mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-27 14:43:58 +08:00
4dc0da8696
The perf_event overflow handler does not receive any caller-derived argument, so many callers need to resort to looking up the perf_event in their local data structure. This is ugly and doesn't scale if a single callback services many perf_events. Fix by adding a context parameter to perf_event_create_kernel_counter() (and derived hardware breakpoints APIs) and storing it in the perf_event. The field can be accessed from the callback as event->overflow_handler_context. All callers are updated. Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1309362157-6596-2-git-send-email-avi@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
91 lines
2.9 KiB
C
91 lines
2.9 KiB
C
/*
|
|
* data_breakpoint.c - Sample HW Breakpoint file to watch kernel data address
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
|
*
|
|
* usage: insmod data_breakpoint.ko ksym=<ksym_name>
|
|
*
|
|
* This file is a kernel module that places a breakpoint over ksym_name kernel
|
|
* variable using Hardware Breakpoint register. The corresponding handler which
|
|
* prints a backtrace is invoked every time a write operation is performed on
|
|
* that variable.
|
|
*
|
|
* Copyright (C) IBM Corporation, 2009
|
|
*
|
|
* Author: K.Prasad <prasad@linux.vnet.ibm.com>
|
|
*/
|
|
#include <linux/module.h> /* Needed by all modules */
|
|
#include <linux/kernel.h> /* Needed for KERN_INFO */
|
|
#include <linux/init.h> /* Needed for the macros */
|
|
#include <linux/kallsyms.h>
|
|
|
|
#include <linux/perf_event.h>
|
|
#include <linux/hw_breakpoint.h>
|
|
|
|
struct perf_event * __percpu *sample_hbp;
|
|
|
|
static char ksym_name[KSYM_NAME_LEN] = "pid_max";
|
|
module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
|
|
MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any"
|
|
" write operations on the kernel symbol");
|
|
|
|
static void sample_hbp_handler(struct perf_event *bp,
|
|
struct perf_sample_data *data,
|
|
struct pt_regs *regs)
|
|
{
|
|
printk(KERN_INFO "%s value is changed\n", ksym_name);
|
|
dump_stack();
|
|
printk(KERN_INFO "Dump stack from sample_hbp_handler\n");
|
|
}
|
|
|
|
static int __init hw_break_module_init(void)
|
|
{
|
|
int ret;
|
|
struct perf_event_attr attr;
|
|
|
|
hw_breakpoint_init(&attr);
|
|
attr.bp_addr = kallsyms_lookup_name(ksym_name);
|
|
attr.bp_len = HW_BREAKPOINT_LEN_4;
|
|
attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
|
|
|
|
sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler, NULL);
|
|
if (IS_ERR((void __force *)sample_hbp)) {
|
|
ret = PTR_ERR((void __force *)sample_hbp);
|
|
goto fail;
|
|
}
|
|
|
|
printk(KERN_INFO "HW Breakpoint for %s write installed\n", ksym_name);
|
|
|
|
return 0;
|
|
|
|
fail:
|
|
printk(KERN_INFO "Breakpoint registration failed\n");
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void __exit hw_break_module_exit(void)
|
|
{
|
|
unregister_wide_hw_breakpoint(sample_hbp);
|
|
printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name);
|
|
}
|
|
|
|
module_init(hw_break_module_init);
|
|
module_exit(hw_break_module_exit);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("K.Prasad");
|
|
MODULE_DESCRIPTION("ksym breakpoint");
|