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author | Tom de Vries <tdevries@suse.de> | 2024-03-14 11:25:10 +0100 |
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committer | Tom de Vries <tdevries@suse.de> | 2024-03-14 11:25:10 +0100 |
commit | 9a03f2185347bd8f20da9bf535bc68a8d0f18ce8 (patch) | |
tree | 6ee5258b5bdbef602d17686512b7be04fe96f6ae /gdb/python | |
parent | 3a4c6f1aa958739705ee69526fdeed7c69d7243c (diff) | |
download | gdb-9a03f2185347bd8f20da9bf535bc68a8d0f18ce8.zip gdb-9a03f2185347bd8f20da9bf535bc68a8d0f18ce8.tar.gz gdb-9a03f2185347bd8f20da9bf535bc68a8d0f18ce8.tar.bz2 |
[gdb/tdep] Fix gdb.base/watchpoint-unaligned.exp on aarch64
On aarch64-linux, with test-case gdb.base/watchpoint-unaligned.exp I run into:
...
(gdb) watch data.u.size8twice[1]^M
Hardware watchpoint 241: data.u.size8twice[1]^M
(gdb) PASS: gdb.base/watchpoint-unaligned.exp: watch data.u.size8twice[1]
continue^M
Continuing.^M
FAIL: gdb.base/watchpoint-unaligned.exp: continue (timeout)
FAIL: gdb.base/watchpoint-unaligned.exp: size8twice write
...
This happens as follows.
We start the exec and set an 8-byte hardware watchpoint on
data.u.size8twice[1] at address 0x440048:
...
(gdb) p sizeof (data.u.size8twice[1])
$1 = 8
(gdb) p &data.u.size8twice[1]
$2 = (uint64_t *) 0x440048 <data+16>
...
We continue execution, and a 16-byte write at address 0x440040 triggers the
hardware watchpoint:
...
4101c8: a9000801 stp x1, x2, [x0]
...
When checking whether a watchpoint has triggered in
aarch64_stopped_data_address, we check against address 0x440040 (passed in
parameter addr_trap). This behaviour is documented:
...
/* ADDR_TRAP reports the first address of the memory range
accessed by the CPU, regardless of what was the memory
range watched. ... */
...
and consequently the matching logic compares against an addr_watch_aligned:
...
&& addr_trap >= addr_watch_aligned
&& addr_trap < addr_watch + len)
...
However, the comparison fails:
...
(gdb) p /x addr_watch_aligned
$3 = 0x440048
(gdb) p addr_trap >= addr_watch_aligned
$4 = false
...
Consequently, aarch64_stopped_data_address returns false, and
stopped_by_watchpoint returns false, and watchpoints_triggered returns 0,
which make infrun think it's looking at a delayed hardware
breakpoint/watchpoint trap:
...
[infrun] handle_signal_stop: stop_pc=0x4101c8
[infrun] handle_signal_stop: delayed hardware breakpoint/watchpoint trap, ignoring
...
Infrun then ignores the trap and continues, but runs into the same situation
again and again, causing a hang which then causes the test timeout.
Fix this by allowing a match 8 bytes below addr_watch_aligned. This
introduces the possibility for false positives, so we only do this for regular
"value changed" watchpoints.
An earlier version of this patch worked by aligning addr_watch_aligned to 16
instead of 8:
...
- const CORE_ADDR addr_watch_aligned = align_down (state->dr_addr_wp[i], 8);
+ const CORE_ADDR addr_watch_aligned = align_down (state->dr_addr_wp[i], 16);
...
but while that fixed the test-case, it didn't fix the problem completely, so
extend the test-case to check more scenarios.
Tested on aarch64-linux.
Tested-By: Luis Machado <luis.machado@arm.com>
Approved-By: Luis Machado <luis.machado@arm.com>
PR tdep/29423
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29423
Diffstat (limited to 'gdb/python')
0 files changed, 0 insertions, 0 deletions