On Tue, Feb 6, 2024 at 3:40 PM Ian Rogers <irogers@xxxxxxxxxx> wrote: > > On Tue, Feb 6, 2024 at 3:19 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote: > > > > 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. > > 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 I'm not sure if it's the same thing. Maybe it's for variables with __thread annotation. I don't know if compilers generate a (pseudo) variable for stack canary. Thanks, Namhyung
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