Fix to convert array element type collectly. 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 <stdio.h>

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"

Fixes: b2a3c12b7442 ("perf probe: Support tracing an entry of array") Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Cc: stable@vger.kernel.org --- tools/perf/util/probe-finder.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)

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 */