AI Trajectory

null

{
  "EnableConfigs": [
    "UPROBES"
  ],
  "FocusSymbols": [
    "prepare_uretprobe",
    "hprobe_expire",
    "hprobe_finalize",
    "ri_timer",
    "dup_utask",
    "free_ret_instance",
    "uprobe_handle_trampoline"
  ],
  "Reasoning": "The patch modifies the uprobes subsystem to use the new fast up/down SRCU read lock variants (`srcu_down_read_fast` and `srcu_up_read_fast`) for `uretprobes_srcu`. This is a functional change in core kernel logic that affects how uprobes are leased and expired, particularly during task duplication and timer callbacks. It is reachable and should be fuzzed.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 509aadd4c1d5e4cf812760ec27c3646d8f89e44d\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Tue Jul 7 01:15:38 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/include/linux/srcu.h b/include/linux/srcu.h\nindex a54ce9e808b92c..72c86d3b23f2e4 100644\n--- a/include/linux/srcu.h\n+++ b/include/linux/srcu.h\n@@ -638,4 +638,11 @@ DEFINE_LOCK_GUARD_1(srcu_fast_notrace, struct srcu_struct,\n DECLARE_LOCK_GUARD_1_ATTRS(srcu_fast_notrace, __acquires_shared(_T), __releases_shared(*(struct srcu_struct **)_T))\n #define class_srcu_fast_notrace_constructor(_T) WITH_LOCK_GUARD_1_ATTRS(srcu_fast_notrace, _T)\n \n+DEFINE_LOCK_GUARD_1(srcu_fast_updown, struct srcu_struct,\n+\t\t    _T-\u003escp = srcu_read_lock_fast_updown(_T-\u003elock),\n+\t\t    srcu_read_unlock_fast_updown(_T-\u003elock, _T-\u003escp),\n+\t\t    struct srcu_ctr __percpu *scp)\n+DECLARE_LOCK_GUARD_1_ATTRS(srcu_fast_updown, __acquires_shared(_T), __releases_shared(*(struct srcu_struct **)_T))\n+#define class_srcu_fast_updown_constructor(_T) WITH_LOCK_GUARD_1_ATTRS(srcu_fast_updown, _T)\n+\n #endif\ndiff --git a/include/linux/uprobes.h b/include/linux/uprobes.h\nindex f548fea2adec8f..f3b07753c2f3d8 100644\n--- a/include/linux/uprobes.h\n+++ b/include/linux/uprobes.h\n@@ -25,6 +25,7 @@ struct mm_struct;\n struct inode;\n struct notifier_block;\n struct page;\n+struct srcu_ctr;\n \n /*\n  * Allowed return values from uprobe consumer's handler callback\n@@ -106,7 +107,7 @@ enum hprobe_state {\n  *     underlying uprobe is not guaranteed anymore. __UPROBE_DEAD is just an\n  *     internal marker and is handled transparently by hprobe_fetch() helper.\n  *\n- * When uprobe is SRCU-protected, we also record srcu_idx value, necessary for\n+ * When uprobe is SRCU-protected, we also record srcu_scp value, necessary for\n  * SRCU unlocking.\n  *\n  * See hprobe_expire() and hprobe_fetch() for details of race-free uprobe\n@@ -115,7 +116,7 @@ enum hprobe_state {\n  */\n struct hprobe {\n \tenum hprobe_state state;\n-\tint srcu_idx;\n+\tstruct srcu_ctr __percpu *srcu_scp;\n \tstruct uprobe *uprobe;\n };\n \ndiff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c\nindex 4084e926e28448..afa491b0bd3f90 100644\n--- a/kernel/events/uprobes.c\n+++ b/kernel/events/uprobes.c\n@@ -54,7 +54,7 @@ static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ];\n DEFINE_STATIC_PERCPU_RWSEM(dup_mmap_sem);\n \n /* Covers return_instance's uprobe lifetime. */\n-DEFINE_STATIC_SRCU(uretprobes_srcu);\n+DEFINE_STATIC_SRCU_FAST_UPDOWN(uretprobes_srcu);\n \n /* Have a copy of original instruction */\n #define UPROBE_COPY_INSN\t0\n@@ -707,12 +707,13 @@ static void put_uprobe(struct uprobe *uprobe)\n }\n \n /* Initialize hprobe as SRCU-protected \"leased\" uprobe */\n-static void hprobe_init_leased(struct hprobe *hprobe, struct uprobe *uprobe, int srcu_idx)\n+static void hprobe_init_leased(struct hprobe *hprobe, struct uprobe *uprobe,\n+\t\t\t       struct srcu_ctr __percpu *srcu_scp)\n {\n \tWARN_ON(!uprobe);\n \thprobe-\u003estate = HPROBE_LEASED;\n \thprobe-\u003euprobe = uprobe;\n-\thprobe-\u003esrcu_idx = srcu_idx;\n+\thprobe-\u003esrcu_scp = srcu_scp;\n }\n \n /* Initialize hprobe as refcounted (\"stable\") uprobe (uprobe can be NULL). */\n@@ -720,7 +721,7 @@ static void hprobe_init_stable(struct hprobe *hprobe, struct uprobe *uprobe)\n {\n \thprobe-\u003estate = uprobe ? HPROBE_STABLE : HPROBE_GONE;\n \thprobe-\u003euprobe = uprobe;\n-\thprobe-\u003esrcu_idx = -1;\n+\thprobe-\u003esrcu_scp = NULL;\n }\n \n /*\n@@ -757,7 +758,7 @@ static void hprobe_finalize(struct hprobe *hprobe, enum hprobe_state hstate)\n {\n \tswitch (hstate) {\n \tcase HPROBE_LEASED:\n-\t\t__srcu_read_unlock(\u0026uretprobes_srcu, hprobe-\u003esrcu_idx);\n+\t\tsrcu_up_read_fast(\u0026uretprobes_srcu, hprobe-\u003esrcu_scp);\n \t\tbreak;\n \tcase HPROBE_STABLE:\n \t\tput_uprobe(hprobe-\u003euprobe);\n@@ -829,7 +830,7 @@ static struct uprobe *hprobe_expire(struct hprobe *hprobe, bool get)\n \t\t */\n \t\tif (try_cmpxchg(\u0026hprobe-\u003estate, \u0026hstate, uprobe ? HPROBE_STABLE : HPROBE_GONE)) {\n \t\t\t/* We won the race, we are the ones to unlock SRCU */\n-\t\t\t__srcu_read_unlock(\u0026uretprobes_srcu, hprobe-\u003esrcu_idx);\n+\t\t\tsrcu_up_read_fast(\u0026uretprobes_srcu, hprobe-\u003esrcu_scp);\n \t\t\treturn get ? get_uprobe(uprobe) : uprobe;\n \t\t}\n \n@@ -2045,7 +2046,7 @@ static void ri_timer(struct timer_list *timer)\n \tstruct return_instance *ri;\n \n \t/* SRCU protects uprobe from reuse for the cmpxchg() inside hprobe_expire(). */\n-\tguard(srcu)(\u0026uretprobes_srcu);\n+\tguard(srcu_fast_updown)(\u0026uretprobes_srcu);\n \t/* RCU protects return_instance from freeing. */\n \tguard(rcu)();\n \n@@ -2142,7 +2143,7 @@ static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask)\n \tt-\u003eutask = n_utask;\n \n \t/* protect uprobes from freeing, we'll need try_get_uprobe() them */\n-\tguard(srcu)(\u0026uretprobes_srcu);\n+\tguard(srcu_fast_updown)(\u0026uretprobes_srcu);\n \n \tp = \u0026n_utask-\u003ereturn_instances;\n \tfor (o = o_utask-\u003ereturn_instances; o; o = o-\u003enext) {\n@@ -2254,8 +2255,8 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs,\n {\n \tstruct uprobe_task *utask = current-\u003eutask;\n \tunsigned long orig_ret_vaddr, trampoline_vaddr;\n+\tstruct srcu_ctr __percpu *srcu_scp;\n \tbool chained;\n-\tint srcu_idx;\n \n \tif (!get_xol_area())\n \t\tgoto free;\n@@ -2293,8 +2294,12 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs,\n \t\torig_ret_vaddr = utask-\u003ereturn_instances-\u003eorig_ret_vaddr;\n \t}\n \n-\t/* __srcu_read_lock() because SRCU lock survives switch to user space */\n-\tsrcu_idx = __srcu_read_lock(\u0026uretprobes_srcu);\n+\t/*\n+\t * Use srcu_down_read_fast() because the SRCU lock survives a switch to\n+\t * user space and can be unlocked from a different context by ri_timer()\n+\t * or dup_utask().\n+\t */\n+\tsrcu_scp = srcu_down_read_fast(\u0026uretprobes_srcu);\n \n \tri-\u003efunc = instruction_pointer(regs);\n \tri-\u003estack = user_stack_pointer(regs);\n@@ -2303,7 +2308,7 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs,\n \n \tutask-\u003edepth++;\n \n-\thprobe_init_leased(\u0026ri-\u003ehprobe, uprobe, srcu_idx);\n+\thprobe_init_leased(\u0026ri-\u003ehprobe, uprobe, srcu_scp);\n \tri-\u003enext = utask-\u003ereturn_instances;\n \trcu_assign_pointer(utask-\u003ereturn_instances, ri);\n \n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": [
    "UPROBES"
  ],
  "FocusSymbols": [
    "prepare_uretprobe",
    "hprobe_expire",
    "hprobe_finalize",
    "ri_timer",
    "dup_utask",
    "free_ret_instance",
    "uprobe_handle_trampoline"
  ],
  "Reasoning": "The patch modifies the uprobes subsystem to use the new fast up/down SRCU read lock variants (`srcu_down_read_fast` and `srcu_up_read_fast`) for `uretprobes_srcu`. This is a functional change in core kernel logic that affects how uprobes are leased and expired, particularly during task duplication and timer callbacks. It is reachable and should be fuzzed.",
  "WorthFuzzing": true
}

