Merge tag 'v4.20-rc2' into next-general
[linux-2.6-microblaze.git] / arch / riscv / kernel / mcount.S
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright (C) 2017 Andes Technology Corporation */
3
4 #include <linux/init.h>
5 #include <linux/linkage.h>
6 #include <asm/asm.h>
7 #include <asm/csr.h>
8 #include <asm/unistd.h>
9 #include <asm/thread_info.h>
10 #include <asm/asm-offsets.h>
11 #include <asm-generic/export.h>
12 #include <asm/ftrace.h>
13
14         .text
15
16         .macro SAVE_ABI_STATE
17         addi    sp, sp, -16
18         sd      s0, 0(sp)
19         sd      ra, 8(sp)
20         addi    s0, sp, 16
21         .endm
22
23         /*
24          * The call to ftrace_return_to_handler would overwrite the return
25          * register if a0 was not saved.
26          */
27         .macro SAVE_RET_ABI_STATE
28         addi    sp, sp, -32
29         sd      s0, 16(sp)
30         sd      ra, 24(sp)
31         sd      a0, 8(sp)
32         addi    s0, sp, 32
33         .endm
34
35         .macro RESTORE_ABI_STATE
36         ld      ra, 8(sp)
37         ld      s0, 0(sp)
38         addi    sp, sp, 16
39         .endm
40
41         .macro RESTORE_RET_ABI_STATE
42         ld      ra, 24(sp)
43         ld      s0, 16(sp)
44         ld      a0, 8(sp)
45         addi    sp, sp, 32
46         .endm
47
48 ENTRY(ftrace_stub)
49 #ifdef CONFIG_DYNAMIC_FTRACE
50        .global _mcount
51        .set    _mcount, ftrace_stub
52 #endif
53         ret
54 ENDPROC(ftrace_stub)
55
56 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
57 ENTRY(return_to_handler)
58 /*
59  * On implementing the frame point test, the ideal way is to compare the
60  * s0 (frame pointer, if enabled) on entry and the sp (stack pointer) on return.
61  * However, the psABI of variable-length-argument functions does not allow this.
62  *
63  * So alternatively we check the *old* frame pointer position, that is, the
64  * value stored in -16(s0) on entry, and the s0 on return.
65  */
66 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
67         mv      t6, s0
68 #endif
69         SAVE_RET_ABI_STATE
70 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
71         mv      a0, t6
72 #endif
73         call    ftrace_return_to_handler
74         mv      a1, a0
75         RESTORE_RET_ABI_STATE
76         jalr    a1
77 ENDPROC(return_to_handler)
78 #endif
79
80 #ifndef CONFIG_DYNAMIC_FTRACE
81 ENTRY(_mcount)
82         la      t4, ftrace_stub
83 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
84         la      t0, ftrace_graph_return
85         ld      t1, 0(t0)
86         bne     t1, t4, do_ftrace_graph_caller
87
88         la      t3, ftrace_graph_entry
89         ld      t2, 0(t3)
90         la      t6, ftrace_graph_entry_stub
91         bne     t2, t6, do_ftrace_graph_caller
92 #endif
93         la      t3, ftrace_trace_function
94         ld      t5, 0(t3)
95         bne     t5, t4, do_trace
96         ret
97
98 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
99 /*
100  * A pseudo representation for the function graph tracer:
101  * prepare_to_return(&ra_to_caller_of_caller, ra_to_caller)
102  */
103 do_ftrace_graph_caller:
104         addi    a0, s0, -8
105         mv      a1, ra
106 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
107         ld      a2, -16(s0)
108 #endif
109         SAVE_ABI_STATE
110         call    prepare_ftrace_return
111         RESTORE_ABI_STATE
112         ret
113 #endif
114
115 /*
116  * A pseudo representation for the function tracer:
117  * (*ftrace_trace_function)(ra_to_caller, ra_to_caller_of_caller)
118  */
119 do_trace:
120         ld      a1, -8(s0)
121         mv      a0, ra
122
123         SAVE_ABI_STATE
124         jalr    t5
125         RESTORE_ABI_STATE
126         ret
127 ENDPROC(_mcount)
128 #endif
129 EXPORT_SYMBOL(_mcount)