* [PATCH 2/3] powerpc: Add trap_nr to thread_struct
2012-08-24 7:26 [PATCH 1/3] powerpc: Consolidate *probe definitions Ananth N Mavinakayanahalli
@ 2012-08-24 7:27 ` Ananth N Mavinakayanahalli
2012-08-24 7:31 ` [PATCH v5 3/3] powerpc: Uprobes port to powerpc Ananth N Mavinakayanahalli
1 sibling, 0 replies; 5+ messages in thread
From: Ananth N Mavinakayanahalli @ 2012-08-24 7:27 UTC (permalink / raw)
To: ppcdev, lkml
Cc: Srikar Dronamraju, peterz, oleg, Paul Mackerras, Anton Blanchard,
Ingo Molnar
From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Add thread_struct.trap_nr and use it to store the last exception
the thread experienced. In this patch, we populate the field at
various places where we force_sig_info() to the process.
This is also used in uprobes to determine if the probed instruction
caused an exception.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
---
arch/powerpc/include/asm/processor.h | 1 +
arch/powerpc/kernel/process.c | 2 ++
arch/powerpc/kernel/traps.c | 1 +
arch/powerpc/mm/fault.c | 1 +
4 files changed, 5 insertions(+)
Index: linux-26jul/arch/powerpc/include/asm/processor.h
===================================================================
--- linux-26jul.orig/arch/powerpc/include/asm/processor.h
+++ linux-26jul/arch/powerpc/include/asm/processor.h
@@ -219,6 +219,7 @@ struct thread_struct {
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
#endif
unsigned long dabr; /* Data address breakpoint register */
+ unsigned long trap_nr; /* last trap # on this thread */
#ifdef CONFIG_ALTIVEC
/* Complete AltiVec register set */
vector128 vr[32] __attribute__((aligned(16)));
Index: linux-26jul/arch/powerpc/kernel/process.c
===================================================================
--- linux-26jul.orig/arch/powerpc/kernel/process.c
+++ linux-26jul/arch/powerpc/kernel/process.c
@@ -258,6 +258,7 @@ void do_send_trap(struct pt_regs *regs,
{
siginfo_t info;
+ current->thread.trap_nr = signal_code;
if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
11, SIGSEGV) == NOTIFY_STOP)
return;
@@ -275,6 +276,7 @@ void do_dabr(struct pt_regs *regs, unsig
{
siginfo_t info;
+ current->thread.trap_nr = TRAP_HWBKPT;
if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
11, SIGSEGV) == NOTIFY_STOP)
return;
Index: linux-26jul/arch/powerpc/kernel/traps.c
===================================================================
--- linux-26jul.orig/arch/powerpc/kernel/traps.c
+++ linux-26jul/arch/powerpc/kernel/traps.c
@@ -251,6 +251,7 @@ void _exception(int signr, struct pt_reg
if (arch_irqs_disabled() && !arch_irq_disabled_regs(regs))
local_irq_enable();
+ current->thread.trap_nr = code;
memset(&info, 0, sizeof(info));
info.si_signo = signr;
info.si_code = code;
Index: linux-26jul/arch/powerpc/mm/fault.c
===================================================================
--- linux-26jul.orig/arch/powerpc/mm/fault.c
+++ linux-26jul/arch/powerpc/mm/fault.c
@@ -133,6 +133,7 @@ static int do_sigbus(struct pt_regs *reg
up_read(¤t->mm->mmap_sem);
if (user_mode(regs)) {
+ current->thread.trap_nr = BUS_ADRERR;
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH v5 3/3] powerpc: Uprobes port to powerpc
2012-08-24 7:26 [PATCH 1/3] powerpc: Consolidate *probe definitions Ananth N Mavinakayanahalli
2012-08-24 7:27 ` [PATCH 2/3] powerpc: Add trap_nr to thread_struct Ananth N Mavinakayanahalli
@ 2012-08-24 7:31 ` Ananth N Mavinakayanahalli
2012-09-05 5:26 ` Benjamin Herrenschmidt
1 sibling, 1 reply; 5+ messages in thread
From: Ananth N Mavinakayanahalli @ 2012-08-24 7:31 UTC (permalink / raw)
To: ppcdev, lkml
Cc: Srikar Dronamraju, peterz, oleg, Paul Mackerras, Anton Blanchard,
Ingo Molnar
From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
This is the port of uprobes to powerpc. Usage is similar to x86.
[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
...
# 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
The trap_nr addition patch is a prereq.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
---
Tested on POWER6; I don't see anything here that should stop it from
working on a ppc32; since I don't have access to a ppc32 machine, it
would be good if somoene could verify that part.
TODO:
Testsuite for uprobes (Not powerpc specific).
V5:
a. Incorporated Oleg's suggestion to make arch_uprobe a union for
easier deref of u32 on powerpc.
b. Incorporated various review comments by Michael Ellerman and
Benjamin Herrenschmidt.
V4:
Enhance arch_analyze_uprobe_insn() to reject uprobes on trap variants.
V3:
Added abort_xol() logic for powerpc, using thread_struct.trap_nr to
determine if the stepped instruction caused an exception.
