LoongArch: Replace kretprobe with rethook

This is an adaptation of commit f3a112c0c4 ("x86,rethook,kprobes:
Replace kretprobe with rethook on x86") and commit b57c2f1240 ("riscv:
add riscv rethook implementation") to LoongArch. Mainly refer to commit
b57c2f1240 ("riscv: add riscv rethook implementation").

Replaces the kretprobe code with rethook on LoongArch. With this patch,
kretprobe on LoongArch uses the rethook instead of kretprobe specific
trampoline code.

Signed-off-by: Haoran Jiang <jianghaoran@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/Kconfig

@@ -127,6 +127,7 @@ config LOONGARCH
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
 	select HAVE_REGS_AND_STACK_ACCESS_API
+	select HAVE_RETHOOK
 	select HAVE_RSEQ
 	select HAVE_SAMPLE_FTRACE_DIRECT
 	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI

arch/loongarch/include/asm/kprobes.h

@@ -49,9 +49,6 @@ bool kprobe_fault_handler(struct pt_regs *regs, int trapnr);
 bool kprobe_breakpoint_handler(struct pt_regs *regs);
 bool kprobe_singlestep_handler(struct pt_regs *regs);
 
-void __kretprobe_trampoline(void);
-void *trampoline_probe_handler(struct pt_regs *regs);
-
 #else /* !CONFIG_KPROBES */
 
 static inline bool kprobe_breakpoint_handler(struct pt_regs *regs) { return false; }

arch/loongarch/kernel/Makefile

@@ -28,6 +28,8 @@ ifdef CONFIG_FUNCTION_TRACER
   CFLAGS_REMOVE_inst.o = $(CC_FLAGS_FTRACE)
   CFLAGS_REMOVE_time.o = $(CC_FLAGS_FTRACE)
   CFLAGS_REMOVE_perf_event.o = $(CC_FLAGS_FTRACE)
+  CFLAGS_REMOVE_rethook.o = $(CC_FLAGS_FTRACE)
+  CFLAGS_REMOVE_rethook_trampoline.o = $(CC_FLAGS_FTRACE)
 endif
 
 obj-$(CONFIG_MODULES)		+= module.o module-sections.o
@@ -52,7 +54,8 @@ obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
 obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o perf_regs.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o
 
-obj-$(CONFIG_KPROBES)		+= kprobes.o kprobes_trampoline.o
+obj-$(CONFIG_KPROBES)		+= kprobes.o
+obj-$(CONFIG_RETHOOK)		+= rethook.o rethook_trampoline.o
 
 obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
 

arch/loongarch/kernel/kprobes.c

@@ -378,27 +378,6 @@ int __init arch_init_kprobes(void)
 	return 0;
 }
 
-/* ASM function that handles the kretprobes must not be probed */
-NOKPROBE_SYMBOL(__kretprobe_trampoline);
-
-/* Called from __kretprobe_trampoline */
-void __used *trampoline_probe_handler(struct pt_regs *regs)
-{
-	return (void *)kretprobe_trampoline_handler(regs, NULL);
-}
-NOKPROBE_SYMBOL(trampoline_probe_handler);
-
-void arch_prepare_kretprobe(struct kretprobe_instance *ri,
-			    struct pt_regs *regs)
-{
-	ri->ret_addr = (kprobe_opcode_t *)regs->regs[1];
-	ri->fp = NULL;
-
-	/* Replace the return addr with trampoline addr */
-	regs->regs[1] = (unsigned long)&__kretprobe_trampoline;
-}
-NOKPROBE_SYMBOL(arch_prepare_kretprobe);
-
 int arch_trampoline_kprobe(struct kprobe *p)
 {
 	return 0;

arch/loongarch/kernel/rethook.c

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic return hook for LoongArch.
+ */
+
+#include <linux/kprobes.h>
+#include <linux/rethook.h>
+#include "rethook.h"
+
+/* This is called from arch_rethook_trampoline() */
+unsigned long __used arch_rethook_trampoline_callback(struct pt_regs *regs)
+{
+	return rethook_trampoline_handler(regs, 0);
+}
+NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);
+
+void arch_rethook_prepare(struct rethook_node *rhn, struct pt_regs *regs, bool mcount)
+{
+	rhn->frame = 0;
+	rhn->ret_addr = regs->regs[1];
+
+	/* replace return addr with trampoline */
+	regs->regs[1] = (unsigned long)arch_rethook_trampoline;
+}
+NOKPROBE_SYMBOL(arch_rethook_prepare);
+
+/* ASM function that handles the rethook must not be probed itself */
+NOKPROBE_SYMBOL(arch_rethook_trampoline);

arch/loongarch/kernel/rethook.h

@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LOONGARCH_RETHOOK_H
+#define __LOONGARCH_RETHOOK_H
+
+unsigned long arch_rethook_trampoline_callback(struct pt_regs *regs);
+void arch_rethook_prepare(struct rethook_node *rhn, struct pt_regs *regs, bool mcount);
+
+#endif

arch/loongarch/kernel/rethook_trampoline.S

@@ -75,7 +75,7 @@
 	csrxchg t0, t1, LOONGARCH_CSR_CRMD
 	.endm
 
-SYM_CODE_START(__kretprobe_trampoline)
+SYM_CODE_START(arch_rethook_trampoline)
 	addi.d	sp, sp, -PT_SIZE
 	save_all_base_regs
 
@@ -84,7 +84,7 @@ SYM_CODE_START(__kretprobe_trampoline)
 
 	move a0, sp /* pt_regs */
 
-	bl trampoline_probe_handler
+	bl arch_rethook_trampoline_callback
 
 	/* use the result as the return-address */
 	move ra, a0
@@ -93,4 +93,4 @@ SYM_CODE_START(__kretprobe_trampoline)
 	addi.d	sp, sp, PT_SIZE
 
 	jr ra
-SYM_CODE_END(__kretprobe_trampoline)
+SYM_CODE_END(arch_rethook_trampoline)