pointer; just follow stack... */
+		return sp >= PAGE_OFFSET && sp < (unsigned long)high_memory;
+	return sp >= kstack_base && sp < kstack_base + THREAD_SIZE;
+}
+
+/* Is address in the specified kernel code? */
+static int in_kernel_text(VirtualAddress address)
+{
+	return (address >= MEM_SV_INTRPT &&
+		address < MEM_SV_INTRPT + HPAGE_SIZE);
+}
+
+/* Is address valid for reading? */
+static int valid_address(struct KBacktraceIterator *kbt, VirtualAddress address)
+{
+	HV_PTE *l1_pgtable = kbt->pgtable;
+	HV_PTE *l2_pgtable;
+	unsigned long pfn;
+	HV_PTE pte;
+	struct page *page;
+
+	pte = l1_pgtable[HV_L1_INDEX(address)];
+	if (!hv_pte_get_present(pte))
+		return 0;
+	pfn = hv_pte_get_pfn(pte);
+	if (pte_huge(pte)) {
+		if (!pfn_valid(pfn)) {
+			printk(KERN_ERR "huge page has bad pfn %#lx\n", pfn);
+			return 0;
+		}
+		return hv_pte_get_present(pte) && hv_pte_get_readable(pte);
+	}
+
+	page = pfn_to_page(pfn);
+	if (PageHighMem(page)) {
+		printk(KERN_ERR "L2 page table not in LOWMEM (%#llx)\n",
+		       HV_PFN_TO_CPA(pfn));
+		return 0;
+	}
+	l2_pgtable = (HV_PTE *)pfn_to_kaddr(pfn);
+	pte = l2_pgtable[HV_L2_INDEX(address)];
+	return hv_pte_get_present(pte) && hv_pte_get_readable(pte);
+}
+
+/* Callback for backtracer; basically a glorified memcpy */
+static bool read_memory_func(void *result, VirtualAddress address,
+			     unsigned int size, void *vkbt)
+{
+	int retval;
+	struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt;
+	if (in_kernel_text(address)) {
+		/* OK to read kernel code. */
+	} else if (address >= PAGE_OFFSET) {
+		/* We only tolerate kernel-space reads of this task's stack */
+		if (!in_kernel_stack(kbt, address))
+			return 0;
+	} else if (kbt->pgtable == NULL) {
+		return 0;	/* can't read user space in other tasks */
+	} else if (!valid_address(kbt, address)) {
+		return 0;	/* invalid user-space address */
+	}
+	pagefault_disable();
+	retval = __copy_from_user_inatomic(result, (const void *)address,
+					   size);
+	pagefault_enable();
+	return (retval == 0);
+}
+
+/* Return a pt_regs pointer for a valid fault handler frame */
+static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt)
+{
+#ifndef __tilegx__
+	const char *fault = NULL;  /* happy compiler */
+	char fault_buf[64];
+	VirtualAddress sp = kbt->it.sp;
+	struct pt_regs *p;
+
+	if (!in_kernel_stack(kbt, sp))
+		return NULL;
+	if (!in_kernel_stack(kbt, sp + C_ABI_SAVE_AREA_SIZE + PTREGS_SIZE-1))
+		return NULL;
+	p = (struct pt_regs *)(sp + C_ABI_SAVE_AREA_SIZE);
+	if (p->faultnum == INT_SWINT_1 || p->faultnum == INT_SWINT_1_SIGRETURN)
+		fault = "syscall";
+	else {
+		if (kbt->verbose) {     /* else we aren't going to use it */
+			snprintf(fault_buf, sizeof(fault_buf),
+				 "interrupt %ld", p->faultnum);
+			fault = fault_buf;
+		}
+	}
+	if (EX1_PL(p->ex1) == KERNEL_PL &&
+	    in_kernel_text(p->pc) &&
+	    in_kernel_stack(kbt, p->sp) &&
+	    p->sp >= sp) {
+		if (kbt->verbose)
+			printk(KERN_ERR "  <%s while in kernel mode>\n", fault);
+	} else if (EX1_PL(p->ex1) == USER_PL &&
+	    p->pc < PAGE_OFFSET &&
+	    p->sp < PAGE_OFFSET) {
+		if (kbt->verbose)
+			printk(KERN_ERR "  <%s while in user mode>\n", fault);
+	} else if (kbt->verbose) {
+		printk(KERN_ERR "  (odd fault: pc %#lx, sp %#lx, ex1 %#lx?)\n",
+		       p->pc, p->sp, p->ex1);
+		p = NULL;
