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The test proves that a function that is being kprobed and uses a post_handler cannot be livepatched. Only one ftrace_ops with FTRACE_OPS_FL_IPMODIFY set may be registered to any given function at a time. Note that the conflicting kprobe could not be created using the tracefs interface, see Documentation/trace/kprobetrace.rst. This interface uses only the pre_handler(), see alloc_trace_kprobe(). But FTRACE_OPS_FL_IPMODIFY is used only when the kprobe is using a post_handler, see arm_kprobe_ftrace(). Signed-off-by: Michael Vetter <mvetter@suse.com> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Tested-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Tested-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20241017200132.21946-4-mvetter@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com>
39 lines
870 B
C
39 lines
870 B
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2024 Marcos Paulo de Souza <mpdesouza@suse.com>
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// Copyright (C) 2024 Michael Vetter <mvetter@suse.com>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/kprobes.h>
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static bool has_post_handler = true;
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module_param(has_post_handler, bool, 0444);
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static void __kprobes post_handler(struct kprobe *p, struct pt_regs *regs,
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unsigned long flags)
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{
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}
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static struct kprobe kp = {
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.symbol_name = "cmdline_proc_show",
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};
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static int __init kprobe_init(void)
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{
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if (has_post_handler)
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kp.post_handler = post_handler;
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return register_kprobe(&kp);
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}
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static void __exit kprobe_exit(void)
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{
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unregister_kprobe(&kp);
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}
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module_init(kprobe_init)
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module_exit(kprobe_exit)
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Michael Vetter <mvetter@suse.com>");
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MODULE_DESCRIPTION("Livepatch test: kprobe function");
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