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-rw-r--r--arch/microblaze/kernel/ftrace.c151
1 files changed, 151 insertions, 0 deletions
diff --git a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c
new file mode 100644
index 000000000000..c1889b101cb8
--- /dev/null
+++ b/arch/microblaze/kernel/ftrace.c
@@ -0,0 +1,151 @@
+/*
+ * Ftrace support for Microblaze.
+ *
+ * Copyright (C) 2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2009 PetaLogix
+ *
+ * Based on MIPS and PowerPC ftrace code
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <asm/cacheflush.h>
+#include <linux/ftrace.h>
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+/* save value to addr - it is save to do it in asm */
+static int ftrace_modify_code(unsigned long addr, unsigned int value)
+{
+ int faulted = 0;
+
+ __asm__ __volatile__(" 1: swi %2, %1, 0; \
+ addik %0, r0, 0; \
+ 2: \
+ .section .fixup, \"ax\"; \
+ 3: brid 2b; \
+ addik %0, r0, 1; \
+ .previous; \
+ .section __ex_table,\"a\"; \
+ .word 1b,3b; \
+ .previous;" \
+ : "=r" (faulted)
+ : "r" (addr), "r" (value)
+ );
+
+ if (unlikely(faulted))
+ return -EFAULT;
+
+ return 0;
+}
+
+#define MICROBLAZE_NOP 0x80000000
+#define MICROBLAZE_BRI 0xb800000C
+
+static unsigned int recorded; /* if save was or not */
+static unsigned int imm; /* saving whole imm instruction */
+
+/* There are two approaches howto solve ftrace_make nop function - look below */
+#undef USE_FTRACE_NOP
+
+#ifdef USE_FTRACE_NOP
+static unsigned int bralid; /* saving whole bralid instruction */
+#endif
+
+int ftrace_make_nop(struct module *mod,
+ struct dyn_ftrace *rec, unsigned long addr)
+{
+ /* we have this part of code which we are working with
+ * b000c000 imm -16384
+ * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
+ * 80000000 or r0, r0, r0
+ *
+ * The first solution (!USE_FTRACE_NOP-could be called branch solution)
+ * b000c000 bri 12 (0xC - jump to any other instruction)
+ * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
+ * 80000000 or r0, r0, r0
+ * any other instruction
+ *
+ * The second solution (USE_FTRACE_NOP) - no jump just nops
+ * 80000000 or r0, r0, r0
+ * 80000000 or r0, r0, r0
+ * 80000000 or r0, r0, r0
+ */
+ int ret = 0;
+
+ if (recorded == 0) {
+ recorded = 1;
+ imm = *(unsigned int *)rec->ip;
+ pr_debug("%s: imm:0x%x\n", __func__, imm);
+#ifdef USE_FTRACE_NOP
+ bralid = *(unsigned int *)(rec->ip + 4);
+ pr_debug("%s: bralid 0x%x\n", __func__, bralid);
+#endif /* USE_FTRACE_NOP */
+ }
+
+#ifdef USE_FTRACE_NOP
+ ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
+ ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
+#else /* USE_FTRACE_NOP */
+ ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
+#endif /* USE_FTRACE_NOP */
+ return ret;
+}
+
+static int ret_addr; /* initialized as 0 by default */
+
+/* I believe that first is called ftrace_make_nop before this function */
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ int ret;
+ ret_addr = addr; /* saving where the barrier jump is */
+ pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
+ __func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
+ ret = ftrace_modify_code(rec->ip, imm);
+#ifdef USE_FTRACE_NOP
+ pr_debug("%s: bralid:0x%x\n", __func__, bralid);
+ ret += ftrace_modify_code(rec->ip + 4, bralid);
+#endif /* USE_FTRACE_NOP */
+ return ret;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+ /* The return code is retured via data */
+ *(unsigned long *)data = 0;
+
+ return 0;
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+ unsigned long ip = (unsigned long)(&ftrace_call);
+ unsigned int upper = (unsigned int)func;
+ unsigned int lower = (unsigned int)func;
+ int ret = 0;
+
+ /* create proper saving to ftrace_call poll */
+ upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
+ lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */
+
+ pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
+ __func__, (unsigned int)func, (unsigned int)ip, upper, lower);
+
+ /* save upper and lower code */
+ ret = ftrace_modify_code(ip, upper);
+ ret += ftrace_modify_code(ip + 4, lower);
+
+ /* We just need to remove the rtsd r15, 8 by NOP */
+ BUG_ON(!ret_addr);
+ if (ret_addr)
+ ret += ftrace_modify_code(ret_addr, MICROBLAZE_NOP);
+ else
+ ret = 1; /* fault */
+
+ /* All changes are done - lets do caches consistent */
+ flush_icache();
+ return ret;
+}
+
+#endif /* CONFIG_DYNAMIC_FTRACE */