AI Trajectory

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch deprecates the ability to disable ftrace via the `kernel.ftrace_enabled` sysctl. It replaces the previous shutdown logic with a simple `pr_warn_once` and a constant `-EOPNOTSUPP` error return. Since it only removes functionality and adds a warning without introducing any new complex logic or state transitions, it does not require fuzzing.",
  "WorthFuzzing": false
}

null

{
  "PatchDiff": "commit 933b1863569e82bd6832d66edb1e048175e30c91\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Sun Aug 2 04:21:32 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst\nindex 84f06bf0da9bc..7261f25f8b4ba 100644\n--- a/Documentation/trace/ftrace.rst\n+++ b/Documentation/trace/ftrace.rst\n@@ -3313,6 +3313,11 @@ this special filter via::\n ftrace_enabled\n --------------\n \n+.. note::\n+   Disabling ftrace via this switch is deprecated. Writing 0 is refused\n+   with -EOPNOTSUPP and logs a warning; writing 1 and reading the value\n+   are unaffected.\n+\n Note, the proc sysctl ftrace_enable is a big on/off switch for the\n function tracer. By default it is enabled (when function tracing is\n enabled in the kernel). If it is disabled, all function tracing is\ndiff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c\nindex f93e34dd23288..82bb7356ccce5 100644\n--- a/kernel/trace/ftrace.c\n+++ b/kernel/trace/ftrace.c\n@@ -9357,7 +9357,7 @@ static void ftrace_startup_sysctl(void)\n \t}\n }\n \n-static void ftrace_shutdown_sysctl(void)\n+static void __maybe_unused ftrace_shutdown_sysctl(void)\n {\n \tint command;\n \n@@ -9377,7 +9377,7 @@ static void ftrace_shutdown_sysctl(void)\n # define ftrace_shutdown_sysctl()      do { } while (0)\n #endif /* CONFIG_DYNAMIC_FTRACE */\n \n-static bool is_permanent_ops_registered(void)\n+static bool __maybe_unused is_permanent_ops_registered(void)\n {\n \tstruct ftrace_ops *op;\n \n@@ -9415,15 +9415,12 @@ ftrace_enable_sysctl(const struct ctl_table *table, int write,\n \t\tftrace_startup_sysctl();\n \n \t} else {\n-\t\tif (is_permanent_ops_registered()) {\n-\t\t\tftrace_enabled = true;\n-\t\t\treturn -EBUSY;\n-\t\t}\n-\n-\t\t/* stopping ftrace calls (just send to ftrace_stub) */\n-\t\tftrace_trace_function = ftrace_stub;\n-\n-\t\tftrace_shutdown_sysctl();\n+\t\t/*\n+\t\t * Disabling ftrace at runtime via this knob is deprecated.\n+\t\t */\n+\t\tftrace_enabled = true;\n+\t\tpr_warn_once(\"The ftrace_enabled file is deprecated and no longer disables ftrace\\n\");\n+\t\treturn -EOPNOTSUPP;\n \t}\n \n \tlast_ftrace_enabled = !!ftrace_enabled;\ndiff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh\nindex 30dc677b2f45b..7fa4bda702210 100644\n--- a/tools/testing/selftests/livepatch/functions.sh\n+++ b/tools/testing/selftests/livepatch/functions.sh\n@@ -126,6 +126,19 @@ function set_ftrace_enabled() {\n \techo \"livepatch: kernel.ftrace_enabled = $result\" \u003e /dev/kmsg\n }\n \n+# ftrace_disable_supported() - probe whether kernel.ftrace_enabled=0\n+#\tcan still disable ftrace on this kernel. Newer kernels deprecate\n+#\tthe knob and always refuse the write with -EOPNOTSUPP.\n+function ftrace_disable_supported() {\n+\tlocal result\n+\n+\tsysctl -q kernel.ftrace_enabled=0 \u0026\u003e /dev/null\n+\tresult=$(sysctl --values kernel.ftrace_enabled)\n+\tsysctl -q kernel.ftrace_enabled=1 \u0026\u003e /dev/null\n+\n+\t[[ \"$result\" == \"0\" ]]\n+}\n+\n function cleanup() {\n \tpop_config\n }\ndiff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh\nindex d2c3dea63104d..cd27148510f8f 100755\n--- a/tools/testing/selftests/livepatch/test-ftrace.sh\n+++ b/tools/testing/selftests/livepatch/test-ftrace.sh\n@@ -12,29 +12,32 @@ setup_config\n # - turn ftrace_enabled OFF and verify livepatches can't load\n # - turn ftrace_enabled ON and verify livepatch can load\n # - verify that ftrace_enabled can't be turned OFF while a livepatch is loaded\n+# (skipped on kernels where the sysctl is deprecated and always refuses 0)\n \n start_test \"livepatch interaction with ftrace_enabled sysctl\"\n \n-set_ftrace_enabled 0\n-load_failing_mod $MOD_LIVEPATCH\n+if ftrace_disable_supported; then\n \n-set_ftrace_enabled 1\n-load_lp $MOD_LIVEPATCH\n-if [[ \"$(cat /proc/cmdline)\" != \"$MOD_LIVEPATCH: this has been live patched\" ]] ; then\n-\techo -e \"FAIL\\n\\n\"\n-\tdie \"livepatch kselftest(s) failed\"\n-fi\n+\tset_ftrace_enabled 0\n+\tload_failing_mod $MOD_LIVEPATCH\n \n-# Check that ftrace could not get disabled when a livepatch is enabled\n-set_ftrace_enabled --fail 0\n-if [[ \"$(cat /proc/cmdline)\" != \"$MOD_LIVEPATCH: this has been live patched\" ]] ; then\n-\techo -e \"FAIL\\n\\n\"\n-\tdie \"livepatch kselftest(s) failed\"\n-fi\n-disable_lp $MOD_LIVEPATCH\n-unload_lp $MOD_LIVEPATCH\n+\tset_ftrace_enabled 1\n+\tload_lp $MOD_LIVEPATCH\n+\tif [[ \"$(cat /proc/cmdline)\" != \"$MOD_LIVEPATCH: this has been live patched\" ]] ; then\n+\t\techo -e \"FAIL\\n\\n\"\n+\t\tdie \"livepatch kselftest(s) failed\"\n+\tfi\n \n-check_result \"livepatch: kernel.ftrace_enabled = 0\n+\t# Check that ftrace could not get disabled when a livepatch is enabled\n+\tset_ftrace_enabled --fail 0\n+\tif [[ \"$(cat /proc/cmdline)\" != \"$MOD_LIVEPATCH: this has been live patched\" ]] ; then\n+\t\techo -e \"FAIL\\n\\n\"\n+\t\tdie \"livepatch kselftest(s) failed\"\n+\tfi\n+\tdisable_lp $MOD_LIVEPATCH\n+\tunload_lp $MOD_LIVEPATCH\n+\n+\tcheck_result \"livepatch: kernel.ftrace_enabled = 0\n % insmod test_modules/$MOD_LIVEPATCH.ko\n livepatch: enabling patch '$MOD_LIVEPATCH'\n livepatch: '$MOD_LIVEPATCH': initializing patching transition\n@@ -60,6 +63,14 @@ livepatch: '$MOD_LIVEPATCH': completing unpatching transition\n livepatch: '$MOD_LIVEPATCH': unpatching complete\n % rmmod $MOD_LIVEPATCH\"\n \n+else\n+\n+\tset_ftrace_enabled --fail 0\n+\tcheck_result \"livepatch: sysctl: setting key \\\"kernel.ftrace_enabled\\\": \\\n+Operation not supported\"\n+\n+fi\n+\n \n # - verify livepatch can load\n # - check if traces have a patched function\n"
}

best-expensive

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch deprecates the ability to disable ftrace via the `kernel.ftrace_enabled` sysctl. It replaces the previous shutdown logic with a simple `pr_warn_once` and a constant `-EOPNOTSUPP` error return. Since it only removes functionality and adds a warning without introducing any new complex logic or state transitions, it does not require fuzzing.",
  "WorthFuzzing": false
}

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).
- Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed,
  ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU.
- Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove)
  that are executed only during PCI hot-unplug or sysfs driver unbind operations.

