Re: [PATCH][gdb] Fix warning in foreach_arch selftests

Tom de Vries via Gdb-patches
2022-06-04T07:24:19Z

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On 6/2/22 20:35, Tom de Vries wrote:
> Subject:
> Re: [PATCH][gdb] Fix warning in foreach_arch selftests
> From:
> Tom de Vries <tdevries@suse.de>
> Date:
> 6/2/22, 20:35
>
> To:
> Simon Marchi <simark@simark.ca>, Pedro Alves <pedro@palves.net>,
> gdb-patches@sourceware.org
>
>
> On 6/2/22 19:44, Simon Marchi wrote:
>> On 6/2/22 11:44, Tom de Vries via Gdb-patches wrote:
>>> On 6/1/22 21:08, Simon Marchi wrote:
>>>> Hi Tom,
>>>>
>>>> This introduces some failures for me:
>>>>
>>>> Running selftest print_one_insn::A6.^M
>>>> Self test failed: Cannot access memory at address 0x0^M
>>>
>>> Hi Simon,
>>>
>>> sorry for not catching this, I forgot to test with
>>> --enable-targets=all, I'll try to fix the default in my build scripts.
>>>
>>> I've done a new version of the existing patch (so it applies once the
>>> old one is reverted).
>>>
>>> Mainly because I realized that there's an easier way to handle the
>>> osabi none setting:
>>> ...
>>> @@ -68,6 +68,7 @@ foreach_arch_test_generator (const std::string &name,
>>>             {
>>>               struct gdbarch_info info;
>>>               info.bfd_arch_info = bfd_scan_arch (arch);
>>> +            info.osabi = GDB_OSABI_NONE;
>>>               struct gdbarch *gdbarch = gdbarch_find_by_info (info);
>>>               SELF_CHECK (gdbarch != NULL);
>>>               function (gdbarch);
>>> ...
>>>
>>> Currently regression testing, but at least fixes the ARC regression.
>>
>> It fixes the gdb.gdb/unittest.exp failure, but introduces:
>>
>> FAIL: gdb.arch/amd64-osabi.exp: arch=i386:x86-64: print sizeof (void*)
>> FAIL: gdb.arch/amd64-osabi.exp: arch=i386:x86-64: print sizeof (long
>> double)
>> FAIL: gdb.arch/amd64-osabi.exp: arch=i386:x64-32: print sizeof (long
>> double)
>
> Ack, I also encountered that during testing, that was a thinko in the
> refactoring of gdbarch_init_osabi, now fixed and fully tested.
>

I've committed this version.

I ended up doing this slightly different:
...
const char *arch = gdbarch_bfd_arch_info (gdbarch)->printable_name;
...
struct gdbarch_info info;
info.bfd_arch_info = bfd_scan_arch (arch);
info.osabi = it;
...
and used instead:
...
struct gdbarch_info info;

info.bfd_arch_info = gdbarch_bfd_arch_info (gdbarch);

...
info.osabi = it;
...

Thanks,
- Tom

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[gdb] Fix warning in foreach_arch selftests

When running the selftests, I run into:
...
$ gdb -q -batch -ex "maint selftest"
...
Running selftest execute_cfa_program::aarch64:ilp32.
warning: A handler for the OS ABI "GNU/Linux" is not built into this
configuration of GDB. Attempting to continue with the default aarch64:ilp32
settings.
...
and likewise for execute_cfa_program::i8086 and
execute_cfa_program::ia64-elf32.

The warning can easily be reproduced outside the selftests by doing:
...
$ gdb -q -batch -ex "set arch aarch64:ilp32"
...
and can be prevented by first doing "set osabi none".

Fix the warning by setting osabi to none while doing selftests that iterate
over all architectures.

This causes a regression in the print_one_insn selftests for the ARC
architecture.

The problem is pre-existing, and can be demonstrated (already without this
patch) using:
...
$ gdb -q -batch -ex "set osabi none" -ex "maint selftest print_one_insn::A6"
Running selftest print_one_insn::A6.
Self test failed: Cannot access memory at address 0x0
Ran 1 unit tests, 1 failed
$
...

For ARC, we use the generic case in print_one_insn_test, containing this code:
...
int kind = gdbarch_breakpoint_kind_from_pc (gdbarch, &pc);
...
insn = gdbarch_sw_breakpoint_from_kind (gdbarch, kind, &bplen);
...

The problem is that with osabi linux we trigger:
...
static int
arc_linux_breakpoint_kind_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr)
{
return trap_size;
}
...
but with osabi none:
...
arc_breakpoint_kind_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr)
{
size_t length_with_limm = gdb_insn_length (gdbarch, *pcptr);
...
which needs access to memory, and will consequently fail.

Fix this in print_one_insn_test, in the default case, by iterating over
supported osabi's to makes sure we trigger arc_linux_breakpoint_kind_from_pc
which will give us a usable instruction to disassemble.

Tested on x86_64-linux.