+	}
+	if (!kbt->profile || (INT_MASK(p->faultnum) & QUEUED_INTERRUPTS) == 0)
+		return p;
+#endif
+	return NULL;
+}
+
+/* Is the pc pointing to a sigreturn trampoline? */
+static int is_sigreturn(VirtualAddress pc)
+{
+	return (pc == VDSO_BASE);
+}
+
+/* Return a pt_regs pointer for a valid signal handler frame */
+static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt)
+{
+	BacktraceIterator *b = &kbt->it;
+
+	if (b->pc == VDSO_BASE) {
+		struct rt_sigframe *frame;
+		unsigned long sigframe_top =
+			b->sp + sizeof(struct rt_sigframe) - 1;
+		if (!valid_address(kbt, b->sp) ||
+		    !valid_address(kbt, sigframe_top)) {
+			if (kbt->verbose)
+				printk("  (odd signal: sp %#lx?)\n",
+				       (unsigned long)(b->sp));
+			return NULL;
+		}
+		frame = (struct rt_sigframe *)b->sp;
+		if (kbt->verbose) {
+			printk(KERN_ERR "  <received signal %d>\n",
+			       frame->info.si_signo);
+		}
+		return &frame->uc.uc_mcontext.regs;
+	}
+	return NULL;
+}
+
+int KBacktraceIterator_is_sigreturn(struct KBacktraceIterator *kbt)
+{
+	return is_sigreturn(kbt->it.pc);
+}
+
+static int KBacktraceIterator_restart(struct KBacktraceIterator *kbt)
+{
+	struct pt_regs *p;
+
+	p = valid_fault_handler(kbt);
+	if (p == NULL)
+		p = valid_sigframe(kbt);
+	if (p == NULL)
+		return 0;
+	backtrace_init(&kbt->it, read_memory_func, kbt,
+		       p->pc, p->lr, p->sp, p->regs[52]);
+	kbt->new_context = 1;
+	return 1;
+}
+
+/* Find a frame that isn't a sigreturn, if there is one. */
+static int KBacktraceIterator_next_item_inclusive(
+	struct KBacktraceIterator *kbt)
+{
+	for (;;) {
+		do {
+			if (!KBacktraceIterator_is_sigreturn(kbt))
+				return 1;
+		} while (backtrace_next(&kbt->it));
+
+		if (!KBacktraceIterator_restart(kbt))
+			return 0;
+	}
+}
+
+/*
+ * If the current sp is on a page different than what we recorded
+ * as the top-of-kernel-stack last time we context switched, we have
+ * probably blown the stack, and nothing is going to work out well.
+ * If we can at least get out a warning, that may help the debug,
+ * though we probably won't be able to backtrace into the code that
+ * actually did the recursive damage.
+ */
+static void validate_stack(struct pt_regs *regs)
+{
+	int cpu = smp_processor_id();
+	unsigned long ksp0 = get_current_ksp0();
+	unsigned long ksp0_base = ksp0 - THREAD_SIZE;
+	unsigned long sp = stack_pointer;
+
+	if (EX1_PL(regs->ex1) == KERNEL_PL && regs->sp >= ksp0) {
+		printk("WARNING: cpu %d: kernel stack page %#lx underrun!\n"
+		       "  sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
+		       cpu, ksp0_base, sp, regs->sp, regs->pc, regs->lr);
+	}
+
+	else if (sp < ksp0_base + sizeof(struct thread_info)) {
+		printk("WARNING: cpu %d: kernel stack page %#lx overrun!\n"
+		       "  sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
+		       cpu, ksp0_base, sp, regs->sp, regs->pc, regs->lr);
+	}
+}
+
+void KBacktraceIterator_init(struct KBacktraceIterator *kbt,
+			     struct task_struct *t, struct pt_regs *regs)
+{
+	VirtualAddress pc, lr, sp, r52;
+	int is_current;
+
+	/*
+	 * Set up callback information.  We grab the kernel stack base
+	 * so we will allow reads of that address range, and if we're
+	 * asking about the current process we grab the page table
+	 * so we can check user accesses before trying to read them.
+	 * We flush the TLB to avoid any weird skew issues.
+	 */
+	is_current = (t == NULL);
+	kbt->is_current = is_current;
+	if (is_current)
+		t = validate_current();
+	kbt->task = t;
+	kbt->pgtable = NULL;
+	kbt->verbose = 0;   /* override in caller if desired */
+	kbt->profile = 0;   /* override in caller if desired */
+	kbt->end = 0;
+	kbt->new_context = 0;
+	if (is_current) {
+		HV_PhysAddr pgdir_pa = hv_inquire_context().page_table;
+		if (pgdir_pa == (unsigned long)swapper_pg_dir - PAGE_OFFSET) {
+			/*
+			 * Not just an optimization: this also allows
+			 * this to work at all before va/pa mappings
+			 * are set up.
+			 */
+			kbt->pgtable = swapper_pg_dir;
+		} else {
+			struct page *page = pfn_to_page(PFN_DOWN(pgdir_pa));
+			if (!PageHighMem(page))
+				kbt->pgtable = __va(pgdir_pa);
+			else
+				printk(KERN_ERR "page table not in LOWMEM"
+				       " (%#llx)\n", pgdir_pa);
+		}
+		local_flush_tlb_all();
+		validate_stack(regs);
+	}
+
+	if (regs == NULL) {
+		extern const void *get_switch_to_pc(void);
+		if (is_current || t->state == TASK_RUNNING) {
+			/* Can't do this; we need registers */
+			kbt->end = 1;
+			return;
+		}
+		pc = (ulong) get_switch_to_pc();
+		lr = t->thread.pc;
+		sp = t->thread.ksp;
+		r52 = 0;
+	} else {
+		pc = regs->pc;
+		lr = regs->lr;
+		sp = regs->sp;
+		r52 = regs->regs[52];
+	}
+
+	backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52);
+	kbt->end = !KBacktraceIterator_next_item_inclusive(kbt);
+}
+EXPORT_SYMBOL(KBacktraceIterator_init);
+
+int KBacktraceIterator_end(struct KBacktraceIterator *kbt)
+{
+	return kbt->end;
+}
+EXPORT_SYMBOL(KBacktraceIterator_end);
+
+void KBacktraceIterator_next(struct KBacktraceIterator *kbt)
+{
+	kbt->new_context = 0;
+	if (!backtrace_next(&kbt->it) &&
+	    !KBacktraceIterator_restart(kbt)) {
+			kbt->end = 1;
+			return;
+		}
+
+	kbt->end = !KBacktraceIterator_next_item_inclusive(kbt);
+}
+EXPORT_SYMBOL(KBacktraceIterator_next);
+
+/*
+ * This method wraps the backtracer's more generic support.
+ * It is only invoked from the architecture-specific code; show_stack()
+ * and dump_stack() (in entry.S) are architecture-independent entry points.
+ */
+void tile_show_stack(struct KBacktraceIterator *kbt, int headers)
+{
+	int i;
+
+	if (headers) {
+		/*
+		 * Add a blank line since if we are called from panic(),
+		 * then bust_spinlocks() spit out a space in front of us
+		 * and it will mess up our KERN_ERR.