You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Do not list too generic configs (we already have them enabled). Only list those that
   specifically cover the modified code. List them in the EnableConfigs output array,
   and DO NOT add a 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.


Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.

For your convenience, here is the diff of the changes:
commit 509aadd4c1d5e4cf812760ec27c3646d8f89e44d
Author: syz-cluster <triage@syzkaller.com>
Date:   Tue Jul 7 01:15:38 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index a54ce9e808b92c..72c86d3b23f2e4 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -638,4 +638,11 @@ DEFINE_LOCK_GUARD_1(srcu_fast_notrace, struct srcu_struct,
 DECLARE_LOCK_GUARD_1_ATTRS(srcu_fast_notrace, __acquires_shared(_T), __releases_shared(*(struct srcu_struct **)_T))
 #define class_srcu_fast_notrace_constructor(_T) WITH_LOCK_GUARD_1_ATTRS(srcu_fast_notrace, _T)
 
+DEFINE_LOCK_GUARD_1(srcu_fast_updown, struct srcu_struct,
+		    _T->scp = srcu_read_lock_fast_updown(_T->lock),
+		    srcu_read_unlock_fast_updown(_T->lock, _T->scp),
+		    struct srcu_ctr __percpu *scp)
+DECLARE_LOCK_GUARD_1_ATTRS(srcu_fast_updown, __acquires_shared(_T), __releases_shared(*(struct srcu_struct **)_T))
+#define class_srcu_fast_updown_constructor(_T) WITH_LOCK_GUARD_1_ATTRS(srcu_fast_updown, _T)
+
 #endif
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index f548fea2adec8f..f3b07753c2f3d8 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -25,6 +25,7 @@ struct mm_struct;
 struct inode;
 struct notifier_block;
 struct page;
+struct srcu_ctr;
 
 /*
  * Allowed return values from uprobe consumer's handler callback
@@ -106,7 +107,7 @@ enum hprobe_state {
  *     underlying uprobe is not guaranteed anymore. __UPROBE_DEAD is just an
  *     internal marker and is handled transparently by hprobe_fetch() helper.
  *
- * When uprobe is SRCU-protected, we also record srcu_idx value, necessary for
+ * When uprobe is SRCU-protected, we also record srcu_scp value, necessary for
  * SRCU unlocking.
  *
  * See hprobe_expire() and hprobe_fetch() for details of race-free uprobe
@@ -115,7 +116,7 @@ enum hprobe_state {
  */
 struct hprobe {
 	enum hprobe_state state;
-	int srcu_idx;
+	struct srcu_ctr __percpu *srcu_scp;
 	struct uprobe *uprobe;
 };
 
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 4084e926e28448..afa491b0bd3f90 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -54,7 +54,7 @@ static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ];
 DEFINE_STATIC_PERCPU_RWSEM(dup_mmap_sem);
 
 /* Covers return_instance's uprobe lifetime. */
-DEFINE_STATIC_SRCU(uretprobes_srcu);
+DEFINE_STATIC_SRCU_FAST_UPDOWN(uretprobes_srcu);
 
 /* Have a copy of original instruction */
 #define UPROBE_COPY_INSN	0
@@ -707,12 +707,13 @@ static void put_uprobe(struct uprobe *uprobe)
 }
 
 /* Initialize hprobe as SRCU-protected "leased" uprobe */
-static void hprobe_init_leased(struct hprobe *hprobe, struct uprobe *uprobe, int srcu_idx)
+static void hprobe_init_leased(struct hprobe *hprobe, struct uprobe *uprobe,
+			       struct srcu_ctr __percpu *srcu_scp)
 {
 	WARN_ON(!uprobe);
 	hprobe->state = HPROBE_LEASED;
 	hprobe->uprobe = uprobe;
-	hprobe->srcu_idx = srcu_idx;
+	hprobe->srcu_scp = srcu_scp;
 }
 
 /* Initialize hprobe as refcounted ("stable") uprobe (uprobe can be NULL). */
@@ -720,7 +721,7 @@ static void hprobe_init_stable(struct hprobe *hprobe, struct uprobe *uprobe)
 {
 	hprobe->state = uprobe ? HPROBE_STABLE : HPROBE_GONE;
 	hprobe->uprobe = uprobe;
-	hprobe->srcu_idx = -1;
+	hprobe->srcu_scp = NULL;
 }
 
 /*
@@ -757,7 +758,7 @@ static void hprobe_finalize(struct hprobe *hprobe, enum hprobe_state hstate)
 {
 	switch (hstate) {
 	case HPROBE_LEASED:
-		__srcu_read_unlock(&uretprobes_srcu, hprobe->srcu_idx);
+		srcu_up_read_fast(&uretprobes_srcu, hprobe->srcu_scp);
 		break;
 	case HPROBE_STABLE:
 		put_uprobe(hprobe->uprobe);
@@ -829,7 +830,7 @@ static struct uprobe *hprobe_expire(struct hprobe *hprobe, bool get)
 		 */
 		if (try_cmpxchg(&hprobe->state, &hstate, uprobe ? HPROBE_STABLE : HPROBE_GONE)) {
 			/* We won the race, we are the ones to unlock SRCU */
-			__srcu_read_unlock(&uretprobes_srcu, hprobe->srcu_idx);
+			srcu_up_read_fast(&uretprobes_srcu, hprobe->srcu_scp);
 			return get ? get_uprobe(uprobe) : uprobe;
 		}
 
@@ -2045,7 +2046,7 @@ static void ri_timer(struct timer_list *timer)
 	struct return_instance *ri;
 
 	/* SRCU protects uprobe from reuse for the cmpxchg() inside hprobe_expire(). */
-	guard(srcu)(&uretprobes_srcu);
+	guard(srcu_fast_updown)(&uretprobes_srcu);
 	/* RCU protects return_instance from freeing. */
 	guard(rcu)();
 
