From d0461794a1dcaf552b507e23788777f718b736a1 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Sat, 17 Mar 2018 21:52:25 +0900 Subject: perf probe: Use right type to access array elements Current 'perf probe' converts the type of array-elements incorrectly. It always converts the types as a pointer of array. This passes the "array" type DIE to the type converter so that it can get correct "element of array" type DIE from it. E.g. ==== $ cat hello.c #include void foo(int a[]) { printf("%d\n", a[1]); } void main() { int a[3] = {4, 5, 6}; printf("%d\n", a[0]); foo(a); } $ gcc -g hello.c -o hello $ perf probe -x ./hello -D "foo a[1]" ==== Without this fix, above outputs ==== p:probe_hello/foo /tmp/hello:0x4d3 a=+4(-8(%bp)):u64 ==== The "u64" means "int *", but a[1] is "int". With this, ==== p:probe_hello/foo /tmp/hello:0x4d3 a=+4(-8(%bp)):s32 ==== So, "int" correctly converted to "s32" Signed-off-by: Masami Hiramatsu Tested-by: Arnaldo Carvalho de Melo Cc: Namhyung Kim Cc: Ravi Bangoria Cc: Shuah Khan Cc: Steven Rostedt Cc: Tom Zanussi Cc: linux-kselftest@vger.kernel.org Cc: linux-trace-users@vger.kernel.org Fixes: b2a3c12b7442 ("perf probe: Support tracing an entry of array") Link: http://lkml.kernel.org/r/152129114502.31874.2474068470011496356.stgit@devbox Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-finder.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 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 a5731de0e5eb..c37fbef1711d 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -423,20 +423,20 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname, pr_warning("Failed to get the type of %s.\n", varname); return -ENOENT; } - pr_debug2("Var real type: (%x)\n", (unsigned)dwarf_dieoffset(&type)); + pr_debug2("Var real type: %s (%x)\n", dwarf_diename(&type), + (unsigned)dwarf_dieoffset(&type)); tag = dwarf_tag(&type); if (field->name[0] == '[' && (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) { - if (field->next) - /* Save original type for next field */ - memcpy(die_mem, &type, sizeof(*die_mem)); + /* Save original type for next field or type */ + memcpy(die_mem, &type, sizeof(*die_mem)); /* Get the type of this array */ if (die_get_real_type(&type, &type) == NULL) { pr_warning("Failed to get the type of %s.\n", varname); return -ENOENT; } - pr_debug2("Array real type: (%x)\n", + pr_debug2("Array real type: %s (%x)\n", dwarf_diename(&type), (unsigned)dwarf_dieoffset(&type)); if (tag == DW_TAG_pointer_type) { ref = zalloc(sizeof(struct probe_trace_arg_ref)); @@ -448,9 +448,6 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname, *ref_ptr = ref; } ref->offset += dwarf_bytesize(&type) * field->index; - if (!field->next) - /* Save vr_die for converting types */ - memcpy(die_mem, vr_die, sizeof(*die_mem)); goto next; } else if (tag == DW_TAG_pointer_type) { /* Check the pointer and dereference */ -- cgit v1.2.3-55-g7522