[PATCH] tile: support ftrace on tilegx

[PATCH] tile: support ftrace on tilegx

[Tony Lu]

This commit adds support for static ftrace, graph function support,
and dynamic tracer support.

Signed-off-by: Tony Lu <zlu@tilera.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
---
I assume it makes sense for this to be pushed via the tile tree;
it's currently queued in tile-next.

 arch/tile/Kconfig              |   7 +-
 arch/tile/include/asm/ftrace.h |  22 +++-
 arch/tile/kernel/Makefile      |   6 +
 arch/tile/kernel/ftrace.c      | 246 +++++++++++++++++++++++++++++++++++++++++
 arch/tile/kernel/mcount_64.S   | 224 +++++++++++++++++++++++++++++++++++++
 arch/tile/kernel/vmlinux.lds.S |   1 +
 arch/tile/lib/exports.c        |   6 +
 scripts/recordmcount.pl        |   4 +
 8 files changed, 514 insertions(+), 2 deletions(-)
 create mode 100644 arch/tile/kernel/ftrace.c
 create mode 100644 arch/tile/kernel/mcount_64.S

diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
index e76180e..e1600be 100644
--- a/arch/tile/Kconfig
+++ b/arch/tile/Kconfig
@@ -119,7 +119,12 @@ config HVC_TILE
 	def_bool y
 
 config TILEGX
-	bool "Building with TILE-Gx (64-bit) compiler and toolchain"
+	bool "Building for TILE-Gx (64-bit) processor"
+	select HAVE_FUNCTION_TRACER
+	select HAVE_FUNCTION_TRACE_MCOUNT_TEST
+	select HAVE_FUNCTION_GRAPH_TRACER
+	select HAVE_DYNAMIC_FTRACE
+	select HAVE_FTRACE_MCOUNT_RECORD
 
 config TILEPRO
 	def_bool !TILEGX
diff --git a/arch/tile/include/asm/ftrace.h b/arch/tile/include/asm/ftrace.h
index 461459b..13a9bb81 100644
--- a/arch/tile/include/asm/ftrace.h
+++ b/arch/tile/include/asm/ftrace.h
@@ -15,6 +15,26 @@
 #ifndef _ASM_TILE_FTRACE_H
 #define _ASM_TILE_FTRACE_H
 
-/* empty */
+#ifdef CONFIG_FUNCTION_TRACER
+
+#define MCOUNT_ADDR ((unsigned long)(__mcount))
+#define MCOUNT_INSN_SIZE 8		/* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void __mcount(void);
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+	return addr;
+}
+
+struct dyn_arch_ftrace {
+};
+#endif /*  CONFIG_DYNAMIC_FTRACE */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* CONFIG_FUNCTION_TRACER */
 
 #endif /* _ASM_TILE_FTRACE_H */
diff --git a/arch/tile/kernel/Makefile b/arch/tile/kernel/Makefile
index c4a957a..2e6eaa1 100644
--- a/arch/tile/kernel/Makefile
+++ b/arch/tile/kernel/Makefile
@@ -9,6 +9,11 @@ obj-y := backtrace.o entry.o hvglue.o irq.o messaging.o \
 	sysfs.o time.o traps.o unaligned.o vdso.o \
 	intvec_$(BITS).o regs_$(BITS).o tile-desc_$(BITS).o
 
