From 6b1d6d2fba37129f690ee7e9164f225c55626cac Mon Sep 17 00:00:00 2001 From: Zong Li Date: Wed, 15 Aug 2018 11:00:08 +0800 Subject: nds32/ftrace: Support dynamic function tracer This patch contains the implementation of dynamic function tracer. The mcount call is composed of three instructions, so there are three nop for enough placeholder. Signed-off-by: Zong Li Acked-by: Greentime Hu Signed-off-by: Greentime Hu --- arch/nds32/kernel/ftrace.c | 164 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 164 insertions(+) (limited to 'arch/nds32/kernel/ftrace.c') diff --git a/arch/nds32/kernel/ftrace.c b/arch/nds32/kernel/ftrace.c index 707fce76522e..3ca676b75d97 100644 --- a/arch/nds32/kernel/ftrace.c +++ b/arch/nds32/kernel/ftrace.c @@ -4,6 +4,7 @@ #include #include +#ifndef CONFIG_DYNAMIC_FTRACE extern void (*ftrace_trace_function)(unsigned long, unsigned long, struct ftrace_ops*, struct pt_regs*); extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace); @@ -35,6 +36,168 @@ noinline void _mcount(unsigned long parent_ip) } EXPORT_SYMBOL(_mcount); +#else /* CONFIG_DYNAMIC_FTRACE */ + +noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, struct pt_regs *regs) +{ + __asm__ (""); /* avoid to optimize as pure function */ +} + +noinline void __naked _mcount(unsigned long parent_ip) +{ + __asm__ (""); /* avoid to optimize as pure function */ +} +EXPORT_SYMBOL(_mcount); + +#define XSTR(s) STR(s) +#define STR(s) #s +void _ftrace_caller(unsigned long parent_ip) +{ + /* save all state needed by the compiler prologue */ + + /* + * prepare arguments for real tracing function + * first arg : __builtin_return_address(0) - MCOUNT_INSN_SIZE + * second arg : parent_ip + */ + __asm__ __volatile__ ( + "move $r1, %0 \n\t" + "addi $r0, %1, #-" XSTR(MCOUNT_INSN_SIZE) "\n\t" + : + : "r" (parent_ip), "r" (__builtin_return_address(0))); + + /* a placeholder for the call to a real tracing function */ + __asm__ __volatile__ ( + "ftrace_call: \n\t" + "nop \n\t" + "nop \n\t" + "nop \n\t"); + + /* restore all state needed by the compiler epilogue */ +} + +int __init ftrace_dyn_arch_init(void) +{ + return 0; +} + +int ftrace_arch_code_modify_prepare(void) +{ + set_all_modules_text_rw(); + return 0; +} + +int ftrace_arch_code_modify_post_process(void) +{ + set_all_modules_text_ro(); + return 0; +} + +static unsigned long gen_sethi_insn(unsigned long addr) +{ + unsigned long opcode = 0x46000000; + unsigned long imm = addr >> 12; + unsigned long rt_num = 0xf << 20; + + return ENDIAN_CONVERT(opcode | rt_num | imm); +} + +static unsigned long gen_ori_insn(unsigned long addr) +{ + unsigned long opcode = 0x58000000; + unsigned long imm = addr & 0x0000fff; + unsigned long rt_num = 0xf << 20; + unsigned long ra_num = 0xf << 15; + + return ENDIAN_CONVERT(opcode | rt_num | ra_num | imm); +} + +static unsigned long gen_jral_insn(unsigned long addr) +{ + unsigned long opcode = 0x4a000001; + unsigned long rt_num = 0x1e << 20; + unsigned long rb_num = 0xf << 10; + + return ENDIAN_CONVERT(opcode | rt_num | rb_num); +} + +static void ftrace_gen_call_insn(unsigned long *call_insns, + unsigned long addr) +{ + call_insns[0] = gen_sethi_insn(addr); /* sethi $r15, imm20u */ + call_insns[1] = gen_ori_insn(addr); /* ori $r15, $r15, imm15u */ + call_insns[2] = gen_jral_insn(addr); /* jral $lp, $r15 */ +} + +static int __ftrace_modify_code(unsigned long pc, unsigned long *old_insn, + unsigned long *new_insn, bool validate) +{ + unsigned long orig_insn[3]; + + if (validate) { + if (probe_kernel_read(orig_insn, (void *)pc, MCOUNT_INSN_SIZE)) + return -EFAULT; + if (memcmp(orig_insn, old_insn, MCOUNT_INSN_SIZE)) + return -EINVAL; + } + + if (probe_kernel_write((void *)pc, new_insn, MCOUNT_INSN_SIZE)) + return -EPERM; + + return 0; +} + +static int ftrace_modify_code(unsigned long pc, unsigned long *old_insn, + unsigned long *new_insn, bool validate) +{ + int ret; + + ret = __ftrace_modify_code(pc, old_insn, new_insn, validate); + if (ret) + return ret; + + flush_icache_range(pc, pc + MCOUNT_INSN_SIZE); + + return ret; +} + +int ftrace_update_ftrace_func(ftrace_func_t func) +{ + unsigned long pc = (unsigned long)&ftrace_call; + unsigned long old_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP}; + unsigned long new_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP}; + + if (func != ftrace_stub) + ftrace_gen_call_insn(new_insn, (unsigned long)func); + + return ftrace_modify_code(pc, old_insn, new_insn, false); +} + +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned long pc = rec->ip; + unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP}; + unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP}; + + ftrace_gen_call_insn(call_insn, addr); + + return ftrace_modify_code(pc, nop_insn, call_insn, true); +} + +int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, + unsigned long addr) +{ + unsigned long pc = rec->ip; + unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP}; + unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP}; + + ftrace_gen_call_insn(call_insn, addr); + + return ftrace_modify_code(pc, call_insn, nop_insn, true); +} +#endif /* CONFIG_DYNAMIC_FTRACE */ + #ifdef CONFIG_FUNCTION_GRAPH_TRACER void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, unsigned long frame_pointer) @@ -94,4 +257,5 @@ void __naked return_to_handler(void) /* restore state nedded by the ABI */ "lmw.bim $r0,[$sp],$r1,#0x0 \n\t"); } + #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ -- cgit