tile: support kprobes on tilegx

This change includes support for Kprobes, Jprobes and Return Probes.
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Tony Lu <zlu@tilera.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/Kconfig

@@ -125,6 +125,8 @@ config TILEGX
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_FTRACE_MCOUNT_RECORD
+	select HAVE_KPROBES
+	select HAVE_KRETPROBES
 
 config TILEPRO
 	def_bool !TILEGX

arch/tile/include/asm/Kbuild

@@ -15,7 +15,6 @@ generic-y += ioctl.h
 generic-y += ioctls.h
 generic-y += ipcbuf.h
 generic-y += irq_regs.h
-generic-y += kdebug.h
 generic-y += local.h
 generic-y += msgbuf.h
 generic-y += mutex.h

arch/tile/include/asm/kdebug.h

+/*
+ * Copyright 2012 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.
+ */
+
+#ifndef _ASM_TILE_KDEBUG_H
+#define _ASM_TILE_KDEBUG_H
+
+#include <linux/notifier.h>
+
+enum die_val {
+	DIE_OOPS = 1,
+	DIE_BREAK,
+	DIE_SSTEPBP,
+	DIE_PAGE_FAULT,
+	DIE_COMPILED_BPT
+};
+
+#endif /* _ASM_TILE_KDEBUG_H */

arch/tile/include/asm/kprobes.h

+/*
+ * arch/tile/include/asm/kprobes.h
+ *
+ * Copyright 2012 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.
+ */
+
+#ifndef _ASM_TILE_KPROBES_H
+#define _ASM_TILE_KPROBES_H
+
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/percpu.h>
+
+#include <arch/opcode.h>
+
+#define __ARCH_WANT_KPROBES_INSN_SLOT
+#define MAX_INSN_SIZE			2
+
+#define kretprobe_blacklist_size 0
+
+typedef tile_bundle_bits kprobe_opcode_t;
+
+#define flush_insn_slot(p)						\
+	flush_icache_range((unsigned long)p->addr,			\
+			   (unsigned long)p->addr +			\
+			   (MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
+
+struct kprobe;
+
+/* Architecture specific copy of original instruction. */
+struct arch_specific_insn {
+	kprobe_opcode_t *insn;
+};
+
+struct prev_kprobe {
+	struct kprobe *kp;
+	unsigned long status;
+	unsigned long saved_pc;
+};
+
+#define MAX_JPROBES_STACK_SIZE 128
+#define MAX_JPROBES_STACK_ADDR \
+	(((unsigned long)current_thread_info()) + THREAD_SIZE - 32 \
+		- sizeof(struct pt_regs))
+
+#define MIN_JPROBES_STACK_SIZE(ADDR)					\
+	((((ADDR) + MAX_JPROBES_STACK_SIZE) > MAX_JPROBES_STACK_ADDR)	\
+		? MAX_JPROBES_STACK_ADDR - (ADDR)			\
+		: MAX_JPROBES_STACK_SIZE)
+
+/* per-cpu kprobe control block. */
+struct kprobe_ctlblk {
+	unsigned long kprobe_status;
+	unsigned long kprobe_saved_pc;
+	unsigned long jprobe_saved_sp;
+	struct prev_kprobe prev_kprobe;
+	struct pt_regs jprobe_saved_regs;
+	char jprobes_stack[MAX_JPROBES_STACK_SIZE];
+};
+
+extern tile_bundle_bits breakpoint2_insn;
+extern tile_bundle_bits breakpoint_insn;
+
+void arch_remove_kprobe(struct kprobe *);
+
+extern int kprobe_exceptions_notify(struct notifier_block *self,
+			     unsigned long val, void *data);
+
+#endif /* _ASM_TILE_KPROBES_H */

arch/tile/include/asm/ptrace.h

@@ -33,6 +33,7 @@ typedef unsigned long pt_reg_t;
 