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_ftrace.o = -pg
+CFLAGS_REMOVE_early_printk.o = -pg
+endif
+
 obj-$(CONFIG_HARDWALL)		+= hardwall.o
 obj-$(CONFIG_COMPAT)		+= compat.o compat_signal.o
 obj-$(CONFIG_SMP)		+= smpboot.o smp.o tlb.o
@@ -22,5 +27,6 @@ obj-$(CONFIG_PCI)		+= pci.o
 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-y				+= vdso/
diff --git a/arch/tile/kernel/ftrace.c b/arch/tile/kernel/ftrace.c
new file mode 100644
index 0000000..f1c4520
--- /dev/null
+++ b/arch/tile/kernel/ftrace.c
@@ -0,0 +1,246 @@
+/*
+ * 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.
+ *
+ * TILE-Gx specific ftrace support
+ */
+
+#include <linux/ftrace.h>
+#include <linux/uaccess.h>
+
+#include <asm/cacheflush.h>
+#include <asm/ftrace.h>
+#include <asm/sections.h>
+
+#include <arch/opcode.h>
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+static inline tilegx_bundle_bits NOP(void)
+{
+	return create_UnaryOpcodeExtension_X0(FNOP_UNARY_OPCODE_X0) |
+		create_RRROpcodeExtension_X0(UNARY_RRR_0_OPCODE_X0) |
+		create_Opcode_X0(RRR_0_OPCODE_X0) |
+		create_UnaryOpcodeExtension_X1(NOP_UNARY_OPCODE_X1) |
+		create_RRROpcodeExtension_X1(UNARY_RRR_0_OPCODE_X1) |
+		create_Opcode_X1(RRR_0_OPCODE_X1);
+}
+
+static int machine_stopped __read_mostly;
+
+int ftrace_arch_code_modify_prepare(void)
+{
+	machine_stopped = 1;
+	return 0;
+}
+
+int ftrace_arch_code_modify_post_process(void)
+{
+	flush_icache_range(0, CHIP_L1I_CACHE_SIZE());
+	machine_stopped = 0;
+	return 0;
+}
+
+/*
+ * Put { move r10, lr; jal ftrace_caller } in a bundle, this lets dynamic
+ * tracer just add one cycle overhead to every kernel function when disabled.
+ */
+static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
+				       bool link)
+{
+	tilegx_bundle_bits opcode_x0, opcode_x1;
+	long pcrel_by_instr = (addr - pc) >> TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES;
+
+	if (link) {
+		/* opcode: jal addr */
+		opcode_x1 =
+			create_Opcode_X1(JUMP_OPCODE_X1) |
+			create_JumpOpcodeExtension_X1(JAL_JUMP_OPCODE_X1) |
+			create_JumpOff_X1(pcrel_by_instr);
+	} else {
+		/* opcode: j addr */
+		opcode_x1 =
+			create_Opcode_X1(JUMP_OPCODE_X1) |
+			create_JumpOpcodeExtension_X1(J_JUMP_OPCODE_X1) |
+			create_JumpOff_X1(pcrel_by_instr);
+	}
+
+	if (addr == FTRACE_ADDR) {
+		/* opcode: or r10, lr, zero */
+		opcode_x0 =
+			create_Dest_X0(10) |
+			create_SrcA_X0(TREG_LR) |
+			create_SrcB_X0(TREG_ZERO) |
+			create_RRROpcodeExtension_X0(OR_RRR_0_OPCODE_X0) |
+			create_Opcode_X0(RRR_0_OPCODE_X0);
+	} else {
+		/* opcode: fnop */
+		opcode_x0 =
+			create_UnaryOpcodeExtension_X0(FNOP_UNARY_OPCODE_X0) |
+			create_RRROpcodeExtension_X0(UNARY_RRR_0_OPCODE_X0) |
+			create_Opcode_X0(RRR_0_OPCODE_X0);
+	}
+
+	return opcode_x1 | opcode_x0;
+}
+
+static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
+{
+	return NOP();
+}
+
+static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
+{
+	return ftrace_gen_branch(pc, addr, true);
+}
+
+static int ftrace_modify_code(unsigned long pc, unsigned long old,
+			      unsigned long new)
+{
+	unsigned long pc_wr;
+
+	/* Check if the address is in kernel text space and module space. */
+	if (!kernel_text_address(pc))
+		return -EINVAL;
+
+	/* Operate on writable kernel text mapping. */
+	pc_wr = pc - MEM_SV_START + PAGE_OFFSET;
+
+	if (probe_kernel_write((void *)pc_wr, &new, MCOUNT_INSN_SIZE))
+		return -EPERM;
+
+	smp_wmb();
+
+	if (!machine_stopped && num_online_cpus() > 1)
+		flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
+
+	return 0;
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+	unsigned long pc, old;
+	unsigned long new;
+	int ret;
+
+	pc = (unsigned long)&ftrace_call;
+	memcpy(&old, &ftrace_call, MCOUNT_INSN_SIZE);
+	new = ftrace_call_replace(pc, (unsigned long)func);
+
+	ret = ftrace_modify_code(pc, old, new);
+
+	return ret;
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned long new, old;
+	unsigned long ip = rec->ip;
+
+	old = ftrace_nop_replace(rec);
+	new = ftrace_call_replace(ip, addr);
+
+	return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_make_nop(struct module *mod,
+		    struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned long ip = rec->ip;
+	unsigned long old;
+	unsigned long new;
+	int ret;
+
+	old = ftrace_call_replace(ip, addr);
+	new = ftrace_nop_replace(rec);
+	ret = ftrace_modify_code(ip, old, new);
+
+	return ret;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+	*(unsigned long *)data = 0;
+
+	return 0;
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+			   unsigned long frame_pointer)
+{
+	unsigned long return_hooker = (unsigned long) &return_to_handler;
+	struct ftrace_graph_ent trace;
+	unsigned long old;
+	int err;
+
+	if (unlikely(atomic_read(&current->tracing_graph_pause)))
+		return;
+
+	old = *parent;
+	*parent = return_hooker;
+
+	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
+				       frame_pointer);
+	if (err == -EBUSY) {
+		*parent = old;
+		return;
+	}
+
+	trace.func = self_addr;
+
+	/* Only trace if the calling function expects to */
+	if (!ftrace_graph_entry(&trace)) {
+		current->curr_ret_stack--;
+		*parent = old;
+	}
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern unsigned long ftrace_graph_call;
+
+static int __ftrace_modify_caller(unsigned long *callsite,
+				  void (*func) (void), bool enable)
+{
+	unsigned long caller_fn = (unsigned long) func;
+	unsigned long pc = (unsigned long) callsite;
+	unsigned long branch = ftrace_gen_branch(pc, caller_fn, false);
+	unsigned long nop = NOP();
+	unsigned long old = enable ? nop : branch;
+	unsigned long new = enable ? branch : nop;
+
+	return ftrace_modify_code(pc, old, new);
+}
+
+static int ftrace_modify_graph_caller(bool enable)
+{
+	int ret;
+
+	ret = __ftrace_modify_caller(&ftrace_graph_call,
+				     ftrace_graph_caller,
+				     enable);
+
+	return ret;
+}
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+	return ftrace_modify_graph_caller(true);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+	return ftrace_modify_graph_caller(false);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/arch/tile/kernel/mcount_64.S b/arch/tile/kernel/mcount_64.S
new file mode 100644
index 0000000..70d7bb0
--- /dev/null
+++ b/arch/tile/kernel/mcount_64.S
@@ -0,0 +1,224 @@
+/*
+ * 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.
+ *
+ * TILE-Gx specific __mcount support
+ */
+
+#include <linux/linkage.h>
+#include <asm/ftrace.h>
+
+#define REGSIZE 8
+
+	.text
+	.global __mcount
+
+	.macro	MCOUNT_SAVE_REGS
+	addli	sp, sp, -REGSIZE
+	{
+	 st     sp, lr
+	 addli	r29, sp, - (12 * REGSIZE)
+	}
+	{
+	 addli	sp, sp, - (13 * REGSIZE)
+	 st     r29, sp
+	}
+	addli	r29, r29, REGSIZE
+	{ st	r29, r0; addli	r29, r29, REGSIZE }
+	{ st	r29, r1; addli	r29, r29, REGSIZE }
+	{ st	r29, r2; addli	r29, r29, REGSIZE }
+	{ st	r29, r3; addli	r29, r29, REGSIZE }
+	{ st	r29, r4; addli	r29, r29, REGSIZE }
+	{ st	r29, r5; addli	r29, r29, REGSIZE }
+	{ st	r29, r6; addli	r29, r29, REGSIZE }
+	{ st	r29, r7; addli	r29, r29, REGSIZE }
+	{ st	r29, r8; addli	r29, r29, REGSIZE }
+	{ st	r29, r9; addli	r29, r29, REGSIZE }
+	{ st	r29, r10; addli	r29, r29, REGSIZE }
+	.endm
+
+	.macro	MCOUNT_RESTORE_REGS
+	addli	r29, sp, (2 * REGSIZE)
+	{ ld	r0, r29; addli	r29, r29, REGSIZE }
+	{ ld	r1, r29; addli	r29, r29, REGSIZE }
+	{ ld	r2, r29; addli	r29, r29, REGSIZE }
+	{ ld	r3, r29; addli	r29, r29, REGSIZE }
+	{ ld	r4, r29; addli	r29, r29, REGSIZE }
+	{ ld	r5, r29; addli	r29, r29, REGSIZE }
+	{ ld	r6, r29; addli	r29, r29, REGSIZE }
+	{ ld	r7, r29; addli	r29, r29, REGSIZE }
+	{ ld	r8, r29; addli	r29, r29, REGSIZE }
+	{ ld	r9, r29; addli	r29, r29, REGSIZE }
+	{ ld	r10, r29; addli	lr, sp, (13 * REGSIZE) }
+	{ ld	lr, lr;  addli	sp, sp, (14 * REGSIZE) }
+	.endm
+
+	.macro  RETURN_BACK
+	{ move	r12, lr; move	lr, r10 }
+	jrp	r12
+	.endm
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+	.align	64
+STD_ENTRY(__mcount)
+__mcount:
+	j	ftrace_stub
+STD_ENDPROC(__mcount)
+
+	.align	64
+STD_ENTRY(ftrace_caller)
+	moveli	r11, hw2_last(function_trace_stop)
+	{ shl16insli	r11, r11, hw1(function_trace_stop); move r12, lr }
+	{ shl16insli	r11, r11, hw0(function_trace_stop); move lr, r10 }
+	ld	r11, r11
+	beqz	r11, 1f
+	jrp	r12
+
+1:
+	{ move	r10, lr; move	lr, r12 }
+	MCOUNT_SAVE_REGS
+
+	/* arg1: self return address */
+	/* arg2: parent's return address */
+	{ move	r0, lr; move	r1, r10 }
+
+	.global	ftrace_call
+ftrace_call:
+	/*
+	 * a placeholder for the call to a real tracing function, i.e.
+	 * ftrace_trace_function()
+	 */
+	nop
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	.global	ftrace_graph_call
+ftrace_graph_call:
+	/*
+	 * a placeholder for the call to a real tracing function, i.e.
+	 * ftrace_graph_caller()
+	 */
+	nop
+#endif
+	MCOUNT_RESTORE_REGS
+	.global	ftrace_stub
+ftrace_stub:
+	RETURN_BACK
+STD_ENDPROC(ftrace_caller)
+
+#else /* ! CONFIG_DYNAMIC_FTRACE */
+
+	.align	64
+STD_ENTRY(__mcount)
+	moveli	r11, hw2_last(function_trace_stop)
+	{ shl16insli	r11, r11, hw1(function_trace_stop); move r12, lr }
+	{ shl16insli	r11, r11, hw0(function_trace_stop); move lr, r10 }
+	ld	r11, r11
+	beqz	r11, 1f
+	jrp	r12
+
+1:
+	{ move	r10, lr; move	lr, r12 }
+	{
+	 moveli	r11, hw2_last(ftrace_trace_function)
+	 moveli	r13, hw2_last(ftrace_stub)
+	}
+	{
+	 shl16insli	r11, r11, hw1(ftrace_trace_function)
+	 shl16insli	r13, r13, hw1(ftrace_stub)
+	}
+	{
+	 shl16insli	r11, r11, hw0(ftrace_trace_function)
+	 shl16insli	r13, r13, hw0(ftrace_stub)
+	}
+
+	ld	r11, r11
+	sub	r14, r13, r11
+	bnez	r14, static_trace
+
+#ifdef	CONFIG_FUNCTION_GRAPH_TRACER
+	moveli	r15, hw2_last(ftrace_graph_return)
+	shl16insli	r15, r15, hw1(ftrace_graph_return)
+	shl16insli	r15, r15, hw0(ftrace_graph_return)
+	ld	r15, r15
+	sub	r15, r15, r13
+	bnez	r15, ftrace_graph_caller
+
+	{
+	 moveli	r16, hw2_last(ftrace_graph_entry)
+	 moveli	r17, hw2_last(ftrace_graph_entry_stub)
+	}
+	{
+	 shl16insli	r16, r16, hw1(ftrace_graph_entry)
+	 shl16insli	r17, r17, hw1(ftrace_graph_entry_stub)
+	}
+	{
+	 shl16insli	r16, r16, hw0(ftrace_graph_entry)
+	 shl16insli	r17, r17, hw0(ftrace_graph_entry_stub)
+	}
+	ld	r16, r16
+	sub	r17, r16, r17
+	bnez	r17, ftrace_graph_caller
+
+#endif
+	RETURN_BACK
+
+static_trace:
+	MCOUNT_SAVE_REGS
+
+	/* arg1: self return address */
+	/* arg2: parent's return address */
+	{ move	r0, lr; move	r1, r10 }
+
+	/* call ftrace_trace_function() */
+	jalr	r11
+
+	MCOUNT_RESTORE_REGS
+
+	.global ftrace_stub
+ftrace_stub:
+	RETURN_BACK
+STD_ENDPROC(__mcount)
+
+#endif	/* ! CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+
+STD_ENTRY(ftrace_graph_caller)
+ftrace_graph_caller:
+#ifndef CONFIG_DYNAMIC_FTRACE
+	MCOUNT_SAVE_REGS
+#endif
+
+	/* arg1: Get the location of the parent's return address */
+	addi	r0, sp, 12 * REGSIZE
+	/* arg2: Get self return address */
+	move	r1, lr
+
+	jal prepare_ftrace_return
+
+	MCOUNT_RESTORE_REGS
+	RETURN_BACK
+STD_ENDPROC(ftrace_graph_caller)
+
+	.global return_to_handler
+return_to_handler:
+	MCOUNT_SAVE_REGS
+
+	jal	ftrace_return_to_handler
+	/* restore the real parent address */
+	move	r11, r0
+
+	MCOUNT_RESTORE_REGS
+	jr	r11
+
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/arch/tile/kernel/vmlinux.lds.S b/arch/tile/kernel/vmlinux.lds.S
index 0f0edaf..673d00a 100644
--- a/arch/tile/kernel/vmlinux.lds.S
+++ b/arch/tile/kernel/vmlinux.lds.S
@@ -43,6 +43,7 @@ SECTIONS
     HEAD_TEXT
     SCHED_TEXT
     LOCK_TEXT
+    IRQENTRY_TEXT
     __fix_text_end = .;   /* tile-cpack won't rearrange before this */
     TEXT_TEXT
     *(.text.*)
diff --git a/arch/tile/lib/exports.c b/arch/tile/lib/exports.c
index 359b1bc..82733c8 100644
--- a/arch/tile/lib/exports.c
+++ b/arch/tile/lib/exports.c
@@ -33,6 +33,12 @@ EXPORT_SYMBOL(dump_stack);
 /* arch/tile/kernel/head.S */
 EXPORT_SYMBOL(empty_zero_page);
 
+#ifdef CONFIG_FUNCTION_TRACER
+/* arch/tile/kernel/mcount_64.S */
+#include <asm/ftrace.h>
+EXPORT_SYMBOL(__mcount);
+#endif /* CONFIG_FUNCTION_TRACER */
+
 /* arch/tile/lib/, various memcpy files */
 EXPORT_SYMBOL(memcpy);
 EXPORT_SYMBOL(__copy_to_user_inatomic);
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 858966a..a674fd5 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -364,6 +364,10 @@ if ($arch eq "x86_64") {
 } elsif ($arch eq "blackfin") {
     $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s__mcount\$";
     $mcount_adjust = -4;
+} elsif ($arch eq "tilegx") {
+    $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s__mcount\$";
+    $type = ".quad";
+    $alignment = 8;
 } else {
     die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
 }
-- 
1.8.3.1

[PATCH] tile: support kprobes on tilegx

[Tony Lu]

This change includes support for Kprobes, Jprobes and Return Probes.