+		 */
+		printk("\n");
+		printk(KERN_ERR "Starting stack dump of tid %d, pid %d (%s)"
+		       " on cpu %d at cycle %lld\n",
+		       kbt->task->pid, kbt->task->tgid, kbt->task->comm,
+		       smp_processor_id(), get_cycles());
+	}
+#ifdef __tilegx__
+	if (kbt->is_current) {
+		__insn_mtspr(SPR_SIM_CONTROL,
+			     SIM_DUMP_SPR_ARG(SIM_DUMP_BACKTRACE));
+	}
+#endif
+	kbt->verbose = 1;
+	i = 0;
+	for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) {
+		char *modname;
+		const char *name;
+		unsigned long address = kbt->it.pc;
+		unsigned long offset, size;
+		char namebuf[KSYM_NAME_LEN+100];
+
+		if (address >= PAGE_OFFSET)
+			name = kallsyms_lookup(address, &size, &offset,
+					       &modname, namebuf);
+		else
+			name = NULL;
+
+		if (!name)
+			namebuf[0] = '\0';
+		else {
+			size_t namelen = strlen(namebuf);
+			size_t remaining = (sizeof(namebuf) - 1) - namelen;
+			char *p = namebuf + namelen;
+			int rc = snprintf(p, remaining, "+%#lx/%#lx ",
+					  offset, size);
+			if (modname && rc < remaining)
+				snprintf(p + rc, remaining - rc,
+					 "[%s] ", modname);
+			namebuf[sizeof(namebuf)-1] = '\0';
+		}
+
+		printk(KERN_ERR "  frame %d: 0x%lx %s(sp 0x%lx)\n",
+		       i++, address, namebuf, (unsigned long)(kbt->it.sp));
+
+		if (i >= 100) {
+			printk(KERN_ERR "Stack dump truncated"
+			       " (%d frames)\n", i);
+			break;
+		}
+	}
+	if (headers)
+		printk(KERN_ERR "Stack dump complete\n");
+}
+EXPORT_SYMBOL(tile_show_stack);
+
+
+/* This is called from show_regs() and _dump_stack() */
+void dump_stack_regs(struct pt_regs *regs)
+{
+	struct KBacktraceIterator kbt;
+	KBacktraceIterator_init(&kbt, NULL, regs);
+	tile_show_stack(&kbt, 1);
+}
+EXPORT_SYMBOL(dump_stack_regs);
+
+static struct pt_regs *regs_to_pt_regs(struct pt_regs *regs,
+				       ulong pc, ulong lr, ulong sp, ulong r52)
+{
+	memset(regs, 0, sizeof(struct pt_regs));
+	regs->pc = pc;
+	regs->lr = lr;
+	regs->sp = sp;
+	regs->regs[52] = r52;
+	return regs;
+}
+
+/* This is called from dump_stack() and just converts to pt_regs */
+void _dump_stack(int dummy, ulong pc, ulong lr, ulong sp, ulong r52)
+{
+	struct pt_regs regs;
+	dump_stack_regs(regs_to_pt_regs(&regs, pc, lr, sp, r52));
+}
+
+/* This is called from KBacktraceIterator_init_current() */
+void _KBacktraceIterator_init_current(struct KBacktraceIterator *kbt, ulong pc,
+				      ulong lr, ulong sp, ulong r52)
+{
+	struct pt_regs regs;
+	KBacktraceIterator_init(kbt, NULL,
+				regs_to_pt_regs(&regs, pc, lr, sp, r52));
+}
+
+/* This is called only from kernel/sched.c, with esp == NULL */
+void show_stack(struct task_struct *task, unsigned long *esp)
+{
+	struct KBacktraceIterator kbt;
+	if (task == NULL || task == current)
+		KBacktraceIterator_init_current(&kbt);
+	else
+		KBacktraceIterator_init(&kbt, task, NULL);
+	tile_show_stack(&kbt, 0);
+}
+
+#ifdef CONFIG_STACKTRACE
+
+/* Support generic Linux stack API too */
+
+void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace)
+{
+	struct KBacktraceIterator kbt;
+	int skip = trace->skip;
+	int i = 0;
+
+	if (task == NULL || task == current)
+		KBacktraceIterator_init_current(&kbt);
+	else
+		KBacktraceIterator_init(&kbt, task, NULL);
+	for (; !KBacktraceIterator_end(&kbt); KBacktraceIterator_next(&kbt)) {
+		if (skip) {
+			--skip;
+			continue;
+		}
+		if (i >= trace->max_entries || kbt.it.pc < PAGE_OFFSET)
+			break;
+		trace->entries[i++] = kbt.it.pc;
+	}
+	trace->nr_entries = i;
+}
+EXPORT_SYMBOL(save_stack_trace_tsk);
+
+void save_stack_trace(struct stack_trace *trace)
+{
+	save_stack_trace_tsk(NULL, trace);
+}
+
+#endif
+
+/* In entry.S */
+EXPORT_SYMBOL(KBacktraceIterator_init_current);