| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame^] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | #include <linux/spinlock.h> |
| 3 | #include <linux/hardirq.h> |
| 4 | #include <linux/ftrace.h> |
| 5 | #include <linux/percpu.h> |
| 6 | #include <linux/init.h> |
| 7 | #include <linux/list.h> |
| 8 | #include <trace/syscall.h> |
| 9 | |
| 10 | #include <asm/ftrace.h> |
| 11 | |
| 12 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 13 | static const u32 ftrace_nop = 0x01000000; |
| 14 | |
| 15 | static u32 ftrace_call_replace(unsigned long ip, unsigned long addr) |
| 16 | { |
| 17 | u32 call; |
| 18 | s32 off; |
| 19 | |
| 20 | off = ((s32)addr - (s32)ip); |
| 21 | call = 0x40000000 | ((u32)off >> 2); |
| 22 | |
| 23 | return call; |
| 24 | } |
| 25 | |
| 26 | static int ftrace_modify_code(unsigned long ip, u32 old, u32 new) |
| 27 | { |
| 28 | u32 replaced; |
| 29 | int faulted; |
| 30 | |
| 31 | __asm__ __volatile__( |
| 32 | "1: cas [%[ip]], %[old], %[new]\n" |
| 33 | " flush %[ip]\n" |
| 34 | " mov 0, %[faulted]\n" |
| 35 | "2:\n" |
| 36 | " .section .fixup,#alloc,#execinstr\n" |
| 37 | " .align 4\n" |
| 38 | "3: sethi %%hi(2b), %[faulted]\n" |
| 39 | " jmpl %[faulted] + %%lo(2b), %%g0\n" |
| 40 | " mov 1, %[faulted]\n" |
| 41 | " .previous\n" |
| 42 | " .section __ex_table,\"a\"\n" |
| 43 | " .align 4\n" |
| 44 | " .word 1b, 3b\n" |
| 45 | " .previous\n" |
| 46 | : "=r" (replaced), [faulted] "=r" (faulted) |
| 47 | : [new] "0" (new), [old] "r" (old), [ip] "r" (ip) |
| 48 | : "memory"); |
| 49 | |
| 50 | if (replaced != old && replaced != new) |
| 51 | faulted = 2; |
| 52 | |
| 53 | return faulted; |
| 54 | } |
| 55 | |
| 56 | int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) |
| 57 | { |
| 58 | unsigned long ip = rec->ip; |
| 59 | u32 old, new; |
| 60 | |
| 61 | old = ftrace_call_replace(ip, addr); |
| 62 | new = ftrace_nop; |
| 63 | return ftrace_modify_code(ip, old, new); |
| 64 | } |
| 65 | |
| 66 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
| 67 | { |
| 68 | unsigned long ip = rec->ip; |
| 69 | u32 old, new; |
| 70 | |
| 71 | old = ftrace_nop; |
| 72 | new = ftrace_call_replace(ip, addr); |
| 73 | return ftrace_modify_code(ip, old, new); |
| 74 | } |
| 75 | |
| 76 | int ftrace_update_ftrace_func(ftrace_func_t func) |
| 77 | { |
| 78 | unsigned long ip = (unsigned long)(&ftrace_call); |
| 79 | u32 old, new; |
| 80 | |
| 81 | old = *(u32 *) &ftrace_call; |
| 82 | new = ftrace_call_replace(ip, (unsigned long)func); |
| 83 | return ftrace_modify_code(ip, old, new); |
| 84 | } |
| 85 | |
| 86 | int __init ftrace_dyn_arch_init(void) |
| 87 | { |
| 88 | return 0; |
| 89 | } |
| 90 | #endif |
| 91 | |
| 92 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| 93 | |
| 94 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 95 | extern void ftrace_graph_call(void); |
| 96 | |
| 97 | int ftrace_enable_ftrace_graph_caller(void) |
| 98 | { |
| 99 | unsigned long ip = (unsigned long)(&ftrace_graph_call); |
| 100 | u32 old, new; |
| 101 | |
| 102 | old = *(u32 *) &ftrace_graph_call; |
| 103 | new = ftrace_call_replace(ip, (unsigned long) &ftrace_graph_caller); |
| 104 | return ftrace_modify_code(ip, old, new); |
| 105 | } |
| 106 | |
| 107 | int ftrace_disable_ftrace_graph_caller(void) |
| 108 | { |
| 109 | unsigned long ip = (unsigned long)(&ftrace_graph_call); |
| 110 | u32 old, new; |
| 111 | |
| 112 | old = *(u32 *) &ftrace_graph_call; |
| 113 | new = ftrace_call_replace(ip, (unsigned long) &ftrace_stub); |
| 114 | |
| 115 | return ftrace_modify_code(ip, old, new); |
| 116 | } |
| 117 | |
| 118 | #endif /* !CONFIG_DYNAMIC_FTRACE */ |
| 119 | |
| 120 | /* |
| 121 | * Hook the return address and push it in the stack of return addrs |
| 122 | * in current thread info. |
| 123 | */ |
| 124 | unsigned long prepare_ftrace_return(unsigned long parent, |
| 125 | unsigned long self_addr, |
| 126 | unsigned long frame_pointer) |
| 127 | { |
| 128 | unsigned long return_hooker = (unsigned long) &return_to_handler; |
| 129 | |
| 130 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
| 131 | return parent + 8UL; |
| 132 | |
| 133 | if (function_graph_enter(parent, self_addr, frame_pointer, NULL)) |
| 134 | return parent + 8UL; |
| 135 | |
| 136 | return return_hooker; |
| 137 | } |
| 138 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |