On Tue, Feb 07, 2017 at 01:08:23PM -0600, Daniel Drake wrote:
> The Intel Compute Stick STCK1A8LFC and Weibu F3C platforms both
> log 2 error messages during boot:
>
> efi: requested map not found.
> esrt: ESRT header is not in the memory map.
>
> Searching the web, this seems to affect many other platforms too.
> Since these messages are logged as errors, they appear on-screen during
> the boot process even when using the "quiet" boot parameter used by
> distros.
>
> Demote the ESRT error to a warning so that it does not appear on-screen,
> and delete the error logging from efi_mem_desc_lookup; both callsites
> of that function log more specific messages upon failure.
>
> Out of curiosity I looked closer at the Weibu F3C. There is no entry in
> the UEFI-provided memory map which corresponds to the ESRT pointer, but
> hacking the code to map it anyway, the ESRT does appear to be valid with
> 2 entries.
The machine you've got does seem to be presenting a valid (if poorly
considered) table, but I don't quite think this is the right approach.
The first hunk of your patch is fine, but the test on the result of
efi_mem_desc_lookup() is more or less our check for "might reading this
table reboot the system or worse". You're demoting it to a warning
while still /treating/ it as an error, so at least it remains safe,
but the when we get to that point, they've (plausibly) given us data
that could cause horrible behavior, and that is a thing worth logging an
error about.
It would be better to /check/ if it straddles multiple contiguous
segments which both have reasonable access modes and print an error if
there are gaps. I'm still in favor of printing a warning to the log if
it straddles them and there /aren't/ gaps, because we're *going* to see
other weird bugs from any code base that decides it's stitching config
tables together from separate allocations. It's not a fundamentally
reasonable thing to do, and as a lens it shows us some code with a
really worrisome internal structure.
>
> Signed-off-by: Daniel Drake <drake@xxxxxxxxxxxx>
> ---
> drivers/firmware/efi/efi.c | 1 -
> drivers/firmware/efi/esrt.c | 2 +-
> 2 files changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 9291480..8c3ebcb 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -389,7 +389,6 @@ int __init efi_mem_desc_lookup(u64 phys_addr, efi_memory_desc_t *out_md)
> return 0;
> }
> }
> - pr_err_once("requested map not found.\n");
> return -ENOENT;
> }
>
> diff --git a/drivers/firmware/efi/esrt.c b/drivers/firmware/efi/esrt.c
> index 1491407..d81560f 100644
> --- a/drivers/firmware/efi/esrt.c
> +++ b/drivers/firmware/efi/esrt.c
> @@ -254,7 +254,7 @@ void __init efi_esrt_init(void)
>
> rc = efi_mem_desc_lookup(efi.esrt, &md);
> if (rc < 0) {
> - pr_err("ESRT header is not in the memory map.\n");
> + pr_warn("ESRT header is not in the memory map.\n");
> return;
> }
>
> --
> 2.9.3
>
--
Peter
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