1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Copyright (C) 2022 Loongson Technology Corporation Limited
6 #include <asm/ftrace.h>
7 #include <asm/regdef.h>
8 #include <asm/stackframe.h>
12 * Due to -fpatchable-function-entry=2: the compiler inserted 2 NOPs before the
13 * regular C function prologue. When PC arrived here, the last 2 instructions
16 * bl callsite (for modules, callsite is a tramplione)
18 * modules trampoline is as follows:
19 * lu12i.w t1, callsite[31:12]
20 * lu32i.d t1, callsite[51:32]
21 * lu52i.d t1, t1, callsite[63:52]
22 * jirl zero, t1, callsite[11:0] >> 2
24 * See arch/loongarch/kernel/ftrace_dyn.c for details. Here, pay attention to
25 * that the T series regs are available and safe because each C functions
26 * follows the LoongArch's psABI as well.
29 .macro ftrace_regs_entry allregs=0
30 PTR_ADDI sp, sp, -PT_SIZE
31 PTR_S t0, sp, PT_R1 /* Save parent ra at PT_R1(RA) */
61 /* Clear it for later use as a flag sometimes. */
64 PTR_S ra, sp, PT_ERA /* Save trace function ra at PT_ERA */
67 PTR_ADDI t8, sp, PT_SIZE
71 SYM_FUNC_START(ftrace_stub)
73 SYM_FUNC_END(ftrace_stub)
75 SYM_CODE_START(ftrace_common)
76 PTR_ADDI a0, ra, -8 /* arg0: ip */
77 move a1, t0 /* arg1: parent_ip */
78 la.pcrel t1, function_trace_op
79 PTR_L a2, t1, 0 /* arg2: op */
80 move a3, sp /* arg3: regs */
82 SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
84 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
85 SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL)
86 nop /* b ftrace_graph_caller */
90 * As we didn't use S series regs in this assmembly code and all calls
91 * are C function which will save S series regs by themselves, there is
92 * no need to restore S series regs. The T series is available and safe
93 * at the callsite, so there is no need to restore the T series regs.
108 PTR_ADDI sp, sp, PT_SIZE
113 SYM_CODE_END(ftrace_common)
115 SYM_CODE_START(ftrace_caller)
116 ftrace_regs_entry allregs=0
118 SYM_CODE_END(ftrace_caller)
120 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
121 SYM_CODE_START(ftrace_regs_caller)
122 ftrace_regs_entry allregs=1
124 SYM_CODE_END(ftrace_regs_caller)
127 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
128 SYM_CODE_START(ftrace_graph_caller)
130 PTR_ADDI a0, a0, -8 /* arg0: self_addr */
131 PTR_ADDI a1, sp, PT_R1 /* arg1: parent */
132 bl prepare_ftrace_return
133 b ftrace_common_return
134 SYM_CODE_END(ftrace_graph_caller)
136 SYM_CODE_START(return_to_handler)
137 /* Save return value regs */
138 PTR_ADDI sp, sp, -FGRET_REGS_SIZE
139 PTR_S a0, sp, FGRET_REGS_A0
140 PTR_S a1, sp, FGRET_REGS_A1
141 PTR_S zero, sp, FGRET_REGS_FP
144 bl ftrace_return_to_handler
147 /* Restore return value regs */
148 PTR_L a0, sp, FGRET_REGS_A0
149 PTR_L a1, sp, FGRET_REGS_A1
150 PTR_ADDI sp, sp, FGRET_REGS_SIZE
153 SYM_CODE_END(return_to_handler)
156 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
157 SYM_CODE_START(ftrace_stub_direct_tramp)
159 SYM_CODE_END(ftrace_stub_direct_tramp)
160 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */