linux-kernel - Re: [PATCH] remoteproc: elf_loader: Update resource table name check

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Date:   Fri, 9 Dec 2022 15:52:42 -0500
From:   Stephen Boyd <swboyd@...omium.org>
To:     Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>,
        agross@...nel.org, andersson@...nel.org, bgoswami@...cinc.com,
        broonie@...nel.org, devicetree@...r.kernel.org,
        judyhsiao@...omium.org, krzysztof.kozlowski@...aro.org,
        lgirdwood@...il.com, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        mathieu.poirier@...aro.org, perex@...ex.cz, quic_plai@...cinc.com,
        quic_rohkumar@...cinc.com, robh+dt@...nel.org,
        srinivas.kandagatla@...aro.org, tiwai@...e.com
Subject: Re: [PATCH] remoteproc: elf_loader: Update resource table name check

Quoting Srinivasa Rao Mandadapu (2022-12-08 05:40:54)
>
> On 12/7/2022 7:25 AM, Stephen Boyd wrote:
> Thanks for Your Time Stephen!!!
> > Quoting Srinivasa Rao Mandadapu (2022-12-01 04:20:48)
> >> Update resource table name check with sub string search instead of
> >> complete string search.
> >> In general Qualcomm binary contains, section header name
> >> (e.g. .resource_table), amended with extra string to differentiate
> >> with other sections.
> >> So far Android adsp binaries are being authenticated using TZ,
> >> hence this mismatch hasn't created any problem.
> >> In recent developments, ADSP binary is being used in Chrome based
> >> platforms, which doesn't have TZ path, hence resource table is
> >> required for memory sandboxing.
> >>
> > Does this need a Fixes tag?
> I don't think so. I feel It's kind of enhancement.
> >
> >> Signed-off-by: Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>
> >> ---
> >>   drivers/remoteproc/remoteproc_elf_loader.c | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/remoteproc/remoteproc_elf_loader.c b/drivers/remoteproc/remoteproc_elf_loader.c
> >> index 5a412d7..0feb120 100644
> >> --- a/drivers/remoteproc/remoteproc_elf_loader.c
> >> +++ b/drivers/remoteproc/remoteproc_elf_loader.c
> >> @@ -272,7 +272,7 @@ find_table(struct device *dev, const struct firmware *fw)
> >>                  u64 offset = elf_shdr_get_sh_offset(class, shdr);
> >>                  u32 name = elf_shdr_get_sh_name(class, shdr);
> >>
> >> -               if (strcmp(name_table + name, ".resource_table"))
> >> +               if (!strstr(name_table + name, ".resource_table"))
> > Was the strcmp not working before because the 'name_table' has something
> > else in it? It really looks like your elf file is malformed.
>
> Actually, DSP binary is prepared by combining different elfs. So Section
> header names are appended with
>
> something else to distinguish same section name of different elfs, by
> using some Qualcomm specific QURT scripts.
> Hence final binary contains resource_table name appended with module
> specific name.
>
> So this patch is required to handle such modified name.
>

Can you clarify how the section header name looks? Probably you can
objdump the section here and provide that information to help us
understand.

I think remoteproc_elf_loader.c assumes the ELF file is properly formed.
There should be a section named '.resource_table', so the strcmp will
find it by looking at the section header names.