@@ -2142,7 +2143,7 @@ static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask)
 	t->utask = n_utask;
 
 	/* protect uprobes from freeing, we'll need try_get_uprobe() them */
-	guard(srcu)(&uretprobes_srcu);
+	guard(srcu_fast_updown)(&uretprobes_srcu);
 
 	p = &n_utask->return_instances;
 	for (o = o_utask->return_instances; o; o = o->next) {
@@ -2254,8 +2255,8 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs,
 {
 	struct uprobe_task *utask = current->utask;
 	unsigned long orig_ret_vaddr, trampoline_vaddr;
+	struct srcu_ctr __percpu *srcu_scp;
 	bool chained;
-	int srcu_idx;
 
 	if (!get_xol_area())
 		goto free;
@@ -2293,8 +2294,12 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs,
 		orig_ret_vaddr = utask->return_instances->orig_ret_vaddr;
 	}
 
-	/* __srcu_read_lock() because SRCU lock survives switch to user space */
-	srcu_idx = __srcu_read_lock(&uretprobes_srcu);
+	/*
+	 * Use srcu_down_read_fast() because the SRCU lock survives a switch to
+	 * user space and can be unlocked from a different context by ri_timer()
+	 * or dup_utask().
+	 */
+	srcu_scp = srcu_down_read_fast(&uretprobes_srcu);
 
 	ri->func = instruction_pointer(regs);
 	ri->stack = user_stack_pointer(regs);
@@ -2303,7 +2308,7 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs,
 
 	utask->depth++;
 
-	hprobe_init_leased(&ri->hprobe, uprobe, srcu_idx);
+	hprobe_init_leased(&ri->hprobe, uprobe, srcu_scp);
 	ri->next = utask->return_instances;
 	rcu_assign_pointer(utask->return_instances, ri);
 

gemini-3.1-pro-preview

null

null

							input: 4001
							output: 25
							thoughts: 257
						

**My Analysis of This Kernel Patch**

Okay, so I'm looking at a patch here that's making some pretty significant changes to uprobes and SRCU. The core of it seems to be about optimizing SRCU, introducing this `srcu_fast_updown` and changing `uretprobes_srcu` to use `DEFINE_STATIC_SRCU_FAST_UPDOWN`.  Basically, it looks like they're trying to speed up read operations with `srcu_down_read_fast` replacing `__srcu_read_lock` and `srcu_up_read_fast` replacing `__srcu_read_unlock`. Functionally, this is a definite change in how uprobes and SRCU interact within the kernel, so this needs to be fuzzed heavily.

I need to focus my fuzzing efforts on the specific functions that this patch actually modifies: `hprobe_init_leased`, `hprobe_init_stable`, `hprobe_finalize`, `hprobe_expire`, `ri_timer`, `dup_utask`, and `prepare_uretprobe`. These are the key areas where the new SRCU mechanisms are going to be interacting.

Alright, I need to check to make sure that `CONFIG_UPROBES` is enabled. Since SRCU is core, I don't need to check for any special configurations for SRCU itself. I'll need to use my tools to verify that `CONFIG_UPROBES` is set correctly before I get started.

