Commit c1bf207d authored by David Daney's avatar David Daney Committed by Ralf Baechle

MIPS: kprobe: Add support.

This patch is based on previous work by Sony and Himanshu Chauhan.

I have done some cleanup and implemented JProbes and KRETPROBES.  The
KRETPROBES part is pretty much copied verbatim from powerpc.  A possible
future enhance might be to factor out the common code.
Signed-off-by: default avatarDavid Daney <ddaney@caviumnetworks.com>
Cc: Himanshu Chauhan <hschauhan@nulltrace.org>
To: linux-mips@linux-mips.org
To: ananth@in.ibm.com,
To: anil.s.keshavamurthy@intel.com
To: davem@davemloft.net
To: masami.hiramatsu.pt@hitachi.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1525/
Patchwork: https://patchwork.linux-mips.org/patch/1530/Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 2ea6399f
......@@ -10,6 +10,8 @@ config MIPS
select HAVE_DYNAMIC_FTRACE
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_KPROBES
select HAVE_KRETPROBES
select RTC_LIB if !MACH_LOONGSON
mainmenu "Linux/MIPS Kernel Configuration"
......
......@@ -259,6 +259,9 @@ endif
vmlinux.32: vmlinux
$(OBJCOPY) -O $(32bit-bfd) $(OBJCOPYFLAGS) $< $@
#obj-$(CONFIG_KPROBES) += kprobes.o
#
# The 64-bit ELF tools are pretty broken so at this time we generate 64-bit
# ELF files from 32-bit files by conversion.
......
......@@ -30,6 +30,8 @@
#define BRK_BUG 512 /* Used by BUG() */
#define BRK_KDB 513 /* Used in KDB_ENTER() */
#define BRK_MEMU 514 /* Used by FPU emulator */
#define BRK_KPROBE_BP 515 /* Kprobe break */
#define BRK_KPROBE_SSTEPBP 516 /* Kprobe single step software implementation */
#define BRK_MULOVF 1023 /* Multiply overflow */
#endif /* __ASM_BREAK_H */
......@@ -8,6 +8,9 @@ enum die_val {
DIE_FP,
DIE_TRAP,
DIE_RI,
DIE_PAGE_FAULT,
DIE_BREAK,
DIE_SSTEPBP
};
#endif /* _ASM_MIPS_KDEBUG_H */
/*
* Kernel Probes (KProbes)
* include/asm-mips/kprobes.h
*
* Copyright 2006 Sony Corp.
* Copyright 2010 Cavium Networks
*
* 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; version 2 of the License.
*
* 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
*/
#ifndef _ASM_KPROBES_H
#define _ASM_KPROBES_H
#include <linux/ptrace.h>
#include <linux/types.h>
#include <asm/cacheflush.h>
#include <asm/kdebug.h>
#include <asm/inst.h>
#define __ARCH_WANT_KPROBES_INSN_SLOT
struct kprobe;
struct pt_regs;
typedef union mips_instruction kprobe_opcode_t;
#define MAX_INSN_SIZE 2
#define flush_insn_slot(p) \
do { \
flush_icache_range((unsigned long)p->addr, \
(unsigned long)p->addr + \
(MAX_INSN_SIZE * sizeof(kprobe_opcode_t))); \
} while (0)
#define kretprobe_blacklist_size 0
void arch_remove_kprobe(struct kprobe *p);
/* Architecture specific copy of original instruction*/
struct arch_specific_insn {
/* copy of the original instruction */
kprobe_opcode_t *insn;
};
struct prev_kprobe {
struct kprobe *kp;
unsigned long status;
unsigned long old_SR;
unsigned long saved_SR;
unsigned long saved_epc;
};
#define MAX_JPROBES_STACK_SIZE 128
#define MAX_JPROBES_STACK_ADDR \
(((unsigned long)current_thread_info()) + THREAD_SIZE - 32 - sizeof(struct pt_regs))
#define MIN_JPROBES_STACK_SIZE(ADDR) \
((((ADDR) + MAX_JPROBES_STACK_SIZE) > MAX_JPROBES_STACK_ADDR) \
? MAX_JPROBES_STACK_ADDR - (ADDR) \
: MAX_JPROBES_STACK_SIZE)
/* per-cpu kprobe control block */
struct kprobe_ctlblk {
unsigned long kprobe_status;
unsigned long kprobe_old_SR;
unsigned long kprobe_saved_SR;
unsigned long kprobe_saved_epc;
unsigned long jprobe_saved_sp;
struct pt_regs jprobe_saved_regs;
u8 jprobes_stack[MAX_JPROBES_STACK_SIZE];
struct prev_kprobe prev_kprobe;
};
extern int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
#endif /* _ASM_KPROBES_H */
......@@ -76,6 +76,7 @@ obj-$(CONFIG_IRQ_TXX9) += irq_txx9.o
obj-$(CONFIG_IRQ_GT641XX) += irq-gt641xx.o
obj-$(CONFIG_IRQ_GIC) += irq-gic.o
obj-$(CONFIG_KPROBES) += kprobes.o
obj-$(CONFIG_32BIT) += scall32-o32.o
obj-$(CONFIG_64BIT) += scall64-64.o
obj-$(CONFIG_MIPS32_COMPAT) += linux32.o ptrace32.o signal32.o
......
