From 62261490a36c6911c5eb61be7cddcfb1bd19ba18 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Thu, 16 Jan 2014 17:43:26 +0000 Subject: [PATCH] Fix gdb.trace/mi-traceframe-changed.exp on s390. The test fails on s390 with: -trace-find frame-number 0^M &"PC not available\n"^M ^done,found="1",tracepoint="1",traceframe="0",frame={level="-1",addr="",func="??",args=[]}^M (gdb) ^M FAIL: gdb.trace/mi-traceframe-changed.exp: tfile: -trace-find frame-number 0 tfile knows to infer the PC from the tracepoint's address if the PC wasn't collected (tfile_fetch_registers) but, that only works on targets whose PC register is a raw register, and on s390, the PC register is a pseudo register. But even if GDB doesn't know how to infer the value of PC, saying the current frame is level -1 is a bug: ^done,found="1",tracepoint="1",traceframe="0",frame={level="-1",addr="",func="??",args=[]}^M ^^^^^^^^^ '-1' is the level of the sentinel frame, which should never be visible. This is caused by the s390's heuristic unwinder accepting the frame (the fallback heuristic unwinders _always_ accept the frame), but then the unwind->this_id method throws that "PC not available\n" error. IOW, the s390's heuristic unwinder was never adjusted to handle unavailable register values gracefully, which can happen with e.g., a trimmed core file too. This is just the minimal necessary for frames, which at least gets us: (gdb) tfind Found trace frame 0, tracepoint 1 #0 in ?? () That is, frame #0 instead of -1. We could get better info out of "info frame" (this patch makes us show "outermost"), but this change would still be necessary. gdb/ 2014-01-16 Pedro Alves * s390-linux-tdep.c (s390_frame_unwind_cache): Swallow NOT_AVAILABLE_ERROR errors while parsing the prologue or reading the backchain. --- gdb/ChangeLog | 6 ++++++ gdb/s390-linux-tdep.c | 15 +++++++++++---- 2 files changed, 17 insertions(+), 4 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index f614f1b7a5..6eef81ac9d 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2014-01-16 Pedro Alves + + * s390-linux-tdep.c (s390_frame_unwind_cache): Swallow + NOT_AVAILABLE_ERROR errors while parsing the prologue or reading + the backchain. + 2014-01-16 Doug Evans * dwarf2read.c (open_and_init_dwp_file): Fix typo in comment. diff --git a/gdb/s390-linux-tdep.c b/gdb/s390-linux-tdep.c index b75c86a578..8b71e780c5 100644 --- a/gdb/s390-linux-tdep.c +++ b/gdb/s390-linux-tdep.c @@ -2039,7 +2039,9 @@ static struct s390_unwind_cache * s390_frame_unwind_cache (struct frame_info *this_frame, void **this_prologue_cache) { + volatile struct gdb_exception ex; struct s390_unwind_cache *info; + if (*this_prologue_cache) return *this_prologue_cache; @@ -2050,10 +2052,15 @@ s390_frame_unwind_cache (struct frame_info *this_frame, info->frame_base = -1; info->local_base = -1; - /* Try to use prologue analysis to fill the unwind cache. - If this fails, fall back to reading the stack backchain. */ - if (!s390_prologue_frame_unwind_cache (this_frame, info)) - s390_backchain_frame_unwind_cache (this_frame, info); + TRY_CATCH (ex, RETURN_MASK_ERROR) + { + /* Try to use prologue analysis to fill the unwind cache. + If this fails, fall back to reading the stack backchain. */ + if (!s390_prologue_frame_unwind_cache (this_frame, info)) + s390_backchain_frame_unwind_cache (this_frame, info); + } + if (ex.reason < 0 && ex.error != NOT_AVAILABLE_ERROR) + throw_exception (ex); return info; }