s390/kprobes: replace kretprobe with rethook

That's an adaptation of commit f3a112c0 ("x86,rethook,kprobes:
Replace kretprobe with rethook on x86") to s390.

Replaces the kretprobe code with rethook on s390. With this patch,
kretprobe on s390 uses the rethook instead of kretprobe specific
trampoline code.
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/Kconfig

@@ -187,6 +187,7 @@ config S390
 	select HAVE_KPROBES
 	select HAVE_KPROBES_ON_FTRACE
 	select HAVE_KRETPROBES
+	select HAVE_RETHOOK
 	select HAVE_KVM
 	select HAVE_LIVEPATCH
 	select HAVE_MEMBLOCK_PHYS_MAP

arch/s390/include/asm/kprobes.h

@@ -70,8 +70,7 @@ struct kprobe_ctlblk {
 };
 
 void arch_remove_kprobe(struct kprobe *p);
-void __kretprobe_trampoline(void);
-void trampoline_probe_handler(struct pt_regs *regs);
+unsigned long arch_rethook_trampoline_callback(struct pt_regs *regs);
 
 int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
 int kprobe_exceptions_notify(struct notifier_block *self,

arch/s390/include/asm/unwind.h

@@ -4,7 +4,7 @@
 
 #include <linux/sched.h>
 #include <linux/ftrace.h>
-#include <linux/kprobes.h>
+#include <linux/rethook.h>
 #include <linux/llist.h>
 #include <asm/ptrace.h>
 #include <asm/stacktrace.h>
@@ -43,13 +43,15 @@ struct unwind_state {
 	bool error;
 };
 
-/* Recover the return address modified by kretprobe and ftrace_graph. */
+/* Recover the return address modified by rethook and ftrace_graph. */
 static inline unsigned long unwind_recover_ret_addr(struct unwind_state *state,
 						    unsigned long ip)
 {
 	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, (void *)state->sp);
-	if (is_kretprobe_trampoline(ip))
-		ip = kretprobe_find_ret_addr(state->task, (void *)state->sp, &state->kr_cur);
+#ifdef CONFIG_RETHOOK
+	if (is_rethook_trampoline(ip))
+		ip = rethook_find_ret_addr(state->task, state->sp, &state->kr_cur);
+#endif
 	return ip;
 }
 

arch/s390/kernel/Makefile

@@ -58,6 +58,7 @@ obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o
 obj-$(CONFIG_KPROBES)		+= kprobes_insn_page.o
 obj-$(CONFIG_KPROBES)		+= mcount.o
+obj-$(CONFIG_RETHOOK)		+= rethook.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o

arch/s390/kernel/kprobes.c

@@ -281,16 +281,6 @@ static void pop_kprobe(struct kprobe_ctlblk *kcb)
 }
 NOKPROBE_SYMBOL(pop_kprobe);
 
-void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
-{
-	ri->ret_addr = (kprobe_opcode_t *)regs->gprs[14];
-	ri->fp = (void *)regs->gprs[15];
-
-	/* Replace the return addr with trampoline addr */
-	regs->gprs[14] = (unsigned long)&__kretprobe_trampoline;
-}
-NOKPROBE_SYMBOL(arch_prepare_kretprobe);
-
 static void kprobe_reenter_check(struct kprobe_ctlblk *kcb, struct kprobe *p)
 {
 	switch (kcb->kprobe_status) {
@@ -371,26 +361,6 @@ static int kprobe_handler(struct pt_regs *regs)
 }
 NOKPROBE_SYMBOL(kprobe_handler);
 
-void arch_kretprobe_fixup_return(struct pt_regs *regs,
-				 kprobe_opcode_t *correct_ret_addr)
-{
-	/* Replace fake return address with real one. */
-	regs->gprs[14] = (unsigned long)correct_ret_addr;
-}
-NOKPROBE_SYMBOL(arch_kretprobe_fixup_return);
-
-/*
- * Called from __kretprobe_trampoline
- */
-void trampoline_probe_handler(struct pt_regs *regs)
-{
-	kretprobe_trampoline_handler(regs, (void *)regs->gprs[15]);
-}
-NOKPROBE_SYMBOL(trampoline_probe_handler);
-
-/* assembler function that handles the kretprobes must not be probed itself */
-NOKPROBE_SYMBOL(__kretprobe_trampoline);
-
 /*
  * Called after single-stepping.  p->addr is the address of the
  * instruction whose first byte has been replaced by the "breakpoint"

arch/s390/kernel/mcount.S

@@ -135,9 +135,9 @@ SYM_FUNC_END(return_to_handler)
 #endif
 #endif /* CONFIG_FUNCTION_TRACER */
 
