csky: Add kprobes supported

This patch enable kprobes, kretprobes, ftrace interface. It utilized
software breakpoint and single step debug exceptions, instructions
simulation on csky.

We use USR_BKPT replace origin instruction, and the kprobe handler
prepares an excutable memory slot for out-of-line execution with a
copy of the original instruction being probed. Most of instructions
could be executed by single-step, but some instructions need origin
pc value to execute and we need software simulate these instructions.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>

4 files changed, 74 insertions, 1 deletions

diff --git a/arch/csky/include/asm/Kbuild b/arch/csky/include/asm/Kbuild
index 4130e3eaa766..59d3186578fd 100644
--- a/arch/csky/include/asm/Kbuild
+++ b/arch/csky/include/asm/Kbuild
@@ -20,7 +20,6 @@ generic-y += irq_regs.h
 generic-y += irq_work.h
 generic-y += kdebug.h
 generic-y += kmap_types.h
-generic-y += kprobes.h
 generic-y += kvm_para.h
 generic-y += linkage.h
 generic-y += local.h
diff --git a/arch/csky/include/asm/kprobes.h b/arch/csky/include/asm/kprobes.h
new file mode 100644
index 000000000000..b647bbde4d6d
--- /dev/null
+++ b/arch/csky/include/asm/kprobes.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASM_CSKY_KPROBES_H
+#define __ASM_CSKY_KPROBES_H
+
+#include <asm-generic/kprobes.h>
+
+#ifdef CONFIG_KPROBES
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/percpu.h>
+
+#define __ARCH_WANT_KPROBES_INSN_SLOT
+#define MAX_INSN_SIZE			1
+
+#define flush_insn_slot(p)		do { } while (0)
+#define kretprobe_blacklist_size	0
+
+#include <asm/probes.h>
+
+struct prev_kprobe {
+	struct kprobe *kp;
+	unsigned int status;
+};
+
+/* Single step context for kprobe */
+struct kprobe_step_ctx {
+	unsigned long ss_pending;
+	unsigned long match_addr;
+};
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+	unsigned int kprobe_status;
+	unsigned long saved_sr;
+	struct prev_kprobe prev_kprobe;
+	struct kprobe_step_ctx ss_ctx;
+};
+
+void arch_remove_kprobe(struct kprobe *p);
+int kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr);
+int kprobe_breakpoint_handler(struct pt_regs *regs);
+int kprobe_single_step_handler(struct pt_regs *regs);
+void kretprobe_trampoline(void);
+void __kprobes *trampoline_probe_handler(struct pt_regs *regs);
+
+#endif /* CONFIG_KPROBES */
+#endif /* __ASM_CSKY_KPROBES_H */
diff --git a/arch/csky/include/asm/probes.h b/arch/csky/include/asm/probes.h
new file mode 100644
index 000000000000..5e526334e6f9
--- /dev/null
+++ b/arch/csky/include/asm/probes.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_CSKY_PROBES_H
+#define __ASM_CSKY_PROBES_H
+
+typedef u32 probe_opcode_t;
+typedef void (probes_handler_t) (u32 opcode, long addr, struct pt_regs *);
+
+/* architecture specific copy of original instruction */
+struct arch_probe_insn {
+	probe_opcode_t *insn;
+	probes_handler_t *handler;
+	/* restore address after simulation */
+	unsigned long restore;
+};
+
+#ifdef CONFIG_KPROBES
+typedef u32 kprobe_opcode_t;
+struct arch_specific_insn {
+	struct arch_probe_insn api;
+};
+#endif
+
+#endif /* __ASM_CSKY_PROBES_H */
diff --git a/arch/csky/include/asm/ptrace.h b/arch/csky/include/asm/ptrace.h
index f16ca256e007..aae5aa96cf54 100644
--- a/arch/csky/include/asm/ptrace.h
+++ b/arch/csky/include/asm/ptrace.h
@@ -13,6 +13,8 @@
 
 #define PS_S	0x80000000 /* Supervisor Mode */
 
+#define USR_BKPT	0x1464
+
 #define arch_has_single_step() (1)
 #define current_pt_regs() \
 ({ (struct pt_regs *)((char *)current_thread_info() + THREAD_SIZE) - 1; })