{
  "Expression": "CONFIG_UPROBES",
  "PathPrefix": ""
}

{
  "Output": "arch/arm/probes/Makefile-1-# SPDX-License-Identifier: GPL-2.0\narch/arm/probes/Makefile:2:obj-$(CONFIG_UPROBES)\t\t+= decode.o decode-arm.o uprobes/\narch/arm/probes/Makefile-3-obj-$(CONFIG_KPROBES)\t\t+= decode.o kprobes/\n--\narch/arm/probes/uprobes/Makefile-1-# SPDX-License-Identifier: GPL-2.0-only\narch/arm/probes/uprobes/Makefile:2:obj-$(CONFIG_UPROBES)\t\t+= core.o actions-arm.o\n--\narch/arm64/include/asm/uprobes.h=31=int uprobe_brk_handler(struct pt_regs *regs, unsigned long esr);\narch/arm64/include/asm/uprobes.h:32:#ifdef CONFIG_UPROBES\narch/arm64/include/asm/uprobes.h-33-int uprobe_single_step_handler(struct pt_regs *regs, unsigned long esr);\n--\narch/arm64/kernel/debug-monitors.c=254=void do_el0_brk64(unsigned long esr, struct pt_regs *regs)\narch/arm64/kernel/debug-monitors.c-255-{\narch/arm64/kernel/debug-monitors.c:256:\tif (IS_ENABLED(CONFIG_UPROBES) \u0026\u0026\narch/arm64/kernel/debug-monitors.c-257-\t\tesr_brk_comment(esr) == UPROBES_BRK_IMM \u0026\u0026\n--\narch/arm64/kernel/probes/Makefile=2=obj-$(CONFIG_KPROBES)\t\t+= kprobes.o decode-insn.o\t\\\n--\narch/arm64/kernel/probes/Makefile-4-\t\t\t\t   simulate-insn.o\narch/arm64/kernel/probes/Makefile:5:obj-$(CONFIG_UPROBES)\t\t+= uprobes.o decode-insn.o\t\\\narch/arm64/kernel/probes/Makefile-6-\t\t\t\t   simulate-insn.o\n--\narch/csky/kernel/probes/Makefile=4=obj-$(CONFIG_KPROBES_ON_FTRACE)\t+= ftrace.o\narch/csky/kernel/probes/Makefile:5:obj-$(CONFIG_UPROBES)\t\t+= uprobes.o decode-insn.o simulate-insn.o\narch/csky/kernel/probes/Makefile-6-\n--\narch/csky/kernel/traps.c=169=asmlinkage void do_trap_bkpt(struct pt_regs *regs)\n--\narch/csky/kernel/traps.c-174-#endif\narch/csky/kernel/traps.c:175:#ifdef CONFIG_UPROBES\narch/csky/kernel/traps.c-176-\tif (uprobe_single_step_handler(regs))\n--\narch/csky/kernel/traps.c=188=asmlinkage void do_trap_illinsn(struct pt_regs *regs)\n--\narch/csky/kernel/traps.c-195-#endif\narch/csky/kernel/traps.c:196:#ifdef CONFIG_UPROBES\narch/csky/kernel/traps.c-197-\tif (uprobe_breakpoint_handler(regs))\n--\narch/loongarch/include/asm/uprobes.h=23=struct arch_uprobe_task {\n--\narch/loongarch/include/asm/uprobes.h-26-\narch/loongarch/include/asm/uprobes.h:27:#ifdef CONFIG_UPROBES\narch/loongarch/include/asm/uprobes.h-28-bool uprobe_breakpoint_handler(struct pt_regs *regs);\narch/loongarch/include/asm/uprobes.h=29=bool uprobe_singlestep_handler(struct pt_regs *regs);\narch/loongarch/include/asm/uprobes.h:30:#else /* !CONFIG_UPROBES */\narch/loongarch/include/asm/uprobes.h-31-static inline bool uprobe_breakpoint_handler(struct pt_regs *regs) { return false; }\narch/loongarch/include/asm/uprobes.h=32=static inline bool uprobe_singlestep_handler(struct pt_regs *regs) { return false; }\narch/loongarch/include/asm/uprobes.h:33:#endif /* CONFIG_UPROBES */\narch/loongarch/include/asm/uprobes.h-34-\n--\narch/loongarch/kernel/Makefile=77=obj-$(CONFIG_RETHOOK)\t\t+= rethook.o rethook_trampoline.o\narch/loongarch/kernel/Makefile:78:obj-$(CONFIG_UPROBES)\t\t+= uprobes.o\narch/loongarch/kernel/Makefile-79-\n--\narch/mips/kernel/Makefile=105=obj-$(CONFIG_JUMP_LABEL)\t+= jump_label.o\narch/mips/kernel/Makefile:106:obj-$(CONFIG_UPROBES)\t\t+= uprobes.o\narch/mips/kernel/Makefile-107-\n--\narch/mips/kernel/branch.c=849=int __compute_return_epc(struct pt_regs *regs)\n--\narch/mips/kernel/branch.c-875-\narch/mips/kernel/branch.c:876:#if (defined CONFIG_KPROBES) || (defined CONFIG_UPROBES)\narch/mips/kernel/branch.c-877-\n--\narch/mips/kernel/branch.c=906=EXPORT_SYMBOL_GPL(__insn_is_compact_branch);\narch/mips/kernel/branch.c-907-\narch/mips/kernel/branch.c:908:#endif  /* CONFIG_KPROBES || CONFIG_UPROBES */\n--\narch/powerpc/kernel/Makefile=140=obj-$(CONFIG_KPROBES_ON_FTRACE)\t+= kprobes-ftrace.o\narch/powerpc/kernel/Makefile:141:obj-$(CONFIG_UPROBES)\t\t+= uprobes.o\narch/powerpc/kernel/Makefile-142-obj-$(CONFIG_RETHOOK)           += rethook.o\n--\narch/riscv/include/asm/uprobes.h=27=struct arch_uprobe {\n--\narch/riscv/include/asm/uprobes.h-36-\narch/riscv/include/asm/uprobes.h:37:#ifdef CONFIG_UPROBES\narch/riscv/include/asm/uprobes.h-38-bool uprobe_breakpoint_handler(struct pt_regs *regs);\n--\narch/riscv/include/asm/uprobes.h=46=static inline bool uprobe_single_step_handler(struct pt_regs *regs)\n--\narch/riscv/include/asm/uprobes.h-49-}\narch/riscv/include/asm/uprobes.h:50:#endif /* CONFIG_UPROBES */\narch/riscv/include/asm/uprobes.h-51-#endif /* _ASM_RISCV_UPROBES_H */\n--\narch/riscv/kernel/probes/Makefile=3=obj-$(CONFIG_RETHOOK)\t\t+= rethook.o rethook_trampoline.o\narch/riscv/kernel/probes/Makefile:4:obj-$(CONFIG_UPROBES)\t\t+= uprobes.o decode-insn.o simulate-insn.o\narch/riscv/kernel/probes/Makefile-5-CFLAGS_REMOVE_simulate-insn.o = $(CC_FLAGS_FTRACE)\n--\narch/s390/kernel/Makefile=68=obj-$(CONFIG_VMCORE_INFO)\t+= vmcore_info.o\narch/s390/kernel/Makefile:69:obj-$(CONFIG_UPROBES)\t\t+= uprobes.o\narch/s390/kernel/Makefile-70-obj-$(CONFIG_JUMP_LABEL)\t+= jump_label.o\n--\narch/s390/kernel/traps.c=140=static void illegal_op(struct pt_regs *regs)\n--\narch/s390/kernel/traps.c-155-\t\t\t\tsignal = SIGILL;\narch/s390/kernel/traps.c:156:#ifdef CONFIG_UPROBES\narch/s390/kernel/traps.c-157-\t\t} else if (opcode == UPROBE_SWBP_INSN) {\n--\narch/s390/lib/Makefile=13=lib-$(CONFIG_KPROBES) += probes.o\narch/s390/lib/Makefile:14:lib-$(CONFIG_UPROBES) += probes.o\narch/s390/lib/Makefile-15-obj-$(CONFIG_S390_KPROBES_SANITY_TEST) += test_kprobes_s390.o\n--\narch/sparc/include/asm/ttable.h-189-\narch/sparc/include/asm/ttable.h:190:#ifdef CONFIG_UPROBES\narch/sparc/include/asm/ttable.h-191-#define UPROBES_TRAP(lvl) TRAP_ARG(uprobe_trap, lvl)\n--\narch/sparc/kernel/Makefile=117=obj-$(CONFIG_SPARC64)\t+= $(pc--y)\narch/sparc/kernel/Makefile-118-\narch/sparc/kernel/Makefile:119:obj-$(CONFIG_UPROBES)\t+= uprobes.o\narch/sparc/kernel/Makefile-120-obj-$(CONFIG_JUMP_LABEL) += jump_label.o\n--\narch/x86/include/asm/uprobes.h=57=struct arch_uprobe_task {\n--\narch/x86/include/asm/uprobes.h-64-\narch/x86/include/asm/uprobes.h:65:#ifdef CONFIG_UPROBES\narch/x86/include/asm/uprobes.h-66-extern bool is_uprobe_at_func_entry(struct pt_regs *regs);\n--\narch/x86/include/asm/uprobes.h=68=static bool is_uprobe_at_func_entry(struct pt_regs *regs)\n--\narch/x86/include/asm/uprobes.h-71-}\narch/x86/include/asm/uprobes.h:72:#endif /* CONFIG_UPROBES */\narch/x86/include/asm/uprobes.h-73-\n--\narch/x86/kernel/Makefile=154=obj-$(CONFIG_OF)\t\t\t+= devicetree.o\narch/x86/kernel/Makefile:155:obj-$(CONFIG_UPROBES)\t\t\t+= uprobes.o\narch/x86/kernel/Makefile-156-\n--\ninclude/linux/sched.h=826=struct task_struct {\n--\ninclude/linux/sched.h-1566-\ninclude/linux/sched.h:1567:#ifdef CONFIG_UPROBES\ninclude/linux/sched.h-1568-\tstruct uprobe_task\t\t*utask;\n--\ninclude/linux/uprobes.h=46=struct uprobe_consumer {\n--\ninclude/linux/uprobes.h-65-\ninclude/linux/uprobes.h:66:#ifdef CONFIG_UPROBES\ninclude/linux/uprobes.h-67-#include \u003casm/uprobes.h\u003e\n--\ninclude/linux/uprobes.h=246=extern unsigned long arch_uprobe_get_xol_area(void);\ninclude/linux/uprobes.h:247:#else /* !CONFIG_UPROBES */\ninclude/linux/uprobes.h-248-struct uprobes_state {\n--\ninclude/linux/uprobes.h=305=static inline void uprobe_clear_state(struct mm_struct *mm)\n--\ninclude/linux/uprobes.h-307-}\ninclude/linux/uprobes.h:308:#endif /* !CONFIG_UPROBES */\ninclude/linux/uprobes.h-309-#endif\t/* _LINUX_UPROBES_H */\n--\nkernel/events/Makefile=5=obj-$(CONFIG_HW_BREAKPOINT_KUNIT_TEST) += hw_breakpoint_test.o\nkernel/events/Makefile:6:obj-$(CONFIG_UPROBES) += uprobes.o\n--\nkernel/events/callchain.c=181=static void fixup_uretprobe_trampoline_entries(struct perf_callchain_entry *entry,\n--\nkernel/events/callchain.c-183-{\nkernel/events/callchain.c:184:#ifdef CONFIG_UPROBES\nkernel/events/callchain.c-185-\tstruct uprobe_task *utask = current-\u003eutask;\n--\nkernel/fork.c=1068=static void mm_init_uprobes_state(struct mm_struct *mm)\nkernel/fork.c-1069-{\nkernel/fork.c:1070:#ifdef CONFIG_UPROBES\nkernel/fork.c-1071-\tmm-\u003euprobes_state.xol_area = NULL;\n--\nkernel/trace/bpf_trace.c=1084=BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)\n--\nkernel/trace/bpf_trace.c-1088-\nkernel/trace/bpf_trace.c:1089:#ifdef CONFIG_UPROBES\nkernel/trace/bpf_trace.c-1090-\trun_ctx = container_of(current-\u003ebpf_ctx, struct bpf_trace_run_ctx, run_ctx);\n--\nkernel/trace/bpf_trace.c=2944=static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx)\n--\nkernel/trace/bpf_trace.c-2949-\nkernel/trace/bpf_trace.c:2950:#ifdef CONFIG_UPROBES\nkernel/trace/bpf_trace.c-2951-struct bpf_uprobe_multi_link;\n--\nkernel/trace/bpf_trace.c=3251=int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)\n--\nkernel/trace/bpf_trace.c-3401-}\nkernel/trace/bpf_trace.c:3402:#else /* !CONFIG_UPROBES */\nkernel/trace/bpf_trace.c-3403-int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)\n--\nkernel/trace/bpf_trace.c=3411=static u64 bpf_uprobe_multi_entry_ip(struct bpf_run_ctx *ctx)\n--\nkernel/trace/bpf_trace.c-3414-}\nkernel/trace/bpf_trace.c:3415:#endif /* CONFIG_UPROBES */\nkernel/trace/bpf_trace.c-3416-\n--\ntools/sched_ext/Kconfig=53=CONFIG_KPROBE_EVENTS=y\ntools/sched_ext/Kconfig:54:CONFIG_UPROBES=y\ntools/sched_ext/Kconfig-55-CONFIG_UPROBE_EVENTS=y\n--\ntools/testing/selftests/bpf/config.aarch64=148=CONFIG_UNIX=y\ntools/testing/selftests/bpf/config.aarch64:149:CONFIG_UPROBES=y\ntools/testing/selftests/bpf/config.aarch64-150-CONFIG_USER_NS=y\n--\ntools/testing/selftests/bpf/config.ppc64el=85=CONFIG_UNIX=y\ntools/testing/selftests/bpf/config.ppc64el:86:CONFIG_UPROBES=y\ntools/testing/selftests/bpf/config.ppc64el-87-CONFIG_USER_NS=y\n--\ntools/testing/selftests/bpf/config.riscv64=77=CONFIG_UNIX=y\ntools/testing/selftests/bpf/config.riscv64:78:CONFIG_UPROBES=y\ntools/testing/selftests/bpf/config.riscv64-79-CONFIG_USER_NS=y\n--\ntools/testing/selftests/bpf/config.s390x=119=CONFIG_UNIX=y\ntools/testing/selftests/bpf/config.s390x:120:CONFIG_UPROBES=y\ntools/testing/selftests/bpf/config.s390x-121-CONFIG_USER_NS=y\n--\ntools/testing/selftests/ftrace/config=27=CONFIG_TRACER_SNAPSHOT=y\ntools/testing/selftests/ftrace/config:28:CONFIG_UPROBES=y\ntools/testing/selftests/ftrace/config-29-CONFIG_UPROBE_EVENTS=y\n--\ntools/testing/selftests/mm/config=12=CONFIG_PROFILING=y\ntools/testing/selftests/mm/config:13:CONFIG_UPROBES=y\ntools/testing/selftests/mm/config-14-CONFIG_MEMORY_FAILURE=y\n--\ntools/testing/selftests/vsock/config=14=CONFIG_ARCH_SUPPORTS_UPROBES=y\ntools/testing/selftests/vsock/config:15:CONFIG_UPROBES=y\ntools/testing/selftests/vsock/config-16-CONFIG_UPROBE_EVENTS=y\n"
}

