[S390] ftrace: add dynamic ftrace support
Dynamic ftrace support for s390.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
new file mode 100644
index 0000000..0b81a78
--- /dev/null
+++ b/arch/s390/kernel/ftrace.c
@@ -0,0 +1,132 @@
+/*
+ * Dynamic function tracer architecture backend.
+ *
+ * Copyright IBM Corp. 2009
+ *
+ * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
+ *
+ */
+
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <asm/lowcore.h>
+
+void ftrace_disable_code(void);
+void ftrace_call_code(void);
+void ftrace_nop_code(void);
+
+#define FTRACE_INSN_SIZE 4
+
+#ifdef CONFIG_64BIT
+
+asm(
+ " .align 4\n"
+ "ftrace_disable_code:\n"
+ " j 0f\n"
+ " .word 0x0024\n"
+ " lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
+ " basr %r14,%r1\n"
+ " lg %r14,8(15)\n"
+ " lgr %r0,%r0\n"
+ "0:\n");
+
+asm(
+ " .align 4\n"
+ "ftrace_nop_code:\n"
+ " j .+"__stringify(MCOUNT_INSN_SIZE)"\n");
+
+asm(
+ " .align 4\n"
+ "ftrace_call_code:\n"
+ " stg %r14,8(%r15)\n");
+
+#else /* CONFIG_64BIT */
+
+asm(
+ " .align 4\n"
+ "ftrace_disable_code:\n"
+ " j 0f\n"
+ " l %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
+ " basr %r14,%r1\n"
+ " l %r14,4(%r15)\n"
+ " j 0f\n"
+ " bcr 0,%r7\n"
+ " bcr 0,%r7\n"
+ " bcr 0,%r7\n"
+ " bcr 0,%r7\n"
+ " bcr 0,%r7\n"
+ " bcr 0,%r7\n"
+ "0:\n");
+
+asm(
+ " .align 4\n"
+ "ftrace_nop_code:\n"
+ " j .+"__stringify(MCOUNT_INSN_SIZE)"\n");
+
+asm(
+ " .align 4\n"
+ "ftrace_call_code:\n"
+ " st %r14,4(%r15)\n");
+
+#endif /* CONFIG_64BIT */
+
+static int ftrace_modify_code(unsigned long ip,
+ void *old_code, int old_size,
+ void *new_code, int new_size)
+{
+ unsigned char replaced[MCOUNT_INSN_SIZE];
+
+ /*
+ * Note: Due to modules code can disappear and change.
+ * We need to protect against faulting as well as code
+ * changing. We do this by using the probe_kernel_*
+ * functions.
+ * This however is just a simple sanity check.
+ */
+ if (probe_kernel_read(replaced, (void *)ip, old_size))
+ return -EFAULT;
+ if (memcmp(replaced, old_code, old_size) != 0)
+ return -EINVAL;
+ if (probe_kernel_write((void *)ip, new_code, new_size))
+ return -EPERM;
+ return 0;
+}
+
+static int ftrace_make_initial_nop(struct module *mod, struct dyn_ftrace *rec,
+ unsigned long addr)
+{
+ return ftrace_modify_code(rec->ip,
+ ftrace_call_code, FTRACE_INSN_SIZE,
+ ftrace_disable_code, MCOUNT_INSN_SIZE);
+}
+
+int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
+ unsigned long addr)
+{
+ if (addr == MCOUNT_ADDR)
+ return ftrace_make_initial_nop(mod, rec, addr);
+ return ftrace_modify_code(rec->ip,
+ ftrace_call_code, FTRACE_INSN_SIZE,
+ ftrace_nop_code, FTRACE_INSN_SIZE);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ return ftrace_modify_code(rec->ip,
+ ftrace_nop_code, FTRACE_INSN_SIZE,
+ ftrace_call_code, FTRACE_INSN_SIZE);
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+ ftrace_dyn_func = (unsigned long)func;
+ return 0;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+ *(unsigned long *)data = 0;
+ return 0;
+}