* [PATCH 1/2] MIPS: KProbes Support
2010-06-15 14:42 [PATCH 0/2] MIPS: Kprobes and Kretprobes Support Himanshu Chauhan
@ 2010-06-15 14:42 ` Himanshu Chauhan
2010-06-15 14:42 ` [PATCH 2/2] MIPS: Kretprobe support Himanshu Chauhan
1 sibling, 0 replies; 3+ messages in thread
From: Himanshu Chauhan @ 2010-06-15 14:42 UTC (permalink / raw)
To: linux-kernel; +Cc: ralf, linux-mips, ddaney
This incorporates some of the comments from Daney.
Break codes being used are 515 and 516. do_break
has been removed and kprobes are handled in do_bp itself.
Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
---
arch/mips/Kconfig | 13 ++
arch/mips/include/asm/break.h | 2 +
arch/mips/include/asm/kdebug.h | 5 +
arch/mips/include/asm/kprobes.h | 86 +++++++++
arch/mips/kernel/Makefile | 2 +
arch/mips/kernel/kprobes.c | 378 +++++++++++++++++++++++++++++++++++++++
arch/mips/kernel/traps.c | 43 +++++-
arch/mips/mm/fault.c | 12 +-
8 files changed, 538 insertions(+), 3 deletions(-)
create mode 100644 arch/mips/include/asm/kprobes.h
create mode 100644 arch/mips/kernel/kprobes.c
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index cdaae94..ba7cc87 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2243,6 +2243,19 @@ source "kernel/power/Kconfig"
endmenu
+menu "Instrumentation Support"
+
+config KPROBES
+ bool "MIPS Kprobes Support (Experimental)"
+ depends on EXPERIMENTAL && MODULES
+ help
+ Kprobes allow you to trap at almost any kernel address
+ and execute a callback function. Kprobes is useful for
+ kernel debugging, non-intrusive instrumetation and testing.
+ If in doubt, say N.
+
+endmenu
+
source "arch/mips/kernel/cpufreq/Kconfig"
source "net/Kconfig"
diff --git a/arch/mips/include/asm/break.h b/arch/mips/include/asm/break.h
index 44437ed..9ee3014 100644
--- a/arch/mips/include/asm/break.h
+++ b/arch/mips/include/asm/break.h
@@ -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_KPRB_BP 515 /* Used by Kprobes for pre-handling */
+#define BRK_KPRB_SSTP 516 /* Used by Kprobes for post-handling */
#define BRK_MULOVF 1023 /* Multiply overflow */
#endif /* __ASM_BREAK_H */
diff --git a/arch/mips/include/asm/kdebug.h b/arch/mips/include/asm/kdebug.h
index 5bf62aa..52818ac 100644
--- a/arch/mips/include/asm/kdebug.h
+++ b/arch/mips/include/asm/kdebug.h
@@ -8,6 +8,11 @@ enum die_val {
DIE_FP,
DIE_TRAP,
DIE_RI,
+#ifdef CONFIG_KPROBES
+ DIE_PAGE_FAULT,
+ DIE_BREAK,
+ DIE_SSTEPBP,
+#endif
};
#endif /* _ASM_MIPS_KDEBUG_H */
diff --git a/arch/mips/include/asm/kprobes.h b/arch/mips/include/asm/kprobes.h
new file mode 100644
index 0000000..c7dc6cf
--- /dev/null
+++ b/arch/mips/include/asm/kprobes.h
@@ -0,0 +1,86 @@
+/*
+ * Kernel Probes (KProbes)
+ * include/asm-mips/kprobes.h
+ *
+ * Copyright 2006 Sony Corp.
+ *
+ * Himanshu Chauhan <hschauhan@nulltrace.org>
+ * for >2.6.35 kernels.