/*
* Kernel Probes (KProbes)
* arch/mips/kernel/kprobes.c
*
* Copyright 2006 Sony Corp.
* Copyright 2010 Cavium Networks
*
* Some portions copied from the powerpc version.
*
* Copyright (C) IBM Corporation, 2002, 2004
*
* 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; version 2 of the License.
*
* 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
*/
#include <linux/kprobes.h>
#include <linux/preempt.h>
#include <linux/kdebug.h>
#include <linux/slab.h>
#include <asm/ptrace.h>
#include <asm/break.h>
#include <asm/inst.h>
static const union mips_instruction breakpoint_insn = {
.b_format = {
.opcode = spec_op,
.code = BRK_KPROBE_BP,
.func = break_op
}
};
static const union mips_instruction breakpoint2_insn = {
.b_format = {
.opcode = spec_op,
.code = BRK_KPROBE_SSTEPBP,
.func = break_op
}
};
DEFINE_PER_CPU(struct kprobe *, current_kprobe);
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
static int __kprobes insn_has_delayslot(union mips_instruction insn)
{
switch (insn.i_format.opcode) {
/*
* This group contains:
* jr and jalr are in r_format format.
*/
case spec_op:
switch (insn.r_format.func) {
case jr_op:
case jalr_op:
break;
default:
goto insn_ok;
}
/*
* This group contains:
* bltz_op, bgez_op, bltzl_op, bgezl_op,
* bltzal_op, bgezal_op, bltzall_op, bgezall_op.
*/
case bcond_op:
/*
* These are unconditional and in j_format.
*/
case jal_op:
case j_op:
/*
* These are conditional and in i_format.
*/
case beq_op:
case beql_op:
case bne_op:
case bnel_op:
case blez_op:
case blezl_op:
case bgtz_op:
case bgtzl_op:
/*
* These are the FPA/cp1 branch instructions.
*/
case cop1_op:
#ifdef CONFIG_CPU_CAVIUM_OCTEON
case lwc2_op: /* This is bbit0 on Octeon */
case ldc2_op: /* This is bbit032 on Octeon */
case swc2_op: /* This is bbit1 on Octeon */
case sdc2_op: /* This is bbit132 on Octeon */
#endif
return 1;
default:
break;
}
insn_ok:
return 0;
}
int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
union mips_instruction insn;
union mips_instruction prev_insn;
int ret = 0;
prev_insn = p->addr[-1];
insn = p->addr[0];
if (insn_has_delayslot(insn) || insn_has_delayslot(prev_insn)) {
pr_notice("Kprobes for branch and jump instructions are not supported\n");
ret = -EINVAL;
goto out;
}
/* insn: must be on special executable page on mips. */
p->ainsn.insn = get_insn_slot();
if (!p->ainsn.insn) {
ret = -ENOMEM;
goto out;
}
/*
* In the kprobe->ainsn.insn[] array we store the original
* instruction at index zero and a break trap instruction at
* index one.
