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![Srikar Dronamraju](/assets/img/avatar_default.png)
Implements trace_event support for uprobes. In its current form it can be used to put probes at a specified offset in a file and dump the required registers when the code flow reaches the probed address. The following example shows how to dump the instruction pointer and %ax a register at the probed text address. Here we are trying to probe zfree in /bin/zsh: # cd /sys/kernel/debug/tracing/ # cat /proc/`pgrep zsh`/maps | grep /bin/zsh | grep r-xp 00400000-0048a000 r-xp 00000000 08:03 130904 /bin/zsh # objdump -T /bin/zsh | grep -w zfree 0000000000446420 g DF .text 0000000000000012 Base zfree # echo 'p /bin/zsh:0x46420 %ip %ax' > uprobe_events # cat uprobe_events p:uprobes/p_zsh_0x46420 /bin/zsh:0x0000000000046420 # echo 1 > events/uprobes/enable # sleep 20 # echo 0 > events/uprobes/enable # cat trace # tracer: nop # # TASK-PID CPU# TIMESTAMP FUNCTION # | | | | | zsh-24842 [006] 258544.995456: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79 zsh-24842 [007] 258545.000270: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79 zsh-24842 [002] 258545.043929: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79 zsh-24842 [004] 258547.046129: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79 Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com> Cc: Linux-mm <linux-mm@kvack.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Anton Arapov <anton@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20120411103043.GB29437@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
161 lines
4.6 KiB
C
161 lines
4.6 KiB
C
/*
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* Common header file for probe-based Dynamic events.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* This code was copied from kernel/trace/trace_kprobe.h written by
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* Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
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*
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* Updates to make this generic:
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* Copyright (C) IBM Corporation, 2010-2011
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* Author: Srikar Dronamraju
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*/
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <linux/smp.h>
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#include <linux/debugfs.h>
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/ctype.h>
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#include <linux/ptrace.h>
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#include <linux/perf_event.h>
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#include <linux/kprobes.h>
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#include <linux/stringify.h>
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#include <linux/limits.h>
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#include <linux/uaccess.h>
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#include <asm/bitsperlong.h>
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#include "trace.h"
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#include "trace_output.h"
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#define MAX_TRACE_ARGS 128
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#define MAX_ARGSTR_LEN 63
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#define MAX_EVENT_NAME_LEN 64
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#define MAX_STRING_SIZE PATH_MAX
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/* Reserved field names */
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#define FIELD_STRING_IP "__probe_ip"
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#define FIELD_STRING_RETIP "__probe_ret_ip"
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#define FIELD_STRING_FUNC "__probe_func"
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#undef DEFINE_FIELD
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#define DEFINE_FIELD(type, item, name, is_signed) \
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do { \
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ret = trace_define_field(event_call, #type, name, \
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offsetof(typeof(field), item), \
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sizeof(field.item), is_signed, \
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FILTER_OTHER); \
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if (ret) \
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return ret; \
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} while (0)
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/* Flags for trace_probe */
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#define TP_FLAG_TRACE 1
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#define TP_FLAG_PROFILE 2
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#define TP_FLAG_REGISTERED 4
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#define TP_FLAG_UPROBE 8
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/* data_rloc: data relative location, compatible with u32 */
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#define make_data_rloc(len, roffs) \
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(((u32)(len) << 16) | ((u32)(roffs) & 0xffff))
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#define get_rloc_len(dl) ((u32)(dl) >> 16)
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#define get_rloc_offs(dl) ((u32)(dl) & 0xffff)
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/*
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* Convert data_rloc to data_loc:
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* data_rloc stores the offset from data_rloc itself, but data_loc
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* stores the offset from event entry.
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*/
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#define convert_rloc_to_loc(dl, offs) ((u32)(dl) + (offs))
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/* Data fetch function type */
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typedef void (*fetch_func_t)(struct pt_regs *, void *, void *);
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/* Printing function type */
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typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *, void *);
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/* Fetch types */
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enum {
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FETCH_MTD_reg = 0,
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FETCH_MTD_stack,
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FETCH_MTD_retval,
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FETCH_MTD_memory,
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FETCH_MTD_symbol,
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FETCH_MTD_deref,
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FETCH_MTD_bitfield,
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FETCH_MTD_END,
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};
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/* Fetch type information table */
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struct fetch_type {
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const char *name; /* Name of type */
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size_t size; /* Byte size of type */
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int is_signed; /* Signed flag */
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print_type_func_t print; /* Print functions */
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const char *fmt; /* Fromat string */
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const char *fmttype; /* Name in format file */
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/* Fetch functions */
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fetch_func_t fetch[FETCH_MTD_END];
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};
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struct fetch_param {
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fetch_func_t fn;
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void *data;
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};
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struct probe_arg {
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struct fetch_param fetch;
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struct fetch_param fetch_size;
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unsigned int offset; /* Offset from argument entry */
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const char *name; /* Name of this argument */
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const char *comm; /* Command of this argument */
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const struct fetch_type *type; /* Type of this argument */
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};
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static inline __kprobes void call_fetch(struct fetch_param *fprm,
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struct pt_regs *regs, void *dest)
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{
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return fprm->fn(regs, fprm->data, dest);
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}
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/* Check the name is good for event/group/fields */
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static inline int is_good_name(const char *name)
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{
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if (!isalpha(*name) && *name != '_')
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return 0;
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while (*++name != '\0') {
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if (!isalpha(*name) && !isdigit(*name) && *name != '_')
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return 0;
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}
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return 1;
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}
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extern int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
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struct probe_arg *parg, bool is_return, bool is_kprobe);
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extern int traceprobe_conflict_field_name(const char *name,
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struct probe_arg *args, int narg);
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extern void traceprobe_update_arg(struct probe_arg *arg);
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extern void traceprobe_free_probe_arg(struct probe_arg *arg);
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extern int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset);
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extern ssize_t traceprobe_probes_write(struct file *file,
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const char __user *buffer, size_t count, loff_t *ppos,
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int (*createfn)(int, char**));
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extern int traceprobe_command(const char *buf, int (*createfn)(int, char**));
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