#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
#define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */
-#define INSN_B_1F_4 0x10000004 /* b 1f; offset = 4 */
-#define INSN_B_1F_5 0x10000005 /* b 1f; offset = 5 */
#define INSN_NOP 0x00000000 /* nop */
#define INSN_JAL(addr) \
((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK)))
return 0;
}
+/*
+ * The details about the calling site of mcount on MIPS
+ *
+ * 1. For kernel:
+ *
+ * move at, ra
+ * jal _mcount --> nop
+ *
+ * 2. For modules:
+ *
+ * 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT
+ *
+ * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
+ * addiu v1, v1, low_16bit_of_mcount
+ * move at, ra
+ * move $12, ra_address
+ * jalr v1
+ * sub sp, sp, 8
+ * 1: offset = 5 instructions
+ * 2.2 For the Other situations
+ *
+ * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
+ * addiu v1, v1, low_16bit_of_mcount
+ * move at, ra
+ * jalr v1
+ * nop | move $12, ra_address | sub sp, sp, 8
+ * 1: offset = 4 instructions
+ */
+
+#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
+#define MCOUNT_OFFSET_INSNS 5
+#else
+#define MCOUNT_OFFSET_INSNS 4
+#endif
+#define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS)
+
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
* If ip is in kernel space, no long call, otherwise, long call is
* needed.
*/
- if (in_kernel_space(ip)) {
- /*
- * move at, ra
- * jal _mcount --> nop
- */
- new = INSN_NOP;
- } else {
-#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
- /*
- * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
- * addiu v1, v1, low_16bit_of_mcount
- * move at, ra
- * move $12, ra_address
- * jalr v1
- * sub sp, sp, 8
- * 1: offset = 5 instructions
- */
- new = INSN_B_1F_5;
-#else
- /*
- * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
- * addiu v1, v1, low_16bit_of_mcount
- * move at, ra
- * jalr v1
- * nop | move $12, ra_address | sub sp, sp, 8
- * 1: offset = 4 instructions
- */
- new = INSN_B_1F_4;
-#endif
- }
+ new = in_kernel_space(ip) ? INSN_NOP : INSN_B_1F;
+
return ftrace_modify_code(ip, new);
}
struct ftrace_graph_ent trace;
unsigned long return_hooker = (unsigned long)
&return_to_handler;
- int faulted;
+ int faulted, insns;
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
return;
}
- trace.func = self_ra;
+ /*
+ * Get the recorded ip of the current mcount calling site in the
+ * __mcount_loc section, which will be used to filter the function
+ * entries configured through the tracing/set_graph_function interface.
+ */
+
+ insns = in_kernel_space(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;
+ trace.func = self_ra - (MCOUNT_INSN_SIZE * insns);
/* Only trace if the calling function expects to */
if (!ftrace_graph_entry(&trace)) {