path: root/samples
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authorWill Deacon <will@kernel.org>2020-04-06 20:11:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-07 10:43:44 -0700
commitd8a84d33a4954b85c53faf77be48b5c2b559692e (patch)
tree98282468de89bb90ddeb3a14e3059961df24b7fd /samples
parentsamples/hw_breakpoint: drop HW_BREAKPOINT_R when reporting writes (diff)
samples/hw_breakpoint: drop use of kallsyms_lookup_name()
The 'data_breakpoint' test code is the only modular user of kallsyms_lookup_name(), which was exported as part of fixing the test in f60d24d2ad04 ("hw-breakpoints: Fix broken hw-breakpoint sample module"). In preparation for un-exporting this symbol, switch the test over to using __symbol_get(), which can be used to place breakpoints on exported symbols. Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Quentin Perret <qperret@google.com> Cc: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Petr Mladek <pmladek@suse.com> Cc: Joe Lawrence <joe.lawrence@redhat.com> Link: http://lkml.kernel.org/r/20200221114404.14641-3-will@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'samples')
1 files changed, 7 insertions, 2 deletions
diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
index 469b36f93696..418c46fe5ffc 100644
--- a/samples/hw_breakpoint/data_breakpoint.c
+++ b/samples/hw_breakpoint/data_breakpoint.c
@@ -23,7 +23,7 @@
struct perf_event * __percpu *sample_hbp;
-static char ksym_name[KSYM_NAME_LEN] = "pid_max";
+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");
@@ -41,9 +41,13 @@ 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;
- attr.bp_addr = kallsyms_lookup_name(ksym_name);
+ attr.bp_addr = (unsigned long)addr;
attr.bp_len = HW_BREAKPOINT_LEN_4;
attr.bp_type = HW_BREAKPOINT_W;
@@ -66,6 +70,7 @@ fail:
static void __exit hw_break_module_exit(void)
+ symbol_put(ksym_name);
printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name);