910e230d5f
Macro symbol_put() is defined as __symbol_put(__stringify(x))
ksym_name = "jiffies"
symbol_put(ksym_name)
will be resolved as
__symbol_put("ksym_name")
which is clearly wrong. So symbol_put must be replaced with __symbol_put.
When we uninstall hw_breakpoint.ko (rmmod), a kernel bug occurs with the
following error:
[11381.854152] kernel BUG at kernel/module/main.c:779!
[11381.854159] invalid opcode: 0000 [#2] PREEMPT SMP PTI
[11381.854163] CPU: 8 PID: 59623 Comm: rmmod Tainted: G D OE 6.2.9-200.fc37.x86_64 #1
[11381.854167] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./B360M-HDV, BIOS P3.20 10/23/2018
[11381.854169] RIP: 0010:__symbol_put+0xa2/0xb0
[11381.854175] Code: 00 e8 92 d2 f7 ff 65 8b 05 c3 2f e6 78 85 c0 74 1b 48 8b 44 24 30 65 48 2b 04 25 28 00 00 00 75 12 48 83 c4 38 c3 cc cc cc cc <0f> 0b 0f 1f 44 00 00 eb de e8 c0 df d8 00 90 90 90 90 90 90 90 90
[11381.854178] RSP: 0018:ffffad8ec6ae7dd0 EFLAGS: 00010246
[11381.854181] RAX: 0000000000000000 RBX: ffffffffc1fd1240 RCX: 000000000000000c
[11381.854184] RDX: 000000000000006b RSI: ffffffffc02bf7c7 RDI: ffffffffc1fd001c
[11381.854186] RBP: 000055a38b76e7c8 R08: ffffffff871ccfe0 R09: 0000000000000000
[11381.854188] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
[11381.854190] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[11381.854192] FS: 00007fbf7c62c740(0000) GS:ffff8c5badc00000(0000) knlGS:0000000000000000
[11381.854195] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[11381.854197] CR2: 000055a38b7793f8 CR3: 0000000363e1e001 CR4: 00000000003726e0
[11381.854200] DR0: ffffffffb3407980 DR1: 0000000000000000 DR2: 0000000000000000
[11381.854202] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[11381.854204] Call Trace:
[11381.854207] <TASK>
[11381.854212] s_module_exit+0xc/0xff0 [symbol_getput]
[11381.854219] __do_sys_delete_module.constprop.0+0x198/0x2f0
[11381.854225] do_syscall_64+0x58/0x80
[11381.854231] ? exit_to_user_mode_prepare+0x180/0x1f0
[11381.854237] ? syscall_exit_to_user_mode+0x17/0x40
[11381.854241] ? do_syscall_64+0x67/0x80
[11381.854245] ? syscall_exit_to_user_mode+0x17/0x40
[11381.854248] ? do_syscall_64+0x67/0x80
[11381.854252] ? exc_page_fault+0x70/0x170
[11381.854256] entry_SYSCALL_64_after_hwframe+0x72/0xdc
Signed-off-by: Rong Tao <rongtao@cestc.cn>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
83 lines
2.3 KiB
C
83 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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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((void __force *)sample_hbp)) {
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ret = PTR_ERR((void __force *)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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__symbol_put(ksym_name);
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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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