gemini-3.1-pro-preview

null

null

							input: 9150
							output: 33
							thoughts: 244
						

**My Uprobes Examination**

Okay, so I'm diving into this uprobes code. My focus needs to be on functions related to `CONFIG_UPROBES`. Let me see... I've got a list here: `hprobe_init_leased`, `hprobe_init_stable`, `hprobe_finalize`, `hprobe_expire`, `ri_timer`, `dup_utask`, and `prepare_uretprobe`. I should probably double-check that `CONFIG_UPROBES` is the only relevant config. Yes, it's enabled by default on a lot of architectures, but confirmation is always a good practice.

Now, let's look closer at these functions. Hmm, it seems like `hprobe_init_leased`, `hprobe_init_stable`, `hprobe_finalize`, `hprobe_expire`, `ri_timer`, `dup_utask`, and `prepare_uretprobe` are all marked as static. Okay, so we're primarily dealing with internal implementations here, nothing directly exported. But wait, `dup_utask` is static... but I *seem* to recall it being called from `uprobe_dup_mmap`. That's a point of interest. I'd better confirm that call chain. I don't want to miss anything.

{
  "Expression": "dup_utask",
  "PathPrefix": "kernel/events/uprobes.c"
}

{
  "Output": "kernel/events/uprobes.c=757=static void hprobe_finalize(struct hprobe *hprobe, enum hprobe_state hstate)\n--\nkernel/events/uprobes.c-788- * attempt try_get_uprobe(), if it needs to preserve uprobe beyond current\nkernel/events/uprobes.c:789: * SRCU lock region. See dup_utask().\nkernel/events/uprobes.c-790- */\nkernel/events/uprobes.c=791=static struct uprobe *hprobe_expire(struct hprobe *hprobe, bool get)\n--\nkernel/events/uprobes.c-848-\t\t * return it regardless. Also, if `get` was true, we also have\nkernel/events/uprobes.c:849:\t\t * an extra ref for the caller to own. This is used in dup_utask().\nkernel/events/uprobes.c-850-\t\t */\n--\nkernel/events/uprobes.c=2113=static struct return_instance *dup_return_instance(struct return_instance *old)\n--\nkernel/events/uprobes.c-2133-\nkernel/events/uprobes.c:2134:static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask)\nkernel/events/uprobes.c-2135-{\n--\nkernel/events/uprobes.c=2188=void uprobe_copy_process(struct task_struct *t, u64 flags)\n--\nkernel/events/uprobes.c-2201-\nkernel/events/uprobes.c:2202:\tif (dup_utask(t, utask))\nkernel/events/uprobes.c-2203-\t\treturn uprobe_warn(t, \"dup ret instances\");\n--\nkernel/events/uprobes.c=2253=static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs,\n--\nkernel/events/uprobes.c-2299-\t * user space and can be unlocked from a different context by ri_timer()\nkernel/events/uprobes.c:2300:\t * or dup_utask().\nkernel/events/uprobes.c-2301-\t */\n"
}

gemini-3.1-pro-preview

null

null

							input: 10301
							output: 33
							thoughts: 39
						

Here's my take on the thought process, summarized as you requested:

**Deconstructing the Uprobe Flow**

Okay, so I'm tracing through this uprobe implementation, and the flow is becoming clearer. I see that `uprobe_copy_process` ultimately calls `dup_utask`. Right, that's expected behavior, cloning the user-space task structure. Now, where does `prepare_uretprobe` come into the picture? I need to refresh my memory on the call graph there. I *believe* it's invoked by `uprobe_dispatcher` or something similar, but it's always best to be precise, especially when dealing with such low-level stuff. Time to double-check the code path and solidify that connection in my mind. No room for guesswork in these critical areas.

{
  "Expression": "prepare_uretprobe",
  "PathPrefix": "kernel/events/uprobes.c"
}

{
  "Output": "kernel/events/uprobes.c=2237=static void cleanup_return_instances(struct uprobe_task *utask, bool chained,\n--\nkernel/events/uprobes.c-2252-\nkernel/events/uprobes.c:2253:static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs,\nkernel/events/uprobes.c-2254-\t\t\t      struct return_instance *ri)\n--\nkernel/events/uprobes.c=2554=static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)\n--\nkernel/events/uprobes.c-2588-\tif (!ZERO_OR_NULL_PTR(ri))\nkernel/events/uprobes.c:2589:\t\tprepare_uretprobe(uprobe, regs, ri);\nkernel/events/uprobes.c-2590-\n"
}

gemini-3.1-pro-preview

null

null

							input: 10787
							output: 32
							thoughts: 140
						

**Initial Code Analysis**

Okay, so `handler_chain` is the crucial function, and it's called by `handle_swbp`. Right away, that tells me focusing on `prepare_uretprobe` is a good starting point for understanding how this all works. Let's see... looking at the call stack, I also need to consider `hprobe_expire`, `hprobe_finalize`, `hprobe_init_leased`, `hprobe_init_stable`, `ri_timer`, and `dup_utask`.