 #ifndef __ASSEMBLY__
 
+#define regs_return_value(regs) ((regs)->regs[0])
 #define instruction_pointer(regs) ((regs)->pc)
 #define profile_pc(regs) instruction_pointer(regs)
 #define user_stack_pointer(regs) ((regs)->sp)

arch/tile/include/uapi/arch/opcode_tilegx.h

@@ -61,6 +61,7 @@ typedef tilegx_bundle_bits tile_bundle_bits;
 #define TILE_BUNDLE_ALIGNMENT_IN_BYTES TILEGX_BUNDLE_ALIGNMENT_IN_BYTES
 #define TILE_LOG2_BUNDLE_ALIGNMENT_IN_BYTES \
   TILEGX_LOG2_BUNDLE_ALIGNMENT_IN_BYTES
+#define TILE_BPT_BUNDLE TILEGX_BPT_BUNDLE
 
 /* 64-bit pattern for a { bpt ; nop } bundle. */
 #define TILEGX_BPT_BUNDLE 0x286a44ae51485000ULL

arch/tile/include/uapi/arch/opcode_tilepro.h

@@ -71,6 +71,7 @@ typedef tilepro_bundle_bits tile_bundle_bits;
 #define TILE_BUNDLE_ALIGNMENT_IN_BYTES TILEPRO_BUNDLE_ALIGNMENT_IN_BYTES
 #define TILE_LOG2_BUNDLE_ALIGNMENT_IN_BYTES \
   TILEPRO_LOG2_BUNDLE_ALIGNMENT_IN_BYTES
+#define TILE_BPT_BUNDLE TILEPRO_BPT_BUNDLE
 
 /* 64-bit pattern for a { bpt ; nop } bundle. */
 #define TILEPRO_BPT_BUNDLE 0x400b3cae70166000ULL

arch/tile/kernel/Makefile

@@ -28,5 +28,6 @@ endif
 obj-$(CONFIG_TILE_USB)		+= usb.o
 obj-$(CONFIG_TILE_HVGLUE_TRACE)	+= hvglue_trace.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o mcount_64.o
+obj-$(CONFIG_KPROBES)		+= kprobes.o
 
 obj-y				+= vdso/

arch/tile/kernel/smp.c

@@ -20,6 +20,7 @@
 #include <linux/irq.h>
 #include <linux/module.h>
 #include <asm/cacheflush.h>
+#include <asm/homecache.h>
 
 HV_Topology smp_topology __write_once;
 EXPORT_SYMBOL(smp_topology);
@@ -167,9 +168,16 @@ static void ipi_flush_icache_range(void *info)
 void flush_icache_range(unsigned long start, unsigned long end)
 {
 	struct ipi_flush flush = { start, end };
+
+	/* If invoked with irqs disabled, we can not issue IPIs. */
+	if (irqs_disabled())
+		flush_remote(0, HV_FLUSH_EVICT_L1I, NULL, 0, 0, 0,
+			NULL, NULL, 0);
+	else {
 		preempt_disable();
 		on_each_cpu(ipi_flush_icache_range, &flush, 1);
 		preempt_enable();
+	}
 }
 
 

arch/tile/kernel/traps.c

@@ -15,6 +15,7 @@
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/kprobes.h>
+#include <linux/kdebug.h>
 #include <linux/module.h>
 #include <linux/reboot.h>
 #include <linux/uaccess.h>
@@ -214,6 +215,43 @@ static const char *const int_name[] = {
 #endif
 };
 