Signed-off-by: Tony Lu <zlu@tilera.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
---
I assume it makes sense for this to be pushed via the tile tree;
it's currently queued in tile-next.

 arch/tile/Kconfig                            |   2 +
 arch/tile/include/asm/Kbuild                 |   1 -
 arch/tile/include/asm/kdebug.h               |  28 ++
 arch/tile/include/asm/kprobes.h              |  79 +++++
 arch/tile/include/asm/ptrace.h               |   1 +
 arch/tile/include/uapi/arch/opcode_tilegx.h  |   1 +
 arch/tile/include/uapi/arch/opcode_tilepro.h |   1 +
 arch/tile/kernel/Makefile                    |   1 +
 arch/tile/kernel/kprobes.c                   | 476 +++++++++++++++++++++++++++
 arch/tile/kernel/smp.c                       |  14 +-
 arch/tile/kernel/traps.c                     |  42 +++
 arch/tile/kernel/vmlinux.lds.S               |   1 +
 arch/tile/mm/fault.c                         |  12 +
 samples/kprobes/kprobe_example.c             |   9 +
 14 files changed, 664 insertions(+), 4 deletions(-)
 create mode 100644 arch/tile/include/asm/kdebug.h
 create mode 100644 arch/tile/include/asm/kprobes.h
 create mode 100644 arch/tile/kernel/kprobes.c

diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
index e1600be..ecff467 100644
--- a/arch/tile/Kconfig
+++ b/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
diff --git a/arch/tile/include/asm/Kbuild b/arch/tile/include/asm/Kbuild
index b17b9b8..4c0b3c2 100644
--- a/arch/tile/include/asm/Kbuild
+++ b/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
diff --git a/arch/tile/include/asm/kdebug.h b/arch/tile/include/asm/kdebug.h
new file mode 100644
index 0000000..5bbbfa9
--- /dev/null
+++ b/arch/tile/include/asm/kdebug.h
@@ -0,0 +1,28 @@
+/*
+ * 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 */
diff --git a/arch/tile/include/asm/kprobes.h b/arch/tile/include/asm/kprobes.h
new file mode 100644
index 0000000..d8f9a83
--- /dev/null
+++ b/arch/tile/include/asm/kprobes.h
@@ -0,0 +1,79 @@
+/*
+ * 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 */
diff --git a/arch/tile/include/asm/ptrace.h b/arch/tile/include/asm/ptrace.h
index 73b681b..0d25c21 100644
--- a/arch/tile/include/asm/ptrace.h
+++ b/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)
diff --git a/arch/tile/include/uapi/arch/opcode_tilegx.h b/arch/tile/include/uapi/arch/opcode_tilegx.h
index c14d02c..d76ff2d 100644
--- a/arch/tile/include/uapi/arch/opcode_tilegx.h
+++ b/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
diff --git a/arch/tile/include/uapi/arch/opcode_tilepro.h b/arch/tile/include/uapi/arch/opcode_tilepro.h
index 71b763b..4451cff 100644
--- a/arch/tile/include/uapi/arch/opcode_tilepro.h
+++ b/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
diff --git a/arch/tile/kernel/Makefile b/arch/tile/kernel/Makefile
index 2e6eaa1..b7c8b5e 100644
--- a/arch/tile/kernel/Makefile
+++ b/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/
diff --git a/arch/tile/kernel/kprobes.c b/arch/tile/kernel/kprobes.c
new file mode 100644
index 0000000..926ebad
--- /dev/null
+++ b/arch/tile/kernel/kprobes.c
@@ -0,0 +1,476 @@
+/*
+ * arch/tile/kernel/kprobes.c
+ * Kprobes on TILE-Gx
+ *
+ * Some portions copied from the MIPS version.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ * Copyright 2006 Sony Corp.
+ * Copyright 2010 Cavium Networks
+ *
+ * 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.
+ */
+
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+
+#include <arch/opcode.h>
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+tile_bundle_bits breakpoint_insn = TILEGX_BPT_BUNDLE;
+tile_bundle_bits breakpoint2_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP;
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+	unsigned long addr = (unsigned long)p->addr;
+
+	if (addr & (sizeof(kprobe_opcode_t) - 1))
+		return -EINVAL;
+
+	/* insn: must be on special executable page on tile. */
+	p->ainsn.insn = get_insn_slot();
+	if (!p->ainsn.insn)
+		return -ENOMEM;
+
+	/*
+	 * In the kprobe->ainsn.insn[] array we store the original
+	 * instruction at index zero and a break trap instruction at
+	 * index one.
+	 */
+	memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
+	p->ainsn.insn[1] = breakpoint2_insn;
+	p->opcode = *p->addr;
+
+	return 0;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+	unsigned long addr_wr;
+
+	/* Operate on writable kernel text mapping. */
+	addr_wr = (unsigned long)p->addr - MEM_SV_START + PAGE_OFFSET;
+
+	if (probe_kernel_write((void *)addr_wr, &breakpoint_insn,
+		sizeof(breakpoint_insn)))
+		pr_err("%s: failed to enable kprobe\n", __func__);
+
+	smp_wmb();
+	flush_insn_slot(p);
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *kp)
+{
+	unsigned long addr_wr;
+
+	/* Operate on writable kernel text mapping. */
+	addr_wr = (unsigned long)kp->addr - MEM_SV_START + PAGE_OFFSET;
+
+	if (probe_kernel_write((void *)addr_wr, &kp->opcode,
+		sizeof(kp->opcode)))
+		pr_err("%s: failed to enable kprobe\n", __func__);
+
+	smp_wmb();
+	flush_insn_slot(kp);
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+	if (p->ainsn.insn) {
+		free_insn_slot(p->ainsn.insn, 0);
+		p->ainsn.insn = NULL;
+	}
+}
+
+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+	kcb->prev_kprobe.kp = kprobe_running();
+	kcb->prev_kprobe.status = kcb->kprobe_status;
+	kcb->prev_kprobe.saved_pc = kcb->kprobe_saved_pc;
+}
+
+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+	__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+	kcb->kprobe_status = kcb->prev_kprobe.status;
+	kcb->kprobe_saved_pc = kcb->prev_kprobe.saved_pc;
+}
+
+static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+			struct kprobe_ctlblk *kcb)
+{
+	__get_cpu_var(current_kprobe) = p;
+	kcb->kprobe_saved_pc = regs->pc;
+}
+
+static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+	/* Single step inline if the instruction is a break. */
+	if (p->opcode == breakpoint_insn ||
+	    p->opcode == breakpoint2_insn)
+		regs->pc = (unsigned long)p->addr;
+	else
+		regs->pc = (unsigned long)&p->ainsn.insn[0];
+}
+
+static int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+	struct kprobe *p;
+	int ret = 0;
+	kprobe_opcode_t *addr;
+	struct kprobe_ctlblk *kcb;
+
+	addr = (kprobe_opcode_t *)regs->pc;
+
+	/*
+	 * We don't want to be preempted for the entire
+	 * duration of kprobe processing.
+	 */
+	preempt_disable();
+	kcb = get_kprobe_ctlblk();
+
+	/* Check we're not actually recursing. */
+	if (kprobe_running()) {
+		p = get_kprobe(addr);
+		if (p) {
+			if (kcb->kprobe_status == KPROBE_HIT_SS &&
+			    p->ainsn.insn[0] == breakpoint_insn) {
+				goto no_kprobe;
+			}
+			/*
+			 * We have reentered the kprobe_handler(), since
+			 * another probe was hit while within the handler.
+			 * We here save the original kprobes variables and
+			 * just single step on the instruction of the new probe
+			 * without calling any user handlers.
+			 */
+			save_previous_kprobe(kcb);
+			set_current_kprobe(p, regs, kcb);
+			kprobes_inc_nmissed_count(p);
+			prepare_singlestep(p, regs);
+			kcb->kprobe_status = KPROBE_REENTER;
+			return 1;
+		} else {
+			if (*addr != breakpoint_insn) {
+				/*
+				 * The breakpoint instruction was removed by
+				 * another cpu right after we hit, no further
+				 * handling of this interrupt is appropriate.
+				 */
+				ret = 1;
+				goto no_kprobe;
+			}
+			p = __get_cpu_var(current_kprobe);
+			if (p->break_handler && p->break_handler(p, regs))
+				goto ss_probe;
+		}
+		goto no_kprobe;
+	}
+
+	p = get_kprobe(addr);
+	if (!p) {
+		if (*addr != breakpoint_insn) {
+			/*
+			 * The breakpoint instruction was removed right
+			 * after we hit it.  Another cpu has removed
+			 * either a probepoint or a debugger breakpoint
+			 * at this address.  In either case, no further
+			 * handling of this interrupt is appropriate.
+			 */
+			ret = 1;
+		}
+		/* Not one of ours: let kernel handle it. */
+		goto no_kprobe;
+	}
+
+	set_current_kprobe(p, regs, kcb);
+	kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+
+	if (p->pre_handler && p->pre_handler(p, regs)) {
+		/* Handler has already set things up, so skip ss setup. */
+		return 1;
+	}
+
+ss_probe:
+	prepare_singlestep(p, regs);
+	kcb->kprobe_status = KPROBE_HIT_SS;
+	return 1;
+
+no_kprobe:
+	preempt_enable_no_resched();
+	return ret;
+}
+
+/*
+ * Called after single-stepping.  p->addr is the address of the
+ * instruction whose first byte has been replaced by the "break 0"
+ * temporarily put back the original opcode to single-step, we
+ * single-stepped a copy of the instruction.  The address of this
+ * copy is p->ainsn.insn.
+ *
+ * This function prepares to return from the post-single-step
+ * breakpoint trap.
+ */
+static void __kprobes resume_execution(struct kprobe *p,
+				       struct pt_regs *regs,
+				       struct kprobe_ctlblk *kcb)
+{
+	unsigned long orig_pc = kcb->kprobe_saved_pc;
+	regs->pc = orig_pc + 8;
+}
+
+static inline int post_kprobe_handler(struct pt_regs *regs)
+{
+	struct kprobe *cur = kprobe_running();
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	if (!cur)
+		return 0;
+
+	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+		kcb->kprobe_status = KPROBE_HIT_SSDONE;
+		cur->post_handler(cur, regs, 0);
+	}
+
+	resume_execution(cur, regs, kcb);
+
+	/* Restore back the original saved kprobes variables and continue. */
+	if (kcb->kprobe_status == KPROBE_REENTER) {
+		restore_previous_kprobe(kcb);
+		goto out;
+	}
+	reset_current_kprobe();
+out:
+	preempt_enable_no_resched();
+
+	return 1;
+}
+
+static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+	struct kprobe *cur = kprobe_running();
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
+		return 1;
+
+	if (kcb->kprobe_status & KPROBE_HIT_SS) {
+		/*
+		 * We are here because the instruction being single
+		 * stepped caused a page fault. We reset the current
+		 * kprobe and the ip points back to the probe address
+		 * and allow the page fault handler to continue as a
+		 * normal page fault.
+		 */
+		resume_execution(cur, regs, kcb);
+		reset_current_kprobe();
+		preempt_enable_no_resched();
+	}
+	return 0;
+}
+
+/*
+ * Wrapper routine for handling exceptions.
+ */
+int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+				       unsigned long val, void *data)
+{
+	struct die_args *args = (struct die_args *)data;
+	int ret = NOTIFY_DONE;
+
+	switch (val) {
+	case DIE_BREAK:
+		if (kprobe_handler(args->regs))
+			ret = NOTIFY_STOP;
+		break;
+	case DIE_SSTEPBP:
+		if (post_kprobe_handler(args->regs))
+			ret = NOTIFY_STOP;
+		break;
+	case DIE_PAGE_FAULT:
+		/* kprobe_running() needs smp_processor_id(). */
+		preempt_disable();
+
+		if (kprobe_running()
+		    && kprobe_fault_handler(args->regs, args->trapnr))
+			ret = NOTIFY_STOP;
+		preempt_enable();
+		break;
+	default:
+		break;
+	}
+	return ret;
+}
+
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct jprobe *jp = container_of(p, struct jprobe, kp);
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	kcb->jprobe_saved_regs = *regs;
+	kcb->jprobe_saved_sp = regs->sp;
+
+	memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
+	       MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
+
+	regs->pc = (unsigned long)(jp->entry);
+
+	return 1;
+}
+
+/* Defined in the inline asm below. */
+void jprobe_return_end(void);
+
+void __kprobes jprobe_return(void)
+{
+	asm volatile(
+		"bpt\n\t"
+		".globl jprobe_return_end\n"
+		"jprobe_return_end:\n");
+}
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	if (regs->pc >= (unsigned long)jprobe_return &&
+	    regs->pc <= (unsigned long)jprobe_return_end) {
+		*regs = kcb->jprobe_saved_regs;
+		memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
+		       MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
+		preempt_enable_no_resched();
+
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * Function return probe trampoline:
+ * - init_kprobes() establishes a probepoint here
+ * - When the probed function returns, this probe causes the
+ *   handlers to fire
+ */
+static void __used kretprobe_trampoline_holder(void)
+{
+	asm volatile(
+		"nop\n\t"
+		".global kretprobe_trampoline\n"
+		"kretprobe_trampoline:\n\t"
+		"nop\n\t"
+		: : : "memory");
+}
+
+void kretprobe_trampoline(void);
+
+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+				      struct pt_regs *regs)
+{
+	ri->ret_addr = (kprobe_opcode_t *) regs->lr;
+
+	/* Replace the return addr with trampoline addr */
+	regs->lr = (unsigned long)kretprobe_trampoline;
+}
+
+/*
+ * Called when the probe at kretprobe trampoline is hit.
+ */
+static int __kprobes trampoline_probe_handler(struct kprobe *p,
+						struct pt_regs *regs)
+{
+	struct kretprobe_instance *ri = NULL;
+	struct hlist_head *head, empty_rp;
+	struct hlist_node *tmp;
+	unsigned long flags, orig_ret_address = 0;
+	unsigned long trampoline_address = (unsigned long)kretprobe_trampoline;
+
+	INIT_HLIST_HEAD(&empty_rp);
+	kretprobe_hash_lock(current, &head, &flags);
+
+	/*
+	 * It is possible to have multiple instances associated with a given
+	 * task either because multiple functions in the call path have
+	 * a return probe installed on them, and/or more than one return
+	 * return probe was registered for a target function.
+	 *
+	 * We can handle this because:
+	 *     - instances are always inserted at the head of the list
+	 *     - when multiple return probes are registered for the same
+	 *       function, the first instance's ret_addr will point to the
+	 *       real return address, and all the rest will point to
+	 *       kretprobe_trampoline
+	 */
+	hlist_for_each_entry_safe(ri, tmp, head, hlist) {
+		if (ri->task != current)
+			/* another task is sharing our hash bucket */
+			continue;
+
+		if (ri->rp && ri->rp->handler)
+			ri->rp->handler(ri, regs);
+
+		orig_ret_address = (unsigned long)ri->ret_addr;
+		recycle_rp_inst(ri, &empty_rp);
+
+		if (orig_ret_address != trampoline_address) {
+			/*
+			 * This is the real return address. Any other
+			 * instances associated with this task are for
+			 * other calls deeper on the call stack
+			 */
+			break;
+		}
+	}
+
+	kretprobe_assert(ri, orig_ret_address, trampoline_address);
+	instruction_pointer(regs) = orig_ret_address;
+
+	reset_current_kprobe();
+	kretprobe_hash_unlock(current, &flags);
+	preempt_enable_no_resched();
+
+	hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
+		hlist_del(&ri->hlist);
+		kfree(ri);
+	}
+	/*
+	 * By returning a non-zero value, we are telling
+	 * kprobe_handler() that we don't want the post_handler
+	 * to run (and have re-enabled preemption)
+	 */
+	return 1;
+}
+
+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+{
+	if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline)
+		return 1;
+
+	return 0;
+}
+
+static struct kprobe trampoline_p = {
+	.addr = (kprobe_opcode_t *)kretprobe_trampoline,
+	.pre_handler = trampoline_probe_handler
+};
+
+int __init arch_init_kprobes(void)
+{
+	register_kprobe(&trampoline_p);
+	return 0;
+}
diff --git a/arch/tile/kernel/smp.c b/arch/tile/kernel/smp.c
index 6cc520d..0ae1c59 100644
--- a/arch/tile/kernel/smp.c
+++ b/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 };
-	preempt_disable();
-	on_each_cpu(ipi_flush_icache_range, &flush, 1);
-	preempt_enable();
+
+	/* 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();
+	}
 }
 
