bf794bf52a
Currently, all non-dot symbols are being treated as function descriptors
in ABIv1. This is incorrect and is resulting in perf probe not working:
# perf probe do_fork
Added new event:
Failed to write event: Invalid argument
Error: Failed to add events.
# dmesg | tail -1
[192268.073063] Could not insert probe at _text+768432: -22
perf probe bases all kernel probes on _text and writes,
for example, "p:probe/do_fork _text+768432" to
/sys/kernel/debug/tracing/kprobe_events. In-kernel, _text is being
considered to be a function descriptor and is resulting in the above
error.
Fix this by changing how we lookup symbol addresses on ppc64. We first
check for the dot variant of a symbol and look at the non-dot variant
only if that fails. In this manner, we avoid having to look at the
function descriptor.
While at it, also separate out how this works on ABIv2 where
we don't have dot symbols, but need to use the local entry point.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
134 lines
4.1 KiB
C
134 lines
4.1 KiB
C
#ifndef _ASM_POWERPC_KPROBES_H
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#define _ASM_POWERPC_KPROBES_H
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#ifdef __KERNEL__
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/*
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* Kernel Probes (KProbes)
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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 as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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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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* Copyright (C) IBM Corporation, 2002, 2004
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*
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* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
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* Probes initial implementation ( includes suggestions from
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* Rusty Russell).
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* 2004-Nov Modified for PPC64 by Ananth N Mavinakayanahalli
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* <ananth@in.ibm.com>
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*/
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/percpu.h>
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#include <asm/probes.h>
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#include <asm/code-patching.h>
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#define __ARCH_WANT_KPROBES_INSN_SLOT
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struct pt_regs;
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struct kprobe;
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typedef ppc_opcode_t kprobe_opcode_t;
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#define MAX_INSN_SIZE 1
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#ifdef CONFIG_PPC64
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#if defined(_CALL_ELF) && _CALL_ELF == 2
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/* PPC64 ABIv2 needs local entry point */
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#define kprobe_lookup_name(name, addr) \
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{ \
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addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); \
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if (addr) \
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addr = (kprobe_opcode_t *)ppc_function_entry(addr); \
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}
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#else
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/*
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* 64bit powerpc ABIv1 uses function descriptors:
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* - Check for the dot variant of the symbol first.
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* - If that fails, try looking up the symbol provided.
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*
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* This ensures we always get to the actual symbol and not the descriptor.
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* Also handle <module:symbol> format.
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*/
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#define kprobe_lookup_name(name, addr) \
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{ \
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char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN]; \
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char *modsym; \
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bool dot_appended = false; \
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if ((modsym = strchr(name, ':')) != NULL) { \
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modsym++; \
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if (*modsym != '\0' && *modsym != '.') { \
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/* Convert to <module:.symbol> */ \
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strncpy(dot_name, name, modsym - name); \
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dot_name[modsym - name] = '.'; \
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dot_name[modsym - name + 1] = '\0'; \
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strncat(dot_name, modsym, \
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sizeof(dot_name) - (modsym - name) - 2);\
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dot_appended = true; \
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} else { \
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dot_name[0] = '\0'; \
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strncat(dot_name, name, sizeof(dot_name) - 1); \
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} \
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} else if (name[0] != '.') { \
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dot_name[0] = '.'; \
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dot_name[1] = '\0'; \
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strncat(dot_name, name, KSYM_NAME_LEN - 2); \
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dot_appended = true; \
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} else { \
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dot_name[0] = '\0'; \
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strncat(dot_name, name, KSYM_NAME_LEN - 1); \
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} \
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addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name); \
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if (!addr && dot_appended) { \
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/* Let's try the original non-dot symbol lookup */ \
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addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); \
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} \
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}
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#endif /* defined(_CALL_ELF) && _CALL_ELF == 2 */
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#endif /* CONFIG_PPC64 */
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#define flush_insn_slot(p) do { } while (0)
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#define kretprobe_blacklist_size 0
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void kretprobe_trampoline(void);
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extern void arch_remove_kprobe(struct kprobe *p);
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/* Architecture specific copy of original instruction */
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struct arch_specific_insn {
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/* copy of original instruction */
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kprobe_opcode_t *insn;
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/*
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* Set in kprobes code, initially to 0. If the instruction can be
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* eumulated, this is set to 1, if not, to -1.
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*/
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int boostable;
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};
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struct prev_kprobe {
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struct kprobe *kp;
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unsigned long status;
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unsigned long saved_msr;
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};
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/* per-cpu kprobe control block */
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struct kprobe_ctlblk {
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unsigned long kprobe_status;
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unsigned long kprobe_saved_msr;
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struct pt_regs jprobe_saved_regs;
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struct prev_kprobe prev_kprobe;
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};
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extern int kprobe_exceptions_notify(struct notifier_block *self,
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unsigned long val, void *data);
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extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_KPROBES_H */
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