*/
memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
p->ainsn.insn[1] = breakpoint2_insn;
p->opcode = *p->addr;
out:
return ret;
}
void __kprobes arch_arm_kprobe(struct kprobe *p)
{
*p->addr = breakpoint_insn;
flush_insn_slot(p);
}
void __kprobes arch_disarm_kprobe(struct kprobe *p)
{
*p->addr = p->opcode;
flush_insn_slot(p);
}
void __kprobes arch_remove_kprobe(struct kprobe *p)
{
free_insn_slot(p->ainsn.insn, 0);
}
static void save_previous_kprobe(struct kprobe_ctlblk *kcb)
{
kcb->prev_kprobe.kp = kprobe_running();
kcb->prev_kprobe.status = kcb->kprobe_status;
kcb->prev_kprobe.old_SR = kcb->kprobe_old_SR;
kcb->prev_kprobe.saved_SR = kcb->kprobe_saved_SR;
kcb->prev_kprobe.saved_epc = kcb->kprobe_saved_epc;
}
static void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
kcb->kprobe_status = kcb->prev_kprobe.status;
kcb->kprobe_old_SR = kcb->prev_kprobe.old_SR;
kcb->kprobe_saved_SR = kcb->prev_kprobe.saved_SR;
kcb->kprobe_saved_epc = kcb->prev_kprobe.saved_epc;
}
static void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = p;
kcb->kprobe_saved_SR = kcb->kprobe_old_SR = (regs->cp0_status & ST0_IE);
kcb->kprobe_saved_epc = regs->cp0_epc;
}
static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
regs->cp0_status &= ~ST0_IE;
/* single step inline if the instruction is a break */
if (p->opcode.word == breakpoint_insn.word ||
p->opcode.word == breakpoint2_insn.word)
regs->cp0_epc = (unsigned long)p->addr;
else
regs->cp0_epc = (unsigned long)&p->ainsn.insn[0];
}
static int __kprobes kprobe_handler(struct pt_regs *regs)
{
struct kprobe *p;
int ret = 0;
kprobe_opcode_t *addr;
struct kprobe_ctlblk *kcb;
addr = (kprobe_opcode_t *) regs->cp0_epc;
/*
* We don't want to be preempted for the entire
* duration of kprobe processing
*/
preempt_disable();
kcb = get_kprobe_ctlblk();
/* Check we're not actually recursing */
if (kprobe_running()) {
p = get_kprobe(addr);
if (p) {
if (kcb->kprobe_status == KPROBE_HIT_SS &&
p->ainsn.insn->word == breakpoint_insn.word) {
regs->cp0_status &= ~ST0_IE;
regs->cp0_status |= kcb->kprobe_saved_SR;
goto no_kprobe;
}
/*
* We have reentered the kprobe_handler(), since
* another probe was hit while within the handler.
* We here save the original kprobes variables and
* just single step on the instruction of the new probe
* without calling any user handlers.
*/
save_previous_kprobe(kcb);
set_current_kprobe(p, regs, kcb);
kprobes_inc_nmissed_count(p);
prepare_singlestep(p, regs);
kcb->kprobe_status = KPROBE_REENTER;
return 1;
} else {
if (addr->word != breakpoint_insn.word) {
/*
* The breakpoint instruction was removed by
* another cpu right after we hit, no further
* handling of this interrupt is appropriate
*/
ret = 1;
goto no_kprobe;
}
p = __get_cpu_var(current_kprobe);
if (p->break_handler && p->break_handler(p, regs))
goto ss_probe;
}
goto no_kprobe;
}
p = get_kprobe(addr);
if (!p) {
if (addr->word != breakpoint_insn.word) {
/*
* The breakpoint instruction was removed right
* after we hit it. Another cpu has removed
* either a probepoint or a debugger breakpoint
* at this address. In either case, no further
* handling of this interrupt is appropriate.
