1 files changed, 260 insertions, 0 deletions
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
new file mode 100644
index 00000000000..82ddfd3a75a
--- /dev/null
+++ b/arch/s390/kernel/ftrace.c
@@ -0,0 +1,260 @@
+/*
+ * Dynamic function tracer architecture backend.
+ *
+ * Copyright IBM Corp. 2009
+ *
+ *   Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
+ *
+ */
+
+#include <linux/hardirq.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <trace/syscall.h>
+#include <asm/lowcore.h>
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+void ftrace_disable_code(void);
+void ftrace_disable_return(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"
+	"ftrace_disable_return:\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"
+	"ftrace_disable_return:\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;
+}
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#ifdef CONFIG_DYNAMIC_FTRACE
+/*
+ * Patch the kernel code at ftrace_graph_caller location:
+ * The instruction there is branch relative on condition. The condition mask
+ * is either all ones (always branch aka disable ftrace_graph_caller) or all
+ * zeroes (nop aka enable ftrace_graph_caller).
+ * Instruction format for brc is a7m4xxxx where m is the condition mask.
+ */
+int ftrace_enable_ftrace_graph_caller(void)
+{
+	unsigned short opcode = 0xa704;
+
+	return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+	unsigned short opcode = 0xa7f4;
+
+	return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
+}
+
+static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
+{
+	return addr - (ftrace_disable_return - ftrace_disable_code);
+}
+
+#else /* CONFIG_DYNAMIC_FTRACE */
+
+static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
+{
+	return addr - MCOUNT_OFFSET_RET;
+}
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+/*
+ * Hook the return address and push it in the stack of return addresses
+ * in current thread info.
+ */
+unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent)
+{
+	struct ftrace_graph_ent trace;
+
+	/* Nmi's are currently unsupported. */
+	if (unlikely(in_nmi()))
+		goto out;
+	if (unlikely(atomic_read(&current->tracing_graph_pause)))
+		goto out;
+	if (ftrace_push_return_trace(parent, ip, &trace.depth) == -EBUSY)
+		goto out;
+	trace.func = ftrace_mcount_call_adjust(ip) & PSW_ADDR_INSN;
+	/* Only trace if the calling function expects to. */
+	if (!ftrace_graph_entry(&trace)) {
+		current->curr_ret_stack--;
+		goto out;
+	}
+	parent = (unsigned long)return_to_handler;
+out:
+	return parent;
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
+#ifdef CONFIG_FTRACE_SYSCALLS
+
+extern unsigned long __start_syscalls_metadata[];
+extern unsigned long __stop_syscalls_metadata[];
+extern unsigned int sys_call_table[];
+
+static struct syscall_metadata **syscalls_metadata;
+
+struct syscall_metadata *syscall_nr_to_meta(int nr)
+{
+	if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
+		return NULL;
+
+	return syscalls_metadata[nr];
+}
+
+static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
+{
+	struct syscall_metadata *start;
+	struct syscall_metadata *stop;
+	char str[KSYM_SYMBOL_LEN];
+
+	start = (struct syscall_metadata *)__start_syscalls_metadata;
+	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
+	kallsyms_lookup(syscall, NULL, NULL, NULL, str);
+
+	for ( ; start < stop; start++) {
+		if (start->name && !strcmp(start->name + 3, str + 3))
+			return start;
+	}
+	return NULL;
+}
+
+void arch_init_ftrace_syscalls(void)
+{
+	struct syscall_metadata *meta;
+	int i;
+	static atomic_t refs;
+
+	if (atomic_inc_return(&refs) != 1)
+		goto out;
+	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) * NR_syscalls,
+				    GFP_KERNEL);
+	if (!syscalls_metadata)
+		goto out;
+	for (i = 0; i < NR_syscalls; i++) {
+		meta = find_syscall_meta((unsigned long)sys_call_table[i]);
+		syscalls_metadata[i] = meta;
+	}
+	return;
+out:
+	atomic_dec(&refs);
+}
+#endif