 
diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
index a1bbc5de..f110785 100644
--- a/arch/tile/kernel/traps.c
+++ b/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)
 {
@@ -233,6 +271,10 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
 	if (!user_mode(regs)) {
 		const char *name;
 		char buf[100];
+		if (fault_num == INT_ILL && do_bpt(regs)) {
+			/* breakpoint */
+			return;
+		}
 		if (fixup_exception(regs))  /* ILL_TRANS or UNALIGN_DATA */
 			return;
 		if (fault_num >= 0 &&
diff --git a/arch/tile/kernel/vmlinux.lds.S b/arch/tile/kernel/vmlinux.lds.S
index 673d00a..aab9955 100644
--- a/arch/tile/kernel/vmlinux.lds.S
+++ b/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
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index 502664a..64eec3f 100644
--- a/arch/tile/mm/fault.c
+++ b/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
diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
index ebf5e0c..366db1a 100644
--- a/samples/kprobes/kprobe_example.c
+++ b/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
 }
 
 /*
-- 
1.8.3.1

Re: [PATCH] tile: support kprobes on tilegx

[Masami Hiramatsu]

Hello Tony,

(2013/08/10 4:08), Tony Lu wrote:
> This change includes support for Kprobes, Jprobes and Return Probes.

Thank you for the effort, this looks good for the first step.

However, it seems this only supports instructions which doesn't touch
the execution path. I don't know tile ISA, but it should have jump/branch/
call/return etc. Those should be fixed after singlestep out-of-line in
resume_execution(). Or, kprobes should reject to probe on such instructions
by arch_prepare_kprobe().

> +int __kprobes arch_prepare_kprobe(struct kprobe *p)
> +{
> +	unsigned long addr = (unsigned long)p->addr;
> +
> +	if (addr & (sizeof(kprobe_opcode_t) - 1))
> +		return -EINVAL;
> +
> +	/* insn: must be on special executable page on tile. */
> +	p->ainsn.insn = get_insn_slot();
> +	if (!p->ainsn.insn)
> +		return -ENOMEM;
> +
> +	/*
> +	 * In the kprobe->ainsn.insn[] array we store the original
> +	 * instruction at index zero and a break trap instruction at
> +	 * index one.
> +	 */
> +	memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
> +	p->ainsn.insn[1] = breakpoint2_insn;
> +	p->opcode = *p->addr;
> +
> +	return 0;
> +}
[...]
> +/*
> + * Called after single-stepping.  p->addr is the address of the
> + * instruction whose first byte has been replaced by the "break 0"
> + * temporarily put back the original opcode to single-step, we
> + * single-stepped a copy of the instruction.  The address of this
> + * copy is p->ainsn.insn.
> + *
> + * This function prepares to return from the post-single-step
> + * breakpoint trap.
> + */
> +static void __kprobes resume_execution(struct kprobe *p,
> +				       struct pt_regs *regs,
> +				       struct kprobe_ctlblk *kcb)
> +{
> +	unsigned long orig_pc = kcb->kprobe_saved_pc;
> +	regs->pc = orig_pc + 8;
> +}
> +

I recommend you to fix that, at least filter out non-supported instructions
by arch_prepare_kprobe(), because no other users don't know which
instruction they can probe. :)

Thank you again!

-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com

[PATCH v2] tile: support kprobes on tilegx

[Tony Lu]

This change includes support for Kprobes, Jprobes and Return Probes.