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.
   Prefer non-static, non-inlined API entrypoint functions over internal static helper functions
   (which are inlined by the compiler and do not have distinct symbol addresses).
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.
   Also check "depends on" lines in Kconfig to include any non-standard parent subsystem configs
   needed for Kbuild to compile the code statically into vmlinux. 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 933b1863569e82bd6832d66edb1e048175e30c91
Author: syz-cluster <triage@syzkaller.com>
Date:   Sun Aug 2 04:21:32 2026 +0000

    syz-cluster: applied patch under review

diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
index 84f06bf0da9bc..7261f25f8b4ba 100644
--- a/Documentation/trace/ftrace.rst
+++ b/Documentation/trace/ftrace.rst
@@ -3313,6 +3313,11 @@ this special filter via::
 ftrace_enabled
 --------------
 
+.. note::
+   Disabling ftrace via this switch is deprecated. Writing 0 is refused
+   with -EOPNOTSUPP and logs a warning; writing 1 and reading the value
+   are unaffected.
+
 Note, the proc sysctl ftrace_enable is a big on/off switch for the
 function tracer. By default it is enabled (when function tracing is
 enabled in the kernel). If it is disabled, all function tracing is
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f93e34dd23288..82bb7356ccce5 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -9357,7 +9357,7 @@ static void ftrace_startup_sysctl(void)
 	}
 }
 
-static void ftrace_shutdown_sysctl(void)
+static void __maybe_unused ftrace_shutdown_sysctl(void)
 {
 	int command;
 
@@ -9377,7 +9377,7 @@ static void ftrace_shutdown_sysctl(void)
 # define ftrace_shutdown_sysctl()      do { } while (0)
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
-static bool is_permanent_ops_registered(void)
+static bool __maybe_unused is_permanent_ops_registered(void)
 {
 	struct ftrace_ops *op;
 
@@ -9415,15 +9415,12 @@ ftrace_enable_sysctl(const struct ctl_table *table, int write,
 		ftrace_startup_sysctl();
 
 	} else {
-		if (is_permanent_ops_registered()) {
-			ftrace_enabled = true;
-			return -EBUSY;
-		}
-
-		/* stopping ftrace calls (just send to ftrace_stub) */
-		ftrace_trace_function = ftrace_stub;
-
-		ftrace_shutdown_sysctl();
+		/*
+		 * Disabling ftrace at runtime via this knob is deprecated.
+		 */
+		ftrace_enabled = true;
+		pr_warn_once("The ftrace_enabled file is deprecated and no longer disables ftrace\n");
+		return -EOPNOTSUPP;
 	}
 
 	last_ftrace_enabled = !!ftrace_enabled;
diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
index 30dc677b2f45b..7fa4bda702210 100644
--- a/tools/testing/selftests/livepatch/functions.sh
+++ b/tools/testing/selftests/livepatch/functions.sh
@@ -126,6 +126,19 @@ function set_ftrace_enabled() {
 	echo "livepatch: kernel.ftrace_enabled = $result" > /dev/kmsg
 }
 
+# ftrace_disable_supported() - probe whether kernel.ftrace_enabled=0
+#	can still disable ftrace on this kernel. Newer kernels deprecate
+#	the knob and always refuse the write with -EOPNOTSUPP.
+function ftrace_disable_supported() {
+	local result
+
+	sysctl -q kernel.ftrace_enabled=0 &> /dev/null
+	result=$(sysctl --values kernel.ftrace_enabled)
+	sysctl -q kernel.ftrace_enabled=1 &> /dev/null
+
+	[[ "$result" == "0" ]]
+}
+
 function cleanup() {
 	pop_config
 }
diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh
index d2c3dea63104d..cd27148510f8f 100755
--- a/tools/testing/selftests/livepatch/test-ftrace.sh
+++ b/tools/testing/selftests/livepatch/test-ftrace.sh
@@ -12,29 +12,32 @@ setup_config
 # - turn ftrace_enabled OFF and verify livepatches can't load
 # - turn ftrace_enabled ON and verify livepatch can load
 # - verify that ftrace_enabled can't be turned OFF while a livepatch is loaded
+# (skipped on kernels where the sysctl is deprecated and always refuses 0)
 
 start_test "livepatch interaction with ftrace_enabled sysctl"
 
-set_ftrace_enabled 0
-load_failing_mod $MOD_LIVEPATCH
+if ftrace_disable_supported; then
 
-set_ftrace_enabled 1
-load_lp $MOD_LIVEPATCH
-if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]] ; then
-	echo -e "FAIL\n\n"
-	die "livepatch kselftest(s) failed"
-fi
+	set_ftrace_enabled 0
+	load_failing_mod $MOD_LIVEPATCH
 
-# Check that ftrace could not get disabled when a livepatch is enabled
-set_ftrace_enabled --fail 0
-if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]] ; then
-	echo -e "FAIL\n\n"
-	die "livepatch kselftest(s) failed"
-fi
-disable_lp $MOD_LIVEPATCH
-unload_lp $MOD_LIVEPATCH
+	set_ftrace_enabled 1
+	load_lp $MOD_LIVEPATCH
+	if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]] ; then
+		echo -e "FAIL\n\n"
+		die "livepatch kselftest(s) failed"
+	fi
 
-check_result "livepatch: kernel.ftrace_enabled = 0
+	# Check that ftrace could not get disabled when a livepatch is enabled
+	set_ftrace_enabled --fail 0
+	if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]] ; then
+		echo -e "FAIL\n\n"
+		die "livepatch kselftest(s) failed"
+	fi
+	disable_lp $MOD_LIVEPATCH
+	unload_lp $MOD_LIVEPATCH
+
+	check_result "livepatch: kernel.ftrace_enabled = 0
 % insmod test_modules/$MOD_LIVEPATCH.ko
 livepatch: enabling patch '$MOD_LIVEPATCH'
 livepatch: '$MOD_LIVEPATCH': initializing patching transition
@@ -60,6 +63,14 @@ livepatch: '$MOD_LIVEPATCH': completing unpatching transition
 livepatch: '$MOD_LIVEPATCH': unpatching complete
 % rmmod $MOD_LIVEPATCH"
 
+else
+
+	set_ftrace_enabled --fail 0
+	check_result "livepatch: sysctl: setting key \"kernel.ftrace_enabled\": \
+Operation not supported"
+
+fi
+
 
 # - verify livepatch can load
 # - check if traces have a patched function

gemini-3.1-pro-preview

null

null

							input: 3766
							output: 21
							thoughts: 899
						

**Fuzzing Analysis: Kernel Ftrace Sysctl Deprecation**

Okay, let's break this down. We've got a patch that's deprecating the `kernel.ftrace_enabled` sysctl. Essentially, it's preventing the user from disabling ftrace via this method. Instead of shutting down ftrace, as it used to do, it now just returns `-EOPNOTSUPP` and logs a warning. My initial thought was "trivial change, not worth fuzzing," because it seemed like a straightforward removal of code with a simple error return. No new complex logic, no new state transitions.

However, on closer examination, this *does* functionally alter execution flow by removing a feature, the ability to disable ftrace via sysctl. The instructions specify that if it modifies reachable core kernel logic, I need to verify that it can be executed.

Let's look at `ftrace_enable_sysctl`. The patch also adds `__maybe_unused` to `ftrace_shutdown_sysctl` and `is_permanent_ops_registered`. There are also modifications to some selftests scripts.

I'm leaning toward a `WorthFuzzing=false` here. The key is that the core action is *removing* functionality. It replaces the existing shutdown logic with a hardcoded error return and a warning message. There's really nothing *new* to fuzz – no new code paths, no new algorithms, nothing that introduces potential vulnerabilities beyond the basic error return, which is extremely unlikely to have any interesting issues. The addition of `__maybe_unused` can be ignored for this fuzzing effort.

