1 // SPDX-License-Identifier: GPL-2.0-only
15 #include <asm/debug-monitors.h>
25 static int ftrace_modify_code(unsigned long pc, u32 old, u32 new,  in ftrace_modify_code()  argument
33 	 * could cause us to read or write to someplace that could cause harm.  in ftrace_modify_code()
39 		if (aarch64_insn_read((void *)pc, &replaced))  in ftrace_modify_code()
40 			return -EFAULT;  in ftrace_modify_code()
43 			return -EINVAL;  in ftrace_modify_code()
45 	if (aarch64_insn_patch_text_nosync((void *)pc, new))  in ftrace_modify_code()
46 		return -EPERM;  in ftrace_modify_code()
56 	unsigned long pc;  in ftrace_update_ftrace_func()  local
59 	pc = (unsigned long)ftrace_call;  in ftrace_update_ftrace_func()
60 	new = aarch64_insn_gen_branch_imm(pc, (unsigned long)func,  in ftrace_update_ftrace_func()
63 	return ftrace_modify_code(pc, 0, new, false);  in ftrace_update_ftrace_func()
69 	struct plt_entry *plt = mod->arch.ftrace_trampolines;  in get_ftrace_plt()
93 	unsigned long pc = rec->ip;  in ftrace_find_callable_addr()  local
94 	long offset = (long)*addr - (long)pc;  in ftrace_find_callable_addr()
99 	 * as-is and branch to that directly.  in ftrace_find_callable_addr()
101 	if (offset >= -SZ_128M && offset < SZ_128M)  in ftrace_find_callable_addr()
107 	 * only when module PLT support is built-in.  in ftrace_find_callable_addr()
114 	 * dealing with an out-of-range condition, we can assume it  in ftrace_find_callable_addr()
123 		mod = __module_text_address(pc);  in ftrace_find_callable_addr()
132 		pr_err("ftrace: no module PLT for %ps\n", (void *)*addr);  in ftrace_find_callable_addr()
145 	unsigned long pc = rec->ip;  in ftrace_make_call()  local
149 		return -EINVAL;  in ftrace_make_call()
152 	new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);  in ftrace_make_call()
154 	return ftrace_modify_code(pc, old, new, true);  in ftrace_make_call()
161 	unsigned long pc = rec->ip;  in ftrace_modify_call()  local
165 		return -EINVAL;  in ftrace_modify_call()
167 		return -EINVAL;  in ftrace_modify_call()
169 	old = aarch64_insn_gen_branch_imm(pc, old_addr,  in ftrace_modify_call()
171 	new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);  in ftrace_modify_call()
173 	return ftrace_modify_code(pc, old, new, true);  in ftrace_modify_call()
178  * All instrumented functions follow the AAPCS, so x0-x8 and x19-x30 are live,
179  * and x9-x18 are free for our use.
181  * At runtime we want to be able to swing a single NOP <-> BL to enable or
187  * +----------+------------+------------+
195  * Note: ftrace_process_locs() has pre-adjusted rec->ip to be the address of
200 	unsigned long pc = rec->ip - AARCH64_INSN_SIZE;  in ftrace_init_nop()  local
207 	return ftrace_modify_code(pc, old, new, true);  in ftrace_init_nop()
217 	unsigned long pc = rec->ip;  in ftrace_make_nop()  local
233 		return aarch64_insn_patch_text_nosync((void *)pc, new);  in ftrace_make_nop()
237 		return -EINVAL;  in ftrace_make_nop()
239 	old = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);  in ftrace_make_nop()
241 	return ftrace_modify_code(pc, old, new, true);  in ftrace_make_nop()
264 	if (unlikely(atomic_read(&current->tracing_graph_pause)))  in prepare_ftrace_return()
269 	 * No protection against faulting at *parent, which may be seen  in prepare_ftrace_return()
288 	 * and arch_ftrace_get_regs(fregs) will always give a non-NULL pt_regs  in ftrace_graph_func()
303 	unsigned long pc = (unsigned long)&ftrace_graph_call;  in ftrace_modify_graph_caller()  local
306 	branch = aarch64_insn_gen_branch_imm(pc,  in ftrace_modify_graph_caller()
312 		return ftrace_modify_code(pc, nop, branch, true);  in ftrace_modify_graph_caller()
314 		return ftrace_modify_code(pc, branch, nop, true);  in ftrace_modify_graph_caller()