Signed-off-by: Tony Lu <zlu@tilera.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
---
v2: implement Masami Hiramatsu's suggestion to add an insn_has_control()
check to disallow placing probes on instructions that modify control flow.
We can improve this in a later change if it seems useful.

 arch/tile/Kconfig                            |   2 +
 arch/tile/include/asm/Kbuild                 |   1 -
 arch/tile/include/asm/kdebug.h               |  28 ++
 arch/tile/include/asm/kprobes.h              |  79 ++++
 arch/tile/include/asm/ptrace.h               |   1 +
 arch/tile/include/uapi/arch/opcode_tilegx.h  |   1 +
 arch/tile/include/uapi/arch/opcode_tilepro.h |   1 +
 arch/tile/kernel/Makefile                    |   1 +
 arch/tile/kernel/kprobes.c                   | 528 +++++++++++++++++++++++++++
 arch/tile/kernel/smp.c                       |  14 +-
 arch/tile/kernel/traps.c                     |  42 +++
 arch/tile/kernel/vmlinux.lds.S               |   1 +
 arch/tile/mm/fault.c                         |  12 +
 samples/kprobes/kprobe_example.c             |   9 +
 14 files changed, 716 insertions(+), 4 deletions(-)
 create mode 100644 arch/tile/include/asm/kdebug.h
 create mode 100644 arch/tile/include/asm/kprobes.h
 create mode 100644 arch/tile/kernel/kprobes.c

diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
index e1600be..ecff467 100644
--- a/arch/tile/Kconfig
+++ b/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
diff --git a/arch/tile/include/asm/Kbuild b/arch/tile/include/asm/Kbuild
index b17b9b8..4c0b3c2 100644
--- a/arch/tile/include/asm/Kbuild
+++ b/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
diff --git a/arch/tile/include/asm/kdebug.h b/arch/tile/include/asm/kdebug.h
new file mode 100644
index 0000000..5bbbfa9
--- /dev/null
+++ b/arch/tile/include/asm/kdebug.h
@@ -0,0 +1,28 @@
+/*
+ * 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 */
diff --git a/arch/tile/include/asm/kprobes.h b/arch/tile/include/asm/kprobes.h
new file mode 100644
index 0000000..d8f9a83
--- /dev/null
+++ b/arch/tile/include/asm/kprobes.h
@@ -0,0 +1,79 @@
+/*
+ * 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 */
diff --git a/arch/tile/include/asm/ptrace.h b/arch/tile/include/asm/ptrace.h
index 73b681b..0d25c21 100644
--- a/arch/tile/include/asm/ptrace.h
+++ b/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)
diff --git a/arch/tile/include/uapi/arch/opcode_tilegx.h b/arch/tile/include/uapi/arch/opcode_tilegx.h
index c14d02c..d76ff2d 100644
--- a/arch/tile/include/uapi/arch/opcode_tilegx.h
+++ b/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
diff --git a/arch/tile/include/uapi/arch/opcode_tilepro.h b/arch/tile/include/uapi/arch/opcode_tilepro.h
index 71b763b..4451cff 100644
--- a/arch/tile/include/uapi/arch/opcode_tilepro.h
+++ b/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
diff --git a/arch/tile/kernel/Makefile b/arch/tile/kernel/Makefile
index 2e6eaa1..b7c8b5e 100644
--- a/arch/tile/kernel/Makefile
+++ b/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/
diff --git a/arch/tile/kernel/kprobes.c b/arch/tile/kernel/kprobes.c
new file mode 100644
index 0000000..1129f52
--- /dev/null
+++ b/arch/tile/kernel/kprobes.c
@@ -0,0 +1,528 @@
+/*
+ * arch/tile/kernel/kprobes.c
+ * Kprobes on TILE-Gx
+ *
+ * Some portions copied from the MIPS version.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ * Copyright 2006 Sony Corp.
+ * Copyright 2010 Cavium Networks
+ *
+ * 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.
+ */
+
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+
+#include <arch/opcode.h>
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+tile_bundle_bits breakpoint_insn = TILEGX_BPT_BUNDLE;
+tile_bundle_bits breakpoint2_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP;
+
+/*
+ * Check whether instruction is branch or jump, or if executing it
+ * has different results depending on where it is executed (e.g. lnk).
+ */
+static int __kprobes insn_has_control(kprobe_opcode_t insn)
+{
+	if (get_Mode(insn) != 0) {   /* Y-format bundle */
+		if (get_Opcode_Y1(insn) != RRR_1_OPCODE_Y1 ||
+		    get_RRROpcodeExtension_Y1(insn) != UNARY_RRR_1_OPCODE_Y1)
+			return 0;
+
+		switch (get_UnaryOpcodeExtension_Y1(insn)) {
+		case JALRP_UNARY_OPCODE_Y1:
+		case JALR_UNARY_OPCODE_Y1:
+		case JRP_UNARY_OPCODE_Y1:
+		case JR_UNARY_OPCODE_Y1:
+		case LNK_UNARY_OPCODE_Y1:
+			return 1;
+		default:
+			return 0;
+		}
+	}
+
+	switch (get_Opcode_X1(insn)) {
+	case BRANCH_OPCODE_X1:	/* branch instructions */
+	case JUMP_OPCODE_X1:	/* jump instructions: j and jal */
+		return 1;
+
+	case RRR_0_OPCODE_X1:   /* other jump instructions */
+		if (get_RRROpcodeExtension_X1(insn) != UNARY_RRR_0_OPCODE_X1)
+			return 0;
+		switch (get_UnaryOpcodeExtension_X1(insn)) {
+		case JALRP_UNARY_OPCODE_X1:
+		case JALR_UNARY_OPCODE_X1:
+		case JRP_UNARY_OPCODE_X1:
+		case JR_UNARY_OPCODE_X1:
+		case LNK_UNARY_OPCODE_X1:
+			return 1;
+		default:
+			return 0;
+		}
+	default:
+		return 0;
+	}
+}
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+	unsigned long addr = (unsigned long)p->addr;
+
+	if (addr & (sizeof(kprobe_opcode_t) - 1))
+		return -EINVAL;
+
+	if (insn_has_control(*p->addr)) {
+		pr_notice("Kprobes for control instructions are not "
+			  "supported\n");
+		return -EINVAL;
+	}
+
+	/* insn: must be on special executable page on tile. */
+	p->ainsn.insn = get_insn_slot();
+	if (!p->ainsn.insn)
+		return -ENOMEM;
+
+	/*
+	 * In the kprobe->ainsn.insn[] array we store the original
+	 * instruction at index zero and a break trap instruction at
+	 * index one.
+	 */
+	memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
+	p->ainsn.insn[1] = breakpoint2_insn;
+	p->opcode = *p->addr;
+
+	return 0;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+	unsigned long addr_wr;
+
+	/* Operate on writable kernel text mapping. */
+	addr_wr = (unsigned long)p->addr - MEM_SV_START + PAGE_OFFSET;
+
+	if (probe_kernel_write((void *)addr_wr, &breakpoint_insn,
+		sizeof(breakpoint_insn)))
+		pr_err("%s: failed to enable kprobe\n", __func__);
+
+	smp_wmb();
+	flush_insn_slot(p);
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *kp)
+{
+	unsigned long addr_wr;
+
+	/* Operate on writable kernel text mapping. */
+	addr_wr = (unsigned long)kp->addr - MEM_SV_START + PAGE_OFFSET;
+
+	if (probe_kernel_write((void *)addr_wr, &kp->opcode,
+		sizeof(kp->opcode)))
+		pr_err("%s: failed to enable kprobe\n", __func__);
+
+	smp_wmb();
+	flush_insn_slot(kp);
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+	if (p->ainsn.insn) {
+		free_insn_slot(p->ainsn.insn, 0);
+		p->ainsn.insn = NULL;
+	}
+}
+
+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+	kcb->prev_kprobe.kp = kprobe_running();
+	kcb->prev_kprobe.status = kcb->kprobe_status;
+	kcb->prev_kprobe.saved_pc = kcb->kprobe_saved_pc;
+}
+
+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+	__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+	kcb->kprobe_status = kcb->prev_kprobe.status;
+	kcb->kprobe_saved_pc = kcb->prev_kprobe.saved_pc;
+}
+
+static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+			struct kprobe_ctlblk *kcb)
+{
+	__get_cpu_var(current_kprobe) = p;
+	kcb->kprobe_saved_pc = regs->pc;
+}
+
+static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+	/* Single step inline if the instruction is a break. */
+	if (p->opcode == breakpoint_insn ||
+	    p->opcode == breakpoint2_insn)
+		regs->pc = (unsigned long)p->addr;
+	else
+		regs->pc = (unsigned long)&p->ainsn.insn[0];
+}
+
+static int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+	struct kprobe *p;
+	int ret = 0;
+	kprobe_opcode_t *addr;
+	struct kprobe_ctlblk *kcb;
+
+	addr = (kprobe_opcode_t *)regs->pc;
+
+	/*
+	 * We don't want to be preempted for the entire
+	 * duration of kprobe processing.
+	 */
+	preempt_disable();
+	kcb = get_kprobe_ctlblk();
+
+	/* Check we're not actually recursing. */
+	if (kprobe_running()) {
+		p = get_kprobe(addr);
+		if (p) {
+			if (kcb->kprobe_status == KPROBE_HIT_SS &&
+			    p->ainsn.insn[0] == breakpoint_insn) {
+				goto no_kprobe;
+			}
+			/*
+			 * We have reentered the kprobe_handler(), since
+			 * another probe was hit while within the handler.
+			 * We here save the original kprobes variables and
+			 * just single step on the instruction of the new probe
+			 * without calling any user handlers.
+			 */
+			save_previous_kprobe(kcb);
+			set_current_kprobe(p, regs, kcb);
+			kprobes_inc_nmissed_count(p);
+			prepare_singlestep(p, regs);
+			kcb->kprobe_status = KPROBE_REENTER;
+			return 1;
+		} else {
+			if (*addr != breakpoint_insn) {
+				/*
+				 * The breakpoint instruction was removed by
+				 * another cpu right after we hit, no further
+				 * handling of this interrupt is appropriate.
+				 */
+				ret = 1;
+				goto no_kprobe;
+			}
+			p = __get_cpu_var(current_kprobe);
+			if (p->break_handler && p->break_handler(p, regs))
+				goto ss_probe;
+		}
+		goto no_kprobe;
+	}
+
+	p = get_kprobe(addr);
+	if (!p) {
+		if (*addr != breakpoint_insn) {
+			/*
+			 * The breakpoint instruction was removed right
+			 * after we hit it.  Another cpu has removed
+			 * either a probepoint or a debugger breakpoint
+			 * at this address.  In either case, no further
+			 * handling of this interrupt is appropriate.
+			 */
+			ret = 1;
+		}
+		/* Not one of ours: let kernel handle it. */
+		goto no_kprobe;
+	}
+
+	set_current_kprobe(p, regs, kcb);
+	kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+
+	if (p->pre_handler && p->pre_handler(p, regs)) {
+		/* Handler has already set things up, so skip ss setup. */
+		return 1;
+	}
+
+ss_probe:
+	prepare_singlestep(p, regs);
+	kcb->kprobe_status = KPROBE_HIT_SS;
+	return 1;
+
+no_kprobe:
+	preempt_enable_no_resched();
+	return ret;
+}
+
+/*
+ * Called after single-stepping.  p->addr is the address of the
+ * instruction that has been replaced by the breakpoint. To avoid the
+ * SMP problems that can occur when we temporarily put back the
+ * original opcode to single-step, we single-stepped a copy of the
+ * instruction.  The address of this copy is p->ainsn.insn.
+ *
+ * This function prepares to return from the post-single-step
+ * breakpoint trap.
+ */
+static void __kprobes resume_execution(struct kprobe *p,
+				       struct pt_regs *regs,
+				       struct kprobe_ctlblk *kcb)
+{
+	unsigned long orig_pc = kcb->kprobe_saved_pc;
+	regs->pc = orig_pc + 8;
+}
+
+static inline int post_kprobe_handler(struct pt_regs *regs)
+{
+	struct kprobe *cur = kprobe_running();
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	if (!cur)
+		return 0;
+
+	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+		kcb->kprobe_status = KPROBE_HIT_SSDONE;
+		cur->post_handler(cur, regs, 0);
+	}
+
+	resume_execution(cur, regs, kcb);
+
+	/* Restore back the original saved kprobes variables and continue. */
+	if (kcb->kprobe_status == KPROBE_REENTER) {
+		restore_previous_kprobe(kcb);
+		goto out;
+	}
+	reset_current_kprobe();
+out:
+	preempt_enable_no_resched();
+
+	return 1;
+}
+
+static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+	struct kprobe *cur = kprobe_running();
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
+		return 1;
+
+	if (kcb->kprobe_status & KPROBE_HIT_SS) {
+		/*
+		 * We are here because the instruction being single
+		 * stepped caused a page fault. We reset the current
+		 * kprobe and the ip points back to the probe address
+		 * and allow the page fault handler to continue as a
+		 * normal page fault.
+		 */
+		resume_execution(cur, regs, kcb);
+		reset_current_kprobe();
+		preempt_enable_no_resched();
+	}
+	return 0;
+}
+
+/*
+ * Wrapper routine for handling exceptions.
+ */
+int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+				       unsigned long val, void *data)
+{
+	struct die_args *args = (struct die_args *)data;
+	int ret = NOTIFY_DONE;
+
+	switch (val) {
+	case DIE_BREAK:
+		if (kprobe_handler(args->regs))
+			ret = NOTIFY_STOP;
+		break;
+	case DIE_SSTEPBP:
+		if (post_kprobe_handler(args->regs))
+			ret = NOTIFY_STOP;
+		break;
+	case DIE_PAGE_FAULT:
+		/* kprobe_running() needs smp_processor_id(). */
+		preempt_disable();
+
+		if (kprobe_running()
+		    && kprobe_fault_handler(args->regs, args->trapnr))
+			ret = NOTIFY_STOP;
+		preempt_enable();
+		break;
+	default:
+		break;
+	}
+	return ret;
+}
+
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct jprobe *jp = container_of(p, struct jprobe, kp);
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	kcb->jprobe_saved_regs = *regs;
+	kcb->jprobe_saved_sp = regs->sp;
+
+	memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
+	       MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
+
+	regs->pc = (unsigned long)(jp->entry);
+
+	return 1;
+}
+
+/* Defined in the inline asm below. */
+void jprobe_return_end(void);
+
+void __kprobes jprobe_return(void)
+{
+	asm volatile(
+		"bpt\n\t"
+		".globl jprobe_return_end\n"
+		"jprobe_return_end:\n");
+}
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	if (regs->pc >= (unsigned long)jprobe_return &&
+	    regs->pc <= (unsigned long)jprobe_return_end) {
+		*regs = kcb->jprobe_saved_regs;
+		memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
+		       MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
+		preempt_enable_no_resched();
+
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * Function return probe trampoline:
+ * - init_kprobes() establishes a probepoint here
+ * - When the probed function returns, this probe causes the
+ *   handlers to fire
+ */
+static void __used kretprobe_trampoline_holder(void)
+{
+	asm volatile(
+		"nop\n\t"
+		".global kretprobe_trampoline\n"
+		"kretprobe_trampoline:\n\t"
+		"nop\n\t"
+		: : : "memory");
+}
+
+void kretprobe_trampoline(void);
+
+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+				      struct pt_regs *regs)
+{
+	ri->ret_addr = (kprobe_opcode_t *) regs->lr;
+
+	/* Replace the return addr with trampoline addr */
+	regs->lr = (unsigned long)kretprobe_trampoline;
+}
+
+/*
+ * Called when the probe at kretprobe trampoline is hit.
+ */
+static int __kprobes trampoline_probe_handler(struct kprobe *p,
+						struct pt_regs *regs)
+{
+	struct kretprobe_instance *ri = NULL;
+	struct hlist_head *head, empty_rp;
+	struct hlist_node *tmp;
+	unsigned long flags, orig_ret_address = 0;
+	unsigned long trampoline_address = (unsigned long)kretprobe_trampoline;
+
+	INIT_HLIST_HEAD(&empty_rp);
+	kretprobe_hash_lock(current, &head, &flags);
+
+	/*
+	 * It is possible to have multiple instances associated with a given
+	 * task either because multiple functions in the call path have
+	 * a return probe installed on them, and/or more than one return
+	 * return probe was registered for a target function.
+	 *
+	 * We can handle this because:
+	 *     - instances are always inserted at the head of the list
+	 *     - when multiple return probes are registered for the same
+	 *       function, the first instance's ret_addr will point to the
+	 *       real return address, and all the rest will point to
+	 *       kretprobe_trampoline
+	 */
+	hlist_for_each_entry_safe(ri, tmp, head, hlist) {
+		if (ri->task != current)
+			/* another task is sharing our hash bucket */
+			continue;
+
+		if (ri->rp && ri->rp->handler)
+			ri->rp->handler(ri, regs);
+
+		orig_ret_address = (unsigned long)ri->ret_addr;
+		recycle_rp_inst(ri, &empty_rp);
+
+		if (orig_ret_address != trampoline_address) {
+			/*
+			 * This is the real return address. Any other
+			 * instances associated with this task are for
+			 * other calls deeper on the call stack
+			 */
+			break;
+		}
+	}
+
+	kretprobe_assert(ri, orig_ret_address, trampoline_address);
+	instruction_pointer(regs) = orig_ret_address;
+
+	reset_current_kprobe();
+	kretprobe_hash_unlock(current, &flags);
+	preempt_enable_no_resched();
+
+	hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
+		hlist_del(&ri->hlist);
+		kfree(ri);
+	}
+	/*
+	 * By returning a non-zero value, we are telling
+	 * kprobe_handler() that we don't want the post_handler
+	 * to run (and have re-enabled preemption)
+	 */
+	return 1;
+}
+
+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+{
+	if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline)
+		return 1;
+
+	return 0;
+}
+
+static struct kprobe trampoline_p = {
+	.addr = (kprobe_opcode_t *)kretprobe_trampoline,
+	.pre_handler = trampoline_probe_handler
+};
+
+int __init arch_init_kprobes(void)
+{
+	register_kprobe(&trampoline_p);
+	return 0;
+}
diff --git a/arch/tile/kernel/smp.c b/arch/tile/kernel/smp.c
index 6cc520d..0ae1c59 100644
--- a/arch/tile/kernel/smp.c
+++ b/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 };
-	preempt_disable();
-	on_each_cpu(ipi_flush_icache_range, &flush, 1);
-	preempt_enable();
+
+	/* 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();
+	}
 }
 
