From: Simon Marchi <simon.marchi@polymtl.ca>
To: gdb-patches@sourceware.org
Cc: Simon Marchi <simon.marchi@efficios.com>,
Lancelot SIX <lancelot.six@amd.com>
Subject: [PATCH v2 6/8] gdb/solib-svr4: don't disable probes interface if probe not found
Date: Thu, 5 Jan 2023 15:02:35 -0500 [thread overview]
Message-ID: <20230105200237.987771-7-simon.marchi@polymtl.ca> (raw)
In-Reply-To: <20230105200237.987771-1-simon.marchi@polymtl.ca>
From: Simon Marchi <simon.marchi@efficios.com>
In ROCm-GDB, we install an solib provider for the GPU code objects on
top of the svr4 provider for the host, in order to add solibs
representing the GPU code objects to the solib list containing the host
process' shared libraries. We override the target_so_ops::handle_event
function pointer with our own, in which we call svr4_so_ops.handle_event
(which contains svr4_handle_solib_event) manually. When the host
(un)loads a library, the ROCm part of handle_event is a no-op. When the
GPU (un)loads a code object, we want the host side (svr4) to be a no-op.
The problem is that when handle_event is called because of a GPU event,
svr4_handle_solib_event gets called while not stopped at an svr4
probe. It then assumes this means there's a problem with the probes
interface and disables it through the following sequence of events:
- solib_event_probe_at return nullptr
- svr4_handle_solib_event returns early
- the make_scope_exit callback calls disable_probes_interface
We could fix that by making the ROCm handle_event callback check if an
svr4 probe is that the stop address, and only call
svr4_so_ops.handle_event if so. However, it doesn't feel right to
include some svr4 implementation detail in the ROCm event handler.
Instead, this patch changes svr4_handle_solib_event to not assume it is
an error if called while not at an svr4 probe location, and therefore
not disable the probes interface. That just means moving the
make_scope_exit call below where we lookup the probe by pc.
Change-Id: Ie8ddf5beffa2e92b8ebfdd016454546252519244
Co-Authored-By: Lancelot SIX <lancelot.six@amd.com>
---
gdb/solib-svr4.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index fe009a1581d8..33577b7ddd2b 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -1977,6 +1977,16 @@ svr4_handle_solib_event (void)
if (info->probes_table == NULL)
return;
+ pc = regcache_read_pc (get_current_regcache ());
+ pa = solib_event_probe_at (info, pc);
+ if (pa == nullptr)
+ {
+ /* When some solib ops sits above us, it can respond to a solib event
+ by calling in here. This is done assuming that if the current event
+ is not an SVR4 solib event, calling here should be a no-op. */
+ return;
+ }
+
/* If anything goes wrong we revert to the original linker
interface. */
auto cleanup = make_scope_exit ([info] ()
@@ -1984,11 +1994,6 @@ svr4_handle_solib_event (void)
disable_probes_interface (info);
});
- pc = regcache_read_pc (get_current_regcache ());
- pa = solib_event_probe_at (info, pc);
- if (pa == NULL)
- return;
-
action = solib_event_probe_action (pa);
if (action == PROBES_INTERFACE_FAILED)
return;
--
2.39.0
next prev parent reply other threads:[~2023-01-05 20:12 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-05 20:02 [PATCH v2 0/8] Initial support for ROCm platform (AMD GPU) debugging Simon Marchi
2023-01-05 20:02 ` [PATCH v2 1/8] gdb: add supports_arch_info callback to gdbarch_register Simon Marchi
2023-01-05 20:02 ` [PATCH v2 2/8] gdb: make install_breakpoint return a non-owning reference Simon Marchi
2023-01-05 20:02 ` [PATCH v2 3/8] gdbsupport: add type definitions for pid, lwp and tid Simon Marchi
2023-01-05 20:02 ` [PATCH v2 4/8] gdb: add inferior_pre_detach observable Simon Marchi
2023-01-05 20:02 ` [PATCH v2 5/8] gdb: add gdbarch_up Simon Marchi
2023-01-05 20:31 ` Tom Tromey
2023-01-05 20:36 ` Simon Marchi
2023-01-05 20:41 ` Tom Tromey
2023-01-06 0:48 ` Simon Marchi
2023-01-05 20:02 ` Simon Marchi [this message]
2023-01-05 20:02 ` [PATCH v2 7/8] gdb: make gdb_printing_disassembler::stream public Simon Marchi
2023-01-05 20:02 ` [PATCH v2 8/8] gdb: initial support for ROCm platform (AMDGPU) debugging Simon Marchi
2023-01-05 20:17 ` Simon Marchi
2023-01-25 17:03 ` [PATCH v2 0/8] Initial support for ROCm platform (AMD GPU) debugging Simon Marchi
2023-02-02 15:08 ` Simon Marchi
2023-02-06 11:47 ` Tom de Vries
2023-02-06 14:01 ` Lancelot Six
2023-02-06 16:53 ` Tom de Vries
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