kernel.git/arch/arm/kernel/hw_breakpoint.c, branch linux-5.4.y

hw_breakpoint: fix single-stepping when using bpf_overflow_handler

2023-09-23T09:00:03Z

[ Upstream commit d11a69873d9a7435fe6a48531e165ab80a8b1221 ] Arm platforms use is_default_overflow_handler() to determine if the hw_breakpoint code should single-step over the breakpoint trigger or let the custom handler deal with it. Since bpf_overflow_handler() currently isn't recognized as a default handler, attaching a BPF program to a PERF_TYPE_BREAKPOINT event causes it to keep firing (the instruction triggering the data abort exception is never skipped). For example: # bpftrace -e 'watchpoint:0x10000:4:w { print("hit") }' -c ./test Attaching 1 probe... hit hit [...] ^C (./test performs a single 4-byte store to 0x10000) This patch replaces the check with uses_default_overflow_handler(), which accounts for the bpf_overflow_handler() case by also testing if one of the perf_event_output functions gets invoked indirectly, via orig_default_handler. Signed-off-by: Tomislav Novak Tested-by: Samuel Gosselin # arm64 Reviewed-by: Catalin Marinas Acked-by: Alexei Starovoitov Link: https://lore.kernel.org/linux-arm-kernel/20220923203644.2731604-1-tnovak@fb.com/ Link: https://lore.kernel.org/r/20230605191923.1219974-1-tnovak@meta.com Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

ARM: 9064/1: hw_breakpoint: Do not directly check the event's overflow_handler hook

2021-05-19T08:08:25Z

[ Upstream commit a506bd5756290821a4314f502b4bafc2afcf5260 ] The commit 1879445dfa7b ("perf/core: Set event's default ::overflow_handler()") set a default event->overflow_handler in perf_event_alloc(), and replace the check event->overflow_handler with is_default_overflow_handler(), but one is missing. Currently, the bp->overflow_handler can not be NULL. As a result, enable_single_step() is always not invoked. Comments from Zhen Lei: https://patchwork.kernel.org/project/linux-arm-kernel/patch/20210207105934.2001-1-thunder.leizhen@huawei.com/ Fixes: 1879445dfa7b ("perf/core: Set event's default ::overflow_handler()") Signed-off-by: Zhen Lei Cc: Wang Nan Acked-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Sasha Levin

ARM: 8997/2: hw_breakpoint: Handle inexact watchpoint addresses

2020-11-05T10:43:14Z

[ Upstream commit 22c9e58299e5f18274788ce54c03d4fb761e3c5d ] This is commit fdfeff0f9e3d ("arm64: hw_breakpoint: Handle inexact watchpoint addresses") but ported to arm32, which has the same problem. This problem was found by Android CTS tests, notably the "watchpoint_imprecise" test [1]. I tested locally against a copycat (simplified) version of the test though. [1] https://android.googlesource.com/platform/bionic/+/master/tests/sys_ptrace_test.cpp Link: https://lkml.kernel.org/r/20191019111216.1.I82eae759ca6dc28a245b043f485ca490e3015321@changeid Signed-off-by: Douglas Anderson Reviewed-by: Matthias Kaehlcke Acked-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Sasha Levin

ARM: 8986/1: hw_breakpoint: Don't invoke overflow handler on uaccess watchpoints

2020-08-05T07:59:42Z

commit eec13b42d41b0f3339dcf0c4da43734427c68620 upstream. Unprivileged memory accesses generated by the so-called "translated" instructions (e.g. LDRT) in kernel mode can cause user watchpoints to fire unexpectedly. In such cases, the hw_breakpoint logic will invoke the user overflow handler which will typically raise a SIGTRAP back to the current task. This is futile when returning back to the kernel because (a) the signal won't have been delivered and (b) userspace can't handle the thing anyway. Avoid invoking the user overflow handler for watchpoints triggered by kernel uaccess routines, and instead single-step over the faulting instruction as we would if no overflow handler had been installed. Cc: Fixes: f81ef4a920c8 ("ARM: 6356/1: hw-breakpoint: add ARM backend for the hw-breakpoint framework") Reported-by: Luis Machado Tested-by: Luis Machado Signed-off-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman

ARM/hw_breakpoint: Mark expected switch fall-throughs

2019-08-10T00:45:01Z

Mark switch cases where we are expecting to fall through. This patch fixes the following warnings: arch/arm/kernel/hw_breakpoint.c: In function 'hw_breakpoint_arch_parse': arch/arm/kernel/hw_breakpoint.c:609:6: warning: this statement may fall through [-Wimplicit-fallthrough=] if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2) ^ arch/arm/kernel/hw_breakpoint.c:611:2: note: here case 3: ^~~~ arch/arm/kernel/hw_breakpoint.c:613:6: warning: this statement may fall through [-Wimplicit-fallthrough=] if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1) ^ arch/arm/kernel/hw_breakpoint.c:615:2: note: here default: ^~~~~~~ arch/arm/kernel/hw_breakpoint.c: In function 'arch_build_bp_info': arch/arm/kernel/hw_breakpoint.c:544:6: warning: this statement may fall through [-Wimplicit-fallthrough=] if ((hw->ctrl.type != ARM_BREAKPOINT_EXECUTE) ^ arch/arm/kernel/hw_breakpoint.c:547:2: note: here default: ^~~~~~~ In file included from include/linux/kernel.h:11, from include/linux/list.h:9, from include/linux/preempt.h:11, from include/linux/hardirq.h:5, from arch/arm/kernel/hw_breakpoint.c:16: arch/arm/kernel/hw_breakpoint.c: In function 'hw_breakpoint_pending': include/linux/compiler.h:78:22: warning: this statement may fall through [-Wimplicit-fallthrough=] # define unlikely(x) __builtin_expect(!!(x), 0) ^~~~~~~~~~~~~~~~~~~~~~~~~~ include/asm-generic/bug.h:136:2: note: in expansion of macro 'unlikely' unlikely(__ret_warn_on); \ ^~~~~~~~ arch/arm/kernel/hw_breakpoint.c:863:3: note: in expansion of macro 'WARN' WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n"); ^~~~ arch/arm/kernel/hw_breakpoint.c:864:2: note: here case ARM_ENTRY_SYNC_WATCHPOINT: ^~~~ arch/arm/kernel/hw_breakpoint.c: In function 'core_has_os_save_restore': arch/arm/kernel/hw_breakpoint.c:910:6: warning: this statement may fall through [-Wimplicit-fallthrough=] if (oslsr & ARM_OSLSR_OSLM0) ^ arch/arm/kernel/hw_breakpoint.c:912:2: note: here default: ^~~~~~~ Reported-by: Stephen Rothwell Reviewed-by: Kees Cook Signed-off-by: Gustavo A. R. Silva

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333

2019-06-05T15:37:06Z

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 version 2 as published by the free software foundation 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-only has been chosen to replace the boilerplate/reference in 136 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Alexios Zavras Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190530000436.384967451@linutronix.de Signed-off-by: Greg Kroah-Hartman

perf/arch/arm: Implement hw_breakpoint_arch_parse()

2018-06-26T07:07:56Z

Migrate to the new API in order to remove arch_validate_hwbkpt_settings() that clumsily mixes up architecture validation and commit. Signed-off-by: Frederic Weisbecker Acked-by: Mark Rutland Cc: Alexander Shishkin Cc: Andy Lutomirski Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Benjamin Herrenschmidt Cc: Catalin Marinas Cc: Chris Zankel Cc: Jiri Olsa Cc: Joel Fernandes Cc: Linus Torvalds Cc: Max Filippov Cc: Michael Ellerman Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Rich Felker Cc: Thomas Gleixner Cc: Will Deacon Cc: Yoshinori Sato Link: http://lkml.kernel.org/r/1529981939-8231-6-git-send-email-frederic@kernel.org Signed-off-by: Ingo Molnar

perf/hw_breakpoint: Pass arch breakpoint struct to arch_check_bp_in_kernelspace()

2018-06-26T07:07:54Z

We can't pass the breakpoint directly on arch_check_bp_in_kernelspace() anymore because its architecture internal datas (struct arch_hw_breakpoint) are not yet filled by the time we call the function, and most implementation need this backend to be up to date. So arrange the function to take the probing struct instead. Signed-off-by: Frederic Weisbecker Cc: Alexander Shishkin Cc: Andy Lutomirski Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Benjamin Herrenschmidt Cc: Catalin Marinas Cc: Chris Zankel Cc: Jiri Olsa Cc: Joel Fernandes Cc: Linus Torvalds Cc: Mark Rutland Cc: Max Filippov Cc: Michael Ellerman Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Rich Felker Cc: Thomas Gleixner Cc: Will Deacon Cc: Yoshinori Sato Link: http://lkml.kernel.org/r/1529981939-8231-3-git-send-email-frederic@kernel.org Signed-off-by: Ingo Molnar

ARM: 8733/1: hw_breakpoint: Mark variables as __ro_after_init

2017-12-17T22:16:20Z

core_num_brps, core_num_wrps, debug_arch, has_ossr, max_watchpoint_len are setup once while init stage, and never changed after that. so it is good candidate for __ro_after_init. Reviewed-by: Kees Cook Signed-off-by: Jinbum Park Signed-off-by: Russell King

ARM/hw_breakpoint: Fix possible recursive locking for arch_hw_breakpoint_init

2017-06-20T10:25:22Z

Recent change to use cpuhp_setup_state_cpuslocked() with commit fe2a5cd8aa03 ("ARM/hw_breakpoint: Use cpuhp_setup_state_cpuslocked()") missed to change the related paired cpuhp_remove_state_nocalls_cpuslocked(). Now if arch_hw_breakpoint_init() fails, we get "WARNING: possible recursive locking detected" on the exit path. Fixes: fe2a5cd8aa03 ("ARM/hw_breakpoint: Use cpuhp_setup_state_cpuslocked()") Signed-off-by: Tony Lindgren Acked-by: Sebastian Andrzej Siewior Cc: Mark Rutland Cc: linux-omap@vger.kernel.org Cc: Peter Zijlstra Cc: Will Deacon Cc: Steven Rostedt Cc: Russell King Cc: "Paul E . McKenney" Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/20170616082238.15553-1-tony@atomide.com Signed-off-by: Thomas Gleixner