tile: support ftrace on tilegx

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>

7 files changed, 510 insertions, 2 deletions

diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
index 7b87318ee690..d2277c4f949e 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 461459b06d98..13a9bb81a8ab 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 c4a957aad26a..2e6eaa11b60d 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 000000000000..f1c452092eeb
--- /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 000000000000..70d7bb0c4d8f
--- /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 0f0edaf68f94..673d00afa83b 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 359b1bc52d84..82733c87d67e 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);