 
diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
index a1bbc5de..f110785 100644
--- a/arch/tile/kernel/traps.c
+++ b/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)
 {
@@ -233,6 +271,10 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
 	if (!user_mode(regs)) {
 		const char *name;
 		char buf[100];
+		if (fault_num == INT_ILL && do_bpt(regs)) {
+			/* breakpoint */
+			return;
+		}
 		if (fixup_exception(regs))  /* ILL_TRANS or UNALIGN_DATA */
 			return;
 		if (fault_num >= 0 &&
diff --git a/arch/tile/kernel/vmlinux.lds.S b/arch/tile/kernel/vmlinux.lds.S
index 673d00a..aab9955 100644
--- a/arch/tile/kernel/vmlinux.lds.S
+++ b/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
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index 502664a..64eec3f 100644
--- a/arch/tile/mm/fault.c
+++ b/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
diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
index ebf5e0c..366db1a 100644
--- a/samples/kprobes/kprobe_example.c
+++ b/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
 }
 
 /*
-- 
1.8.3.1

Re: [PATCH v2] tile: support kprobes on tilegx

[Masami Hiramatsu]

(2013/08/13 23:08), Tony Lu wrote:
> This change includes support for Kprobes, Jprobes and Return Probes.
> 

This looks OK for me, just reviewed, not tested :).

Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Thank you!

