Probes update for v6.13:

Kprobes cleanups. Functionality does not change.
 - kprobes: Cleanup the config comment
   Adjust #endif comments.
 - kprobes: Cleanup collect_one_slot() and __disable_kprobe()
   Make fail fast to reduce code nested level.
 - kprobes: Use struct_size() in __get_insn_slot()
   Use struct_size() to avoid special macro.
 - x86/kprobes: Cleanup kprobes on ftrace code
   Use macro instead of direct field access/magic number, and avoid
   redundant instruction pointer setting.
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Merge tag 'probes-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes updates from Masami Hiramatsu:
 "Kprobes cleanups. Functionality does not change.

   - kprobes: Cleanup the config comment

     Adjust #endif comments.

   - kprobes: Cleanup collect_one_slot() and __disable_kprobe()

     Make fail fast to reduce code nested level.

   - kprobes: Use struct_size() in __get_insn_slot()

     Use struct_size() to avoid special macro.

   - x86/kprobes: Cleanup kprobes on ftrace code

     Use macro instead of direct field access/magic number, and avoid
     redundant instruction pointer setting"

* tag 'probes-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  x86/kprobes: Cleanup kprobes on ftrace code
  kprobes: Use struct_size() in __get_insn_slot()
  kprobes: Cleanup collect_one_slot() and __disable_kprobe()
  kprobes: Cleanup the config comment

arch/x86/kernel/kprobes/ftrace.c

@@ -9,6 +9,7 @@
 #include <linux/hardirq.h>
 #include <linux/preempt.h>
 #include <linux/ftrace.h>
+#include <asm/text-patching.h>
 
 #include "common.h"
 
@@ -36,23 +37,25 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 	if (kprobe_running()) {
 		kprobes_inc_nmissed_count(p);
 	} else {
-		unsigned long orig_ip = regs->ip;
+		unsigned long orig_ip = instruction_pointer(regs);
+
 		/* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
-		regs->ip = ip + sizeof(kprobe_opcode_t);
+		instruction_pointer_set(regs, ip + INT3_INSN_SIZE);
 
 		__this_cpu_write(current_kprobe, p);
 		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 		if (!p->pre_handler || !p->pre_handler(p, regs)) {
+			if (unlikely(p->post_handler)) {
 				/*
 				 * Emulate singlestep (and also recover regs->ip)
 				 * as if there is a 5byte nop
 				 */
-			regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
+				instruction_pointer_set(regs, ip + MCOUNT_INSN_SIZE);
-			if (unlikely(p->post_handler)) {
 				kcb->kprobe_status = KPROBE_HIT_SSDONE;
 				p->post_handler(p, regs, 0);
 			}
-			regs->ip = orig_ip;
+			/* Recover IP address */
+			instruction_pointer_set(regs, orig_ip);
 		}
 		/*
 		 * If pre_handler returns !0, it changes regs->ip. We have to

kernel/kprobes.c

@@ -95,10 +95,6 @@ struct kprobe_insn_page {
 	char slot_used[];
 };
 
-#define KPROBE_INSN_PAGE_SIZE(slots)			\
-	(offsetof(struct kprobe_insn_page, slot_used) +	\
-	 (sizeof(char) * (slots)))
-
 static int slots_per_page(struct kprobe_insn_cache *c)
 {
 	return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
@@ -175,7 +171,7 @@ kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
 		goto retry;
 
 	/* All out of space.  Need to allocate a new page. */
-	kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
+	kip = kmalloc(struct_size(kip, slot_used, slots_per_page(c)), GFP_KERNEL);
 	if (!kip)
 		goto out;
 
@@ -206,7 +202,9 @@ static bool collect_one_slot(struct kprobe_insn_page *kip, int idx)
 {
 	kip->slot_used[idx] = SLOT_CLEAN;
 	kip->nused--;
-	if (kip->nused == 0) {
+	if (kip->nused != 0)
+		return false;
+
 	/*
 	 * Page is no longer in use.  Free it unless
 	 * it's the last one.  We keep the last one
@@ -228,8 +226,6 @@ static bool collect_one_slot(struct kprobe_insn_page *kip, int idx)
 	}
 	return true;
 }
-	return false;
-}
 
 static int collect_garbage_slots(struct kprobe_insn_cache *c)
 {
@@ -353,8 +349,8 @@ struct kprobe_insn_cache kprobe_optinsn_slots = {
 	/* .insn_size is initialized later */
 	.nr_garbage = 0,
 };
-#endif
+#endif /* CONFIG_OPTPROBES */
-#endif
+#endif /* __ARCH_WANT_KPROBES_INSN_SLOT */
 
 /* We have preemption disabled.. so it is safe to use __ versions */
 static inline void set_kprobe_instance(struct kprobe *kp)
@@ -1543,7 +1539,7 @@ static int check_ftrace_location(struct kprobe *p)
 	if (ftrace_location(addr) == addr) {
 #ifdef CONFIG_KPROBES_ON_FTRACE
 		p->flags |= KPROBE_FLAG_FTRACE;
-#else	/* !CONFIG_KPROBES_ON_FTRACE */
+#else
 		return -EINVAL;
 #endif
 	}
@@ -1725,7 +1721,9 @@ static struct kprobe *__disable_kprobe(struct kprobe *p)
 	if (unlikely(orig_p == NULL))
 		return ERR_PTR(-EINVAL);
 
-	if (!kprobe_disabled(p)) {
+	if (kprobe_disabled(p))
+		return orig_p;
+
 	/* Disable probe if it is a child probe */
 	if (p != orig_p)
 		p->flags |= KPROBE_FLAG_DISABLED;
@@ -1747,7 +1745,6 @@ static struct kprobe *__disable_kprobe(struct kprobe *p)
 		}
 		orig_p->flags |= KPROBE_FLAG_DISABLED;
 	}
-	}
 
 	return orig_p;
 }