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Subject[patch 2/4] Kprobes support for IA64

This is an IA64 arch specific handling of Kprobes

signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
signed-off-by: Rusty Lynch <Rusty.lynch@intel.com>
=========================================================================
arch/ia64/Kconfig.debug | 11 +
arch/ia64/kernel/Makefile | 1
arch/ia64/kernel/kprobes.c | 332 +++++++++++++++++++++++++++++++++++++++++++++
include/asm-ia64/kprobes.h | 70 +++++++++
4 files changed, 414 insertions(+)
Index: linux-2.6.12-rc4/arch/ia64/Kconfig.debug
===================================================================
--- linux-2.6.12-rc4.orig/arch/ia64/Kconfig.debug 2005-05-22 23:27:22.000000000 -0700
+++ linux-2.6.12-rc4/arch/ia64/Kconfig.debug 2005-05-22 23:28:12.000000000 -0700
@@ -2,6 +2,17 @@

source "lib/Kconfig.debug"

+config KPROBES
+ bool "Kprobes"
+ depends on DEBUG_KERNEL
+ help
+ Kprobes allows you to trap at almost any kernel address and
+ execute a callback function. register_kprobe() establishes
+ a probepoint and specifies the callback. Kprobes is useful
+ for kernel debugging, non-intrusive instrumentation and testing.
+ If in doubt, say "N".
+
+
choice
prompt "Physical memory granularity"
default IA64_GRANULE_64MB
Index: linux-2.6.12-rc4/arch/ia64/kernel/kprobes.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.12-rc4/arch/ia64/kernel/kprobes.c 2005-05-23 07:57:43.106362451 -0700
@@ -0,0 +1,332 @@
+/*
+ * Kernel Probes (KProbes)
+ * arch/ia64/kernel/kprobes.c
+ *
+ * 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.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ * Copyright (C) Intel Corporation, 2005
+ *
+ * 2005-Apr Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
+ * <anil.s.keshavamurthy@intel.com> adapted from i386
+ */
+
+#include <linux/config.h>
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/preempt.h>
+#include <linux/moduleloader.h>
+
+#include <asm/pgtable.h>
+#include <asm/kdebug.h>
+
+/* kprobe_status settings */
+#define KPROBE_HIT_ACTIVE 0x00000001
+#define KPROBE_HIT_SS 0x00000002
+
+static struct kprobe *current_kprobe;
+static unsigned long kprobe_status;
+
+enum instruction_type {A, I, M, F, B, L, X, u};
+static enum instruction_type bundle_encoding[32][3] = {
+ { M, I, I }, /* 00 */
+ { M, I, I }, /* 01 */
+ { M, I, I }, /* 02 */
+ { M, I, I }, /* 03 */
+ { M, L, X }, /* 04 */
+ { M, L, X }, /* 05 */
+ { u, u, u }, /* 06 */
+ { u, u, u }, /* 07 */
+ { M, M, I }, /* 08 */
+ { M, M, I }, /* 09 */
+ { M, M, I }, /* 0A */
+ { M, M, I }, /* 0B */
+ { M, F, I }, /* 0C */
+ { M, F, I }, /* 0D */
+ { M, M, F }, /* 0E */
+ { M, M, F }, /* 0F */
+ { M, I, B }, /* 10 */
+ { M, I, B }, /* 11 */
+ { M, B, B }, /* 12 */
+ { M, B, B }, /* 13 */
+ { u, u, u }, /* 14 */
+ { u, u, u }, /* 15 */
+ { B, B, B }, /* 16 */
+ { B, B, B }, /* 17 */
+ { M, M, B }, /* 18 */
+ { M, M, B }, /* 19 */
+ { u, u, u }, /* 1A */
+ { u, u, u }, /* 1B */
+ { M, F, B }, /* 1C */
+ { M, F, B }, /* 1D */
+ { u, u, u }, /* 1E */
+ { u, u, u }, /* 1F */
+};
+
+int arch_prepare_kprobe(struct kprobe *p)
+{
+ unsigned long addr = (unsigned long) p->addr;
+ unsigned long bundle_addr = addr & ~0xFULL;
+ unsigned long slot = addr & 0xf;
+ bundle_t bundle;
+ unsigned long template;
+
+ /*
+ * TODO: Verify that a probe is not being inserted
+ * in sensitive regions of code
+ * TODO: Verify that the memory holding the probe is rwx
+ * TODO: verify this is a kernel address
+ */
+ memcpy(&bundle, (unsigned long *)bundle_addr, sizeof(bundle_t));
+ template = bundle.quad0.template;
+ if (((bundle_encoding[template][1] == L) && slot > 1) || (slot > 2)) {
+ printk(KERN_WARNING "Attempting to insert unaligned kprobe at 0x%lx\n", addr);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+void arch_copy_kprobe(struct kprobe *p)
+{
+ unsigned long addr = (unsigned long)p->addr;
+ unsigned long bundle_addr = addr & ~0xFULL;
+
+ memcpy(&p->ainsn.insn.bundle, (unsigned long *)bundle_addr,
+ sizeof(bundle_t));
+ memcpy(&p->opcode.bundle, &p->ainsn.insn.bundle, sizeof(bundle_t));
+}
+
+void arch_arm_kprobe(struct kprobe *p)
+{
+ unsigned long addr = (unsigned long)p->addr;
+ unsigned long arm_addr = addr & ~0xFULL;
+ unsigned long slot = addr & 0xf;
+ unsigned long template;
+ bundle_t bundle;
+
+ memcpy(&bundle, &p->ainsn.insn.bundle, sizeof(bundle_t));
+
+ template = bundle.quad0.template;
+ if (slot == 1 && bundle_encoding[template][1] == L)
+ slot = 2;
+ switch (slot) {
+ case 0:
+ bundle.quad0.slot0 = BREAK_INST;
+ break;
+ case 1:
+ bundle.quad0.slot1_p0 = BREAK_INST;
+ bundle.quad1.slot1_p1 = (BREAK_INST >> (64-46));
+ break;
+ case 2:
+ bundle.quad1.slot2 = BREAK_INST;
+ break;
+ }
+
+ /* Flush icache for the instruction at the emulated address */
+ flush_icache_range((unsigned long)&p->ainsn.insn.bundle,