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_RETHOOK
 
-SYM_FUNC_START(__kretprobe_trampoline)
+SYM_FUNC_START(arch_rethook_trampoline)
 
 	stg	%r14,(__SF_GPRS+8*8)(%r15)
 	lay	%r15,-STACK_FRAME_SIZE(%r15)
@@ -152,16 +152,16 @@ SYM_FUNC_START(__kretprobe_trampoline)
 	epsw	%r2,%r3
 	risbg	%r3,%r2,0,31,32
 	stg	%r3,STACK_PTREGS_PSW(%r15)
-	larl	%r1,__kretprobe_trampoline
+	larl	%r1,arch_rethook_trampoline
 	stg	%r1,STACK_PTREGS_PSW+8(%r15)
 
 	lay	%r2,STACK_PTREGS(%r15)
-	brasl	%r14,trampoline_probe_handler
+	brasl	%r14,arch_rethook_trampoline_callback
 
 	mvc	__SF_EMPTY(16,%r7),STACK_PTREGS_PSW(%r15)
 	lmg	%r0,%r15,STACK_PTREGS_GPRS(%r15)
 	lpswe	__SF_EMPTY(%r15)
 
-SYM_FUNC_END(__kretprobe_trampoline)
+SYM_FUNC_END(arch_rethook_trampoline)
 
-#endif /* CONFIG_KPROBES */
+#endif /* CONFIG_RETHOOK */

arch/s390/kernel/rethook.c

+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <linux/rethook.h>
+#include <linux/kprobes.h>
+
+void arch_rethook_prepare(struct rethook_node *rh, struct pt_regs *regs, bool mcount)
+{
+	rh->ret_addr = regs->gprs[14];
+	rh->frame = regs->gprs[15];
+
+	/* Replace the return addr with trampoline addr */
+	regs->gprs[14] = (unsigned long)&arch_rethook_trampoline;
+}
+NOKPROBE_SYMBOL(arch_rethook_prepare);
+
+void arch_rethook_fixup_return(struct pt_regs *regs,
+			       unsigned long correct_ret_addr)
+{
+	/* Replace fake return address with real one. */
+	regs->gprs[14] = correct_ret_addr;
+}
+NOKPROBE_SYMBOL(arch_rethook_fixup_return);
+
+/*
+ * Called from arch_rethook_trampoline
+ */
+unsigned long arch_rethook_trampoline_callback(struct pt_regs *regs)
+{
+	return rethook_trampoline_handler(regs, regs->gprs[15]);
+}
+NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);
+
+/* assembler function that handles the rethook must not be probed itself */
+NOKPROBE_SYMBOL(arch_rethook_trampoline);

arch/s390/kernel/stacktrace.c

@@ -40,12 +40,12 @@ int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
 		if (!addr)
 			return -EINVAL;
 
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_RETHOOK
 		/*
-		 * Mark stacktraces with kretprobed functions on them
+		 * Mark stacktraces with krethook functions on them
 		 * as unreliable.
 		 */
-		if (state.ip == (unsigned long)__kretprobe_trampoline)
+		if (state.ip == (unsigned long)arch_rethook_trampoline)
 			return -EINVAL;
 #endif
 

arch/s390/lib/test_unwind.c

@@ -47,7 +47,7 @@ static void print_backtrace(char *bt)
 static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs,
 				unsigned long sp)
 {
-	int frame_count, prev_is_func2, seen_func2_func1, seen_kretprobe_trampoline;
+	int frame_count, prev_is_func2, seen_func2_func1, seen_arch_rethook_trampoline;
 	const int max_frames = 128;
 	struct unwind_state state;
 	size_t bt_pos = 0;
@@ -63,7 +63,7 @@ static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs,
 	frame_count = 0;
 	prev_is_func2 = 0;
 	seen_func2_func1 = 0;
-	seen_kretprobe_trampoline = 0;
+	seen_arch_rethook_trampoline = 0;
 	unwind_for_each_frame(&state, task, regs, sp) {
 		unsigned long addr = unwind_get_return_address(&state);
 		char sym[KSYM_SYMBOL_LEN];
@@ -89,8 +89,8 @@ static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs,
 		if (prev_is_func2 && str_has_prefix(sym, "unwindme_func1"))
 			seen_func2_func1 = 1;
 		prev_is_func2 = str_has_prefix(sym, "unwindme_func2");
-		if (str_has_prefix(sym, "__kretprobe_trampoline+0x0/"))
-			seen_kretprobe_trampoline = 1;
+		if (str_has_prefix(sym, "arch_rethook_trampoline+0x0/"))
+			seen_arch_rethook_trampoline = 1;
 	}
 
 	/* Check the results. */
@@ -106,8 +106,8 @@ static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs,
 		kunit_err(current_test, "Maximum number of frames exceeded\n");
 		ret = -EINVAL;
 	}
-	if (seen_kretprobe_trampoline) {
-		kunit_err(current_test, "__kretprobe_trampoline+0x0 in unwinding results\n");
+	if (seen_arch_rethook_trampoline) {
+		kunit_err(current_test, "arch_rethook_trampoline+0x0 in unwinding results\n");
 		ret = -EINVAL;
 	}
 	if (ret || force_bt)