samples/kprobes: Fix typo in handler_post()

It should use post_handler instead of pre_handler in handler_post().

As Joe Perches suggested, it would be better to use pr_fmt and remove
all the embedded pre/post/fault strings. This would change the style of
the output through.

Fixes: e16c5dd5 ("samples/kprobes: Add s390 case in kprobe example module")
Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Marc Koderer <marc@koderer.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/1621218083-23519-3-git-send-email-yangtiezhu@loongson.cnSigned-off-by: Jonathan Corbet <corbet@lwn.net>

samples/kprobes/kprobe_example.c

@@ -10,6 +10,8 @@
  * whenever kernel_clone() is invoked to create a new process.
  */
 
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/kprobes.h>
@@ -27,32 +29,31 @@ static struct kprobe kp = {
 static int __kprobes handler_pre(struct kprobe *p, struct pt_regs *regs)
 {
 #ifdef CONFIG_X86
-	pr_info("<%s> pre_handler: p->addr = 0x%p, ip = %lx, flags = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, ip = %lx, flags = 0x%lx\n",
 		p->symbol_name, p->addr, regs->ip, regs->flags);
 #endif
 #ifdef CONFIG_PPC
-	pr_info("<%s> pre_handler: p->addr = 0x%p, nip = 0x%lx, msr = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, nip = 0x%lx, msr = 0x%lx\n",
 		p->symbol_name, p->addr, regs->nip, regs->msr);
 #endif
 #ifdef CONFIG_MIPS
-	pr_info("<%s> pre_handler: p->addr = 0x%p, epc = 0x%lx, status = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, epc = 0x%lx, status = 0x%lx\n",
 		p->symbol_name, p->addr, regs->cp0_epc, regs->cp0_status);
 #endif
 #ifdef CONFIG_ARM64
-	pr_info("<%s> pre_handler: p->addr = 0x%p, pc = 0x%lx,"
-			" pstate = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, pstate = 0x%lx\n",
 		p->symbol_name, p->addr, (long)regs->pc, (long)regs->pstate);
 #endif
 #ifdef CONFIG_ARM
-	pr_info("<%s> pre_handler: p->addr = 0x%p, pc = 0x%lx, cpsr = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, cpsr = 0x%lx\n",
 		p->symbol_name, p->addr, (long)regs->ARM_pc, (long)regs->ARM_cpsr);
 #endif
 #ifdef CONFIG_RISCV
-	pr_info("<%s> pre_handler: p->addr = 0x%p, pc = 0x%lx, status = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, status = 0x%lx\n",
 		p->symbol_name, p->addr, regs->epc, regs->status);
 #endif
 #ifdef CONFIG_S390
-	pr_info("<%s> pre_handler: p->addr, 0x%p, ip = 0x%lx, flags = 0x%lx\n",
+	pr_info("<%s> p->addr, 0x%p, ip = 0x%lx, flags = 0x%lx\n",
 		p->symbol_name, p->addr, regs->psw.addr, regs->flags);
 #endif
 
@@ -65,31 +66,31 @@ static void __kprobes handler_post(struct kprobe *p, struct pt_regs *regs,
 				unsigned long flags)
 {
 #ifdef CONFIG_X86
-	pr_info("<%s> post_handler: p->addr = 0x%p, flags = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, flags = 0x%lx\n",
 		p->symbol_name, p->addr, regs->flags);
 #endif
 #ifdef CONFIG_PPC
-	pr_info("<%s> post_handler: p->addr = 0x%p, msr = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, msr = 0x%lx\n",
 		p->symbol_name, p->addr, regs->msr);
 #endif
 #ifdef CONFIG_MIPS
-	pr_info("<%s> post_handler: p->addr = 0x%p, status = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",
 		p->symbol_name, p->addr, regs->cp0_status);
 #endif
 #ifdef CONFIG_ARM64
-	pr_info("<%s> post_handler: p->addr = 0x%p, pstate = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, pstate = 0x%lx\n",
 		p->symbol_name, p->addr, (long)regs->pstate);
 #endif
 #ifdef CONFIG_ARM
-	pr_info("<%s> post_handler: p->addr = 0x%p, cpsr = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, cpsr = 0x%lx\n",
 		p->symbol_name, p->addr, (long)regs->ARM_cpsr);
 #endif
 #ifdef CONFIG_RISCV
-	pr_info("<%s> post_handler: p->addr = 0x%p, status = 0x%lx\n",
+	pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",
 		p->symbol_name, p->addr, regs->status);
 #endif
 #ifdef CONFIG_S390
-	pr_info("<%s> pre_handler: p->addr, 0x%p, flags = 0x%lx\n",
+	pr_info("<%s> p->addr, 0x%p, flags = 0x%lx\n",
 		p->symbol_name, p->addr, regs->flags);
 #endif
 }
@@ -101,7 +102,7 @@ static void __kprobes handler_post(struct kprobe *p, struct pt_regs *regs,
  */
 static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
 {
-	pr_info("fault_handler: p->addr = 0x%p, trap #%d\n", p->addr, trapnr);
+	pr_info("p->addr = 0x%p, trap #%d\n", p->addr, trapnr);
 	/* Return 0 because we don't handle the fault. */
 	return 0;
 }