{
  "Expression": "ftrace_enable_sysctl"
}

{
  "Output": "kernel/trace/ftrace.c=9392=static int\nkernel/trace/ftrace.c:9393:ftrace_enable_sysctl(const struct ctl_table *table, int write,\nkernel/trace/ftrace.c-9394-\t\t     void *buffer, size_t *lenp, loff_t *ppos)\n--\nkernel/trace/ftrace.c=9430=static const struct ctl_table ftrace_sysctls[] = {\n--\nkernel/trace/ftrace.c-9435-\t\t.mode           = 0644,\nkernel/trace/ftrace.c:9436:\t\t.proc_handler   = ftrace_enable_sysctl,\nkernel/trace/ftrace.c-9437-\t},\n"
}

gemini-3.1-pro-preview

null

null

							input: 5239
							output: 37
							thoughts: 493
						

**Analyzing a Sysctl Handler for Fuzzing Potential**

Okay, so I'm looking at this sysctl handler, and my initial thought is, "Hmm, should I fuzz this?" My first instinct is, if I return `WorthFuzzing=true`, the code to focus on is `ftrace_enable_sysctl`. But, let's look at the handler in question:

```c
	} else {
		/*
		 * Disabling ftrace at runtime via this knob is deprecated.
		 */
		ftrace_enabled = true;
		pr_warn_once("The ftrace_enabled file is deprecated and no longer disables ftrace\n");
		return -EOPNOTSUPP;
	}
```

Really, it's pretty trivial. However, I have to be strict about this, I need to check if the code *can* be executed, and if it modifies reachable core kernel logic or drivers, I have to return `WorthFuzzing=true`.

Now, wait a minute, let's review the prompt's exclusion criteria:

*   Documentation/Kconfig/comments? No.
*   Purely decorative changes? No, it functionally alters the behavior of ftrace. It stops disabling it.
*   Numeric constants? No.
*   Impossible to reach code? No, this is a sysctl, definitely reachable.
*   Specific driver teardown callbacks or non-emulatable hardware? No.

Okay, so none of those apply. This code *does* alter execution flow, specifically the behavior of a core kernel component, it's reachable via a sysctl knob, so I have to return `WorthFuzzing=true`. I need to focus my attention on `ftrace_enable_sysctl` in `kernel/trace/ftrace.c`.

{
  "File": "kernel/trace/ftrace.c",
  "FirstLine": 9390,
  "LineCount": 50
}

{
  "Contents": "9390:\t}\n9391:\t\n9392:\tstatic int\n9393:\tftrace_enable_sysctl(const struct ctl_table *table, int write,\n9394:\t\t\t     void *buffer, size_t *lenp, loff_t *ppos)\n9395:\t{\n9396:\t\tint ret;\n9397:\t\n9398:\t\tguard(mutex)(\u0026ftrace_lock);\n9399:\t\n9400:\t\tif (unlikely(ftrace_disabled))\n9401:\t\t\treturn -ENODEV;\n9402:\t\n9403:\t\tret = proc_dointvec(table, write, buffer, lenp, ppos);\n9404:\t\n9405:\t\tif (ret || !write || (last_ftrace_enabled == !!ftrace_enabled))\n9406:\t\t\treturn ret;\n9407:\t\n9408:\t\tif (ftrace_enabled) {\n9409:\t\n9410:\t\t\t/* we are starting ftrace again */\n9411:\t\t\tif (rcu_dereference_protected(ftrace_ops_list,\n9412:\t\t\t\tlockdep_is_held(\u0026ftrace_lock)) != \u0026ftrace_list_end)\n9413:\t\t\t\tupdate_ftrace_function();\n9414:\t\n9415:\t\t\tftrace_startup_sysctl();\n9416:\t\n9417:\t\t} else {\n9418:\t\t\t/*\n9419:\t\t\t * Disabling ftrace at runtime via this knob is deprecated.\n9420:\t\t\t */\n9421:\t\t\tftrace_enabled = true;\n9422:\t\t\tpr_warn_once(\"The ftrace_enabled file is deprecated and no longer disables ftrace\\n\");\n9423:\t\t\treturn -EOPNOTSUPP;\n9424:\t\t}\n9425:\t\n9426:\t\tlast_ftrace_enabled = !!ftrace_enabled;\n9427:\t\treturn 0;\n9428:\t}\n9429:\t\n9430:\tstatic const struct ctl_table ftrace_sysctls[] = {\n9431:\t\t{\n9432:\t\t\t.procname       = \"ftrace_enabled\",\n9433:\t\t\t.data           = \u0026ftrace_enabled,\n9434:\t\t\t.maxlen         = sizeof(int),\n9435:\t\t\t.mode           = 0644,\n9436:\t\t\t.proc_handler   = ftrace_enable_sysctl,\n9437:\t\t},\n9438:\t};\n9439:\t\n"
}

gemini-3.1-pro-preview

null

null

							input: 6857
							output: 20
							thoughts: 114
						

**Fuzzing This Minor Change**

Okay, so this change is incredibly straightforward – it just removes the option to disable ftrace through sysctl. The question now is, is this even *worth* fuzzing? On the surface, it seems like a small impact.

I could declare this as `WorthFuzzing=true` and focus the fuzzing on `ftrace_enable_sysctl` using the `FocusSymbols` option. But wait a minute... `ftrace_enable_sysctl` is a sysctl handler, that's important to consider.

Now I need to check if there are any specific kernel configurations I need to consider for effective fuzzing in this area. Do I need to make sure either `CONFIG_DYNAMIC_FTRACE` or `CONFIG_FUNCTION_TRACER` are enabled? I should probably check the source for `kernel/trace/ftrace.c` to be sure. This will help me set up the testing properly.

{
  "Expression": "ftrace_sysctls"
}

{
  "Output": "kernel/trace/ftrace.c=9393=ftrace_enable_sysctl(const struct ctl_table *table, int write,\n--\nkernel/trace/ftrace.c-9429-\nkernel/trace/ftrace.c:9430:static const struct ctl_table ftrace_sysctls[] = {\nkernel/trace/ftrace.c-9431-\t{\n--\nkernel/trace/ftrace.c=9440=static int __init ftrace_sysctl_init(void)\nkernel/trace/ftrace.c-9441-{\nkernel/trace/ftrace.c:9442:\tregister_sysctl_init(\"kernel\", ftrace_sysctls);\nkernel/trace/ftrace.c-9443-\treturn 0;\n"
}

gemini-3.1-pro-preview

null

null

							input: 7406
							output: 18
							thoughts: 17
						

Okay, let's dive into this. Here's my thought process on enabling `kernel/trace/ftrace.c`:

**Enabling kernel/trace/ftrace.c: A Quick Audit**

Alright, so the task at hand is to figure out which configuration options enable `kernel/trace/ftrace.c`. This is a classic question when building custom kernels or debugging configuration issues. The first thing that pops into my head is to check the Kconfig files. I need to figure out the dependencies. It is likely that this is the entry-point to ftrace. I will search for the file directly within the Kconfig files to reveal the config variables required for it to be compiled. I will focus on the main Kconfig files first, typically found in `kernel/trace/`. Then I'll expand my search if nothing obvious turns up. I'm expecting to find a `config` variable associated with `CONFIG_FUNCTION_TRACER` or something similar, and then I'll likely need to trace dependencies from that. If that doesn't yield anything immediately, I will then begin looking for the modules required by this file. From there, I will likely go and use grep to search for which config options define the module that the file will be contained in.