> Signed-off-by: Tony Lu <zlu@tilera.com>
> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
> ---
> v2: implement Masami Hiramatsu's suggestion to add an insn_has_control()
> check to disallow placing probes on instructions that modify control flow.
> We can improve this in a later change if it seems useful.
> 
>  arch/tile/Kconfig                            |   2 +
>  arch/tile/include/asm/Kbuild                 |   1 -
>  arch/tile/include/asm/kdebug.h               |  28 ++
>  arch/tile/include/asm/kprobes.h              |  79 ++++
>  arch/tile/include/asm/ptrace.h               |   1 +
>  arch/tile/include/uapi/arch/opcode_tilegx.h  |   1 +
>  arch/tile/include/uapi/arch/opcode_tilepro.h |   1 +
>  arch/tile/kernel/Makefile                    |   1 +
>  arch/tile/kernel/kprobes.c                   | 528 +++++++++++++++++++++++++++
>  arch/tile/kernel/smp.c                       |  14 +-
>  arch/tile/kernel/traps.c                     |  42 +++
>  arch/tile/kernel/vmlinux.lds.S               |   1 +
>  arch/tile/mm/fault.c                         |  12 +
>  samples/kprobes/kprobe_example.c             |   9 +
>  14 files changed, 716 insertions(+), 4 deletions(-)
>  create mode 100644 arch/tile/include/asm/kdebug.h
>  create mode 100644 arch/tile/include/asm/kprobes.h
>  create mode 100644 arch/tile/kernel/kprobes.c
> 
> diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
> index e1600be..ecff467 100644
> --- a/arch/tile/Kconfig
> +++ b/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
> diff --git a/arch/tile/include/asm/Kbuild b/arch/tile/include/asm/Kbuild
> index b17b9b8..4c0b3c2 100644
> --- a/arch/tile/include/asm/Kbuild
> +++ b/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
> diff --git a/arch/tile/include/asm/kdebug.h b/arch/tile/include/asm/kdebug.h
> new file mode 100644
> index 0000000..5bbbfa9
> --- /dev/null
> +++ b/arch/tile/include/asm/kdebug.h
> @@ -0,0 +1,28 @@
> +/*
> + * 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 */
> diff --git a/arch/tile/include/asm/kprobes.h b/arch/tile/include/asm/kprobes.h
> new file mode 100644
> index 0000000..d8f9a83
> --- /dev/null
> +++ b/arch/tile/include/asm/kprobes.h
> @@ -0,0 +1,79 @@
> +/*
> + * 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 */
> diff --git a/arch/tile/include/asm/ptrace.h b/arch/tile/include/asm/ptrace.h
> index 73b681b..0d25c21 100644
> --- a/arch/tile/include/asm/ptrace.h
> +++ b/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)
> diff --git a/arch/tile/include/uapi/arch/opcode_tilegx.h b/arch/tile/include/uapi/arch/opcode_tilegx.h
> index c14d02c..d76ff2d 100644
> --- a/arch/tile/include/uapi/arch/opcode_tilegx.h
> +++ b/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
> diff --git a/arch/tile/include/uapi/arch/opcode_tilepro.h b/arch/tile/include/uapi/arch/opcode_tilepro.h
> index 71b763b..4451cff 100644
> --- a/arch/tile/include/uapi/arch/opcode_tilepro.h
> +++ b/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
> diff --git a/arch/tile/kernel/Makefile b/arch/tile/kernel/Makefile
> index 2e6eaa1..b7c8b5e 100644
> --- a/arch/tile/kernel/Makefile
> +++ b/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/
> diff --git a/arch/tile/kernel/kprobes.c b/arch/tile/kernel/kprobes.c
> new file mode 100644
> index 0000000..1129f52
> --- /dev/null
> +++ b/arch/tile/kernel/kprobes.c
> @@ -0,0 +1,528 @@
> +/*
> + * arch/tile/kernel/kprobes.c
> + * Kprobes on TILE-Gx
> + *
> + * Some portions copied from the MIPS version.
> + *
> + * Copyright (C) IBM Corporation, 2002, 2004
> + * Copyright 2006 Sony Corp.
> + * Copyright 2010 Cavium Networks
> + *
> + * 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.
> + */
> +
> +#include <linux/kprobes.h>
> +#include <linux/kdebug.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +#include <asm/cacheflush.h>
> +
> +#include <arch/opcode.h>
> +
> +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
> +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
> +
> +tile_bundle_bits breakpoint_insn = TILEGX_BPT_BUNDLE;
> +tile_bundle_bits breakpoint2_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP;
> +
> +/*
> + * Check whether instruction is branch or jump, or if executing it
> + * has different results depending on where it is executed (e.g. lnk).
> + */
> +static int __kprobes insn_has_control(kprobe_opcode_t insn)
> +{
> +	if (get_Mode(insn) != 0) {   /* Y-format bundle */
> +		if (get_Opcode_Y1(insn) != RRR_1_OPCODE_Y1 ||
> +		    get_RRROpcodeExtension_Y1(insn) != UNARY_RRR_1_OPCODE_Y1)
> +			return 0;
> +
> +		switch (get_UnaryOpcodeExtension_Y1(insn)) {
> +		case JALRP_UNARY_OPCODE_Y1:
> +		case JALR_UNARY_OPCODE_Y1:
> +		case JRP_UNARY_OPCODE_Y1:
> +		case JR_UNARY_OPCODE_Y1:
> +		case LNK_UNARY_OPCODE_Y1:
> +			return 1;
> +		default:
> +			return 0;
> +		}
> +	}
> +
> +	switch (get_Opcode_X1(insn)) {
> +	case BRANCH_OPCODE_X1:	/* branch instructions */
> +	case JUMP_OPCODE_X1:	/* jump instructions: j and jal */
> +		return 1;
> +
> +	case RRR_0_OPCODE_X1:   /* other jump instructions */
> +		if (get_RRROpcodeExtension_X1(insn) != UNARY_RRR_0_OPCODE_X1)
> +			return 0;
> +		switch (get_UnaryOpcodeExtension_X1(insn)) {
> +		case JALRP_UNARY_OPCODE_X1:
> +		case JALR_UNARY_OPCODE_X1:
> +		case JRP_UNARY_OPCODE_X1:
> +		case JR_UNARY_OPCODE_X1:
> +		case LNK_UNARY_OPCODE_X1:
> +			return 1;
> +		default:
> +			return 0;
> +		}
> +	default:
> +		return 0;
> +	}
> +}
> +
> +int __kprobes arch_prepare_kprobe(struct kprobe *p)
> +{
> +	unsigned long addr = (unsigned long)p->addr;
> +
> +	if (addr & (sizeof(kprobe_opcode_t) - 1))
> +		return -EINVAL;
> +
> +	if (insn_has_control(*p->addr)) {
> +		pr_notice("Kprobes for control instructions are not "
> +			  "supported\n");
> +		return -EINVAL;
> +	}
> +
> +	/* insn: must be on special executable page on tile. */
> +	p->ainsn.insn = get_insn_slot();
> +	if (!p->ainsn.insn)
> +		return -ENOMEM;
> +
> +	/*
> +	 * In the kprobe->ainsn.insn[] array we store the original
> +	 * instruction at index zero and a break trap instruction at
> +	 * index one.
> +	 */
> +	memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
> +	p->ainsn.insn[1] = breakpoint2_insn;
> +	p->opcode = *p->addr;
> +
> +	return 0;
> +}
> +
> +void __kprobes arch_arm_kprobe(struct kprobe *p)
> +{
> +	unsigned long addr_wr;
> +
> +	/* Operate on writable kernel text mapping. */
> +	addr_wr = (unsigned long)p->addr - MEM_SV_START + PAGE_OFFSET;
> +
> +	if (probe_kernel_write((void *)addr_wr, &breakpoint_insn,
> +		sizeof(breakpoint_insn)))
> +		pr_err("%s: failed to enable kprobe\n", __func__);
> +
> +	smp_wmb();
> +	flush_insn_slot(p);
> +}
> +
> +void __kprobes arch_disarm_kprobe(struct kprobe *kp)
> +{
> +	unsigned long addr_wr;
> +
> +	/* Operate on writable kernel text mapping. */
> +	addr_wr = (unsigned long)kp->addr - MEM_SV_START + PAGE_OFFSET;
> +
> +	if (probe_kernel_write((void *)addr_wr, &kp->opcode,
> +		sizeof(kp->opcode)))
> +		pr_err("%s: failed to enable kprobe\n", __func__);
> +
> +	smp_wmb();
> +	flush_insn_slot(kp);
> +}
> +
> +void __kprobes arch_remove_kprobe(struct kprobe *p)
> +{
> +	if (p->ainsn.insn) {
> +		free_insn_slot(p->ainsn.insn, 0);
> +		p->ainsn.insn = NULL;
> +	}
> +}
> +
> +static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
> +{
> +	kcb->prev_kprobe.kp = kprobe_running();
> +	kcb->prev_kprobe.status = kcb->kprobe_status;
> +	kcb->prev_kprobe.saved_pc = kcb->kprobe_saved_pc;
> +}
> +
> +static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
> +{
> +	__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
> +	kcb->kprobe_status = kcb->prev_kprobe.status;
> +	kcb->kprobe_saved_pc = kcb->prev_kprobe.saved_pc;
> +}
> +
> +static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
> +			struct kprobe_ctlblk *kcb)
> +{
> +	__get_cpu_var(current_kprobe) = p;
> +	kcb->kprobe_saved_pc = regs->pc;
> +}
> +
> +static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
> +{
> +	/* Single step inline if the instruction is a break. */
> +	if (p->opcode == breakpoint_insn ||
> +	    p->opcode == breakpoint2_insn)
> +		regs->pc = (unsigned long)p->addr;
> +	else
> +		regs->pc = (unsigned long)&p->ainsn.insn[0];
> +}
> +
> +static int __kprobes kprobe_handler(struct pt_regs *regs)
> +{
> +	struct kprobe *p;
> +	int ret = 0;
> +	kprobe_opcode_t *addr;
> +	struct kprobe_ctlblk *kcb;
> +
> +	addr = (kprobe_opcode_t *)regs->pc;
> +
> +	/*
> +	 * We don't want to be preempted for the entire
> +	 * duration of kprobe processing.
> +	 */
> +	preempt_disable();
> +	kcb = get_kprobe_ctlblk();
> +
> +	/* Check we're not actually recursing. */
> +	if (kprobe_running()) {
> +		p = get_kprobe(addr);
> +		if (p) {
> +			if (kcb->kprobe_status == KPROBE_HIT_SS &&
> +			    p->ainsn.insn[0] == breakpoint_insn) {
> +				goto no_kprobe;
> +			}
> +			/*
> +			 * We have reentered the kprobe_handler(), since
> +			 * another probe was hit while within the handler.
> +			 * We here save the original kprobes variables and
> +			 * just single step on the instruction of the new probe
> +			 * without calling any user handlers.
> +			 */
> +			save_previous_kprobe(kcb);
> +			set_current_kprobe(p, regs, kcb);
> +			kprobes_inc_nmissed_count(p);
> +			prepare_singlestep(p, regs);
> +			kcb->kprobe_status = KPROBE_REENTER;
> +			return 1;
> +		} else {
> +			if (*addr != breakpoint_insn) {
> +				/*
> +				 * The breakpoint instruction was removed by
> +				 * another cpu right after we hit, no further
> +				 * handling of this interrupt is appropriate.
> +				 */
> +				ret = 1;
> +				goto no_kprobe;
> +			}
> +			p = __get_cpu_var(current_kprobe);
> +			if (p->break_handler && p->break_handler(p, regs))
> +				goto ss_probe;
> +		}
> +		goto no_kprobe;
> +	}
> +
> +	p = get_kprobe(addr);
> +	if (!p) {
> +		if (*addr != breakpoint_insn) {
> +			/*
> +			 * The breakpoint instruction was removed right
> +			 * after we hit it.  Another cpu has removed
> +			 * either a probepoint or a debugger breakpoint
> +			 * at this address.  In either case, no further
> +			 * handling of this interrupt is appropriate.
> +			 */
> +			ret = 1;
> +		}
> +		/* Not one of ours: let kernel handle it. */
> +		goto no_kprobe;
