From 1e032f7cfa141b4424827b0ecb0ea899f84e182e Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Wed, 15 May 2019 14:39:05 +0900 Subject: perf-probe: Add user memory access attribute support Add user memory access attribute for kprobe event arguments. If a given 'local variable' is in user-space, User can specify memory access method by '@user' suffix. This is not only for string but also for data structure. If we access a field of data structure in user memory from kernel on some arch, it will fail. e.g. perf probe -a "sched_setscheduler param->sched_priority" This will fail to access the "param->sched_priority" because the param is __user pointer. Instead, we can now specify @user suffix for such argument. perf probe -a "sched_setscheduler param->sched_priority@user" Note that kernel memory access with "@user" must always fail on any arch. Link: http://lkml.kernel.org/r/155789874562.26965.10836126971405890891.stgit@devnote2 Acked-by: Ingo Molnar Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- tools/perf/util/probe-event.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'tools/perf/util/probe-event.c') diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 198e09ff611e..a7ca17be5fc5 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -1577,6 +1577,17 @@ static int parse_perf_probe_arg(char *str, struct perf_probe_arg *arg) str = tmp + 1; } + tmp = strchr(str, '@'); + if (tmp && tmp != str && strcmp(tmp + 1, "user")) { /* user attr */ + if (!user_access_is_supported()) { + semantic_error("ftrace does not support user access\n"); + return -EINVAL; + } + *tmp = '\0'; + arg->user_access = true; + pr_debug("user_access "); + } + tmp = strchr(str, ':'); if (tmp) { /* Type setting */ *tmp = '\0'; -- cgit v1.2.3