+ *
+ * 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/types.h>
+#include <linux/ptrace.h>
+#include <asm/inst.h>
+#include <asm/break.h> /* BRK_KPROBES_PRE/POSH */
+
+#define __ARCH_WANT_KPROBES_INSN_SLOT
+
+struct kprobe;
+struct pt_regs;
+
+typedef union mips_instruction kprobe_opcode_t;
+
+/*
+ * We do not have hardware single-stepping on MIPS.
+ * So we implement software single-stepping with breakpoint
+ * trap.
+ */
+#define MIPS_KPROBE_BP (0x0000000d | (BRK_KPRB_BP << 6))
+#define MIPS_KPROBE_SSTP (0x0000000d | (BRK_KPRB_SSTP << 6))
+#define MAX_INSN_SIZE 2
+
+#define flush_insn_slot(p) \
+ do { \
+ /* invalidate I-cache */ \
+ asm volatile("cache 0, 0($0)"); \
+ /* invalidate D-cache */ \
+ asm volatile("cache 9, 0($0)"); \
+ } while (0);
+
+#define kretprobe_blacklist_size 0
+
+void arch_remove_kprobe(struct kprobe *p);
+
+/* Architecture specific copy of original instruction*/
+struct arch_specific_insn {
+ /* copy of the original instruction */
+ kprobe_opcode_t *insn;
+};
+
+struct prev_kprobe {
+ struct kprobe *kp;
+ unsigned long status;
+ unsigned long old_SR;
+ unsigned long saved_SR;
+ unsigned long saved_epc;
+};
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+ unsigned long kprobe_status;
+ unsigned long kprobe_old_SR;
+ unsigned long kprobe_saved_SR;
+ unsigned long kprobe_saved_epc;
+ struct prev_kprobe prev_kprobe;
+};
+
+extern int kprobe_exceptions_notify(struct notifier_block *self,
+ unsigned long val, void *data);
+
+#endif /* _ASM_KPROBES_H */
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 7a6ac50..714f3c1 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_MIPS32_N32) += binfmt_elfn32.o scall64-n32.o signal_n32.o
obj-$(CONFIG_MIPS32_O32) += binfmt_elfo32.o scall64-o32.o
obj-$(CONFIG_KGDB) += kgdb.o
+obj-$(CONFIG_KPROBES) += kprobes.o
obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_64BIT) += cpu-bugs64.o
@@ -95,6 +96,7 @@ obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
obj-$(CONFIG_SPINLOCK_TEST) += spinlock_test.o
+
CFLAGS_cpu-bugs64.o = $(shell if $(CC) $(KBUILD_CFLAGS) -Wa,-mdaddi -c -o /dev/null -xc /dev/null >/dev/null 2>&1; then echo "-DHAVE_AS_SET_DADDI"; fi)
obj-$(CONFIG_HAVE_STD_PC_SERIAL_PORT) += 8250-platform.o
diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
new file mode 100644
index 0000000..6b6689f
--- /dev/null
+++ b/arch/mips/kernel/kprobes.c
@@ -0,0 +1,378 @@
+/*
+ * Kernel Probes (KProbes)
+ * arch/mips/kernel/kprobes.c
+ *
+ * Copyright 2006 Sony Corp.
+ *
+ * Himanshu Chauhan <hschauhan@nulltrace.org> for >2.6.35 kernels.
+ *
+ * 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/semaphore.h>
+#include <linux/kdebug.h>
+#include <linux/kprobes.h>
+#include <linux/preempt.h>
+#include <asm/cacheflush.h>
+#include <asm/inst.h>
+#include <asm/ptrace.h>
+
+DECLARE_MUTEX(kprobe_mutex);
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+ union mips_instruction insn;
+ int ret = 0;
+
+ insn = *p->addr;
+
+ switch (insn.i_format.opcode) {
+ /*
+ * This group contains:
+ * jr and jalr are in r_format format.
+ */
+ case spec_op:
+
+ /*
+ * 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:
+ printk(KERN_ERR "Kprobes for branch and jump instructions "
+ "is 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 instruction at
+ * index one.