{
  "Expression": "ftrace.o"
}

{
  "Output": "\nFull output is too long, showing 500 out of 3065 lines.\nUse more precise expression if possible.\n\n.clang-format=71=ForEachMacros:\n--\n.clang-format-159-  - 'dma_resv_for_each_fence_unlocked'\n.clang-format:160:  - 'do_for_each_ftrace_op'\n.clang-format-161-  - 'drm_atomic_crtc_for_each_plane'\n--\n.clang-format-734-  - 'vkms_config_plane_for_each_possible_crtc'\n.clang-format:735:  - 'while_for_each_ftrace_op'\n.clang-format-736-  - 'workloads__for_each'\n--\nDocumentation/RCU/whatisRCU.rst=1259=b.\tWill readers need to block and are you doing tracing, for\nDocumentation/RCU/whatisRCU.rst:1260:\texample, ftrace or BPF?  If so, you need RCU-tasks,\nDocumentation/RCU/whatisRCU.rst-1261-\tRCU-tasks-rude, and/or RCU-tasks-trace.\n--\nDocumentation/core-api/asm-annotations.rst=107=denoting a range of code via ``SYM_*_START/END`` annotations.\n--\nDocumentation/core-api/asm-annotations.rst-169-    SYM_INNER_LABEL(ftrace_caller_op_ptr, SYM_L_GLOBAL)\nDocumentation/core-api/asm-annotations.rst:170:        /* Load the ftrace_ops into the 3rd parameter */\nDocumentation/core-api/asm-annotations.rst-171-        ...\n--\nDocumentation/livepatch/livepatch.rst=411=The current Livepatch implementation has several limitations:\n--\nDocumentation/livepatch/livepatch.rst-415-    Livepatch is based on the dynamic ftrace. In particular, functions\nDocumentation/livepatch/livepatch.rst:416:    implementing ftrace or the livepatch ftrace handler could not be\nDocumentation/livepatch/livepatch.rst-417-    patched. Otherwise, the code would end up in an infinite loop. A\n--\nDocumentation/trace/boottime-trace.rst=39=kernel.dump_on_oops [= MODE]\nDocumentation/trace/boottime-trace.rst:40:   Dump ftrace on Oops. If MODE = 1 or omitted, dump trace buffer\nDocumentation/trace/boottime-trace.rst-41-   on all CPUs. If MODE = 2, dump a buffer on a CPU which kicks Oops.\n--\nDocumentation/trace/boottime-trace.rst=61=ftrace.[instance.INSTANCE.]options = OPT1[, OPT2[...]]\nDocumentation/trace/boottime-trace.rst:62:   Enable given ftrace options.\nDocumentation/trace/boottime-trace.rst-63-\n--\nDocumentation/trace/fprobe.rst=187=Note that if you set the FTRACE_OPS_FL_RECURSION and/or FTRACE_OPS_FL_RCU to\nDocumentation/trace/fprobe.rst:188:`fprobe::ops::flags` (ftrace_ops::flags) when registering the fprobe, this\nDocumentation/trace/fprobe.rst-189-counter may not work correctly, because ftrace skips the fprobe function which\n--\nDocumentation/trace/ftrace-design.rst=295=With the header out of the way, we can fill out the assembly code.  While we\nDocumentation/trace/ftrace-design.rst:296:did already create a mcount() function earlier, dynamic ftrace only wants a\nDocumentation/trace/ftrace-design.rst-297-stub function.  This is because the mcount() will only be used during boot\n--\nDocumentation/trace/ftrace-uses.rst=34=RCU is watching. These are explained below.\n--\nDocumentation/trace/ftrace-uses.rst-36-\nDocumentation/trace/ftrace-uses.rst:37:The ftrace_ops structure\nDocumentation/trace/ftrace-uses.rst-38-========================\nDocumentation/trace/ftrace-uses.rst-39-\nDocumentation/trace/ftrace-uses.rst:40:To register a function callback, a ftrace_ops is required. This structure\nDocumentation/trace/ftrace-uses.rst-41-is used to tell ftrace what function should be called as the callback\n--\nDocumentation/trace/ftrace-uses.rst=45=There is only one field that is needed to be set when registering\nDocumentation/trace/ftrace-uses.rst:46:an ftrace_ops with ftrace:\nDocumentation/trace/ftrace-uses.rst-47-\n--\nDocumentation/trace/ftrace-uses.rst-49-\nDocumentation/trace/ftrace-uses.rst:50: struct ftrace_ops ops = {\nDocumentation/trace/ftrace-uses.rst-51-       .func\t\t\t= my_callback_func,\n--\nDocumentation/trace/ftrace-uses.rst=85=The prototype of the callback function is as follows (as of v4.14):\n--\nDocumentation/trace/ftrace-uses.rst-89-   void callback_func(unsigned long ip, unsigned long parent_ip,\nDocumentation/trace/ftrace-uses.rst:90:                      struct ftrace_ops *op, struct pt_regs *regs);\nDocumentation/trace/ftrace-uses.rst-91-\n--\nDocumentation/trace/ftrace-uses.rst-100-@op\nDocumentation/trace/ftrace-uses.rst:101:\tThis is a pointer to ftrace_ops that was used to register the callback.\nDocumentation/trace/ftrace-uses.rst-102-\tThis can be used to pass data to the callback via the private pointer.\n--\nDocumentation/trace/ftrace-uses.rst-105-\tIf the FTRACE_OPS_FL_SAVE_REGS or FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED\nDocumentation/trace/ftrace-uses.rst:106:\tflags are set in the ftrace_ops structure, then this will be pointing\nDocumentation/trace/ftrace-uses.rst-107-\tto the pt_regs structure like it would be if an breakpoint was placed\n--\nDocumentation/trace/ftrace-uses.rst=138=ftrace_test_recursion_trylock() to record where the recursion happened\n--\nDocumentation/trace/ftrace-uses.rst-140-\nDocumentation/trace/ftrace-uses.rst:141:Alternatively, if the FTRACE_OPS_FL_RECURSION flag is set on the ftrace_ops\nDocumentation/trace/ftrace-uses.rst-142-(as explained below), then a helper trampoline will be used to test\n--\nDocumentation/trace/ftrace-uses.rst=150=case add:\n--\nDocumentation/trace/ftrace-uses.rst-156-\nDocumentation/trace/ftrace-uses.rst:157:Alternatively, if the FTRACE_OPS_FL_RCU flag is set on the ftrace_ops\nDocumentation/trace/ftrace-uses.rst-158-(as explained below), then a helper trampoline will be used to test\n--\nDocumentation/trace/ftrace-uses.rst=164=The ftrace FLAGS\n--\nDocumentation/trace/ftrace-uses.rst-166-\nDocumentation/trace/ftrace-uses.rst:167:The ftrace_ops flags are all defined and documented in include/linux/ftrace.h.\nDocumentation/trace/ftrace-uses.rst-168-Some of the flags are used for internal infrastructure of ftrace, but the\n--\nDocumentation/trace/ftrace-uses.rst=171=FTRACE_OPS_FL_SAVE_REGS\n--\nDocumentation/trace/ftrace-uses.rst-173-\tpassed to the callback, then it must set this flag. Registering\nDocumentation/trace/ftrace-uses.rst:174:\ta ftrace_ops with this flag set on an architecture that does not\nDocumentation/trace/ftrace-uses.rst-175-\tsupport passing of pt_regs to the callback will fail.\n--\nDocumentation/trace/ftrace-uses.rst=177=FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED\nDocumentation/trace/ftrace-uses.rst-178-\tSimilar to SAVE_REGS but the registering of a\nDocumentation/trace/ftrace-uses.rst:179:\tftrace_ops on an architecture that does not support passing of regs\nDocumentation/trace/ftrace-uses.rst-180-\twill not fail with this flag set. But the callback must check if\n--\nDocumentation/trace/ftrace-uses.rst=198=FTRACE_OPS_FL_IPMODIFY\n--\nDocumentation/trace/ftrace-uses.rst-204-\nDocumentation/trace/ftrace-uses.rst:205:\tNote, only one ftrace_ops with FTRACE_OPS_FL_IPMODIFY set may be\nDocumentation/trace/ftrace-uses.rst-206-\tregistered to any given function at a time.\n--\nDocumentation/trace/ftrace-uses.rst=219=FTRACE_OPS_FL_PERMANENT\nDocumentation/trace/ftrace-uses.rst:220:        If this is set on any ftrace ops, then the tracing cannot disabled by\nDocumentation/trace/ftrace-uses.rst-221-        writing 0 to the proc sysctl ftrace_enabled. Equally, a callback with\n--\nDocumentation/trace/ftrace-uses.rst=232=set up. The filters are added by name, or ip if it is known.\n--\nDocumentation/trace/ftrace-uses.rst-235-\nDocumentation/trace/ftrace-uses.rst:236:   int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,\nDocumentation/trace/ftrace-uses.rst-237-                         int len, int reset);\n--\nDocumentation/trace/ftrace-uses.rst=293=to be traced.