V2:
a. arch_uprobe_analyze_insn() now gets unsigned long addr.
b. Verified that mtmsr[d] and rfi[d] are handled correctly by
emulate_step() (no changes to this patch).
arch/powerpc/Kconfig | 3
arch/powerpc/include/asm/thread_info.h | 4
arch/powerpc/include/asm/uprobes.h | 55 +++++++++
arch/powerpc/kernel/Makefile | 1
arch/powerpc/kernel/signal.c | 6 +
arch/powerpc/kernel/uprobes.c | 184 +++++++++++++++++++++++++++++++++
6 files changed, 252 insertions(+), 1 deletion(-)
Index: linux-tip-23aug/arch/powerpc/include/asm/thread_info.h
===================================================================
--- linux-tip-23aug.orig/arch/powerpc/include/asm/thread_info.h
+++ linux-tip-23aug/arch/powerpc/include/asm/thread_info.h
@@ -102,6 +102,7 @@ static inline struct thread_info *curren
#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 */
@@ -118,12 +119,13 @@ static inline struct thread_info *curren
#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-tip-23aug/arch/powerpc/include/asm/uprobes.h
===================================================================
--- /dev/null
+++ linux-tip-23aug/arch/powerpc/include/asm/uprobes.h
@@ -0,0 +1,55 @@
+#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 IBM Corporation, 2007-2012
+ *
+ * Adapted from the x86 port by Ananth N Mavinakayanahalli <ananth@in.ibm.com>
+ */
+
+#include <linux/notifier.h>
+#include <asm/probes.h>
+
+typedef opcode_t uprobe_opcode_t;
+
+#define MAX_UINSN_BYTES 4
+#define UPROBE_XOL_SLOT_BYTES (MAX_UINSN_BYTES)
+
+/* The following alias is needed for reference from arch-agnostic code */
+#define UPROBE_SWBP_INSN BREAKPOINT_INSTRUCTION
+#define UPROBE_SWBP_INSN_SIZE 4 /* swbp insn size in bytes */
+
+struct arch_uprobe {
+ union {
+ u8 insn[MAX_UINSN_BYTES];
+ u32 ainsn;
+ };
+};
+
+struct arch_uprobe_task {
+ unsigned long saved_trap_nr;
+};
+
+extern int arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr);
+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-tip-23aug/arch/powerpc/kernel/Makefile
===================================================================
--- linux-tip-23aug.orig/arch/powerpc/kernel/Makefile
+++ linux-tip-23aug/arch/powerpc/kernel/Makefile
@@ -96,6 +96,7 @@ obj-$(CONFIG_MODULES) += ppc_ksyms.o
obj-$(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-tip-23aug/arch/powerpc/kernel/signal.c
===================================================================
--- linux-tip-23aug.orig/arch/powerpc/kernel/signal.c
+++ linux-tip-23aug/arch/powerpc/kernel/signal.c
@@ -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 @@ static int do_signal(struct pt_regs *reg
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-tip-23aug/arch/powerpc/kernel/uprobes.c
===================================================================
--- /dev/null
+++ linux-tip-23aug/arch/powerpc/kernel/uprobes.c
@@ -0,0 +1,184 @@
+/*
+ * 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 IBM Corporation, 2007-2012
+ *
+ * Adapted from the x86 port by Ananth N Mavinakayanahalli <ananth@in.ibm.com>
+ */
+#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>
+
+#define UPROBE_TRAP_NR UINT_MAX
+
+/**
+ * arch_uprobe_analyze_insn
+ * @mm: the probed address space.
+ * @arch_uprobe: the probepoint information.
+ * @addr: vaddr to probe.
+ * Return 0 on success or a -ve number on error.
+ */
+int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe,
+ struct mm_struct *mm, unsigned long addr)
+{
+ if (addr & 0x03)
+ return -EINVAL;
+
+ /*
+ * We currently don't support a uprobe on an already
+ * existing breakpoint instruction underneath
+ */
+ if (is_trap(auprobe->ainsn))
+ return -ENOTSUPP;
+ 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)
+{
+ struct arch_uprobe_task *autask = ¤t->utask->autask;
+
+ autask->saved_trap_nr = current->thread.trap_nr;
+ current->thread.trap_nr = UPROBE_TRAP_NR;
+ 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 != UINT_MAX.
+ *
+ * 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 == UINT_MAX set by arch_uprobe_pre_xol().
+ */
+bool arch_uprobe_xol_was_trapped(struct task_struct *t)
+{
+ if (t->thread.trap_nr != UPROBE_TRAP_NR)
+ return true;
+
+ 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)
+{
+ struct uprobe_task *utask = current->utask;
+
+ WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
+
+ current->thread.trap_nr = utask->autask.saved_trap_nr;
+
+ /*
+ * 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 = 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;
+
+ /* regs == NULL is a kernel bug */
+ if (WARN_ON(!regs))
+ return NOTIFY_DONE;
+
+ /* We are only interested in userspace traps */
+ if (!user_mode(regs))
+ return NOTIFY_DONE;
+
+ switch (val) {
+ case DIE_BPT:
+ if (uprobe_pre_sstep_notifier(regs))
+ return NOTIFY_STOP;
+ break;
+ case DIE_SSTEP:
+ if (uprobe_post_sstep_notifier(regs))
+ return NOTIFY_STOP;
+ default:
+ break;
+ }
+ return NOTIFY_DONE;
+}
+
+/*
+ * 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)
+{
+ struct uprobe_task *utask = current->utask;
+
+ current->thread.trap_nr = utask->autask.saved_trap_nr;
+ instruction_pointer_set(regs, utask->vaddr);
+}
+
+/*
+ * 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;
+
+ /*
+ * 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, auprobe->ainsn);
+ if (ret > 0)
+ return true;
+
+ return false;
+}
Index: linux-tip-23aug/arch/powerpc/Kconfig
===================================================================
--- linux-tip-23aug.orig/arch/powerpc/Kconfig
+++ linux-tip-23aug/arch/powerpc/Kconfig
@@ -239,6 +239,9 @@ config PPC_OF_PLATFORM_PCI
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
^ permalink raw reply [flat|nested] 5+ messages in thread