[Crash-utility] Re: [PATCH] gdb: set req->typecode when type resolvation success
Hi lianbo,
On Tue, Nov 11, 2025 at 4:14 PM lijiang <lijiang(a)redhat.com> wrote:
On Wed, Nov 5, 2025 at 5:42 PM <devel-request(a)lists.crash-utility.osci.io> wrote:
>
> Date: Tue, 4 Nov 2025 12:44:38 +1300
> From: Tao Liu <ltao(a)redhat.com>
> Subject: [Crash-utility] [PATCH] gdb: set req->typecode when type
> resolvation success
> To: devel(a)lists.crash-utility.osci.io
> Cc: Tao Liu <ltao(a)redhat.com>
> Message-ID: <20251103234438.58969-1-ltao(a)redhat.com>
> Content-Type: text/plain; charset="US-ASCII"; x-default=true
>
> In gdb_get_datatype(), the req->typecode is set as TYPE_CODE_UNDEF, and
> it won't be set to other value in OP_TYPE case. If the type doesn't exist,
> it will bail out in parse_expression() by exception catch of gdb_command_funnel(),
> and req->typecode stays TYPE_CODE_UNDEF, which is expected. But if the type is
> exist, it will be resolved by drillDownType(), so req->typecode shouldn't be
> TYPE_CODE_UNDEF anymore, otherwise upper functions will regard this as a type
> resolvation failure.
Do you know what type it is here? In gdb 16.2, the type code has been extended(see:
gdb-16.2/gdb/type-codes.def).
Sorry I didn't get your point. The drillDownType() will resolve the
types, no matter it is a TYPE_CODE_PTR/INT/STRUCT etc. So the
req->typecode shouldn't be left as TYPE_CODE_UNDEF. This bug is found
for testing "sizeof(struct task_struct)" in eppic script. So
drillDownType() is responsible for resolving task_struct and it is
TYPE_CODE_STRUCT, this is included in gdb-16.2/gdb/type-codes.def. I
don't know if it answers your question.
Thanks,
Tao Liu
Thanks
Lianbo
>
>
> This issue only affects eppic extensions because currently the only user
> of req->tcb is eppic.
>
> Signed-off-by: Tao Liu <ltao(a)redhat.com>
> ---
> gdb-16.2.patch | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/gdb-16.2.patch b/gdb-16.2.patch
> index 6767bf7..78cf605 100644
> --- a/gdb-16.2.patch
> +++ b/gdb-16.2.patch
> @@ -2000,3 +2000,13 @@ exit 0
> /* This may be a static executable. Look for the symbol
> conventionally named _r_debug, as a last resort. */
> bound_minimal_symbol msymbol
> +--- gdb-16.2/gdb/symtab.c.orig
> ++++ gdb-16.2/gdb/symtab.c
> +@@ -7726,6 +7726,7 @@
> + type = expr->evaluate_type()->type();
> +
> + if (req->tcb) {
> ++ req->typecode = TYPE_CODE(type);
> + drillDownType(req, type);
> + } else {
> + req->typecode = TYPE_CODE(type);
> --
> 2.47.0