Re: [PATCH 14/14] perf annotate-data: Add stack canary type

[Namhyung Kim <namhyung@xxxxxxxxxx>]

On Fri, Feb 2, 2024 at 7:21 PM Ian Rogers <irogers@xxxxxxxxxx> wrote:
>
> On Fri, Feb 2, 2024 at 2:05 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
> >
> > When the stack protector is enabled, compiler would generate code to
> > check stack overflow with a special value called 'stack carary' at
> > runtime.  On x86_64, GCC hard-codes the stack canary as %gs:40.
> >
> > While there's a definition of fixed_percpu_data in asm/processor.h,
> > it seems that the header is not included everywhere and many places
> > it cannot find the type info.  As it's in the well-known location (at
> > %gs:40), let's add a pseudo stack canary type to handle it specially.
>
> I wonder if cases like this can be handled by debug info rather than
> special cases in the tool. Special cases are fine too, but are
> potentially less portable.

Agreed, but I couldn't find anything special in DWARF.

Thanks,
Namhyung