---
gdb/disasm-selftests.c | 46 +++++++++++++++++++++++++++++++++++++++++++---
gdb/osabi.c | 35 +++++++++++++++++++++++++++++------
gdb/osabi.h | 3 +++
gdb/selftest-arch.c | 1 +
4 files changed, 76 insertions(+), 9 deletions(-)

diff --git a/gdb/disasm-selftests.c b/gdb/disasm-selftests.c
index 928d26f7018..7daa0138f6f 100644
--- a/gdb/disasm-selftests.c
+++ b/gdb/disasm-selftests.c
@@ -101,12 +101,52 @@ print_one_insn_test (struct gdbarch *gdbarch)
{
/* Test disassemble breakpoint instruction. */
CORE_ADDR pc = 0;
- int kind = gdbarch_breakpoint_kind_from_pc (gdbarch, &pc);
+ int kind;
int bplen;

- insn = gdbarch_sw_breakpoint_from_kind (gdbarch, kind, &bplen);
- len = bplen;
+ struct gdbarch_info info;
+ info.bfd_arch_info = gdbarch_bfd_arch_info (gdbarch);
+
+ enum gdb_osabi it;
+ bool found = false;
+ for (it = GDB_OSABI_UNKNOWN; it != GDB_OSABI_INVALID;
+ it = static_cast<enum gdb_osabi>(static_cast<int>(it) + 1))
+ {
+ if (it == GDB_OSABI_UNKNOWN)
+ continue;
+
+ info.osabi = it;
+
+ if (it != GDB_OSABI_NONE)
+ {
+ if (!has_gdb_osabi_handler (info))
+ /* Unsupported. Skip to prevent warnings like:
+ A handler for the OS ABI <x> is not built into this
+ configuration of GDB. Attempting to continue with the
+ default <y> settings. */
+ continue;
+ }
+
+ gdbarch = gdbarch_find_by_info (info);
+ SELF_CHECK (gdbarch != NULL);
+
+ try
+ {
+ kind = gdbarch_breakpoint_kind_from_pc (gdbarch, &pc);
+ insn = gdbarch_sw_breakpoint_from_kind (gdbarch, kind, &bplen);
+ }
+ catch (...)
+ {
+ continue;
+ }
+ found = true;
+ break;
+ }
+
+ /* Assert that we have found an instruction to disassemble. */
+ SELF_CHECK (found);

+ len = bplen;
break;
}
}
diff --git a/gdb/osabi.c b/gdb/osabi.c
index bbd7635532f..f1b7f227b87 100644
--- a/gdb/osabi.c
+++ b/gdb/osabi.c
@@ -332,9 +332,10 @@ can_run_code_for (const struct bfd_arch_info *a, const struct bfd_arch_info *b)
return (a == b || a->compatible (a, b) == a);
}

+/* Return OS ABI handler for INFO. */

-void
-gdbarch_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
+static struct gdb_osabi_handler *
+gdbarch_osabi_handler (struct gdbarch_info info)
{
struct gdb_osabi_handler *handler;

@@ -367,10 +368,32 @@ gdbarch_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
ISA"). BFD doesn't normally consider 32-bit and 64-bit
"compatible" so it doesn't succeed. */
if (can_run_code_for (info.bfd_arch_info, handler->arch_info))
- {
- (*handler->init_osabi) (info, gdbarch);
- return;
- }
+ return handler;
+ }
+
+ return nullptr;
+}
+
+/* See osabi.h. */
+
+bool
+has_gdb_osabi_handler (struct gdbarch_info info)
+{
+ return gdbarch_osabi_handler (info) != nullptr;
+}
+
+void
+gdbarch_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+ struct gdb_osabi_handler *handler;
+
+ gdb_assert (info.osabi != GDB_OSABI_UNKNOWN);
+ handler = gdbarch_osabi_handler (info);
+
+ if (handler != nullptr)
+ {
+ (*handler->init_osabi) (info, gdbarch);
+ return;
}

if (info.osabi == GDB_OSABI_NONE)
diff --git a/gdb/osabi.h b/gdb/osabi.h
index be016732cbc..478a418aac2 100644
--- a/gdb/osabi.h
+++ b/gdb/osabi.h
@@ -74,6 +74,9 @@ enum gdb_osabi gdbarch_lookup_osabi (bfd *);
string. */
enum gdb_osabi osabi_from_tdesc_string (const char *text);

+/* Return true if there's an OS ABI handler for INFO. */
+bool has_gdb_osabi_handler (struct gdbarch_info info);
+
/* Initialize the gdbarch for the specified OS ABI variant. */
void gdbarch_init_osabi (struct gdbarch_info, struct gdbarch *);

diff --git a/gdb/selftest-arch.c b/gdb/selftest-arch.c
index f434da718d5..1fe0b2d59b4 100644
--- a/gdb/selftest-arch.c
+++ b/gdb/selftest-arch.c
@@ -68,6 +68,7 @@ foreach_arch_test_generator (const std::string &name,
{
struct gdbarch_info info;
info.bfd_arch_info = bfd_scan_arch (arch);
+ info.osabi = GDB_OSABI_NONE;