Hold on... `hprobe_init_leased` and `hprobe_init_stable` are suspiciously small. They probably just do some quick setup. Okay, let's skip them for now. Given my understanding of the problem space, my initial focus should be on `prepare_uretprobe`, `hprobe_expire`, `hprobe_finalize`, `ri_timer`, and `dup_utask`. These seem to be the most complex, and likely where the core logic resides.

Now, let's take a look at `ri_timer`.

{
  "Expression": "ri_timer",
  "PathPrefix": "kernel/events/uprobes.c"
}

{
  "Output": "kernel/events/uprobes.c=1970=static void free_ret_instance(struct uprobe_task *utask,\n--\nkernel/events/uprobes.c-1983-\t * At this point return_instance is unlinked from utask's\nkernel/events/uprobes.c:1984:\t * return_instances list and this has become visible to ri_timer().\nkernel/events/uprobes.c:1985:\t * If seqcount now indicates that ri_timer's return instance\nkernel/events/uprobes.c-1986-\t * processing loop isn't active, we can return ri into the pool of\nkernel/events/uprobes.c:1987:\t * to-be-reused return instances for future uretprobes. If ri_timer()\nkernel/events/uprobes.c-1988-\t * happens to be running right now, though, we fallback to safety and\n--\nkernel/events/uprobes.c-1997-\t} else {\nkernel/events/uprobes.c:1998:\t\t/* we might be racing with ri_timer(), so play it safe */\nkernel/events/uprobes.c-1999-\t\tri_free(ri);\n--\nkernel/events/uprobes.c=2007=void uprobe_free_utask(struct task_struct *t)\n--\nkernel/events/uprobes.c-2017-\nkernel/events/uprobes.c:2018:\ttimer_delete_sync(\u0026utask-\u003eri_timer);\nkernel/events/uprobes.c-2019-\n--\nkernel/events/uprobes.c-2042-\nkernel/events/uprobes.c:2043:static void ri_timer(struct timer_list *timer)\nkernel/events/uprobes.c-2044-{\nkernel/events/uprobes.c:2045:\tstruct uprobe_task *utask = container_of(timer, struct uprobe_task, ri_timer);\nkernel/events/uprobes.c-2046-\tstruct return_instance *ri;\n--\nkernel/events/uprobes.c=2069=static struct uprobe_task *alloc_utask(void)\n--\nkernel/events/uprobes.c-2076-\nkernel/events/uprobes.c:2077:\ttimer_setup(\u0026utask-\u003eri_timer, ri_timer, 0);\nkernel/events/uprobes.c-2078-\tseqcount_init(\u0026utask-\u003eri_seqcount);\n--\nkernel/events/uprobes.c=2253=static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs,\n--\nkernel/events/uprobes.c-2298-\t * Use srcu_down_read_fast() because the SRCU lock survives a switch to\nkernel/events/uprobes.c:2299:\t * user space and can be unlocked from a different context by ri_timer()\nkernel/events/uprobes.c-2300-\t * or dup_utask().\n--\nkernel/events/uprobes.c-2314-\nkernel/events/uprobes.c:2315:\tmod_timer(\u0026utask-\u003eri_timer, jiffies + RI_TIMER_PERIOD);\nkernel/events/uprobes.c-2316-\n"
}

gemini-3.1-pro-preview

null

null

							input: 12062
							output: 31
							thoughts: 192
						

**Analyzing Uprobe and SRCU Configurations**

Okay, let's break this down. My initial understanding is that `ri_timer` is a timer callback, `dup_utask` is triggered during a `fork` operation, `prepare_uretprobe` happens when a uretprobe is hit, `hprobe_expire` handles expiring a leased uprobe, and `hprobe_finalize` is used to finalize a leased uprobe. That's the core functionality, but let's make sure I understand the relevant configurations.

Now, I need to check for other related configurations. My initial review indicates that the patch touches `include/linux/srcu.h` and `kernel/events/uprobes.c`, which is a good starting point. I can see that `CONFIG_UPROBES` is the main configuration option to consider here. But hang on... `CONFIG_SRCU`... that's always enabled, isn't it? I need to keep that in mind as a dependency.

I should double-check `CONFIG_UPROBES` to ensure a full understanding, of course. Are there any other config options? Let's not overlook anything. Ah, there's `CONFIG_UPROBE_EVENTS`! I'll need to check how that interacts.

Finally, I'll thoroughly examine `kernel/events/uprobes.c`. It's likely that other related configurations are defined or used there, and it's essential to understand the context of the whole thing. I need to make sure I have a complete picture of the dependencies and how these features are conditionally enabled and disabled.

no matches

{
  "Expression": "CONFIG_",
  "PathPrefix": "kernel/events/uprobes.c"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 12645
							output: 30
							thoughts: 47
						

Okay, here's my take on those thoughts, framed as my own:

**Investigating Uprobe Configuration Dependencies**

Alright, let's see, I'm diving into the `kernel/events/uprobes.c` file. Hmm, looks like there aren't any other conditional configurations defined within this particular file. That suggests a direct correlation: if `CONFIG_UPROBES` is enabled, the code within this file is included. Good, that simplifies things a bit. No complex nesting or dependencies *within* this specific module.

Now, let's shift gears slightly. I'll need to check `include/linux/srcu.h` to see if there are any related configurations or dependencies declared within the source read-copy-update header. It's a common area for shared resources and potential synchronization points, which might be influenced by how uprobes are used, and therefore indirectly impacted by configurations. I'm looking for anything that might relate to read-copy-update mechanisms or synchronization related to uprobes. That should give me the full picture.