+ (unsigned long)&p->ainsn.insn.bundle +
+ sizeof(bundle_t));
+ /*
+ * Patch the original instruction with the probe instruction
+ * and flush the instruction cache
+ */
+ memcpy((char *) arm_addr, (char *) &bundle, sizeof(bundle_t));
+ flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
+}
+
+void arch_disarm_kprobe(struct kprobe *p)
+{
+ unsigned long addr = (unsigned long)p->addr;
+ unsigned long arm_addr = addr & ~0xFULL;
+
+ /* p->opcode contains the original unaltered bundle */
+ memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
+ flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
+}
+
+void arch_remove_kprobe(struct kprobe *p)
+{
+}
+
+/*
+ * We are resuming execution after a single step fault, so the pt_regs
+ * structure reflects the register state after we executed the instruction
+ * located in the kprobe (p->ainsn.insn.bundle). We still need to adjust
+ * the ip to point back to the original stack address, and if we see that
+ * the slot has incremented back to zero, then we need to point to the next
+ * slot location.
+ */
+static void resume_execution(struct kprobe *p, struct pt_regs *regs)
+{
+ unsigned long bundle = (unsigned long)p->addr & ~0xFULL;
+
+ /*
+ * TODO: Handle cases where kprobe was inserted on a branch instruction
+ */
+
+ if (!ia64_psr(regs)->ri)
+ regs->cr_iip = bundle + 0x10;
+ else
+ regs->cr_iip = bundle;
+
+ ia64_psr(regs)->ss = 0;
+}
+
+static void prepare_ss(struct kprobe *p, struct pt_regs *regs)
+{
+ unsigned long bundle_addr = (unsigned long) &p->ainsn.insn.bundle;
+ unsigned long slot = (unsigned long)p->addr & 0xf;
+
+ /* Update instruction pointer (IIP) and slot number (IPSR.ri) */
+ regs->cr_iip = bundle_addr & ~0xFULL;
+
+ if (slot > 2)
+ slot = 0;
+
+ ia64_psr(regs)->ri = slot;
+
+ /* turn on single stepping */
+ ia64_psr(regs)->ss = 1;
+}
+
+static int pre_kprobes_handler(struct pt_regs *regs)
+{
+ struct kprobe *p;
+ int ret = 0;
+ kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
+
+ preempt_disable();
+
+ /* Handle recursion cases */
+ if (kprobe_running()) {
+ p = get_kprobe(addr);
+ if (p) {
+ if (kprobe_status == KPROBE_HIT_SS) {
+ unlock_kprobes();
+ goto no_kprobe;
+ }
+ arch_disarm_kprobe(p);
+ ret = 1;
+ } else {
+ /*
+ * jprobe instrumented function just completed
+ */
+ p = current_kprobe;
+ if (p->break_handler && p->break_handler(p, regs)) {
+ goto ss_probe;
+ }
+ }
+ }
+
+ lock_kprobes();
+ p = get_kprobe(addr);
+ if (!p) {
+ unlock_kprobes();
+ goto no_kprobe;
+ }
+
+ kprobe_status = KPROBE_HIT_ACTIVE;
+ current_kprobe = p;
+
+ if (p->pre_handler && p->pre_handler(p, regs))
+ /*
+ * Our pre-handler is specifically requesting that we just
+ * do a return. This is handling the case where the
+ * pre-handler is really our special jprobe pre-handler.
+ */
+ return 1;
+
+ss_probe:
+ prepare_ss(p, regs);
+ kprobe_status = KPROBE_HIT_SS;
+ return 1;
+
+no_kprobe:
+ preempt_enable_no_resched();
+ return ret;
+}
+
+static int post_kprobes_handler(struct pt_regs *regs)
+{
+ if (!kprobe_running())
+ return 0;
+
+ if (current_kprobe->post_handler)
+ current_kprobe->post_handler(current_kprobe, regs, 0);
+
+ resume_execution(current_kprobe, regs);
+
+ unlock_kprobes();
+ preempt_enable_no_resched();
+ return 1;
+}
+
+static int kprobes_fault_handler(struct pt_regs *regs, int trapnr)
+{
+ if (!kprobe_running())
+ return 0;
+
+ if (current_kprobe->fault_handler &&
+ current_kprobe->fault_handler(current_kprobe, regs, trapnr))
+ return 1;
+
+ if (kprobe_status & KPROBE_HIT_SS) {
+ resume_execution(current_kprobe, regs);
+ unlock_kprobes();
+ preempt_enable_no_resched();
+ }
+
+ return 0;
+}
+
+int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
+ void *data)
+{
+ struct die_args *args = (struct die_args *)data;
+ switch(val) {
+ case DIE_BREAK:
+ if (pre_kprobes_handler(args->regs))
+ return NOTIFY_STOP;
+ break;
+ case DIE_SS:
+ if (post_kprobes_handler(args->regs))
+ return NOTIFY_STOP;
+ break;
+ case DIE_PAGE_FAULT:
+ if (kprobes_fault_handler(args->regs, args->trapnr))
+ return NOTIFY_STOP;
+ default:
+ break;
+ }
+ return NOTIFY_DONE;
+}
+
+int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ printk(KERN_WARNING "Jprobes is not supported\n");
+ return 0;
+}
+
+void jprobe_return(void)
+{
+}
+
+int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ return 0;
+}
Index: linux-2.6.12-rc4/arch/ia64/kernel/Makefile
===================================================================
--- linux-2.6.12-rc4.orig/arch/ia64/kernel/Makefile 2005-05-22 23:27:22.000000000 -0700
+++ linux-2.6.12-rc4/arch/ia64/kernel/Makefile 2005-05-23 07:57:43.105385888 -0700
@@ -20,6 +20,7 @@
obj-$(CONFIG_PERFMON) += perfmon_default_smpl.o
obj-$(CONFIG_IA64_CYCLONE) += cyclone.o
obj-$(CONFIG_IA64_MCA_RECOVERY) += mca_recovery.o
+obj-$(CONFIG_KPROBES) += kprobes.o
mca_recovery-y += mca_drv.o mca_drv_asm.o