*/
ret = 1;
}
/* Not one of ours: let kernel handle it */
goto no_kprobe;
}
set_current_kprobe(p, regs, kcb);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
if (p->pre_handler && p->pre_handler(p, regs)) {
/* handler has already set things up, so skip ss setup */
return 1;
}
ss_probe:
prepare_singlestep(p, regs);
kcb->kprobe_status = KPROBE_HIT_SS;
return 1;
no_kprobe:
preempt_enable_no_resched();
return ret;
}
/*
* Called after single-stepping. p->addr is the address of the
* instruction whose first byte has been replaced by the "break 0"
* instruction. To avoid the SMP problems that can occur when we
* temporarily put back the original opcode to single-step, we
* single-stepped a copy of the instruction. The address of this
* copy is p->ainsn.insn.
*
* This function prepares to return from the post-single-step
* breakpoint trap.
*/
static void __kprobes resume_execution(struct kprobe *p,
struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
unsigned long orig_epc = kcb->kprobe_saved_epc;
regs->cp0_epc = orig_epc + 4;
}
static inline int post_kprobe_handler(struct pt_regs *regs)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
if (!cur)
return 0;
if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
kcb->kprobe_status = KPROBE_HIT_SSDONE;
cur->post_handler(cur, regs, 0);
}
resume_execution(cur, regs, kcb);
regs->cp0_status |= kcb->kprobe_saved_SR;
/* Restore back the original saved kprobes variables and continue. */
if (kcb->kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe(kcb);
goto out;
}
reset_current_kprobe();
out:
preempt_enable_no_resched();
return 1;
}
static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
return 1;
if (kcb->kprobe_status & KPROBE_HIT_SS) {
resume_execution(cur, regs, kcb);
regs->cp0_status |= kcb->kprobe_old_SR;
reset_current_kprobe();
preempt_enable_no_resched();
}
return 0;
}
/*
* Wrapper routine for handling exceptions.
*/
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data)
{
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
switch (val) {
case DIE_BREAK:
if (kprobe_handler(args->regs))
ret = NOTIFY_STOP;
break;
case DIE_SSTEPBP:
if (post_kprobe_handler(args->regs))
ret = NOTIFY_STOP;
break;
case DIE_PAGE_FAULT:
/* kprobe_running() needs smp_processor_id() */
preempt_disable();
if (kprobe_running()
&& kprobe_fault_handler(args->regs, args->trapnr))
ret = NOTIFY_STOP;
preempt_enable();
break;
default:
break;
}
return ret;
}
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct jprobe *jp = container_of(p, struct jprobe, kp);
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
kcb->jprobe_saved_regs = *regs;
kcb->jprobe_saved_sp = regs->regs[29];
memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
regs->cp0_epc = (unsigned long)(jp->entry);
return 1;
}
/* Defined in the inline asm below. */
void jprobe_return_end(void);
void __kprobes jprobe_return(void)
{
/* Assembler quirk necessitates this '0,code' business. */
asm volatile(
"break 0,%0\n\t"
".globl jprobe_return_end\n"
"jprobe_return_end:\n"
: : "n" (BRK_KPROBE_BP) : "memory");
}
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
if (regs->cp0_epc >= (unsigned long)jprobe_return &&
regs->cp0_epc <= (unsigned long)jprobe_return_end) {
*regs = kcb->jprobe_saved_regs;
memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
preempt_enable_no_resched();
return 1;
}
return 0;
}
/*
* Function return probe trampoline:
* - init_kprobes() establishes a probepoint here
* - When the probed function returns, this probe causes the
* handlers to fire
*/
static void __used kretprobe_trampoline_holder(void)
{
asm volatile(
".set push\n\t"
/* Keep the assembler from reordering and placing JR here. */
".set noreorder\n\t"
"nop\n\t"
".global kretprobe_trampoline\n"
"kretprobe_trampoline:\n\t"
"nop\n\t"
".set pop"
: : : "memory");
}
void kretprobe_trampoline(void);
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *) regs->regs[31];
/* Replace the return addr with trampoline addr */
regs->regs[31] = (unsigned long)kretprobe_trampoline;
}
/*
* Called when the probe at kretprobe trampoline is hit
*/
static int __kprobes trampoline_probe_handler(struct kprobe *p,
struct pt_regs *regs)
{
struct kretprobe_instance *ri = NULL;
struct hlist_head *head, empty_rp;
struct hlist_node *node, *tmp;
unsigned long flags, orig_ret_address = 0;
unsigned long trampoline_address = (unsigned long)kretprobe_trampoline;