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Wed, 03 Sep 2025 17:23:45 -0700 (PDT) From: Jinchao Wang To: Andrew Morton , Masami Hiramatsu , "Naveen N . Rao" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Peter Zijlstra , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-perf-users@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jinchao Wang Subject: [PATCH v2 13/18] mm/ksw: add test module Date: Thu, 4 Sep 2025 08:21:10 +0800 Message-ID: <20250904002126.1514566-14-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250904002126.1514566-1-wangjinchao600@gmail.com> References: <20250904002126.1514566-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 01BF320007 X-Stat-Signature: kcm6b1o95bp1748tncwz1egg9unx6aig X-Rspam-User: X-HE-Tag: 1756945426-194710 X-HE-Meta: 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 UWzPlrga 32MtZtQMOy0D3DUWlGwHWm16eCUHDrVigYWnkGcs80EEIPMAc6YQMKyGZ1Vcf1ofn6isWhWGxhn0AyFwGDXeN4kK0Fc0putFhBzlQLApvPvamrEP2lAP19UNd5tKST9oO40VCvGb/2CgggTx7CufODxhTvoNom/zMCe0qCEYHm1Bx9BefoJZVYRvluyZNKfi9xM53EWpyyhIf0q6WYvh/qUj/iyz5kj9aVTMxwbZXBVCxKM++jhHMsY2irOn0dOZbN4vsIwofFlFFq0zzTj0N9xpR1C/HN7J2l92ibhv2kIbi2slcKKgMmWsR0SU02XL4lTm1lV7FQ3Foy/Otp1ijeDKPyVzs+8t47Na/tl4hs371nkNcArTcPJ5uNKHmmmPTbRXbNoil7nBrHUN9rXwkE10O1vVfmXB/pjXAPMbohcP6cxWZEC26SWGR3NLWtYyfX3bapUdyH+xRhdmhAjWC1Yxk6Ghgd5+SoLCL X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Introduce a separate test module to validate KStackWatch functionality in controlled scenarios, such as stack canary writes and simulated corruption. The module provides a proc interface (/proc/kstackwatch_test) that allows triggering specific test cases via simple commands: - test0: directly corrupt the canary to verify watch/fire behavior This helps development and validation of KStackWatch without affecting normal kernel operation. Test module is built with optimizations disabled to ensure predictable behavior. Signed-off-by: Jinchao Wang --- mm/Kconfig.debug | 10 +++ mm/kstackwatch/Makefile | 6 +- mm/kstackwatch/kstackwatch_test.c | 118 ++++++++++++++++++++++++++++++ 3 files changed, 133 insertions(+), 1 deletion(-) create mode 100644 mm/kstackwatch/kstackwatch_test.c diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index c2cc8c7b595f..7fdf7b03d458 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -319,3 +319,13 @@ config KSTACK_WATCH the recursive depth of the monitored function. If unsure, say N. + +config KSTACK_WATCH_TEST + tristate "KStackWatch Test Module" + depends on KSTACK_WATCH + help + This module provides controlled stack exhaustion and overflow scenarios + to verify the functionality of KStackWatch. It is particularly useful + for development and validation of the KStachWatch mechanism. + + If unsure, say N. diff --git a/mm/kstackwatch/Makefile b/mm/kstackwatch/Makefile index d422f0e114dd..c04c0780da01 100644 --- a/mm/kstackwatch/Makefile +++ b/mm/kstackwatch/Makefile @@ -1,4 +1,8 @@ obj-$(CONFIG_KSTACK_WATCH) += kstackwatch.o kstackwatch-y := kernel.o stack.o watch.o -CFLAGS_kernel.o := -Wno-error=unused-function +obj-$(CONFIG_KSTACK_WATCH_TEST) += kstackwatch_test.o +CFLAGS_kstackwatch_test.o := -fno-ipa-sra -fno-inline \ + -fno-optimize-sibling-calls \ + -fno-section-anchors \ + -fno-pic -fno-pie -O0 -Og diff --git a/mm/kstackwatch/kstackwatch_test.c b/mm/kstackwatch/kstackwatch_test.c new file mode 100644 index 000000000000..bba2ab8530ed --- /dev/null +++ b/mm/kstackwatch/kstackwatch_test.c @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "kstackwatch.h" + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Jinchao Wang"); +MODULE_DESCRIPTION("Simple KStackWatch Test Module"); + +static struct proc_dir_entry *test_proc; +#define BUFFER_SIZE 4 +#define MAX_DEPTH 4 + +/* + * Test Case 0: Write to the canary position directly (Canary Test) + * use a u64 buffer array to ensure the canary will be placed + * corrupt the stack canary using the debug function + */ +static void canary_test_write(void) +{ + u64 buffer[BUFFER_SIZE]; + + pr_info("KSW: test: starting %s with u64 write\n", __func__); + ksw_watch_show(); + ksw_watch_fire(); + + buffer[0] = 0; + + /* make sure the compiler do not drop assign action */ + barrier_data(buffer); + pr_info("KSW: test: canary write test completed\n"); +} + +static ssize_t test_proc_write(struct file *file, const char __user *buffer, + size_t count, loff_t *pos) +{ + char cmd[256]; + int test_num; + + if (count >= sizeof(cmd)) + return -EINVAL; + + if (copy_from_user(cmd, buffer, count)) + return -EFAULT; + + cmd[count] = '\0'; + strim(cmd); + + pr_info("KSW: test: received command: %s\n", cmd); + + if (sscanf(cmd, "test%d", &test_num) == 1) { + switch (test_num) { + case 0: + pr_info("KSW: test: triggering canary write test\n"); + canary_test_write(); + break; + + default: + pr_err("KSW: test: Unknown test number %d\n", test_num); + return -EINVAL; + } + } else { + pr_err("KSW: test: invalid command format. Use 'test1', 'test2', or 'test3'.\n"); + return -EINVAL; + } + + return count; +} + +static ssize_t test_proc_read(struct file *file, char __user *buffer, + size_t count, loff_t *pos) +{ + static const char usage[] = + "KStackWatch Simplified Test Module\n" + "==================================\n" + "Usage:\n" + " echo 'test0' > /proc/kstackwatch_test - canary write test\n"; + + return simple_read_from_buffer(buffer, count, pos, usage, + strlen(usage)); +} + +static const struct proc_ops test_proc_ops = { + .proc_read = test_proc_read, + .proc_write = test_proc_write, +}; + +static int __init kstackwatch_test_init(void) +{ + test_proc = proc_create("kstackwatch_test", 0644, NULL, &test_proc_ops); + if (!test_proc) { + pr_err("KSW: test: Failed to create proc entry\n"); + return -ENOMEM; + } + pr_info("KSW: test: Module loaded, use 'cat /proc/kstackwatch_test' for usage\n"); + return 0; +} + +static void __exit kstackwatch_test_exit(void) +{ + if (test_proc) + remove_proc_entry("kstackwatch_test", NULL); + pr_info("KSW: test: Module unloaded\n"); +} + +module_init(kstackwatch_test_init); +module_exit(kstackwatch_test_exit); -- 2.43.0