projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1c873be7 MF |
1 | /* |
| 2 | * mcount and friends -- ftrace stuff | |
| 3 | * | |
| 4 | * Copyright (C) 2009 Analog Devices Inc. | |
| 5 | * Licensed under the GPL-2 or later. | |
| 6 | */ | |
| 7 | ||
| 8 | #include <linux/linkage.h> | |
| 9 | #include <asm/ftrace.h> | |
| 10 | ||
| 11 | .text | |
| 12 | ||
| 13 | /* GCC will have called us before setting up the function prologue, so we | |
| 14 | * can clobber the normal scratch registers, but we need to make sure to | |
| 15 | * save/restore the registers used for argument passing (R0-R2) in case | |
| 16 | * the profiled function is using them. With data registers, R3 is the | |
| 17 | * only one we can blow away. With pointer registers, we have P0-P2. | |
| 18 | * | |
| 19 | * Upon entry, the RETS will point to the top of the current profiled | |
| 5bf9cbef YL |
20 | * function. And since GCC pushed the previous RETS for us, the previous |
| 21 | * function will be waiting there. mmmm pie. | |
| 1c873be7 MF |
22 | */ |
| 23 | ENTRY(__mcount) | |
| 24 | /* save third function arg early so we can do testing below */ | |
| 25 | [--sp] = r2; | |
| 26 | ||
| 27 | /* load the function pointer to the tracer */ | |
| 28 | p0.l = _ftrace_trace_function; | |
| 29 | p0.h = _ftrace_trace_function; | |
| 30 | r3 = [p0]; | |
| 31 | ||
| 32 | /* optional micro optimization: don't call the stub tracer */ | |
| 33 | r2.l = _ftrace_stub; | |
| 34 | r2.h = _ftrace_stub; | |
| 35 | cc = r2 == r3; | |
| 36 | if ! cc jump .Ldo_trace; | |
| 37 | ||
| 1ee76d7e MF |
38 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| 39 | /* if the ftrace_graph_return function pointer is not set to | |
| 40 | * the ftrace_stub entry, call prepare_ftrace_return(). | |
| 41 | */ | |
| 42 | p0.l = _ftrace_graph_return; | |
| 43 | p0.h = _ftrace_graph_return; | |
| 44 | r3 = [p0]; | |
| 45 | cc = r2 == r3; | |
| 46 | if ! cc jump _ftrace_graph_caller; | |
| 47 | ||
| 48 | /* similarly, if the ftrace_graph_entry function pointer is not | |
| 49 | * set to the ftrace_graph_entry_stub entry, ... | |
| 50 | */ | |
| 51 | p0.l = _ftrace_graph_entry; | |
| 52 | p0.h = _ftrace_graph_entry; | |
| 53 | r2.l = _ftrace_graph_entry_stub; | |
| 54 | r2.h = _ftrace_graph_entry_stub; | |
| 55 | r3 = [p0]; | |
| 56 | cc = r2 == r3; | |
| 57 | if ! cc jump _ftrace_graph_caller; | |
| 58 | #endif | |
| 59 | ||
| 1c873be7 MF |
60 | r2 = [sp++]; |
| 61 | rts; | |
| 62 | ||
| 63 | .Ldo_trace: | |
| 64 | ||
| 65 | /* save first/second function arg and the return register */ | |
| 66 | [--sp] = r0; | |
| 67 | [--sp] = r1; | |
| 68 | [--sp] = rets; | |
| 69 | ||
| 70 | /* setup the tracer function */ | |
| 71 | p0 = r3; | |
| 72 | ||
| 5bf9cbef YL |
73 | /* function_trace_call(unsigned long ip, unsigned long parent_ip): |
| 74 | * ip: this point was called by ... | |
| 75 | * parent_ip: ... this function | |
| 76 | * the ip itself will need adjusting for the mcount call | |
| 1c873be7 | 77 | */ |
| 5bf9cbef YL |
78 | r0 = rets; |
| 79 | r1 = [sp + 16]; /* skip the 4 local regs on stack */ | |
| 80 | r0 += -MCOUNT_INSN_SIZE; | |
| 1c873be7 MF |
81 | |
| 82 | /* call the tracer */ | |
| 83 | call (p0); | |
| 84 | ||
| 85 | /* restore state and get out of dodge */ | |
| 1ee76d7e | 86 | .Lfinish_trace: |
| 1c873be7 MF |
87 | rets = [sp++]; |
| 88 | r1 = [sp++]; | |
| 89 | r0 = [sp++]; | |
| 90 | r2 = [sp++]; | |
| 91 | ||
| 92 | .globl _ftrace_stub | |
| 93 | _ftrace_stub: | |
| 94 | rts; | |
| 95 | ENDPROC(__mcount) | |
| 1ee76d7e MF |
96 | |
| 97 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
| 98 | /* The prepare_ftrace_return() function is similar to the trace function | |
| 99 | * except it takes a pointer to the location of the frompc. This is so | |
| 100 | * the prepare_ftrace_return() can hijack it temporarily for probing | |
| 101 | * purposes. | |
| 102 | */ | |
| 103 | ENTRY(_ftrace_graph_caller) | |
| 104 | /* save first/second function arg and the return register */ | |
| 105 | [--sp] = r0; | |
| 106 | [--sp] = r1; | |
| 107 | [--sp] = rets; | |
| 108 | ||
| 5bf9cbef YL |
109 | /* prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) */ |
| 110 | r0 = sp; | |
| 1ee76d7e | 111 | r1 = rets; |
| 5bf9cbef | 112 | r0 += 16; /* skip the 4 local regs on stack */ |
| 1ee76d7e MF |
113 | r1 += -MCOUNT_INSN_SIZE; |
| 114 | call _prepare_ftrace_return; | |
| 115 | ||
| 116 | jump .Lfinish_trace; | |
| 117 | ENDPROC(_ftrace_graph_caller) | |
| 118 | ||
| 119 | /* Undo the rewrite caused by ftrace_graph_caller(). The common function | |
| 120 | * ftrace_return_to_handler() will return the original rets so we can | |
| 121 | * restore it and be on our way. | |
| 122 | */ | |
| 123 | ENTRY(_return_to_handler) | |
| 124 | /* make sure original return values are saved */ | |
| 125 | [--sp] = p0; | |
| 126 | [--sp] = r0; | |
| 127 | [--sp] = r1; | |
| 128 | ||
| 129 | /* get original return address */ | |
| 130 | call _ftrace_return_to_handler; | |
| 131 | rets = r0; | |
| 132 | ||
| 133 | /* anomaly 05000371 - make sure we have at least three instructions | |
| 134 | * between rets setting and the return | |
| 135 | */ | |
| 136 | r1 = [sp++]; | |
| 137 | r0 = [sp++]; | |
| 138 | p0 = [sp++]; | |
| 139 | rts; | |
| 140 | ENDPROC(_return_to_handler) | |
| 141 | #endif |