> +	}
> +
> +	set_current_kprobe(p, regs, kcb);
> +	kcb->kprobe_status = KPROBE_HIT_ACTIVE;
> +
> +	if (p->pre_handler && p->pre_handler(p, regs)) {
> +		/* Handler has already set things up, so skip ss setup. */
> +		return 1;
> +	}
> +
> +ss_probe:
> +	prepare_singlestep(p, regs);
> +	kcb->kprobe_status = KPROBE_HIT_SS;
> +	return 1;
> +
> +no_kprobe:
> +	preempt_enable_no_resched();
> +	return ret;
> +}
> +
> +/*
> + * Called after single-stepping.  p->addr is the address of the
> + * instruction that has been replaced by the breakpoint. To avoid the
> + * SMP problems that can occur when we temporarily put back the
> + * original opcode to single-step, we single-stepped a copy of the
> + * instruction.  The address of this copy is p->ainsn.insn.
> + *
> + * This function prepares to return from the post-single-step
> + * breakpoint trap.
> + */
> +static void __kprobes resume_execution(struct kprobe *p,
> +				       struct pt_regs *regs,
> +				       struct kprobe_ctlblk *kcb)
> +{
> +	unsigned long orig_pc = kcb->kprobe_saved_pc;
> +	regs->pc = orig_pc + 8;
> +}
> +
> +static inline int post_kprobe_handler(struct pt_regs *regs)
> +{
> +	struct kprobe *cur = kprobe_running();
> +	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
> +
> +	if (!cur)
> +		return 0;
> +
> +	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
> +		kcb->kprobe_status = KPROBE_HIT_SSDONE;
> +		cur->post_handler(cur, regs, 0);
> +	}
> +
> +	resume_execution(cur, regs, kcb);
> +
> +	/* Restore back the original saved kprobes variables and continue. */
> +	if (kcb->kprobe_status == KPROBE_REENTER) {
> +		restore_previous_kprobe(kcb);
> +		goto out;
> +	}
> +	reset_current_kprobe();
> +out:
> +	preempt_enable_no_resched();
> +
> +	return 1;
> +}
> +
> +static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
> +{
> +	struct kprobe *cur = kprobe_running();
> +	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
> +
> +	if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
> +		return 1;
> +
> +	if (kcb->kprobe_status & KPROBE_HIT_SS) {
> +		/*
> +		 * We are here because the instruction being single
> +		 * stepped caused a page fault. We reset the current
> +		 * kprobe and the ip points back to the probe address
> +		 * and allow the page fault handler to continue as a
> +		 * normal page fault.
> +		 */
> +		resume_execution(cur, regs, kcb);
> +		reset_current_kprobe();
> +		preempt_enable_no_resched();
> +	}
> +	return 0;
> +}
> +
> +/*
> + * Wrapper routine for handling exceptions.
> + */
> +int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
> +				       unsigned long val, void *data)
> +{
> +	struct die_args *args = (struct die_args *)data;
> +	int ret = NOTIFY_DONE;
> +
> +	switch (val) {
> +	case DIE_BREAK:
> +		if (kprobe_handler(args->regs))
> +			ret = NOTIFY_STOP;
> +		break;
> +	case DIE_SSTEPBP:
> +		if (post_kprobe_handler(args->regs))
> +			ret = NOTIFY_STOP;
> +		break;
> +	case DIE_PAGE_FAULT:
> +		/* kprobe_running() needs smp_processor_id(). */
> +		preempt_disable();
> +
> +		if (kprobe_running()
> +		    && kprobe_fault_handler(args->regs, args->trapnr))
> +			ret = NOTIFY_STOP;
> +		preempt_enable();
> +		break;
> +	default:
> +		break;
> +	}
> +	return ret;
> +}
> +
> +int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
> +{
> +	struct jprobe *jp = container_of(p, struct jprobe, kp);
> +	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
> +
> +	kcb->jprobe_saved_regs = *regs;
> +	kcb->jprobe_saved_sp = regs->sp;
> +
> +	memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
> +	       MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
> +
> +	regs->pc = (unsigned long)(jp->entry);
> +
> +	return 1;
> +}
> +
> +/* Defined in the inline asm below. */
> +void jprobe_return_end(void);
> +
> +void __kprobes jprobe_return(void)
> +{
> +	asm volatile(
> +		"bpt\n\t"
> +		".globl jprobe_return_end\n"
> +		"jprobe_return_end:\n");
> +}
> +
> +int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
> +{
> +	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
> +
> +	if (regs->pc >= (unsigned long)jprobe_return &&
> +	    regs->pc <= (unsigned long)jprobe_return_end) {
> +		*regs = kcb->jprobe_saved_regs;
> +		memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
> +		       MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
> +		preempt_enable_no_resched();
> +
> +		return 1;
> +	}
> +	return 0;
> +}
> +
> +/*
> + * Function return probe trampoline:
> + * - init_kprobes() establishes a probepoint here
> + * - When the probed function returns, this probe causes the
> + *   handlers to fire
> + */
> +static void __used kretprobe_trampoline_holder(void)
> +{
> +	asm volatile(
> +		"nop\n\t"
> +		".global kretprobe_trampoline\n"
> +		"kretprobe_trampoline:\n\t"
> +		"nop\n\t"
> +		: : : "memory");
> +}
> +
> +void kretprobe_trampoline(void);
> +
> +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
> +				      struct pt_regs *regs)
> +{
> +	ri->ret_addr = (kprobe_opcode_t *) regs->lr;
> +
> +	/* Replace the return addr with trampoline addr */
> +	regs->lr = (unsigned long)kretprobe_trampoline;
> +}
> +
> +/*
> + * Called when the probe at kretprobe trampoline is hit.
> + */
> +static int __kprobes trampoline_probe_handler(struct kprobe *p,
> +						struct pt_regs *regs)
> +{
> +	struct kretprobe_instance *ri = NULL;
> +	struct hlist_head *head, empty_rp;
> +	struct hlist_node *tmp;
> +	unsigned long flags, orig_ret_address = 0;
> +	unsigned long trampoline_address = (unsigned long)kretprobe_trampoline;
> +
> +	INIT_HLIST_HEAD(&empty_rp);
> +	kretprobe_hash_lock(current, &head, &flags);
> +
> +	/*
> +	 * It is possible to have multiple instances associated with a given
> +	 * task either because multiple functions in the call path have
> +	 * a return probe installed on them, and/or more than one return
> +	 * return probe was registered for a target function.
> +	 *
> +	 * We can handle this because:
> +	 *     - instances are always inserted at the head of the list
> +	 *     - when multiple return probes are registered for the same
> +	 *       function, the first instance's ret_addr will point to the
> +	 *       real return address, and all the rest will point to
> +	 *       kretprobe_trampoline
> +	 */
> +	hlist_for_each_entry_safe(ri, tmp, head, hlist) {
> +		if (ri->task != current)
> +			/* another task is sharing our hash bucket */
> +			continue;
> +
> +		if (ri->rp && ri->rp->handler)
> +			ri->rp->handler(ri, regs);
> +
> +		orig_ret_address = (unsigned long)ri->ret_addr;
> +		recycle_rp_inst(ri, &empty_rp);
> +
> +		if (orig_ret_address != trampoline_address) {
> +			/*
> +			 * This is the real return address. Any other
> +			 * instances associated with this task are for
> +			 * other calls deeper on the call stack
> +			 */
> +			break;
> +		}
> +	}
> +
> +	kretprobe_assert(ri, orig_ret_address, trampoline_address);
> +	instruction_pointer(regs) = orig_ret_address;
> +
> +	reset_current_kprobe();
> +	kretprobe_hash_unlock(current, &flags);
> +	preempt_enable_no_resched();
> +
> +	hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
> +		hlist_del(&ri->hlist);
> +		kfree(ri);
> +	}
> +	/*
> +	 * By returning a non-zero value, we are telling
> +	 * kprobe_handler() that we don't want the post_handler
> +	 * to run (and have re-enabled preemption)
> +	 */
> +	return 1;
> +}
> +
> +int __kprobes arch_trampoline_kprobe(struct kprobe *p)
> +{
> +	if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline)
> +		return 1;
> +
> +	return 0;
> +}
> +
> +static struct kprobe trampoline_p = {
> +	.addr = (kprobe_opcode_t *)kretprobe_trampoline,
> +	.pre_handler = trampoline_probe_handler
> +};
> +
> +int __init arch_init_kprobes(void)
> +{
> +	register_kprobe(&trampoline_p);
> +	return 0;
> +}
> diff --git a/arch/tile/kernel/smp.c b/arch/tile/kernel/smp.c
> index 6cc520d..0ae1c59 100644
> --- a/arch/tile/kernel/smp.c
> +++ b/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 };
> -	preempt_disable();
> -	on_each_cpu(ipi_flush_icache_range, &flush, 1);
> -	preempt_enable();
> +
> +	/* 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();
> +	}
>  }
>  
>  
> diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
> index a1bbc5de..f110785 100644
> --- a/arch/tile/kernel/traps.c
> +++ b/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)
>  {
> @@ -233,6 +271,10 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
>  	if (!user_mode(regs)) {
>  		const char *name;
>  		char buf[100];
> +		if (fault_num == INT_ILL && do_bpt(regs)) {
> +			/* breakpoint */
> +			return;
> +		}
>  		if (fixup_exception(regs))  /* ILL_TRANS or UNALIGN_DATA */
>  			return;
>  		if (fault_num >= 0 &&
> diff --git a/arch/tile/kernel/vmlinux.lds.S b/arch/tile/kernel/vmlinux.lds.S
> index 673d00a..aab9955 100644
> --- a/arch/tile/kernel/vmlinux.lds.S
> +++ b/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
> diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
> index 502664a..64eec3f 100644
> --- a/arch/tile/mm/fault.c
> +++ b/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
> diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
> index ebf5e0c..366db1a 100644
> --- a/samples/kprobes/kprobe_example.c
> +++ b/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
>  }
>  
>  /*
> 


-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com

Re: [PATCH] tile: support ftrace on tilegx

[Steven Rostedt]

On Fri, 9 Aug 2013 13:26:09 -0400
Tony Lu <zlu@tilera.com> wrote:


> diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
> index 858966a..a674fd5 100755
> --- a/scripts/recordmcount.pl
> +++ b/scripts/recordmcount.pl
> @@ -364,6 +364,10 @@ if ($arch eq "x86_64") {
>  } elsif ($arch eq "blackfin") {
>      $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s__mcount\$";
>      $mcount_adjust = -4;
> +} elsif ($arch eq "tilegx") {
> +    $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s__mcount\$";
> +    $type = ".quad";
> +    $alignment = 8;
>  } else {
>      die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
>  }


If you want faster build times, you may want to update recordmcount.c,
and then add HAVE_C_RECORDMCOUNT

-- Steve