{
  "Expression": "CONFIG_",
  "PathPrefix": "include/linux/srcu.h"
}

{
  "Output": "include/linux/srcu.h=24=context_lock_struct(srcu_struct, __reentrant_ctx_lock);\ninclude/linux/srcu.h-25-\ninclude/linux/srcu.h:26:#ifdef CONFIG_DEBUG_LOCK_ALLOC\ninclude/linux/srcu.h-27-\ninclude/linux/srcu.h=28=int __init_srcu_struct(struct srcu_struct *ssp, const char *name, struct lock_class_key *key);\ninclude/linux/srcu.h:29:#ifndef CONFIG_TINY_SRCU\ninclude/linux/srcu.h-30-int __init_srcu_struct_fast(struct srcu_struct *ssp, const char *name, struct lock_class_key *key);\ninclude/linux/srcu.h=31=int __init_srcu_struct_fast_updown(struct srcu_struct *ssp, const char *name,\ninclude/linux/srcu.h-32-\t\t\t\t   struct lock_class_key *key);\ninclude/linux/srcu.h:33:#endif // #ifndef CONFIG_TINY_SRCU\ninclude/linux/srcu.h-34-\n--\ninclude/linux/srcu.h-56-#define __SRCU_DEP_MAP_INIT(srcu_name)\t.dep_map = { .name = #srcu_name },\ninclude/linux/srcu.h:57:#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */\ninclude/linux/srcu.h-58-\ninclude/linux/srcu.h=59=int init_srcu_struct(struct srcu_struct *ssp);\ninclude/linux/srcu.h:60:#ifndef CONFIG_TINY_SRCU\ninclude/linux/srcu.h-61-int init_srcu_struct_fast(struct srcu_struct *ssp);\ninclude/linux/srcu.h=62=int init_srcu_struct_fast_updown(struct srcu_struct *ssp);\ninclude/linux/srcu.h:63:#endif // #ifndef CONFIG_TINY_SRCU\ninclude/linux/srcu.h-64-\ninclude/linux/srcu.h-65-#define __SRCU_DEP_MAP_INIT(srcu_name)\ninclude/linux/srcu.h:66:#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */\ninclude/linux/srcu.h-67-\n--\ninclude/linux/srcu.h=80=void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases_shared(ssp);\ninclude/linux/srcu.h-81-\ninclude/linux/srcu.h:82:#ifdef CONFIG_TINY_SRCU\ninclude/linux/srcu.h-83-#include \u003clinux/srcutiny.h\u003e\ninclude/linux/srcu.h:84:#elif defined(CONFIG_TREE_SRCU)\ninclude/linux/srcu.h-85-#include \u003clinux/srcutree.h\u003e\n--\ninclude/linux/srcu.h=128=static inline bool same_state_synchronize_srcu(unsigned long oldstate1, unsigned long oldstate2)\n--\ninclude/linux/srcu.h-132-\ninclude/linux/srcu.h:133:#ifdef CONFIG_NEED_SRCU_NMI_SAFE\ninclude/linux/srcu.h-134-int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires_shared(ssp);\n--\ninclude/linux/srcu.h=142=static inline void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx)\n--\ninclude/linux/srcu.h-146-}\ninclude/linux/srcu.h:147:#endif /* CONFIG_NEED_SRCU_NMI_SAFE */\ninclude/linux/srcu.h-148-\ninclude/linux/srcu.h=149=void srcu_init(void);\ninclude/linux/srcu.h-150-\ninclude/linux/srcu.h:151:#ifdef CONFIG_DEBUG_LOCK_ALLOC\ninclude/linux/srcu.h-152-\n--\ninclude/linux/srcu.h-156- *\ninclude/linux/srcu.h:157: * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU\ninclude/linux/srcu.h:158: * read-side critical section.  In absence of CONFIG_DEBUG_LOCK_ALLOC,\ninclude/linux/srcu.h-159- * this assumes we are in an SRCU read-side critical section unless it can\n--\ninclude/linux/srcu.h=197=static inline void srcu_lock_sync(struct lockdep_map *map)\n--\ninclude/linux/srcu.h-201-\ninclude/linux/srcu.h:202:#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */\ninclude/linux/srcu.h-203-\ninclude/linux/srcu.h=204=static inline int srcu_read_lock_held(const struct srcu_struct *ssp)\n--\ninclude/linux/srcu.h-212-\ninclude/linux/srcu.h:213:#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */\ninclude/linux/srcu.h-214-\n--\ninclude/linux/srcu.h=287=static inline int srcu_read_lock(struct srcu_struct *ssp)\n--\ninclude/linux/srcu.h-310- * cannot be passed to any non-fast variant of srcu_read_{,un}lock() or\ninclude/linux/srcu.h:311: * srcu_{down,up}_read().  In kernels built with CONFIG_PROVE_RCU=y,\ninclude/linux/srcu.h-312- * __srcu_check_read_flavor() will complain bitterly if you ignore this\n--\ninclude/linux/srcu.h=324=static inline struct srcu_ctr __percpu *srcu_read_lock_fast(struct srcu_struct *ssp) __acquires_shared(ssp)\n--\ninclude/linux/srcu.h-350- * variant of srcu_read_{,un}lock() or srcu_{down,up}_read().  In kernels\ninclude/linux/srcu.h:351: * built with CONFIG_PROVE_RCU=y, __srcu_check_read_flavor() will complain\ninclude/linux/srcu.h-352- * bitterly if you ignore this * restriction.\n--\ninclude/linux/srcu.h=402=static inline struct srcu_ctr __percpu *srcu_down_read_fast(struct srcu_struct *ssp) __acquires_shared(ssp)\ninclude/linux/srcu.h-403-{\ninclude/linux/srcu.h:404:\tWARN_ON_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) \u0026\u0026 in_nmi());\ninclude/linux/srcu.h-405-\tRCU_LOCKDEP_WARN(!rcu_is_watching(), \"RCU must be watching srcu_down_read_fast().\");\n--\ninclude/linux/srcu.h=542=static inline void srcu_up_read_fast(struct srcu_struct *ssp, struct srcu_ctr __percpu *scp)\n--\ninclude/linux/srcu.h-544-{\ninclude/linux/srcu.h:545:\tWARN_ON_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) \u0026\u0026 in_nmi());\ninclude/linux/srcu.h-546-\tsrcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST_UPDOWN);\n"
}

gemini-3.1-pro-preview

null

null

							input: 14908
							output: 33
							thoughts: 426
						

**Analyzing the SRCU Implementation for Uretprobes**

Okay, so this patch uses `DEFINE_STATIC_SRCU_FAST_UPDOWN(uretprobes_srcu)`. That's a standard SRCU definition, defined in either `linux/srcutree.h` or `linux/srcutiny.h`, depending on the configuration. But hang on... `CONFIG_TINY_SRCU` and `CONFIG_TREE_SRCU` are specifically for those SRCU variants. We don't need to explicitly define those configurations since `CONFIG_UPROBES` is the relevant one, and the correct SRCU implementation will be selected appropriately.

Now, let's get down to the critical functions to understand: `prepare_uretprobe`, `hprobe_expire`, `hprobe_finalize`, `ri_timer`, and `dup_utask`. I should also make a quick sweep to see if I missed any other functions worth considering. Hmm, `hprobe_init_leased` and `hprobe_init_stable` are small and inline-ish, but they *are* static. The same goes for `dup_utask`, `prepare_uretprobe`, `hprobe_expire`, `hprobe_finalize`, and `ri_timer`. Since they're static I have to verify their reachability.

Let's confirm the call chains, starting with `prepare_uretprobe`. Ah, it's reached; it's called by `handler_chain`, which is called by `handle_swbp`. Excellent. `dup_utask` is called by `uprobe_copy_process`, so that's also reachable. `ri_timer` is a timer callback – easy enough. Now, `hprobe_expire`... it appears to be called by various uprobe-related functions, such as `uprobe_unregister`, `uprobe_apply`, etc. Wait, no, I think it's called from within `hprobe_consume`. Okay, need to verify that. Need to check that `hprobe_expire` call chain.

{
  "Expression": "hprobe_expire",
  "PathPrefix": "kernel/events/uprobes.c"
}

{
  "Output": "kernel/events/uprobes.c=757=static void hprobe_finalize(struct hprobe *hprobe, enum hprobe_state hstate)\n--\nkernel/events/uprobes.c-790- */\nkernel/events/uprobes.c:791:static struct uprobe *hprobe_expire(struct hprobe *hprobe, bool get)\nkernel/events/uprobes.c-792-{\n--\nkernel/events/uprobes.c-825-\t\t * Try to switch hprobe state, guarding against\nkernel/events/uprobes.c:826:\t\t * hprobe_consume() or another hprobe_expire() racing with us.\nkernel/events/uprobes.c-827-\t\t * Note, if we failed to get uprobe refcount, we use special\n--\nkernel/events/uprobes.c-843-\t\t/*\nkernel/events/uprobes.c:844:\t\t * Even if hprobe_consume() or another hprobe_expire() wins\nkernel/events/uprobes.c-845-\t\t * the state update race and unlocks SRCU from under us, we\n--\nkernel/events/uprobes.c=2043=static void ri_timer(struct timer_list *timer)\n--\nkernel/events/uprobes.c-2047-\nkernel/events/uprobes.c:2048:\t/* SRCU protects uprobe from reuse for the cmpxchg() inside hprobe_expire(). */\nkernel/events/uprobes.c-2049-\tguard(srcu_fast_updown)(\u0026uretprobes_srcu);\n--\nkernel/events/uprobes.c-2063-\tfor_each_ret_instance_rcu(ri, utask-\u003ereturn_instances)\nkernel/events/uprobes.c:2064:\t\thprobe_expire(\u0026ri-\u003ehprobe, false);\nkernel/events/uprobes.c-2065-\n--\nkernel/events/uprobes.c=2134=static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask)\n--\nkernel/events/uprobes.c-2154-\t\t/* if uprobe is non-NULL, we'll have an extra refcount for uprobe */\nkernel/events/uprobes.c:2155:\t\tuprobe = hprobe_expire(\u0026o-\u003ehprobe, true);\nkernel/events/uprobes.c-2156-\n"
}

gemini-3.1-pro-preview

null

null

							input: 16438
							output: 33
							thoughts: 31
						

Here's a summary of my thought process, as requested:

**Considering `hprobe` Function Calls**

Okay, so I'm looking at how `hprobe` functions are being called. I'm noting that `hprobe_expire` is initiated by both `ri_timer` and `dup_utask`. That makes sense in the context of [my field; assume context is understood by user]. These are both critical system components that manage resources and tasks, so it's logical they'd need to trigger expiration checks. But, hold on... What about `hprobe_finalize`? Is it used in this process? I need to think about where `hprobe_finalize` fits into the lifecycle of an `hprobe` instance, and if these calls to `hprobe_expire` somehow interact with or are dependent on `hprobe_finalize`'s behavior. I need to investigate where and when `hprobe_finalize` is called to gain a complete picture.

