[PATCH 2/2] [POWERPC] uprobes: powerpc port
From: Ananth N Mavinakayanahalli
Date: Wed Jun 06 2012 - 05:22:07 EST
From: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
This is the port of uprobes to powerpc. Usage is similar to x86.
One TODO in this port compared to x86 is the uprobe abort_xol() logic.
x86 depends on the thread_struct.trap_nr (absent in powerpc) to determine
if a signal was caused when the uprobed instruction was single-stepped/
emulated, in which case, we reset the instruction pointer to the probed
address and retry the probe again.
[root@xxxx ~]# ./bin/perf probe -x /lib64/libc.so.6 malloc
Added new event:
probe_libc:malloc (on 0xb4860)
You can now use it in all perf tools, such as:
perf record -e probe_libc:malloc -aR sleep 1
[root@xxxx ~]# ./bin/perf record -e probe_libc:malloc -aR sleep 20
[ perf record: Woken up 22 times to write data ]
[ perf record: Captured and wrote 5.843 MB perf.data (~255302 samples) ]
[root@xxxx ~]# ./bin/perf report --stdio
# ========
# captured on: Mon Jun 4 05:26:31 2012
# hostname : xxxx.ibm.com
# os release : 3.4.0-uprobe
# perf version : 3.4.0
# arch : ppc64
# nrcpus online : 4
# nrcpus avail : 4
# cpudesc : POWER6 (raw), altivec supported
# cpuid : 62,769
# total memory : 7310528 kB
# cmdline : /root/bin/perf record -e probe_libc:malloc -aR sleep 20
# event : name = probe_libc:malloc, type = 2, config = 0x124, config1 = 0x0, con
# HEADER_CPU_TOPOLOGY info available, use -I to display
# HEADER_NUMA_TOPOLOGY info available, use -I to display
# ========
#
# Samples: 83K of event 'probe_libc:malloc'
# Event count (approx.): 83484
#
# Overhead Command Shared Object Symbol
# ........ ............ ............. ..........
#
69.05% tar libc-2.12.so [.] malloc
28.57% rm libc-2.12.so [.] malloc
1.32% avahi-daemon libc-2.12.so [.] malloc
0.58% bash libc-2.12.so [.] malloc
0.28% sshd libc-2.12.so [.] malloc
0.08% irqbalance libc-2.12.so [.] malloc
0.05% bzip2 libc-2.12.so [.] malloc
0.04% sleep libc-2.12.so [.] malloc
0.03% multipathd libc-2.12.so [.] malloc
0.01% sendmail libc-2.12.so [.] malloc
0.01% automount libc-2.12.so [.] malloc
Signed-off-by: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Index: linux-3.5-rc1/arch/powerpc/include/asm/thread_info.h
===================================================================
--- linux-3.5-rc1.orig/arch/powerpc/include/asm/thread_info.h 2012-06-03 06:59:26.000000000 +0530
+++ linux-3.5-rc1/arch/powerpc/include/asm/thread_info.h 2012-06-03 21:05:48.226233001 +0530
@@ -96,6 +96,7 @@
#define TIF_RESTOREALL 11 /* Restore all regs (implies NOERROR) */
#define TIF_NOERROR 12 /* Force successful syscall return */
#define TIF_NOTIFY_RESUME 13 /* callback before returning to user */
+#define TIF_UPROBE 14 /* breakpointed or single-stepping */
#define TIF_SYSCALL_TRACEPOINT 15 /* syscall tracepoint instrumentation */
/* as above, but as bit values */
@@ -112,12 +113,13 @@
#define _TIF_RESTOREALL (1<<TIF_RESTOREALL)
#define _TIF_NOERROR (1<<TIF_NOERROR)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
+#define _TIF_UPROBE (1<<TIF_UPROBE)
#define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT)
#define _TIF_SYSCALL_T_OR_A (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
_TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT)
#define _TIF_USER_WORK_MASK (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
- _TIF_NOTIFY_RESUME)
+ _TIF_NOTIFY_RESUME | _TIF_UPROBE)
#define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR)
/* Bits in local_flags */
Index: linux-3.5-rc1/arch/powerpc/include/asm/uprobes.h
===================================================================