+ */
+ memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
+ p->ainsn.insn[1].word = MIPS_KPROBE_SSTP;
+ p->opcode = *p->addr;
+
+out:
+ return ret;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+ p->addr->word = MIPS_KPROBE_BP;
+ flush_icache_range((unsigned long)p->addr,
+ (unsigned long)p->addr +
+ (MAX_INSN_SIZE * sizeof(kprobe_opcode_t)));
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
+{
+ *p->addr = p->opcode;
+ flush_icache_range((unsigned long)p->addr,
+ (unsigned long)p->addr +
+ (MAX_INSN_SIZE * sizeof(kprobe_opcode_t)));
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+ down(&kprobe_mutex);
+ free_insn_slot(p->ainsn.insn, 0);
+ up(&kprobe_mutex);
+}
+
+static inline 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 inline 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 inline 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 inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+ regs->cp0_status &= ~ST0_IE;
+
+ /* single step inline if the instruction is an break 0 */
+ if ((MIPSInst_OPCODE(p->opcode.word) == MIPS_KPROBE_BP)
+ || (MIPSInst_OPCODE(p->opcode.word) == MIPS_KPROBE_SSTP))
+ 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 = NULL;
+ 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 == MIPS_KPROBE_BP) {
+ 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 != MIPS_KPROBE_BP) {
+ /* 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 != MIPS_KPROBE_BP) {
+ /*
+ * 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;
+ struct pt_regs *regs = (struct pt_regs *)args->regs;
+ int ret = NOTIFY_DONE;
+ int trapnr = 0;
+
+ switch (val) {
+ case DIE_BREAK:
+ ret = kprobe_handler(regs);
+ if (ret)
+ 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();
+
+ /*
+ * trapnr is the architecture-specific trap
+ * number associated with the fault while handling
+ * the Kprobe (e.g. on mips, 9 for a break or 13 for
+ * a trap).
+ * current die_args structure does not have trapnr.
+ */
+ if (kprobe_running()
+ && kprobe_fault_handler(args->regs, trapnr))
+ ret = NOTIFY_STOP;
+ preempt_enable();
+ break;
+ default:
+ break;
+ }
+ return ret;
+}
+
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ return 0;
+}
+
+void __kprobes jprobe_return(void)
+{
+}
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ return 0;
+}
+
+int __init arch_init_kprobes(void)
+{
+ return 0;
+}
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 8bdd6a6..921d5e2 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -10,6 +10,7 @@
* Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
* Copyright (C) 2000, 01 MIPS Technologies, Inc.
* Copyright (C) 2002, 2003, 2004, 2005, 2007 Maciej W. Rozycki
+ * Himanshu Chauhan <hschauhan@nulltrace.org> KProbes support for MIPS.
*/
#include <linux/bug.h>
#include <linux/compiler.h>
@@ -27,6 +28,7 @@
#include <linux/kdebug.h>
#include <linux/notifier.h>
#include <linux/kdb.h>
+#include <linux/kprobes.h>
#include <asm/bootinfo.h>
#include <asm/branch.h>
@@ -334,7 +336,7 @@ void show_regs(struct pt_regs *regs)
__show_regs((struct pt_regs *)regs);
}
-void show_registers(const struct pt_regs *regs)
+void show_registers(struct pt_regs *regs)
{
const int field = 2 * sizeof(unsigned long);
@@ -706,6 +708,35 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
force_sig_info(SIGFPE, &info, current);
}
+#ifdef CONFIG_KPROBES
+asmlinkage int __kprobes do_kprobes_break(struct pt_regs *regs,
+ unsigned int bcode)
+{
+ /* return 1 if unhandled */
+ int ret = 1;
+
+ /*
+ * Notify the kprobe handlers, if instruction is kprobe
+ * breaks (515, 516).
+ */
+ switch (bcode) {
+ case BRK_KPRB_BP:
+ if (notify_die(DIE_BREAK, "kprb_debug", regs, bcode,
+ 0, 0) == NOTIFY_STOP)
+ ret = 0;
+ break;
+
+ case BRK_KPRB_SSTP:
+ if (notify_die(DIE_SSTEPBP, "kprb_single_step",
+ regs, bcode, 0, 0) == NOTIFY_STOP)
+ ret = 0;
+ break;
+ }
+
+ return ret;
+}
+#endif
+
static void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
const char *str)
{
@@ -783,6 +814,16 @@ asmlinkage void do_bp(struct pt_regs *regs)
if (bcode >= (1 << 10))
bcode >>= 10;
+#ifdef CONFIG_KPROBES
+ /*
+ * Let kprobes handle the break first. If it returns zero
+ * it could handle the break. Otherwise, proceed by normal
+ * course of action.
+ */
+ if (!do_kprobes_break(regs, bcode))
+ return;
+#endif
+
do_trap_or_bp(regs, bcode, "Break");
return;
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index b78f7d9..b45bc69 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -18,6 +18,8 @@
#include <linux/smp.h>
#include <linux/vt_kern.h> /* For unblank_screen() */
#include <linux/module.h>
+#include <linux/kprobes.h>
+#include <linux/kdebug.h> /* notify_die and asm/kdebug.h */
#include <asm/branch.h>
#include <asm/mmu_context.h>
@@ -31,8 +33,9 @@
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
-asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
- unsigned long address)
+asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
+ unsigned long write,
+ unsigned long address)
{
struct vm_area_struct * vma = NULL;
struct task_struct *tsk = current;
@@ -47,6 +50,11 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
field, regs->cp0_epc);
#endif
+ /* Notify kprobes fault handler. */
+ if (notify_die(DIE_PAGE_FAULT, "page fault",
+ regs, -1, SEGV_MAPERR, SEGV_MAPERR) == NOTIFY_STOP)
+ return;
+
info.si_code = SEGV_MAPERR;
/*
--
1.7.0.4
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH 2/2] MIPS: Kretprobe support
2010-06-15 14:42 [PATCH 0/2] MIPS: Kprobes and Kretprobes Support Himanshu Chauhan
2010-06-15 14:42 ` [PATCH 1/2] MIPS: KProbes Support Himanshu Chauhan
@ 2010-06-15 14:42 ` Himanshu Chauhan
1 sibling, 0 replies; 3+ messages in thread
From: Himanshu Chauhan @ 2010-06-15 14:42 UTC (permalink / raw)
To: linux-kernel; +Cc: ralf, linux-mips, ddaney
This patch adds support for kretprobes on MIPS architecture.
Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
---
arch/mips/Kconfig | 1 +
arch/mips/kernel/kprobes.c | 117 +++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 117 insertions(+), 1 deletions(-)
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index ba7cc87..8dd82cf 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2248,6 +2248,7 @@ menu "Instrumentation Support"
config KPROBES
bool "MIPS Kprobes Support (Experimental)"
depends on EXPERIMENTAL && MODULES
+ select HAVE_KRETPROBES
help
Kprobes allow you to trap at almost any kernel address
and execute a callback function. Kprobes is useful for
diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
index 6b6689f..07e8a04 100644
--- a/arch/mips/kernel/kprobes.c
+++ b/arch/mips/kernel/kprobes.c
@@ -4,7 +4,9 @@
*
* Copyright 2006 Sony Corp.
*
- * Himanshu Chauhan <hschauhan@nulltrace.org> for >2.6.35 kernels.
+ * (C) 2010 Himanshu Chauhan <hschauhan@nulltrace.org>
+ * o Kprobes replay on kernels >2.6.35
+ * o Added support for kretprobes.