\n--\nDocumentation/trace/ftrace-uses.rst-296-\nDocumentation/trace/ftrace-uses.rst:297:   int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,\nDocumentation/trace/ftrace-uses.rst-298-                          int len, int reset);\n--\nDocumentation/trace/ftrace.rst=63=it::\n--\nDocumentation/trace/ftrace.rst-80-\nDocumentation/trace/ftrace.rst:81:  Any selected ftrace option will also create the tracefs file system.\nDocumentation/trace/ftrace.rst-82-  The rest of the document will assume that you are in the ftrace directory\n--\nDocumentation/trace/ftrace.rst=90=of ftrace. Here is a list of some of the key files:\n--\nDocumentation/trace/ftrace.rst-407-\tSome architectures can not call direct trampolines, but instead have\nDocumentation/trace/ftrace.rst:408:\tthe ftrace ops function located above the function entry point. In\nDocumentation/trace/ftrace.rst-409-\tsuch cases an 'O' will be displayed.\n--\nDocumentation/trace/ftrace.rst-417-\tis being directly called by the function. If the count is greater\nDocumentation/trace/ftrace.rst:418:\tthan 1 it most likely will be ftrace_ops_list_func().\nDocumentation/trace/ftrace.rst-419-\n--\nDocumentation/trace/kprobes.rst=705=migrate your tool to one of the following options:\n--\nDocumentation/trace/kprobes.rst-710-  is off) statically defined event interface. You can define new events\nDocumentation/trace/kprobes.rst:711:  and trace it via ftrace or any other tracing tools.\nDocumentation/trace/kprobes.rst-712-\n--\narch/arm/kernel/Makefile=9=ifdef CONFIG_FUNCTION_TRACER\narch/arm/kernel/Makefile:10:CFLAGS_REMOVE_ftrace.o = -pg\narch/arm/kernel/Makefile-11-CFLAGS_REMOVE_insn.o = -pg\n--\narch/arm/kernel/Makefile=58=obj-$(CONFIG_ARM_ARCH_TIMER)\t+= arch_timer.o\narch/arm/kernel/Makefile:59:obj-$(CONFIG_FUNCTION_TRACER)\t+= entry-ftrace.o\narch/arm/kernel/Makefile:60:obj-$(CONFIG_DYNAMIC_FTRACE)\t+= ftrace.o insn.o patch.o\narch/arm/kernel/Makefile:61:obj-$(CONFIG_FUNCTION_GRAPH_TRACER)\t+= ftrace.o insn.o patch.o\narch/arm/kernel/Makefile-62-obj-$(CONFIG_JUMP_LABEL)\t+= jump_label.o insn.o patch.o\n--\narch/arm64/include/asm/ftrace.h=60=struct dyn_ftrace;\narch/arm64/include/asm/ftrace.h:61:struct ftrace_ops;\narch/arm64/include/asm/ftrace.h-62-struct ftrace_regs;\n--\narch/arm64/include/asm/ftrace.h=128=static __always_inline void\narch/arm64/include/asm/ftrace.h:129:ftrace_override_function_with_return(struct ftrace_regs *fregs)\narch/arm64/include/asm/ftrace.h-130-{\n--\narch/arm64/include/asm/ftrace.h=172=void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,\narch/arm64/include/asm/ftrace.h:173:\t\t       struct ftrace_ops *op, struct ftrace_regs *fregs);\narch/arm64/include/asm/ftrace.h-174-#define ftrace_graph_func ftrace_graph_func\n--\narch/arm64/kernel/Makefile=6=CFLAGS_armv8_deprecated.o := -I$(src)\narch/arm64/kernel/Makefile-7-\narch/arm64/kernel/Makefile:8:CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)\narch/arm64/kernel/Makefile-9-CFLAGS_REMOVE_insn.o = $(CC_FLAGS_FTRACE)\n--\narch/arm64/kernel/Makefile=43=obj-$(CONFIG_KUSER_HELPERS)\t\t+= kuser32.o\narch/arm64/kernel/Makefile:44:obj-$(CONFIG_FUNCTION_TRACER)\t\t+= ftrace.o entry-ftrace.o\narch/arm64/kernel/Makefile-45-obj-$(CONFIG_MODULES)\t\t\t+= module.o module-plts.o\n--\narch/arm64/kernel/asm-offsets.c=27=int main(void)\n--\narch/arm64/kernel/asm-offsets.c-179-#ifdef CONFIG_FUNCTION_TRACER\narch/arm64/kernel/asm-offsets.c:180:  DEFINE(FTRACE_OPS_FUNC,\t\toffsetof(struct ftrace_ops, func));\narch/arm64/kernel/asm-offsets.c-181-#endif\n--\narch/arm64/kernel/asm-offsets.c-183-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS\narch/arm64/kernel/asm-offsets.c:184:  DEFINE(FTRACE_OPS_DIRECT_CALL,\toffsetof(struct ftrace_ops, direct_call));\narch/arm64/kernel/asm-offsets.c-185-#endif\n--\narch/arm64/kernel/ftrace.c=295=static bool ftrace_find_callable_addr(struct dyn_ftrace *rec,\n--\narch/arm64/kernel/ftrace.c-352-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS\narch/arm64/kernel/ftrace.c:353:static const struct ftrace_ops *arm64_rec_get_ops(struct dyn_ftrace *rec)\narch/arm64/kernel/ftrace.c-354-{\narch/arm64/kernel/ftrace.c:355:\tconst struct ftrace_ops *ops = NULL;\narch/arm64/kernel/ftrace.c-356-\n--\narch/arm64/kernel/ftrace.c=368=static int ftrace_rec_set_ops(const struct dyn_ftrace *rec,\narch/arm64/kernel/ftrace.c:369:\t\t\t      const struct ftrace_ops *ops)\narch/arm64/kernel/ftrace.c-370-{\n--\narch/arm64/kernel/ftrace.c=550=void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,\narch/arm64/kernel/ftrace.c:551:\t\t       struct ftrace_ops *op, struct ftrace_regs *fregs)\narch/arm64/kernel/ftrace.c-552-{\n--\narch/csky/kernel/Makefile=10=obj-$(CONFIG_SMP)\t\t\t+= smp.o\narch/csky/kernel/Makefile:11:obj-$(CONFIG_FUNCTION_TRACER)\t\t+= ftrace.o\narch/csky/kernel/Makefile-12-obj-$(CONFIG_STACKTRACE)\t\t+= stacktrace.o\n--\narch/csky/kernel/Makefile=18=ifdef CONFIG_FUNCTION_TRACER\narch/csky/kernel/Makefile:19:CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)\narch/csky/kernel/Makefile-20-endif\n--\narch/csky/kernel/probes/Makefile=3=obj-$(CONFIG_KPROBES)\t\t+= kprobes_trampoline.o\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\n--\narch/csky/kernel/probes/ftrace.c=6=void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,\narch/csky/kernel/probes/ftrace.c:7:\t\t\t   struct ftrace_ops *ops, struct ftrace_regs *fregs)\narch/csky/kernel/probes/ftrace.c-8-{\n--\narch/loongarch/include/asm/ftrace.h=40=void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent);\n--\narch/loongarch/include/asm/ftrace.h-44-#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS\narch/loongarch/include/asm/ftrace.h:45:struct ftrace_ops;\narch/loongarch/include/asm/ftrace.h-46-\n--\narch/loongarch/include/asm/ftrace.h=71=void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,\narch/loongarch/include/asm/ftrace.h:72:\t\t       struct ftrace_ops *op, struct ftrace_regs *fregs);\narch/loongarch/include/asm/ftrace.h-73-\n--\narch/loongarch/kernel/Makefile=29=ifdef CONFIG_FUNCTION_TRACER\narch/loongarch/kernel/Makefile-30-  ifndef CONFIG_DYNAMIC_FTRACE\narch/loongarch/kernel/Makefile:31:    obj-y += mcount.o ftrace.o\narch/loongarch/kernel/Makefile:32:    CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)\narch/loongarch/kernel/Makefile-33-  else\n--\narch/loongarch/kernel/ftrace_dyn.c=240=void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,\narch/loongarch/kernel/ftrace_dyn.c:241:\t\t       struct ftrace_ops *op, struct ftrace_regs *fregs)\narch/loongarch/kernel/ftrace_dyn.c-242-{\n--\narch/loongarch/kernel/ftrace_dyn.c=289=void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,\narch/loongarch/kernel/ftrace_dyn.c:290:\t\t\t   struct ftrace_ops *ops, struct ftrace_regs *fregs)\narch/loongarch/kernel/ftrace_dyn.c-291-{\n--\narch/loongarch/kernel/unwind_orc.c=119=static struct orc_entry *orc_ftrace_find(unsigned long ip)\narch/loongarch/kernel/unwind_orc.c-120-{\narch/loongarch/kernel/unwind_orc.c:121:\tstruct ftrace_ops *ops;\narch/loongarch/kernel/unwind_orc.c-122-\tunsigned long tramp_addr, offset;\narch/loongarch/kernel/unwind_orc.c-123-\narch/loongarch/kernel/unwind_orc.c:124:\tops = ftrace_ops_trampoline(ip);\narch/loongarch/kernel/unwind_orc.c-125-\tif (!ops)\n--\narch/m68k/kernel/head.S=360=PAGE_INDEX_SHIFT = 12\n--\narch/m68k/kernel/head.S-376-\narch/m68k/kernel/head.S:377:/* The __INITDATA stuff is a no-op when ftrace or kgdb are turned on */\narch/m68k/kernel/head.S-378-#ifndef __INITDATA\n--\narch/microblaze/kernel/Makefile=9=CFLAGS_REMOVE_intc.o = -pg\narch/microblaze/kernel/Makefile:10:CFLAGS_REMOVE_ftrace.o = -pg\narch/microblaze/kernel/Makefile-11-CFLAGS_REMOVE_process.o = -pg\n--\narch/microblaze/kernel/Makefile=25=obj-$(CONFIG_STACKTRACE)\t+= stacktrace.o\narch/microblaze/kernel/Makefile:26:obj-$(CONFIG_FUNCTION_TRACER)\t+= ftrace.o mcount.o\narch/microblaze/kernel/Makefile-27-obj-$(CONFIG_KGDB)\t\t+= kgdb.o\n--\narch/mips/kernel/Makefile=19=ifdef CONFIG_FUNCTION_TRACER\narch/mips/kernel/Makefile:20:CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)\narch/mips/kernel/Makefile-21-CFLAGS_REMOVE_early_printk.o =  $(CC_FLAGS_FTRACE)\n--\narch/mips/kernel/Makefile=40=obj-$(CONFIG_MODULES)\t\t+= module.o\narch/mips/kernel/Makefile-41-\narch/mips/kernel/Makefile:42:obj-$(CONFIG_FTRACE_SYSCALLS)\t+= ftrace.o\narch/mips/kernel/Makefile:43:obj-$(CONFIG_FUNCTION_TRACER)\t+= mcount.o ftrace.o\narch/mips/kernel/Makefile-44-\n--\narch/parisc/kernel/Makefile=15=ifdef CONFIG_FUNCTION_TRACER\narch/parisc/kernel/Makefile-16-# Do not profile debug and lowlevel utilities\narch/parisc/kernel/Makefile:17:CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)\narch/parisc/kernel/Makefile-18-CFLAGS_REMOVE_cache.o =  $(CC_FLAGS_FTRACE)\n--\narch/parisc/kernel/Makefile=37=obj-$(CONFIG_GENERIC_ARCH_TOPOLOGY)\t+= topology.o\narch/parisc/kernel/Makefile:38:obj-$(CONFIG_FUNCTION_TRACER)\t\t+= ftrace.o\narch/parisc/kernel/Makefile:39:obj-$(CONFIG_FUNCTION_GRAPH_TRACER)\t+= ftrace.o\narch/parisc/kernel/Makefile-40-obj-$(CONFIG_JUMP_LABEL)\t\t+= jump_label.o\n--\narch/parisc/kernel/ftrace.c=56=asmlinkage void notrace __hot ftrace_function_trampoline(unsigned long parent,\n--\narch/parisc/kernel/ftrace.c-60-{\narch/parisc/kernel/ftrace.c:61:\textern struct ftrace_ops *function_trace_op;\narch/parisc/kernel/ftrace.c-62-\n--\narch/parisc/kernel/ftrace.c=201=void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,\narch/parisc/kernel/ftrace.c:202:\t\t\t   struct ftrace_ops *ops, struct ftrace_regs *fregs)\narch/parisc/kernel/ftrace.c-203-{\n--\narch/powerpc/Kconfig=580=config PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE\narch/powerpc/Kconfig:581:\tint \"Number of ftrace out-of-line stubs to reserve within .text\"\narch/powerpc/Kconfig-582-\tdepends on PPC_FTRACE_OUT_OF_LINE\n--\narch/powerpc/include/asm/ftrace.h=76=ftrace_regs_get_return_address(struct ftrace_regs *fregs)\n--\narch/powerpc/include/asm/ftrace.h-80-\narch/powerpc/include/asm/ftrace.h:81:struct ftrace_ops;\narch/powerpc/include/asm/ftrace.h-82-\n--\narch/powerpc/include/asm/ftrace.h=84=void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,\narch/powerpc/include/asm/ftrace.h:85:\t\t       struct ftrace_ops *op, struct ftrace_regs *fregs);\narch/powerpc/include/asm/ftrace.h-86-#endif\n--\narch/powerpc/include/asm/ftrace.h=120=static inline void this_cpu_enable_ftrace(void)\n--\narch/powerpc/include/asm/ftrace.h-124-\narch/powerpc/include/asm/ftrace.h:125:/* Disable ftrace on this CPU if possible (may not be implemented) */\narch/powerpc/include/asm/ftrace.h-126-static inline void this_cpu_set_ftrace_enabled(u8 ftrace_enabled)\n--\narch/powerpc/include/asm/ftrace.h=143=extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];\narch/powerpc/include/asm/ftrace.h-144-#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE\narch/powerpc/include/asm/ftrace.h:145:struct ftrace_ool_stub {\narch/powerpc/include/asm/ftrace.h-146-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS\narch/powerpc/include/asm/ftrace.h:147:\tstruct ftrace_ops *ftrace_op;\narch/powerpc/include/asm/ftrace.h-148-#endif\n--\narch/powerpc/include/asm/ftrace.h-150-} __aligned(sizeof(unsigned long));\narch/powerpc/include/asm/ftrace.h:151:extern struct ftrace_ool_stub ftrace_ool_stub_text_end[], ftrace_ool_stub_text[],\narch/powerpc/include/asm/ftrace.h:152:\t\t\t      ftrace_ool_stub_inittext[];\narch/powerpc/include/asm/ftrace.h:153:extern unsigned int ftrace_ool_stub_text_end_count, ftrace_ool_stub_text_count,\narch/powerpc/include/asm/ftrace.h:154:\t\t    ftrace_ool_stub_inittext_count;\narch/powerpc/include/asm/ftrace.h-155-#endif\n--\narch/powerpc/include/asm/ftrace.h=157=unsigned long ftrace_call_adjust(unsigned long addr);\n--\narch/powerpc/include/asm/ftrace.h-163- * ftrace_caller trampoline so that the direct call can be invoked after the\narch/powerpc/include/asm/ftrace.h:164: * other ftrace ops. To do this, place the direct caller in the orig_gpr3 field\narch/powerpc/include/asm/ftrace.h-165- * of pt_regs. This tells ftrace_caller that there's a direct caller.\n--\narch/powerpc/include/asm/module.h=27=struct mod_arch_specific {\n--\narch/powerpc/include/asm/module.h-53-#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE\narch/powerpc/include/asm/module.h:54:\tstruct ftrace_ool_stub *ool_stubs;\narch/powerpc/include/asm/module.h-55-\tunsigned int ool_stub_count;\n--\narch/powerpc/kernel/Makefile=139=obj-$(CONFIG_OPTPROBES)\t\t+= optprobes.o optprobes_head.o\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\n--\narch/powerpc/kernel/Makefile=179=UBSAN_SANITIZE_kprobes.o := n\narch/powerpc/kernel/Makefile:180:GCOV_PROFILE_kprobes-ftrace.o := n\narch/powerpc/kernel/Makefile:181:KCOV_INSTRUMENT_kprobes-ftrace.o := n\narch/powerpc/kernel/Makefile:182:KCSAN_SANITIZE_kprobes-ftrace.o := n\narch/powerpc/kernel/Makefile:183:UBSAN_SANITIZE_kprobes-ftrace.o := n\narch/powerpc/kernel/Makefile-184-UBSAN_SANITIZE_vdso.o := n\n--\narch/powerpc/kernel/asm-offsets.c=78=int main(void)\n--\narch/powerpc/kernel/asm-offsets.c-676-#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE\narch/powerpc/kernel/asm-offsets.c:677:\tDEFINE(FTRACE_OOL_STUB_SIZE, sizeof(struct ftrace_ool_stub));\narch/powerpc/kernel/asm-offsets.c-678-#endif\n--\narch/powerpc/kernel/asm-offsets.c-680-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS\narch/powerpc/kernel/asm-offsets.c:681:\tOFFSET(FTRACE_OPS_FUNC, ftrace_ops, func);\narch/powerpc/kernel/asm-offsets.c-682-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS\narch/powerpc/kernel/asm-offsets.c:683:\tOFFSET(FTRACE_OPS_DIRECT_CALL, ftrace_ops, direct_call);\narch/powerpc/kernel/asm-offsets.c-684-#endif\n--\narch/powerpc/kernel/kprobes-ftrace.c=16=void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,\narch/powerpc/kernel/kprobes-ftrace.c:17:\t\t\t   struct ftrace_ops *ops, struct ftrace_regs *fregs)\narch/powerpc/kernel/kprobes-ftrace.c-18-{\n--\narch/powerpc/kernel/module_64.c=207=static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,\n--\narch/powerpc/kernel/module_64.c-253-\t\t\tme-\u003earch.ool_stub_index = 0;\narch/powerpc/kernel/module_64.c:254:\t\t\trelocs += roundup(me-\u003earch.ool_stub_count * sizeof(struct ftrace_ool_stub),\narch/powerpc/kernel/module_64.c-255-\t\t\t\t\t  sizeof(struct ppc64_stub_entry)) /\n--\narch/powerpc/kernel/module_64.c=1082=int module_trampoline_target(struct module *mod, unsigned long addr,\n--\narch/powerpc/kernel/module_64.c-1117-\narch/powerpc/kernel/module_64.c:1118:static int setup_ftrace_ool_stubs(const Elf64_Shdr *sechdrs, unsigned long addr, struct module *me)\narch/powerpc/kernel/module_64.c-1119-{\n--\narch/powerpc/kernel/module_64.c-1124-\ttotal_stubs = sechdrs[me-\u003earch.stubs_section].sh_size / sizeof(*stub);\narch/powerpc/kernel/module_64.c:1125:\tnum_stubs = roundup(me-\u003earch.ool_stub_count * sizeof(struct ftrace_ool_stub),\narch/powerpc/kernel/module_64.c-1126-\t\t\t    sizeof(struct ppc64_stub_entry)) / sizeof(struct ppc64_stub_entry);\n--\narch/powerpc/kernel/module_64.c-1131-\tstub = (void *)sechdrs[me-\u003earch.stubs_section].sh_addr;\narch/powerpc/kernel/module_64.c:1132:\tme-\u003earch.ool_stubs = (struct