Messages in this thread | | | From | Ian Rogers <> | Date | Tue, 6 Feb 2024 15:40:29 -0800 | Subject | Re: [PATCH 14/14] perf annotate-data: Add stack canary type |
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On Tue, Feb 6, 2024 at 3:19 PM Namhyung Kim <namhyung@kernel.org> wrote: > > On Fri, Feb 2, 2024 at 7:21 PM Ian Rogers <irogers@google.com> wrote: > > > > On Fri, Feb 2, 2024 at 2:05 PM Namhyung Kim <namhyung@kernel.org> 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.
The fs and gs selectors are commonly used for thread local storage, so could something like DW_OP_form_tls_address be used? https://dwarfstd.org/issues/110803.1.html
Thanks, Ian
> Thanks, > Namhyung
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