kernel.git/arch/powerpc/kernel/kprobes.c, branch linux-5.3.y

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

2019-05-30T18:26:35Z

Based on 1 normalized pattern(s): 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 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1334 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Richard Fontana Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de Signed-off-by: Greg Kroah-Hartman

bpf/error-inject/kprobes: Clear current_kprobe and enable preempt in kprobe

2018-06-21T10:33:19Z

Clear current_kprobe and enable preemption in kprobe even if pre_handler returns !0. This simplifies function override using kprobes. Jprobe used to require to keep the preemption disabled and keep current_kprobe until it returned to original function entry. For this reason kprobe_int3_handler() and similar arch dependent kprobe handers checks pre_handler result and exit without enabling preemption if the result is !0. After removing the jprobe, Kprobes does not need to keep preempt disabled even if user handler returns !0 anymore. But since the function override handler in error-inject and bpf is also returns !0 if it overrides a function, to balancing the preempt count, it enables preemption and reset current kprobe by itself. That is a bad design that is very buggy. This fixes such unbalanced preempt-count and current_kprobes setting in kprobes, bpf and error-inject. Note: for powerpc and x86, this removes all preempt_disable from kprobe_ftrace_handler because ftrace callbacks are called under preempt disabled. Signed-off-by: Masami Hiramatsu Acked-by: Thomas Gleixner Acked-by: Naveen N. Rao Cc: Alexei Starovoitov Cc: Ananth N Mavinakayanahalli Cc: Andrew Morton Cc: Benjamin Herrenschmidt Cc: Catalin Marinas Cc: David S. Miller Cc: Fenghua Yu Cc: Heiko Carstens Cc: James Hogan Cc: Josef Bacik Cc: Linus Torvalds Cc: Martin Schwidefsky Cc: Michael Ellerman Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Ralf Baechle Cc: Rich Felker Cc: Russell King Cc: Steven Rostedt Cc: Tony Luck Cc: Vineet Gupta Cc: Will Deacon Cc: Yoshinori Sato Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-ia64@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: linux-s390@vger.kernel.org Cc: linux-sh@vger.kernel.org Cc: linux-snps-arc@lists.infradead.org Cc: linuxppc-dev@lists.ozlabs.org Cc: sparclinux@vger.kernel.org Link: https://lore.kernel.org/lkml/152942494574.15209.12323837825873032258.stgit@devbox Signed-off-by: Ingo Molnar

powerpc/kprobes: Don't call the ->break_handler() in powerpc kprobes code

2018-06-21T10:33:15Z

Don't call the ->break_handler() from the powerpc kprobes code, because it was only used by jprobes which got removed. This also removes skip_singlestep() and embeds it in the caller, kprobe_ftrace_handler(), which simplifies regs->nip operation around there. Signed-off-by: Masami Hiramatsu Acked-by: Thomas Gleixner Acked-by: Naveen N. Rao Cc: Ananth N Mavinakayanahalli Cc: Andrew Morton Cc: Benjamin Herrenschmidt Cc: Linus Torvalds Cc: Michael Ellerman Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Steven Rostedt Cc: linux-arch@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Link: https://lore.kernel.org/lkml/152942477127.15209.8982613703787878618.stgit@devbox Signed-off-by: Ingo Molnar

powerpc/kprobes: Remove jprobe powerpc implementation

2018-06-21T10:33:08Z

Remove arch dependent setjump/longjump functions and unused fields in kprobe_ctlblk for jprobes from arch/powerpc. This also reverts commits related __is_active_jprobe() function. Signed-off-by: Masami Hiramatsu Acked-by: Thomas Gleixner Acked-by: Naveen N. Rao Cc: Ananth N Mavinakayanahalli Cc: Andrew Morton Cc: Benjamin Herrenschmidt Cc: Linus Torvalds Cc: Michael Ellerman Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Steven Rostedt Cc: linux-arch@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Link: https://lore.kernel.org/lkml/152942445234.15209.12868722778364739753.stgit@devbox Signed-off-by: Ingo Molnar