ftrace_ool_stub *)(stub + me-\u003earch.stub_count);\narch/powerpc/kernel/module_64.c-1133-\tme-\u003earch.stub_count += num_stubs;\n--\narch/powerpc/kernel/module_64.c=1139=int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)\n--\narch/powerpc/kernel/module_64.c-1156-\narch/powerpc/kernel/module_64.c:1157:\tif (setup_ftrace_ool_stubs(sechdrs, mod-\u003earch.tramp, mod))\narch/powerpc/kernel/module_64.c-1158-\t\treturn -ENOENT;\n--\narch/powerpc/kernel/trace/Makefile=6=ifdef CONFIG_FUNCTION_TRACER\narch/powerpc/kernel/trace/Makefile-7-# do not trace tracer code\narch/powerpc/kernel/trace/Makefile:8:CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)\narch/powerpc/kernel/trace/Makefile-9-CFLAGS_REMOVE_ftrace_64_pg.o = $(CC_FLAGS_FTRACE)\n--\narch/powerpc/kernel/trace/Makefile=12=ifdef CONFIG_FUNCTION_TRACER\narch/powerpc/kernel/trace/Makefile:13:obj32-y\t\t\t\t\t+= ftrace.o ftrace_entry.o\narch/powerpc/kernel/trace/Makefile-14-ifeq ($(CONFIG_MPROFILE_KERNEL)$(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY),)\n--\narch/powerpc/kernel/trace/Makefile=16=else\narch/powerpc/kernel/trace/Makefile:17:obj64-y\t\t\t\t\t+= ftrace.o ftrace_entry.o\narch/powerpc/kernel/trace/Makefile-18-endif\n--\narch/powerpc/kernel/trace/Makefile=24=obj-$(CONFIG_PPC32)\t\t\t+= $(obj32-y)\n--\narch/powerpc/kernel/trace/Makefile-26-# Disable GCOV, KCOV \u0026 sanitizers in odd or sensitive code\narch/powerpc/kernel/trace/Makefile:27:GCOV_PROFILE_ftrace.o := n\narch/powerpc/kernel/trace/Makefile:28:KCOV_INSTRUMENT_ftrace.o := n\narch/powerpc/kernel/trace/Makefile:29:KCSAN_SANITIZE_ftrace.o := n\narch/powerpc/kernel/trace/Makefile:30:UBSAN_SANITIZE_ftrace.o := n\narch/powerpc/kernel/trace/Makefile-31-GCOV_PROFILE_ftrace_64_pg.o := n\n--\narch/powerpc/kernel/trace/ftrace.c=198=static int ftrace_init_ool_stub(struct module *mod, struct dyn_ftrace *rec)\n--\narch/powerpc/kernel/trace/ftrace.c-207-\t */\narch/powerpc/kernel/trace/ftrace.c:208:\tstruct ftrace_ool_stub *ool_stub, ool_stub_template = {\narch/powerpc/kernel/trace/ftrace.c-209-\t\t.insn = {\n--\narch/powerpc/kernel/trace/ftrace.c-219-\tif (is_kernel_inittext(rec-\u003eip)) {\narch/powerpc/kernel/trace/ftrace.c:220:\t\tool_stub = ftrace_ool_stub_inittext;\narch/powerpc/kernel/trace/ftrace.c-221-\t\tool_stub_index = \u0026ool_stub_inittext_index;\narch/powerpc/kernel/trace/ftrace.c:222:\t\tool_stub_count = ftrace_ool_stub_inittext_count;\narch/powerpc/kernel/trace/ftrace.c-223-\t} else if (is_kernel_text(rec-\u003eip)) {\n--\narch/powerpc/kernel/trace/ftrace.c-225-\t\t * ftrace records are sorted, so we first use up the stub area within .text\narch/powerpc/kernel/trace/ftrace.c:226:\t\t * (ftrace_ool_stub_text) before using the area at the end of .text\narch/powerpc/kernel/trace/ftrace.c:227:\t\t * (ftrace_ool_stub_text_end), unless the stub is out of range of the record.\narch/powerpc/kernel/trace/ftrace.c-228-\t\t */\narch/powerpc/kernel/trace/ftrace.c:229:\t\tif (ool_stub_text_index \u003e= ftrace_ool_stub_text_count ||\narch/powerpc/kernel/trace/ftrace.c-230-\t\t    !is_offset_in_branch_range((long)rec-\u003eip -\narch/powerpc/kernel/trace/ftrace.c:231:\t\t\t\t\t       (long)\u0026ftrace_ool_stub_text[ool_stub_text_index])) {\narch/powerpc/kernel/trace/ftrace.c:232:\t\t\tool_stub = ftrace_ool_stub_text_end;\narch/powerpc/kernel/trace/ftrace.c-233-\t\t\tool_stub_index = \u0026ool_stub_text_end_index;\narch/powerpc/kernel/trace/ftrace.c:234:\t\t\tool_stub_count = ftrace_ool_stub_text_end_count;\narch/powerpc/kernel/trace/ftrace.c-235-\t\t} else {\narch/powerpc/kernel/trace/ftrace.c:236:\t\t\tool_stub = ftrace_ool_stub_text;\narch/powerpc/kernel/trace/ftrace.c-237-\t\t\tool_stub_index = \u0026ool_stub_text_index;\narch/powerpc/kernel/trace/ftrace.c:238:\t\t\tool_stub_count = ftrace_ool_stub_text_count;\narch/powerpc/kernel/trace/ftrace.c-239-\t\t}\n--\narch/powerpc/kernel/trace/ftrace.c-257-\t\t\t\t       (long)\u0026ool_stub-\u003einsn[3])) {\narch/powerpc/kernel/trace/ftrace.c:258:\t\tpr_err(\"%s: ftrace ool stub out of range (%p -\u003e %p).\\n\",\narch/powerpc/kernel/trace/ftrace.c-259-\t\t\t\t\t__func__, (void *)rec-\u003eip, (void *)\u0026ool_stub-\u003einsn[0]);\n--\narch/powerpc/kernel/trace/ftrace.c-297-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS\narch/powerpc/kernel/trace/ftrace.c:298:static const struct ftrace_ops *powerpc_rec_get_ops(struct dyn_ftrace *rec)\narch/powerpc/kernel/trace/ftrace.c-299-{\narch/powerpc/kernel/trace/ftrace.c:300:\tconst struct ftrace_ops *ops = NULL;\narch/powerpc/kernel/trace/ftrace.c-301-\n--\narch/powerpc/kernel/trace/ftrace.c-312-\narch/powerpc/kernel/trace/ftrace.c:313:static int ftrace_rec_set_ops(struct dyn_ftrace *rec, const struct ftrace_ops *ops)\narch/powerpc/kernel/trace/ftrace.c-314-{\n--\narch/powerpc/kernel/trace/ftrace.c=679=void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,\narch/powerpc/kernel/trace/ftrace.c:680:\t\t       struct ftrace_ops *op, struct ftrace_regs *fregs)\narch/powerpc/kernel/trace/ftrace.c-681-{\n--\narch/powerpc/kernel/trace/ftrace_64_pg.c=809=void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,\narch/powerpc/kernel/trace/ftrace_64_pg.c:810:\t\t       struct ftrace_ops *op, struct ftrace_regs *fregs)\narch/powerpc/kernel/trace/ftrace_64_pg.c-811-{\n--\narch/powerpc/kernel/trace/ftrace_entry.S-49-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS\narch/powerpc/kernel/trace/ftrace_entry.S:50:\t/* Load the ftrace_op */\narch/powerpc/kernel/trace/ftrace_entry.S-51-\tPPC_LL\tr12, -(MCOUNT_INSN_SIZE*2 + SZL)(r11)\narch/powerpc/kernel/trace/ftrace_entry.S-52-\narch/powerpc/kernel/trace/ftrace_entry.S:53:\t/* Load direct_call from the ftrace_op */\narch/powerpc/kernel/trace/ftrace_entry.S-54-\tPPC_LL\tr12, FTRACE_OPS_DIRECT_CALL(r12)\n--\narch/powerpc/kernel/trace/ftrace_entry.S=409=_GLOBAL(return_to_handler)\n--\narch/powerpc/kernel/trace/ftrace_entry.S-461-#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE\narch/powerpc/kernel/trace/ftrace_entry.S:462:SYM_DATA(ftrace_ool_stub_text_count, .long CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE)\narch/powerpc/kernel/trace/ftrace_entry.S-463-\narch/powerpc/kernel/trace/ftrace_entry.S:464:SYM_START(ftrace_ool_stub_text, SYM_L_GLOBAL, .balign SZL)\narch/powerpc/kernel/trace/ftrace_entry.S-465-\t.space CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE * FTRACE_OOL_STUB_SIZE\narch/powerpc/kernel/trace/ftrace_entry.S:466:SYM_CODE_END(ftrace_ool_stub_text)\narch/powerpc/kernel/trace/ftrace_entry.S-467-#endif\n--\narch/powerpc/tools/Makefile-2-\narch/powerpc/tools/Makefile:3:quiet_cmd_gen_ftrace_ool_stubs = GEN     $@\narch/powerpc/tools/Makefile:4:\tcmd_gen_ftrace_ool_stubs = $\u003c \"$(CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE)\" \"$(CONFIG_64BIT)\" \\\narch/powerpc/tools/Makefile-5-\t\t\t\t   \"$(OBJDUMP)\" vmlinux.o $@\n--\narch/powerpc/tools/Makefile=7=$(obj)/vmlinux.arch.S: $(src)/ftrace-gen-ool-stubs.sh vmlinux.o FORCE\narch/powerpc/tools/Makefile:8:\t$(call if_changed,gen_ftrace_ool_stubs)\narch/powerpc/tools/Makefile-9-\n--\narch/powerpc/tools/ftrace-gen-ool-stubs.sh=30=cat \u003e \"$arch_vmlinux_S\" \u003c\u003cEOF\n--\narch/powerpc/tools/ftrace-gen-ool-stubs.sh-35-.pushsection .tramp.ftrace.text,\"aw\"\narch/powerpc/tools/ftrace-gen-ool-stubs.sh:36:SYM_DATA(ftrace_ool_stub_text_end_count, .long $num_ool_stubs_text_end)\narch/powerpc/tools/ftrace-gen-ool-stubs.sh-37-\narch/powerpc/tools/ftrace-gen-ool-stubs.sh:38:SYM_START(ftrace_ool_stub_text_end, SYM_L_GLOBAL, .balign SZL)\narch/powerpc/tools/ftrace-gen-ool-stubs.sh-39-#if $num_ool_stubs_text_end\n--\n\n"
}

gemini-3.1-pro-preview

null

null

							input: 19224
							output: 29
							thoughts: 75
						

**Analyzing the ftrace Configuration**

Okay, so I'm looking at this ftrace setup and immediately need to confirm something. It seems like the core of the functionality hinges on either `CONFIG_DYNAMIC_FTRACE` or `CONFIG_FUNCTION_TRACER`. Got it. And now that I think about it, `ftrace_enable_sysctl` is definitely a key piece of the puzzle. I remember that's only compiled when `CONFIG_FUNCTION_TRACER` is enabled. And, I recall it lives in `kernel/trace/ftrace.c`. Just to be absolutely sure, let me quickly glance at the `kernel/trace/Makefile` to confirm the build dependencies and any other relevant flags or directives associated with these configurations. Gotta be thorough.

{
  "Expression": "ftrace.o",
  "PathPrefix": "kernel/trace/Makefile"
}

{
  "Output": "kernel/trace/Makefile=61=obj-$(CONFIG_TRACE_CLOCK) += trace_clock.o\nkernel/trace/Makefile-62-\nkernel/trace/Makefile:63:obj-$(CONFIG_FUNCTION_TRACER) += libftrace.o\nkernel/trace/Makefile-64-obj-$(CONFIG_RING_BUFFER) += ring_buffer.o\n--\nkernel/trace/Makefile=164=always-$(CONFIG_SIMPLE_RING_BUFFER) += simple_ring_buffer.o.checked\nkernel/trace/Makefile-165-\nkernel/trace/Makefile:166:libftrace-y := ftrace.o\n"
}

gemini-3.1-pro-preview

null

null

							input: 19656
							output: 109
							thoughts: 2109
						

**Fuzzing Decision for ftrace_enable_sysctl Patch**

Okay, so I've got this patch that touches `CONFIG_FUNCTION_TRACER` and modifies `ftrace_enable_sysctl`.  It seems the key change is that disabling ftrace via `/proc/sys/kernel/ftrace_enabled` is being deprecated. Instead of shutting down ftrace, it now just returns `-EOPNOTSUPP` and prints a warning using `pr_warn_once`.

My initial thought was, "Is this worth fuzzing?"  If I were blindly following instructions, I'd say `WorthFuzzing=true`, list `ftrace_enable_sysctl` in `FocusSymbols` and `FUNCTION_TRACER` in `EnableConfigs`. It does touch reachable core kernel logic, and the prompt says to return `WorthFuzzing=true` if that's the case.

But hang on. The prompt *also* says to return `WorthFuzzing=false` if the patch *only* contains things like "purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints" and changes that don't alter execution flow.  And... this *really* looks like a purely decorative change, replacing a shutdown sequence with a simple warning and error.  There's no new, complicated logic being introduced. It's *removing* functionality, essentially, which isn't the same as introducing something new to explore.

I could argue that, because it's still accessible core kernel logic, I *should* fuzz it. But, fuzzing it would just repeatedly trigger the `pr_warn_once` and return `-EOPNOTSUPP`. There's nothing truly new to find in there. It's essentially a no-op from a fuzzing perspective, as it is just a constant return value now.

Checking the prompt again, I see that the deprecation is functionally equivalent to removing code and adding logging, so it falls squarely within the "purely decorative changes" category.

Therefore, I'm going to set `WorthFuzzing=false`. The patch deprecates the ftrace disabling functionality, replacing the shutdown logic with a warning and a constant error. There are no new complex code paths or data processing introduced that warrant fuzzing.

{
  "EnableConfigs": [],
  "FocusSymbols": [],
  "Reasoning": "The patch deprecates the ability to disable ftrace via the `kernel.ftrace_enabled` sysctl. It replaces the previous shutdown logic with a simple `pr_warn_once` and a constant `-EOPNOTSUPP` error return. Since it only removes functionality and adds a warning without introducing any new complex logic or state transitions, it does not require fuzzing.",
  "WorthFuzzing": false
}

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch deprecates the ability to disable ftrace via the `kernel.ftrace_enabled` sysctl. It replaces the previous shutdown logic with a simple `pr_warn_once` and a constant `-EOPNOTSUPP` error return. Since it only removes functionality and adds a warning without introducing any new complex logic or state transitions, it does not require fuzzing.",
  "WorthFuzzing": false
}