*
* 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
@@ -24,6 +26,7 @@
#include <linux/kdebug.h>
#include <linux/kprobes.h>
#include <linux/preempt.h>
+#include <linux/slab.h>
#include <asm/cacheflush.h>
#include <asm/inst.h>
#include <asm/ptrace.h>
@@ -358,6 +361,113 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
return ret;
}
+/*
+ * When a retprobed function returns, trampoline_handler() is called,
+ * calling the kretprobe's handler. We need to generate a pt_regs
+ * frame before calling trampoline_handler. Saving RA here makes no
+ * sense because kretprobe_trampoline will have no RA, rather
+ * RA will be returned by trampoline_handler. We would only be
+ * interested in saving v0 and v1 i.e. the return value of the
+ * probed function.
+ */
+void notrace __kprobes kretprobe_trampoline(void)
+{
+ __asm__ __volatile__ (
+ ".set noreorder\n\t"
+#ifdef CONFIG_32BIT
+ "addiu $29, -152\n\t"
+ "sw $2, 32($29)\n\t"
+ "sw $3, 36($29)\n\t"
+#else
+ "addiu $29, -128\n\t"
+ "sw $2, 8($29)\n\t"
+ "sw $3, 12($29)\n\t"
+#endif
+ "jal trampoline_handler\n\t"
+ "move $4, $29\n\t"
+ "move $31, $2\n\t"
+#ifdef CONFIG_32BIT
+ "lw $2, 32($29)\n\t"
+ "lw $3, 36($29)\n\t"
+ "addiu $29, 152\n\t"
+#else
+ "lw $2, 8($29)\n\t"
+ "lw $3, 12($29)\n\t"
+ "addiu $29, 128\n\t"
+#endif
+ : : : "memory");
+}
+
+/* Called from kretprobe_trampoline */
+static __used __kprobes void *trampoline_handler(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;
+
+ INIT_HLIST_HEAD(&empty_rp);
+ kretprobe_hash_lock(current, &head, &flags);
+
+ /*
+ * It is possible to have multiple instances associated with a given
+ * task either because multiple functions in the call path have
+ * a return probe installed on them, and/or more than one return
+ * probe was registered for a target function.
+ *
+ * We can handle this because:
+ * - instances are always inserted at the head of the list
+ * - when multiple return probes are registered for the same
+ * function, the first instance's ret_addr will point to the
+ * real return address, and all the rest will point to
+ * kretprobe_trampoline
+ */
+ hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+ if (ri->task != current)
+ /* another task is sharing our hash bucket */
+ continue;
+
+ if (ri->rp && ri->rp->handler) {
+ __get_cpu_var(current_kprobe) = &ri->rp->kp;
+ get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
+ ri->rp->handler(ri, regs);
+ __get_cpu_var(current_kprobe) = NULL;
+ }
+
+ orig_ret_address = (unsigned long)ri->ret_addr;
+ recycle_rp_inst(ri, &empty_rp);
+
+ if (orig_ret_address != trampoline_address)
+ /*
+ * This is the real return address. Any other
+ * instances associated with this task are for
+ * other calls deeper on the call stack
+ */
+ break;
+ }
+
+ kretprobe_assert(ri, orig_ret_address, trampoline_address);
+ kretprobe_hash_unlock(current, &flags);
+
+ hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+ hlist_del(&ri->hlist);
+ kfree(ri);
+ }
+
+ return (void *)orig_ret_address;
+}
+
+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+ struct pt_regs *regs)
+{
+ /* save the ra */
+ ri->ret_addr = (kprobe_opcode_t *)regs->regs[31];
+
+ /* Replace the return addr with trampoline addr. */
+ regs->regs[31] = (unsigned long)&kretprobe_trampoline;
+}
+
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
return 0;
@@ -376,3 +486,8 @@ int __init arch_init_kprobes(void)
{
return 0;
}
+
+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+{
+ return 0;
+}
--
1.7.0.4
^ permalink raw reply [flat|nested] 3+ messages in thread