+static int do_bpt(struct pt_regs *regs)
+{
+	unsigned long bundle, bcode, bpt;
+
+	bundle = *(unsigned long *)instruction_pointer(regs);
+
+	/*
+	 * bpt shoule be { bpt; nop }, which is 0x286a44ae51485000ULL.
+	 * we encode the unused least significant bits for other purpose.
+	 */
+	bpt = bundle & ~((1ULL << 12) - 1);
+	if (bpt != TILE_BPT_BUNDLE)
+		return 0;
+
+	bcode = bundle & ((1ULL << 12) - 1);
+	/*
+	 * notify the kprobe handlers, if instruction is likely to
+	 * pertain to them.
+	 */
+	switch (bcode) {
+	/* breakpoint_insn */
+	case 0:
+		notify_die(DIE_BREAK, "debug", regs, bundle,
+			INT_ILL, SIGTRAP);
+		break;
+	/* breakpoint2_insn */
+	case DIE_SSTEPBP:
+		notify_die(DIE_SSTEPBP, "single_step", regs, bundle,
+			INT_ILL, SIGTRAP);
+		break;
+	default:
+		return 0;
+	}
+
+	return 1;
+}
+
 void __kprobes do_trap(struct pt_regs *regs, int fault_num,
 		       unsigned long reason)
 {
@@ -221,6 +259,11 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
 	int signo, code;
 	unsigned long address = 0;
 	bundle_bits instr;
+	int is_kernel = !user_mode(regs);
+
+	/* Handle breakpoints, etc. */
+	if (is_kernel && fault_num == INT_ILL && do_bpt(regs))
+		return;
 
 	/* Re-enable interrupts, if they were previously enabled. */
 	if (!(regs->flags & PT_FLAGS_DISABLE_IRQ))
@@ -230,7 +273,7 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
 	 * If it hits in kernel mode and we can't fix it up, just exit the
 	 * current process and hope for the best.
 	 */
-	if (!user_mode(regs)) {
+	if (is_kernel) {
 		const char *name;
 		char buf[100];
 		if (fixup_exception(regs))  /* ILL_TRANS or UNALIGN_DATA */

arch/tile/kernel/vmlinux.lds.S

@@ -43,6 +43,7 @@ SECTIONS
     HEAD_TEXT
     SCHED_TEXT
     LOCK_TEXT
+    KPROBES_TEXT
     IRQENTRY_TEXT
     __fix_text_end = .;   /* tile-cpack won't rearrange before this */
     TEXT_TEXT

arch/tile/mm/fault.c

@@ -34,6 +34,7 @@
 #include <linux/hugetlb.h>
 #include <linux/syscalls.h>
 #include <linux/uaccess.h>
+#include <linux/kdebug.h>
 
 #include <asm/pgalloc.h>
 #include <asm/sections.h>
@@ -721,6 +722,17 @@ void do_page_fault(struct pt_regs *regs, int fault_num,
 {
 	int is_page_fault;
 
+#ifdef CONFIG_KPROBES
+	/*
+	 * This is to notify the fault handler of the kprobes.  The
+	 * exception code is redundant as it is also carried in REGS,
+	 * but we pass it anyhow.
+	 */
+	if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
+		       regs->faultnum, SIGSEGV) == NOTIFY_STOP)
+		return;
+#endif
+
 #ifdef __tilegx__
 	/*
 	 * We don't need early do_page_fault_ics() support, since unlike

samples/kprobes/kprobe_example.c

@@ -37,6 +37,11 @@ static int handler_pre(struct kprobe *p, struct pt_regs *regs)
 			" status = 0x%lx\n",
 		p->addr, regs->cp0_epc, regs->cp0_status);
 #endif
+#ifdef CONFIG_TILEGX
+	printk(KERN_INFO "pre_handler: p->addr = 0x%p, pc = 0x%lx,"
+			" ex1 = 0x%lx\n",
+		p->addr, regs->pc, regs->ex1);
+#endif
 
 	/* A dump_stack() here will give a stack backtrace */
 	return 0;
@@ -58,6 +63,10 @@ static void handler_post(struct kprobe *p, struct pt_regs *regs,
 	printk(KERN_INFO "post_handler: p->addr = 0x%p, status = 0x%lx\n",
 		p->addr, regs->cp0_status);
 #endif
+#ifdef CONFIG_TILEGX
+	printk(KERN_INFO "post_handler: p->addr = 0x%p, ex1 = 0x%lx\n",
+		p->addr, regs->ex1);
+#endif
 }
 
 /*