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-finder.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) (limited to 'tools/perf/util/probe-finder.c') diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index c37fbef1711d..c202027716d0 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -294,7 +294,7 @@ static_var: static int convert_variable_type(Dwarf_Die *vr_die, struct probe_trace_arg *tvar, - const char *cast) + const char *cast, bool user_access) { struct probe_trace_arg_ref **ref_ptr = &tvar->ref; Dwarf_Die type; @@ -334,7 +334,8 @@ static int convert_variable_type(Dwarf_Die *vr_die, pr_debug("%s type is %s.\n", dwarf_diename(vr_die), dwarf_diename(&type)); - if (cast && strcmp(cast, "string") == 0) { /* String type */ + if (cast && (!strcmp(cast, "string") || !strcmp(cast, "ustring"))) { + /* String type */ ret = dwarf_tag(&type); if (ret != DW_TAG_pointer_type && ret != DW_TAG_array_type) { @@ -357,6 +358,7 @@ static int convert_variable_type(Dwarf_Die *vr_die, pr_warning("Out of memory error\n"); return -ENOMEM; } + (*ref_ptr)->user_access = user_access; } if (!die_compare_name(&type, "char") && !die_compare_name(&type, "unsigned char")) { @@ -411,7 +413,7 @@ formatted: static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname, struct perf_probe_arg_field *field, struct probe_trace_arg_ref **ref_ptr, - Dwarf_Die *die_mem) + Dwarf_Die *die_mem, bool user_access) { struct probe_trace_arg_ref *ref = *ref_ptr; Dwarf_Die type; @@ -448,6 +450,7 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname, *ref_ptr = ref; } ref->offset += dwarf_bytesize(&type) * field->index; + ref->user_access = user_access; goto next; } else if (tag == DW_TAG_pointer_type) { /* Check the pointer and dereference */ @@ -519,17 +522,18 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname, } } ref->offset += (long)offs; + ref->user_access = user_access; /* If this member is unnamed, we need to reuse this field */ if (!dwarf_diename(die_mem)) return convert_variable_fields(die_mem, varname, field, - &ref, die_mem); + &ref, die_mem, user_access); next: /* Converting next field */ if (field->next) return convert_variable_fields(die_mem, field->name, - field->next, &ref, die_mem); + field->next, &ref, die_mem, user_access); else return 0; } @@ -555,11 +559,12 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf) else if (ret == 0 && pf->pvar->field) { ret = convert_variable_fields(vr_die, pf->pvar->var, pf->pvar->field, &pf->tvar->ref, - &die_mem); + &die_mem, pf->pvar->user_access); vr_die = &die_mem; } if (ret == 0) - ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type); + ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type, + pf->pvar->user_access); /* *expr will be cached in libdw. Don't free it. */ return ret; } -- cgit v1.2.3-59-g8ed1b