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authorKees Cook <kees+treewide@kernel.org>2026-09-02 15:31:14 -0700
committerKees Cook <kees@kernel.org>2026-09-04 21:37:00 -0700
commit3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d (patch)
treec65086f9bdcd48c6360fb7cb4598bca084da1f32 /samples/hw_breakpoint
downloadlinux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.tar.gz
linux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.zip
treewide: refresh kmalloc_obj() conversionsgrafted
This is another run of the Coccinelle script for converting kmalloc() family of allocations to kmalloc_obj() via the existing rules in scripts/coccinelle/api/kmalloc_objs.cocci This catches both the set of kmalloc() uses added since the first kmalloc_obj() conversions in v7.0 and adds a large group missed in the first pass due to Coccinelle not interacting well with the cleanup.h scoped_...() family of macros[1]. I worked around this with spatch's "--macro-file" argument to a file with all the scoped_...() macros mapped to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control flow indicator I could find. Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc, riscv, and s390 with no new warnings. Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1] Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2] Signed-off-by: Kees Cook <kees+treewide@kernel.org>
Diffstat (limited to 'samples/hw_breakpoint')
-rw-r--r--samples/hw_breakpoint/Makefile2
-rw-r--r--samples/hw_breakpoint/data_breakpoint.c84
2 files changed, 86 insertions, 0 deletions
diff --git a/samples/hw_breakpoint/Makefile b/samples/hw_breakpoint/Makefile
new file mode 100644
index 000000000..ef4b6fdd7
--- /dev/null
+++ b/samples/hw_breakpoint/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_SAMPLE_HW_BREAKPOINT) += data_breakpoint.o
diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
new file mode 100644
index 000000000..fbb03b66d
--- /dev/null
+++ b/samples/hw_breakpoint/data_breakpoint.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * data_breakpoint.c - Sample HW Breakpoint file to watch kernel data address
+ *
+ * usage: insmod data_breakpoint.ko ksym=<ksym_name>
+ *
+ * This file is a kernel module that places a breakpoint over ksym_name kernel
+ * variable using Hardware Breakpoint register. The corresponding handler which
+ * prints a backtrace is invoked every time a write operation is performed on
+ * that variable.
+ *
+ * Copyright (C) IBM Corporation, 2009
+ *
+ * Author: K.Prasad <prasad@linux.vnet.ibm.com>
+ */
+#include <linux/module.h> /* Needed by all modules */
+#include <linux/kernel.h> /* Needed for KERN_INFO */
+#include <linux/init.h> /* Needed for the macros */
+#include <linux/kallsyms.h>
+
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
+
+static struct perf_event * __percpu *sample_hbp;
+
+static char ksym_name[KSYM_NAME_LEN] = "jiffies";
+module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
+MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any"
+ " write operations on the kernel symbol");
+
+static void sample_hbp_handler(struct perf_event *bp,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ printk(KERN_INFO "%s value is changed\n", ksym_name);
+ dump_stack();
+ printk(KERN_INFO "Dump stack from sample_hbp_handler\n");
+}
+
+static int __init hw_break_module_init(void)
+{
+ int ret;
+ struct perf_event_attr attr;
+ void *addr = __symbol_get(ksym_name);
+
+ if (!addr)
+ return -ENXIO;
+
+ hw_breakpoint_init(&attr);
+ attr.bp_addr = (unsigned long)addr;
+ attr.bp_len = HW_BREAKPOINT_LEN_4;
+ attr.bp_type = HW_BREAKPOINT_W;
+
+ sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler, NULL);
+ if (IS_ERR_PCPU(sample_hbp)) {
+ ret = PTR_ERR_PCPU(sample_hbp);
+ goto fail;
+ }
+
+ printk(KERN_INFO "HW Breakpoint for %s write installed\n", ksym_name);
+
+ return 0;
+
+fail:
+ printk(KERN_INFO "Breakpoint registration failed\n");
+
+ return ret;
+}
+
+static void __exit hw_break_module_exit(void)
+{
+ unregister_wide_hw_breakpoint(sample_hbp);
+#ifdef CONFIG_MODULE_UNLOAD
+ __symbol_put(ksym_name);
+#endif
+ printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name);
+}
+
+module_init(hw_break_module_init);
+module_exit(hw_break_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("K.Prasad");
+MODULE_DESCRIPTION("ksym breakpoint");