# The gate DSO image is built using a special linker script.
Index: linux-2.6.12-rc4/include/asm-ia64/kprobes.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.12-rc4/include/asm-ia64/kprobes.h 2005-05-23 07:57:43.107339013 -0700
@@ -0,0 +1,70 @@
+#ifndef _ASM_KPROBES_H
+#define _ASM_KPROBES_H
+/*
+ * Kernel Probes (KProbes)
+ * include/asm-ia64/kprobes.h
+ *
+ * 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.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ * Copyright (C) Intel Corporation, 2005
+ *
+ * 2005-Apr Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
+ * <anil.s.keshavamurthy@intel.com> adapted from i386
+ */
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <asm/break.h>
+
+#define BREAK_INST (long)(__IA64_BREAK_KPROBE << 6)
+
+typedef struct _bundle {
+ struct {
+ unsigned long long template : 5;
+ unsigned long long slot0 : 41;
+ unsigned long long slot1_p0 : 64-46;
+ } quad0;
+ struct {
+ unsigned long long slot1_p1 : 41 - (64-46);
+ unsigned long long slot2 : 41;
+ } quad1;
+} __attribute__((__aligned__(16))) bundle_t;
+
+typedef struct kprobe_opcode {
+ bundle_t bundle;
+} kprobe_opcode_t;
+
+struct fnptr {
+ unsigned long ip;
+ unsigned long gp;
+};
+
+/* Architecture specific copy of original instruction*/
+struct arch_specific_insn {
+ /* copy of the original instruction */
+ kprobe_opcode_t insn;
+};
+
+#ifdef CONFIG_KPROBES
+extern int kprobe_exceptions_notify(struct notifier_block *self,
+ unsigned long val, void *data);
+#else /* !CONFIG_KPROBES */
+static inline int kprobe_exceptions_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ return 0;
+}
+#endif
+#endif /* _ASM_KPROBES_H */
--
-
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