--- linux-3.5-rc1.orig/arch/powerpc/include/asm/uprobes.h 2012-05-31 02:23:15.746233001 +0530
+++ linux-3.5-rc1/arch/powerpc/include/asm/uprobes.h 2012-06-03 21:05:48.226233001 +0530
@@ -0,0 +1,49 @@
+#ifndef _ASM_UPROBES_H
+#define _ASM_UPROBES_H
+/*
+ * User-space Probes (UProbes) for powerpc
+ *
+ * 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, 2007-2012
+ *
+ * Adapted from the x86 port by Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
+ */
+
+#include <linux/notifier.h>
+
+typedef unsigned int uprobe_opcode_t;
+
+#define MAX_UINSN_BYTES 4
+#define UPROBE_XOL_SLOT_BYTES (MAX_UINSN_BYTES)
+
+#define UPROBE_SWBP_INSN 0x7fe00008
+#define UPROBE_SWBP_INSN_SIZE 4 /* swbp insn size in bytes */
+
+struct arch_uprobe {
+ u8 insn[MAX_UINSN_BYTES];
+};
+
+struct arch_uprobe_task {
+};
+
+extern int arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, loff_t vaddr);
+extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs);
+extern int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs);
+extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs);
+extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
+extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data);
+extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs);
+#endif /* _ASM_UPROBES_H */
Index: linux-3.5-rc1/arch/powerpc/kernel/Makefile
===================================================================
--- linux-3.5-rc1.orig/arch/powerpc/kernel/Makefile 2012-06-03 06:59:26.000000000 +0530
+++ linux-3.5-rc1/arch/powerpc/kernel/Makefile 2012-06-03 21:05:48.226233001 +0530
@@ -96,6 +96,7 @@
obj-$(CONFIG_BOOTX_TEXT) += btext.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_KPROBES) += kprobes.o
+obj-$(CONFIG_UPROBES) += uprobes.o
obj-$(CONFIG_PPC_UDBG_16550) += legacy_serial.o udbg_16550.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-$(CONFIG_SWIOTLB) += dma-swiotlb.o
Index: linux-3.5-rc1/arch/powerpc/kernel/signal.c
===================================================================
--- linux-3.5-rc1.orig/arch/powerpc/kernel/signal.c 2012-06-03 06:59:26.000000000 +0530
+++ linux-3.5-rc1/arch/powerpc/kernel/signal.c 2012-06-03 21:05:48.236233000 +0530
@@ -11,6 +11,7 @@
#include <linux/tracehook.h>
#include <linux/signal.h>
+#include <linux/uprobes.h>
#include <linux/key.h>
#include <asm/hw_breakpoint.h>
#include <asm/uaccess.h>
@@ -157,6 +158,11 @@
void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
{
+ if (thread_info_flags & _TIF_UPROBE) {
+ clear_thread_flag(TIF_UPROBE);
+ uprobe_notify_resume(regs);
+ }
+
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(regs);
Index: linux-3.5-rc1/arch/powerpc/kernel/uprobes.c
===================================================================
--- linux-3.5-rc1.orig/arch/powerpc/kernel/uprobes.c 2012-05-31 02:23:15.746233001 +0530
+++ linux-3.5-rc1/arch/powerpc/kernel/uprobes.c 2012-06-03 21:05:48.236233000 +0530
@@ -0,0 +1,163 @@
+/*
+ * User-space Probes (UProbes) for powerpc
+ *
+ * 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, 2007-2012
+ *
+ * Adapted from the x86 port by Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/ptrace.h>
+#include <linux/uprobes.h>
+#include <linux/uaccess.h>
+
+#include <linux/kdebug.h>
+#include <asm/sstep.h>
+
+/**
+ * arch_uprobe_analyze_insn
+ * @mm: the probed address space.
+ * @arch_uprobe: the probepoint information.
+ * Return 0 on success or a -ve number on error.
+ */
+int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, loff_t vaddr)
+{
+ if (vaddr & 0x03)
+ return -EINVAL;
+ return 0;
+}
+
+/*
+ * arch_uprobe_pre_xol - prepare to execute out of line.
