From 13a633541055b790701c81cb716fcf2237e472fb Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 10 Mar 2020 05:03:30 +0000 Subject: [PATCH] FROMGIT: 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. Bug: 149978696 Change-Id: I589142af97a34484f9fa551b934148f445b33243 Link: http://lkml.kernel.org/r/20200221114404.14641-3-will@kernel.org Signed-off-by: Will Deacon Reviewed-by: Christoph Hellwig Reviewed-by: Masami Hiramatsu Cc: K.Prasad Cc: Thomas Gleixner Cc: Greg Kroah-Hartman Cc: Frederic Weisbecker Cc: Quentin Perret Cc: Alexei Starovoitov Cc: Miroslav Benes Cc: Petr Mladek Cc: Joe Lawrence Signed-off-by: Andrew Morton (cherry picked from commit e108898157d888c827a7176e02648cc3bd87025b https://github.com/hnaz/linux-mm.git master) Signed-off-by: Quentin Perret --- samples/hw_breakpoint/data_breakpoint.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c index c4f3177103dd..3739481c6426 100644 --- a/samples/hw_breakpoint/data_breakpoint.c +++ b/samples/hw_breakpoint/data_breakpoint.c @@ -36,7 +36,7 @@ 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"); @@ -54,9 +54,13 @@ 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; hw_breakpoint_init(&attr); - 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; @@ -79,6 +83,7 @@ static int __init hw_break_module_init(void) static void __exit hw_break_module_exit(void) { unregister_wide_hw_breakpoint(sample_hbp); + symbol_put(ksym_name); printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name); }