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ad8f63f935
Use ERR_PTR_PCPU() when returning error pointer in the percpu address space. Use IS_ERR_PCPU() and PTR_ERR_PCPU() when returning the error pointer from the percpu address space. These macros add intermediate cast to unsigned long when switching named address spaces. The patch will avoid future build errors due to pointer address space mismatch with enabled strict percpu address space checks. Link: https://lkml.kernel.org/r/20240924090813.1353586-1-ubizjak@gmail.com Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: "Liang, Kan" <kan.liang@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
85 lines
2.3 KiB
C
85 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* data_breakpoint.c - Sample HW Breakpoint file to watch kernel data address
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*
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* usage: insmod data_breakpoint.ko ksym=<ksym_name>
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*
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* This file is a kernel module that places a breakpoint over ksym_name kernel
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* variable using Hardware Breakpoint register. The corresponding handler which
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* prints a backtrace is invoked every time a write operation is performed on
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* that variable.
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*
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* Copyright (C) IBM Corporation, 2009
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*
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* Author: K.Prasad <prasad@linux.vnet.ibm.com>
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*/
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#include <linux/module.h> /* Needed by all modules */
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#include <linux/kernel.h> /* Needed for KERN_INFO */
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#include <linux/init.h> /* Needed for the macros */
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#include <linux/kallsyms.h>
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#include <linux/perf_event.h>
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#include <linux/hw_breakpoint.h>
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static struct perf_event * __percpu *sample_hbp;
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static char ksym_name[KSYM_NAME_LEN] = "jiffies";
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module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
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MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any"
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" write operations on the kernel symbol");
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static void sample_hbp_handler(struct perf_event *bp,
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struct perf_sample_data *data,
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struct pt_regs *regs)
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{
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printk(KERN_INFO "%s value is changed\n", ksym_name);
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dump_stack();
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printk(KERN_INFO "Dump stack from sample_hbp_handler\n");
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}
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static int __init hw_break_module_init(void)
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{
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int ret;
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struct perf_event_attr attr;
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void *addr = __symbol_get(ksym_name);
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if (!addr)
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return -ENXIO;
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hw_breakpoint_init(&attr);
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attr.bp_addr = (unsigned long)addr;
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attr.bp_len = HW_BREAKPOINT_LEN_4;
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attr.bp_type = HW_BREAKPOINT_W;
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sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler, NULL);
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if (IS_ERR_PCPU(sample_hbp)) {
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ret = PTR_ERR_PCPU(sample_hbp);
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goto fail;
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}
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printk(KERN_INFO "HW Breakpoint for %s write installed\n", ksym_name);
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return 0;
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fail:
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printk(KERN_INFO "Breakpoint registration failed\n");
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return ret;
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}
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static void __exit hw_break_module_exit(void)
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{
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unregister_wide_hw_breakpoint(sample_hbp);
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#ifdef CONFIG_MODULE_UNLOAD
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__symbol_put(ksym_name);
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#endif
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printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name);
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}
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module_init(hw_break_module_init);
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module_exit(hw_break_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("K.Prasad");
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MODULE_DESCRIPTION("ksym breakpoint");
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