1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
4 #include <linux/ftrace.h>
5 #include <linux/uaccess.h>
6 #include <linux/stop_machine.h>
7 #include <asm/cacheflush.h>
9 #ifdef CONFIG_DYNAMIC_FTRACE
12 #define NOP32_HI 0xc400
13 #define NOP32_LO 0x4820
14 #define PUSH_LR 0x14d0
15 #define MOVIH_LINK 0xea3a
16 #define ORI_LINK 0xef5a
17 #define JSR_LINK 0xe8fa
18 #define BSR_LINK 0xe000
21 * Gcc-csky with -pg will insert stub in function prologue:
27 * If the (callee - current_pc) is less then 64MB, we'll use bsr:
32 * else we'll use (movih + ori + jsr):
38 * (r26 is our reserved link-reg)
41 static inline void make_jbsr(unsigned long callee, unsigned long pc,
42 uint16_t *call, bool nolr)
46 call[0] = nolr ? NOP : PUSH_LR;
48 offset = (long) callee - (long) pc;
50 if (unlikely(offset < -67108864 || offset > 67108864)) {
52 call[2] = callee >> 16;
54 call[4] = callee & 0xffff;
61 ((uint16_t)((unsigned long) offset >> 16) & 0x3ff);
62 call[2] = (uint16_t)((unsigned long) offset & 0xffff);
63 call[3] = call[5] = NOP32_HI;
64 call[4] = call[6] = NOP32_LO;
68 static uint16_t nops[7] = {NOP, NOP32_HI, NOP32_LO, NOP32_HI, NOP32_LO,
70 static int ftrace_check_current_nop(unsigned long hook)
73 unsigned long hook_pos = hook - 2;
75 if (probe_kernel_read((void *)olds, (void *)hook_pos, sizeof(nops)))
78 if (memcmp((void *)nops, (void *)olds, sizeof(nops))) {
79 pr_err("%p: nop but get (%04x %04x %04x %04x %04x %04x %04x)\n",
81 olds[0], olds[1], olds[2], olds[3], olds[4], olds[5],
90 static int ftrace_modify_code(unsigned long hook, unsigned long target,
91 bool enable, bool nolr)
95 unsigned long hook_pos = hook - 2;
98 make_jbsr(target, hook, call, nolr);
100 ret = probe_kernel_write((void *)hook_pos, enable ? call : nops,
105 flush_icache_range(hook_pos, hook_pos + MCOUNT_INSN_SIZE);
110 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
112 int ret = ftrace_check_current_nop(rec->ip);
117 return ftrace_modify_code(rec->ip, addr, true, false);
120 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
123 return ftrace_modify_code(rec->ip, addr, false, false);
126 int ftrace_update_ftrace_func(ftrace_func_t func)
128 int ret = ftrace_modify_code((unsigned long)&ftrace_call,
129 (unsigned long)func, true, true);
131 ret = ftrace_modify_code((unsigned long)&ftrace_regs_call,
132 (unsigned long)func, true, true);
136 int __init ftrace_dyn_arch_init(void)
140 #endif /* CONFIG_DYNAMIC_FTRACE */
142 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
143 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
146 return ftrace_modify_code(rec->ip, addr, true, true);
150 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
151 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
152 unsigned long frame_pointer)
154 unsigned long return_hooker = (unsigned long)&return_to_handler;
157 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
162 if (!function_graph_enter(old, self_addr,
163 *(unsigned long *)frame_pointer, parent)) {
165 * For csky-gcc function has sub-call:
169 * st.w r15, (sp, 0x4)
172 * We only need set *parent for resume
174 * For csky-gcc function has no sub-call:
180 * We need set *parent and *(frame_pointer + 4) for resume,
181 * because lr is resumed twice.
183 *parent = return_hooker;
185 if (*(unsigned long *)frame_pointer == old)
186 *(unsigned long *)frame_pointer = return_hooker;
190 #ifdef CONFIG_DYNAMIC_FTRACE
191 int ftrace_enable_ftrace_graph_caller(void)
193 return ftrace_modify_code((unsigned long)&ftrace_graph_call,
194 (unsigned long)&ftrace_graph_caller, true, true);
197 int ftrace_disable_ftrace_graph_caller(void)
199 return ftrace_modify_code((unsigned long)&ftrace_graph_call,
200 (unsigned long)&ftrace_graph_caller, false, true);
202 #endif /* CONFIG_DYNAMIC_FTRACE */
203 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
205 #ifndef CONFIG_CPU_HAS_ICACHE_INS
206 struct ftrace_modify_param {
211 static int __ftrace_modify_code(void *data)
213 struct ftrace_modify_param *param = data;
215 if (atomic_inc_return(¶m->cpu_count) == 1) {
216 ftrace_modify_all_code(param->command);
217 atomic_inc(¶m->cpu_count);
219 while (atomic_read(¶m->cpu_count) <= num_online_cpus())
221 local_icache_inv_all(NULL);
227 void arch_ftrace_update_code(int command)
229 struct ftrace_modify_param param = { command, ATOMIC_INIT(0) };
231 stop_machine(__ftrace_modify_code, ¶m, cpu_online_mask);
235 /* _mcount is defined in abi's mcount.S */
236 EXPORT_SYMBOL(_mcount);