+ * @auprobe: the probepoint information.
+ * @regs: reflects the saved user state of current task.
+ */
+int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ /* FIXME: We don't support abort_xol on powerpc for now */
+ regs->nip = current->utask->xol_vaddr;
+ return 0;
+}
+
+/**
+ * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs
+ * @regs: Reflects the saved state of the task after it has hit a breakpoint
+ * instruction.
+ * Return the address of the breakpoint instruction.
+ */
+unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
+{
+ return instruction_pointer(regs);
+}
+
+/*
+ * If xol insn itself traps and generates a signal (SIGILL/SIGSEGV/etc),
+ * then detect the case where a singlestepped instruction jumps back to its
+ * own address. It is assumed that anything like do_page_fault/do_trap/etc
+ * sets thread.trap_nr != -1.
+ *
+ * FIXME: powerpc however doesn't have thread.trap_nr yet.
+ *
+ * arch_uprobe_pre_xol/arch_uprobe_post_xol save/restore thread.trap_nr,
+ * arch_uprobe_xol_was_trapped() simply checks that ->trap_nr is not equal to
+ * UPROBE_TRAP_NR == -1 set by arch_uprobe_pre_xol().
+ */
+bool arch_uprobe_xol_was_trapped(struct task_struct *t)
+{
+ /* FIXME: We don't support abort_xol on powerpc for now */
+ return false;
+}
+
+/*
+ * Called after single-stepping. 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.
+ *
+ * This function prepares to resume execution after the single-step.
+ */
+int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ /* FIXME: We don't support abort_xol on powerpc for now */
+
+ /*
+ * On powerpc, except for loads and stores, most instructions
+ * including ones that alter code flow (branches, calls, returns)
+ * are emulated in the kernel. We get here only if the emulation
+ * support doesn't exist and have to fix-up the next instruction
+ * to be executed.
+ */
+ regs->nip = current->utask->vaddr + MAX_UINSN_BYTES;
+ return 0;
+}
+
+/* callback routine for handling exceptions. */
+int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data)
+{
+ struct die_args *args = data;
+ struct pt_regs *regs = args->regs;
+ int ret = NOTIFY_DONE;
+
+ /* We are only interested in userspace traps */
+ if (regs && !user_mode(regs))
+ return NOTIFY_DONE;
+
+ switch (val) {
+ case DIE_BPT:
+ if (uprobe_pre_sstep_notifier(regs))
+ ret = NOTIFY_STOP;
+ break;
+ case DIE_SSTEP:
+ if (uprobe_post_sstep_notifier(regs))
+ ret = NOTIFY_STOP;
+ default:
+ break;
+ }
+ return ret;
+}
+
+/*
+ * This function gets called when XOL instruction either gets trapped or
+ * the thread has a fatal signal, so reset the instruction pointer to its
+ * probed address.
+ */
+void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ /* FIXME: We don't support abort_xol on powerpc for now */
+ return;
+}
+
+/*
+ * See if the instruction can be emulated.
+ * Returns true if instruction was emulated, false otherwise.
+ */
+bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ int ret;
+ unsigned int insn;
+
+ memcpy(&insn, auprobe->insn, MAX_UINSN_BYTES);
+
+ /*
+ * emulate_step() returns 1 if the insn was successfully emulated.
+ * For all other cases, we need to single-step in hardware.
+ */
+ ret = emulate_step(regs, insn);
+ if (ret > 0)
+ return true;
+
+ return false;
+}
Index: linux-3.5-rc1/arch/powerpc/Kconfig
===================================================================
--- linux-3.5-rc1.orig/arch/powerpc/Kconfig 2012-06-03 06:59:26.000000000 +0530
+++ linux-3.5-rc1/arch/powerpc/Kconfig 2012-06-03 21:05:48.246233000 +0530
@@ -237,6 +237,9 @@
config ARCH_SUPPORTS_DEBUG_PAGEALLOC
def_bool y
+config ARCH_SUPPORTS_UPROBES
+ def_bool y
+
config PPC_ADV_DEBUG_REGS
bool
depends on 40x || BOOKE
--
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