From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: AndrĂ© Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/arm/kernel/ftrace.c | 274 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 274 insertions(+) create mode 100644 arch/arm/kernel/ftrace.c (limited to 'arch/arm/kernel/ftrace.c') diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c new file mode 100644 index 000000000..709ee1d6d --- /dev/null +++ b/arch/arm/kernel/ftrace.c @@ -0,0 +1,274 @@ +/* + * Dynamic function tracing support. + * + * Copyright (C) 2008 Abhishek Sagar + * Copyright (C) 2010 Rabin Vincent + * + * For licencing details, see COPYING. + * + * Defines low-level handling of mcount calls when the kernel + * is compiled with the -pg flag. When using dynamic ftrace, the + * mcount call-sites get patched with NOP till they are enabled. + * All code mutation routines here are called under stop_machine(). + */ + +#include +#include +#include +#include + +#include +#include +#include +#include + +#ifdef CONFIG_THUMB2_KERNEL +#define NOP 0xf85deb04 /* pop.w {lr} */ +#else +#define NOP 0xe8bd4000 /* pop {lr} */ +#endif + +#ifdef CONFIG_DYNAMIC_FTRACE +#ifdef CONFIG_OLD_MCOUNT +#define OLD_MCOUNT_ADDR ((unsigned long) mcount) +#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old) + +#define OLD_NOP 0xe1a00000 /* mov r0, r0 */ + +static int __ftrace_modify_code(void *data) +{ + int *command = data; + + set_kernel_text_rw(); + ftrace_modify_all_code(*command); + set_kernel_text_ro(); + + return 0; +} + +void arch_ftrace_update_code(int command) +{ + stop_machine(__ftrace_modify_code, &command, NULL); +} + +static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec) +{ + return rec->arch.old_mcount ? OLD_NOP : NOP; +} + +static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr) +{ + if (!rec->arch.old_mcount) + return addr; + + if (addr == MCOUNT_ADDR) + addr = OLD_MCOUNT_ADDR; + else if (addr == FTRACE_ADDR) + addr = OLD_FTRACE_ADDR; + + return addr; +} +#else +static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec) +{ + return NOP; +} + +static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr) +{ + return addr; +} +#endif + +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(); + /* Make sure any TLB misses during machine stop are cleared. */ + flush_tlb_all(); + return 0; +} + +static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr) +{ + return arm_gen_branch_link(pc, addr); +} + +static int ftrace_modify_code(unsigned long pc, unsigned long old, + unsigned long new, bool validate) +{ + unsigned long replaced; + + if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) { + old = __opcode_to_mem_thumb32(old); + new = __opcode_to_mem_thumb32(new); + } else { + old = __opcode_to_mem_arm(old); + new = __opcode_to_mem_arm(new); + } + + if (validate) { + if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE)) + return -EFAULT; + + if (replaced != old) + return -EINVAL; + } + + if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE)) + return -EPERM; + + flush_icache_range(pc, pc + MCOUNT_INSN_SIZE); + + return 0; +} + +int ftrace_update_ftrace_func(ftrace_func_t func) +{ + unsigned long pc; + unsigned long new; + int ret; + + pc = (unsigned long)&ftrace_call; + new = ftrace_call_replace(pc, (unsigned long)func); + + ret = ftrace_modify_code(pc, 0, new, false); + +#ifdef CONFIG_OLD_MCOUNT + if (!ret) { + pc = (unsigned long)&ftrace_call_old; + new = ftrace_call_replace(pc, (unsigned long)func); + + ret = ftrace_modify_code(pc, 0, new, false); + } +#endif + + 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, adjust_address(rec, addr)); + + return ftrace_modify_code(rec->ip, old, new, true); +} + +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, adjust_address(rec, addr)); + new = ftrace_nop_replace(rec); + ret = ftrace_modify_code(ip, old, new, true); + +#ifdef CONFIG_OLD_MCOUNT + if (ret == -EINVAL && addr == MCOUNT_ADDR) { + rec->arch.old_mcount = true; + + old = ftrace_call_replace(ip, adjust_address(rec, addr)); + new = ftrace_nop_replace(rec); + ret = ftrace_modify_code(ip, old, new, true); + } +#endif + + 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; + + trace.func = self_addr; + trace.depth = current->curr_ret_stack + 1; + + /* Only trace if the calling function expects to */ + if (!ftrace_graph_entry(&trace)) { + *parent = old; + return; + } + + err = ftrace_push_return_trace(old, self_addr, &trace.depth, + frame_pointer); + if (err == -EBUSY) { + *parent = old; + return; + } +} + +#ifdef CONFIG_DYNAMIC_FTRACE +extern unsigned long ftrace_graph_call; +extern unsigned long ftrace_graph_call_old; +extern void ftrace_graph_caller_old(void); + +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 = arm_gen_branch(pc, caller_fn); + unsigned long nop = 0xe1a00000; /* mov r0, r0 */ + unsigned long old = enable ? nop : branch; + unsigned long new = enable ? branch : nop; + + return ftrace_modify_code(pc, old, new, true); +} + +static int ftrace_modify_graph_caller(bool enable) +{ + int ret; + + ret = __ftrace_modify_caller(&ftrace_graph_call, + ftrace_graph_caller, + enable); + +#ifdef CONFIG_OLD_MCOUNT + if (!ret) + ret = __ftrace_modify_caller(&ftrace_graph_call_old, + ftrace_graph_caller_old, + enable); +#endif + + 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 */ -- cgit v1.2.3-54-g00ecf