powerpc/kprobes: Fix call trace due to incorrect preempt count

2018-03-30T13:10:33Z

Michael Ellerman reported the following call trace when running ftracetest: BUG: using __this_cpu_write() in preemptible [00000000] code: ftracetest/6178 caller is opt_pre_handler+0xc4/0x110 CPU: 1 PID: 6178 Comm: ftracetest Not tainted 4.15.0-rc7-gcc6x-gb2cd1df #1 Call Trace: [c0000000f9ec39c0] [c000000000ac4304] dump_stack+0xb4/0x100 (unreliable) [c0000000f9ec3a00] [c00000000061159c] check_preemption_disabled+0x15c/0x170 [c0000000f9ec3a90] [c000000000217e84] opt_pre_handler+0xc4/0x110 [c0000000f9ec3af0] [c00000000004cf68] optimized_callback+0x148/0x170 [c0000000f9ec3b40] [c00000000004d954] optinsn_slot+0xec/0x10000 [c0000000f9ec3e30] [c00000000004bae0] kretprobe_trampoline+0x0/0x10 This is showing up since OPTPROBES is now enabled with CONFIG_PREEMPT. trampoline_probe_handler() considers itself to be a special kprobe handler for kretprobes. In doing so, it expects to be called from kprobe_handler() on a trap, and re-enables preemption before returning a non-zero return value so as to suppress any subsequent processing of the trap by the kprobe_handler(). However, with optprobes, we don't deal with special handlers (we ignore the return code) and just try to re-enable preemption causing the above trace. To address this, modify trampoline_probe_handler() to not be special. The only additional processing done in kprobe_handler() is to emulate the instruction (in this case, a 'nop'). We adjust the value of regs->nip for the purpose and delegate the job of re-enabling preemption and resetting current kprobe to the probe handlers (kprobe_handler() or optimized_callback()). Fixes: 8a2d71a3f273 ("powerpc/kprobes: Disable preemption before invoking probe handler for optprobes") Cc: stable@vger.kernel.org # v4.15+ Reported-by: Michael Ellerman Signed-off-by: Naveen N. Rao Acked-by: Ananth N Mavinakayanahalli Signed-off-by: Michael Ellerman

powerpc/kprobes: refactor kprobe_lookup_name for safer string operations

2017-11-12T12:51:43Z

Use safer string manipulation functions when dealing with a user-provided string in kprobe_lookup_name(). Reported-by: David Laight Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman

Merge branch 'fixes' into next

2017-11-10T09:55:03Z

We have some dependencies & conflicts between patches in fixes and things to go in next, both in the radix TLB flush code and the IMC PMU driver. So merge fixes into next.

powerpc/kprobes: Dereference function pointers only if the address does not belong to kernel text

2017-11-01T04:51:03Z

This makes the changes introduced in commit 83e840c770f2c5 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols") to be specific to the kprobe subsystem. We previously changed ppc_function_entry() to always check the provided address to confirm if it needed to be dereferenced. This is actually only an issue for kprobe blacklisted asm labels (through use of _ASM_NOKPROBE_SYMBOL) and can cause other issues with ftrace. Also, the additional checks are not really necessary for our other uses. As such, move this check to the kprobes subsystem. Fixes: 83e840c770f2 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols") Cc: stable@vger.kernel.org # v4.13+ Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman

powerpc/jprobes: Validate break handler invocation as being due to a jprobe_return()

2017-10-05T05:12:48Z

Fix a circa 2005 FIXME by implementing a check to ensure that we actually got into the jprobe break handler() due to the trap in jprobe_return(). Acked-by: Masami Hiramatsu Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman

powerpc/kprobes: Clean up jprobe detection in livepatch handler

2017-10-04T12:42:17Z

In commit c05b8c4474c03 ("powerpc/kprobes: Skip livepatch_handler() for jprobes"), we added a helper is_current_kprobe_addr() to help detect if the modified regs->nip was due to a jprobe or livepatch. Masami felt that the function name was not quite clear. To that end, this patch renames is_current_kprobe_addr() to __is_active_jprobe() and adds a comment to (hopefully) better clarify the purpose of this helper. The helper has also now been moved to kprobes-ftrace.c so that it is only available for KPROBES_ON_FTRACE. Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman