1 // SPDX-License-Identifier: GPL-2.0-only
15 #include <asm/debug-monitors.h>
24 static int ftrace_modify_code(unsigned long pc, u32 old, u32 new,  in ftrace_modify_code()  argument
32 	 * could cause us to read or write to someplace that could cause harm.  in ftrace_modify_code()
38 		if (aarch64_insn_read((void *)pc, &replaced))  in ftrace_modify_code()
39 			return -EFAULT;  in ftrace_modify_code()
42 			return -EINVAL;  in ftrace_modify_code()
44 	if (aarch64_insn_patch_text_nosync((void *)pc, new))  in ftrace_modify_code()
45 		return -EPERM;  in ftrace_modify_code()
55 	unsigned long pc;  in ftrace_update_ftrace_func()  local
58 	pc = (unsigned long)&ftrace_call;  in ftrace_update_ftrace_func()
59 	new = aarch64_insn_gen_branch_imm(pc, (unsigned long)func,  in ftrace_update_ftrace_func()
62 	return ftrace_modify_code(pc, 0, new, false);  in ftrace_update_ftrace_func()
68 	struct plt_entry *plt = mod->arch.ftrace_trampolines;  in get_ftrace_plt()
84 	unsigned long pc = rec->ip;  in ftrace_make_call()  local
86 	long offset = (long)pc - (long)addr;  in ftrace_make_call()
88 	if (offset < -SZ_128M || offset >= SZ_128M) {  in ftrace_make_call()
93 			return -EINVAL;  in ftrace_make_call()
106 		mod = __module_text_address(pc);  in ftrace_make_call()
110 			return -EINVAL;  in ftrace_make_call()
114 			pr_err("ftrace: no module PLT for %ps\n", (void *)addr);  in ftrace_make_call()
115 			return -EINVAL;  in ftrace_make_call()
122 	new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);  in ftrace_make_call()
124 	return ftrace_modify_code(pc, old, new, true);  in ftrace_make_call()
131 	unsigned long pc = rec->ip;  in ftrace_modify_call()  local
134 	old = aarch64_insn_gen_branch_imm(pc, old_addr,  in ftrace_modify_call()
136 	new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);  in ftrace_modify_call()
138 	return ftrace_modify_code(pc, old, new, true);  in ftrace_modify_call()
143  * All instrumented functions follow the AAPCS, so x0-x8 and x19-x30 are live,
144  * and x9-x18 are free for our use.
146  * At runtime we want to be able to swing a single NOP <-> BL to enable or
152  * +----------+------------+------------+
160  * Note: ftrace_process_locs() has pre-adjusted rec->ip to be the address of
165 	unsigned long pc = rec->ip - AARCH64_INSN_SIZE;  in ftrace_init_nop()  local
172 	return ftrace_modify_code(pc, old, new, true);  in ftrace_init_nop()
182 	unsigned long pc = rec->ip;  in ftrace_make_nop()  local
185 	long offset = (long)pc - (long)addr;  in ftrace_make_nop()
187 	if (offset < -SZ_128M || offset >= SZ_128M) {  in ftrace_make_nop()
191 			return -EINVAL;  in ftrace_make_nop()
195 		 * dealing with an out-of-range condition, we can assume it  in ftrace_make_nop()
200 			mod = __module_text_address(pc);  in ftrace_make_nop()
204 				return -EINVAL;  in ftrace_make_nop()
214 		if (aarch64_insn_read((void *)pc, &replaced))  in ftrace_make_nop()
215 			return -EFAULT;  in ftrace_make_nop()
218 		    !within_module(pc + aarch64_get_branch_offset(replaced),  in ftrace_make_nop()
220 			return -EINVAL;  in ftrace_make_nop()
224 		old = aarch64_insn_gen_branch_imm(pc, addr,  in ftrace_make_nop()
230 	return ftrace_modify_code(pc, old, new, validate);  in ftrace_make_nop()
260 	if (unlikely(atomic_read(&current->tracing_graph_pause)))  in prepare_ftrace_return()
265 	 * No protection against faulting at *parent, which may be seen  in prepare_ftrace_return()
281 	unsigned long pc = (unsigned long)&ftrace_graph_call;  in ftrace_modify_graph_caller()  local
284 	branch = aarch64_insn_gen_branch_imm(pc,  in ftrace_modify_graph_caller()
290 		return ftrace_modify_code(pc, nop, branch, true);  in ftrace_modify_graph_caller()
292 		return ftrace_modify_code(pc, branch, nop, true);  in ftrace_modify_graph_caller()