diff options
Diffstat (limited to 'kernel/arch/tile/kernel/ftrace.c')
| -rw-r--r-- | kernel/arch/tile/kernel/ftrace.c | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/kernel/arch/tile/kernel/ftrace.c b/kernel/arch/tile/kernel/ftrace.c new file mode 100644 index 000000000..0c0996175 --- /dev/null +++ b/kernel/arch/tile/kernel/ftrace.c @@ -0,0 +1,248 @@ +/* + * 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); + } + + /* + * Also put { move r10, lr; jal ftrace_stub } in a bundle, which + * is used to replace the instruction in address ftrace_call. + */ + if (addr == FTRACE_ADDR || addr == (unsigned long)ftrace_stub) { + /* 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) +{ + 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(¤t->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 */ |