{
  "Expression": "hprobe_finalize",
  "PathPrefix": "kernel/events/uprobes.c"
}

{
  "Output": "kernel/events/uprobes.c=720=static void hprobe_init_stable(struct hprobe *hprobe, struct uprobe *uprobe)\n--\nkernel/events/uprobes.c-731- *\nkernel/events/uprobes.c:732: * Caller has to call hprobe_finalize() and pass previous hprobe_state, so\nkernel/events/uprobes.c:733: * that hprobe_finalize() can perform SRCU unlock or put uprobe, whichever\nkernel/events/uprobes.c-734- * is appropriate.\n--\nkernel/events/uprobes.c=736=static inline struct uprobe *hprobe_consume(struct hprobe *hprobe, enum hprobe_state *hstate)\n--\nkernel/events/uprobes.c-753- * Reset hprobe state and, if hprobe was LEASED, release SRCU lock.\nkernel/events/uprobes.c:754: * hprobe_finalize() can only be used from current context after\nkernel/events/uprobes.c-755- * hprobe_consume() call (which determines uprobe and hstate value).\nkernel/events/uprobes.c-756- */\nkernel/events/uprobes.c:757:static void hprobe_finalize(struct hprobe *hprobe, enum hprobe_state hstate)\nkernel/events/uprobes.c-758-{\n--\nkernel/events/uprobes.c=1970=static void free_ret_instance(struct uprobe_task *utask,\n--\nkernel/events/uprobes.c-1978-\t\t(void)hprobe_consume(\u0026ri-\u003ehprobe, \u0026hstate);\nkernel/events/uprobes.c:1979:\t\thprobe_finalize(\u0026ri-\u003ehprobe, hstate);\nkernel/events/uprobes.c-1980-\t}\n--\nkernel/events/uprobes.c=2640=void uprobe_handle_trampoline(struct pt_regs *regs)\n--\nkernel/events/uprobes.c-2682-\t\t\t\thandle_uretprobe_chain(ri, uprobe, regs);\nkernel/events/uprobes.c:2683:\t\t\thprobe_finalize(\u0026ri-\u003ehprobe, hstate);\nkernel/events/uprobes.c-2684-\n"
}

gemini-3.1-pro-preview

null

null

							input: 17306
							output: 36
							thoughts: 108
						

**My Current Thinking on Handling uProbes**

Okay, so I'm diving into how these uProbes are being managed, and it seems the critical juncture is where things get cleaned up. `hprobe_finalize` is a key function here, as it's the endpoint of the cleanup process. It's called by two functions: `free_ret_instance` and `uprobe_handle_trampoline`. That means any issues here are likely to bubble up through those two.

Therefore, my immediate focus needs to be on a select few functions. I need to understand what's happening in:

*   `prepare_uretprobe`
*   `hprobe_expire`
*   `hprobe_finalize`
*   `ri_timer`
*   `dup_utask`
*   `free_ret_instance`
*   `uprobe_handle_trampoline`

Right now, I'm going to start by getting a solid grasp on `uprobe_handle_trampoline`. It is likely the place where things start to come apart, and since `hprobe_finalize` is called by it, that will be the obvious place to begin.

{
  "Expression": "uprobe_handle_trampoline",
  "PathPrefix": "kernel/events/uprobes.c"
}

{
  "Output": "kernel/events/uprobes.c=2628=static struct return_instance *find_next_ret_chain(struct return_instance *ri)\n--\nkernel/events/uprobes.c-2639-\nkernel/events/uprobes.c:2640:void uprobe_handle_trampoline(struct pt_regs *regs)\nkernel/events/uprobes.c-2641-{\n--\nkernel/events/uprobes.c=2717=static void handle_swbp(struct pt_regs *regs)\n--\nkernel/events/uprobes.c-2724-\tif (bp_vaddr == uprobe_get_trampoline_vaddr())\nkernel/events/uprobes.c:2725:\t\treturn uprobe_handle_trampoline(regs);\nkernel/events/uprobes.c-2726-\n"
}

gemini-3.1-pro-preview

null

null

							input: 17932
							output: 174
							thoughts: 437
						

**Fuzzing Strategy for Uprobes & SRCU Integration**

Okay, so I'm looking at this patch and immediately, the connection between `uprobe_handle_trampoline` and `handle_swbp` jumps out at me. This seems like a key area of interaction. First, just to be sure, let's verify that `CONFIG_UPROBES` is the *only* configuration option at play here. Yep, it is. Now we can proceed.

Re-reading the patch, I see the introduction of `srcu_fast_updown` and the change to `DEFINE_STATIC_SRCU_FAST_UPDOWN` for `uretprobes_srcu`. The modification of `__srcu_read_lock` to `srcu_down_read_fast` and `__srcu_read_unlock` to `srcu_up_read_fast` is a functional change. This is definitely kernel-level stuff with both uprobes and SRCU in the mix. Worthy of a deep dive in fuzzing.

My list of focus symbols is: `prepare_uretprobe`, `hprobe_expire`, `hprobe_finalize`, `ri_timer`, `dup_utask`, `free_ret_instance`, and `uprobe_handle_trampoline`.

Now, I need to check the visibility of `srcu_down_read_fast` and `srcu_up_read_fast`. Ah, they are inline functions, defined in `include/linux/srcu.h`. That means they won't be exposed as symbols. So, we'll bypass the instrumentation on them.

What about `hprobe_init_leased` and `hprobe_init_stable`? Turns out, those are static functions defined in `kernel/events/uprobes.c`. The compiler might inline them. I'll err on the side of caution and include the core functions, the more complex ones that are less likely to be inlined, within my list: `prepare_uretprobe`, `hprobe_expire`, `hprobe_finalize`, `ri_timer`, `dup_utask`, `free_ret_instance`, and of course, `uprobe_handle_trampoline`.

Time to hand this off to the `set-results` tool now.

{
  "EnableConfigs": [
    "UPROBES"
  ],
  "FocusSymbols": [
    "prepare_uretprobe",
    "hprobe_expire",
    "hprobe_finalize",
    "ri_timer",
    "dup_utask",
    "free_ret_instance",
    "uprobe_handle_trampoline"
  ],
  "Reasoning": "The patch modifies the uprobes subsystem to use the new fast up/down SRCU read lock variants (`srcu_down_read_fast` and `srcu_up_read_fast`) for `uretprobes_srcu`. This is a functional change in core kernel logic that affects how uprobes are leased and expired, particularly during task duplication and timer callbacks. It is reachable and should be fuzzed.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "UPROBES"
  ],
  "FocusSymbols": [
    "prepare_uretprobe",
    "hprobe_expire",
    "hprobe_finalize",
    "ri_timer",
    "dup_utask",
    "free_ret_instance",
    "uprobe_handle_trampoline"
  ],
  "Reasoning": "The patch modifies the uprobes subsystem to use the new fast up/down SRCU read lock variants (`srcu_down_read_fast` and `srcu_up_read_fast`) for `uretprobes_srcu`. This is a functional change in core kernel logic that affects how uprobes are leased and expired, particularly during task duplication and timer callbacks. It is reachable and should be fuzzed.",
  "WorthFuzzing": true
}