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From:   Kairui Song <kasong@redhat.com>
Date:   Wed, 9 Jan 2019 14:56:14 +0800
Message-ID: <CACPcB9eB19F+FDBOypwKK1co+nA-GCpW2ophcwva9AL5Qq+jhA@mail.gmail.com>
Subject: Re: [PATCH 1/2] x86, kexec_file_load: Don't setup EFI info if EFI
 runtime is not enabled
To:     linux-kernel@vger.kernel.org
Cc:     tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
        x86@kernel.org, Dave Young <dyoung@redhat.com>,
        akpm@linux-foundation.org, kexec@lists.infradead.org,
        Baoquan He <bhe@redhat.com>
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CCing more people

On Wed, Jan 9, 2019 at 2:45 PM Kairui Song <kasong@redhat.com> wrote:
>
> Currenly with "efi=noruntime" in kernel command line, calling
> kexec_file_load will raise below problem:
>
> [   97.967067] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
> [   97.967894] #PF error: [normal kernel read fault]
> ...
> [   97.980456] Call Trace:
> [   97.980724]  efi_runtime_map_copy+0x28/0x30
> [   97.981267]  bzImage64_load+0x688/0x872
> [   97.981794]  arch_kexec_kernel_image_load+0x6d/0x70
> [   97.982441]  kimage_file_alloc_init+0x13e/0x220
> [   97.983035]  __x64_sys_kexec_file_load+0x144/0x290
> [   97.983586]  do_syscall_64+0x55/0x1a0
> [   97.983962]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> When efi runtime is not enabled, efi memmap is not mapped, so just skip
> EFI info setup.
>
> Suggested-by: Dave Young <dyoung@redhat.com>
> Signed-off-by: Kairui Song <kasong@redhat.com>
> ---
>  arch/x86/kernel/kexec-bzimage64.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> index 0d5efa34f359..53917a3ebf94 100644
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -167,6 +167,9 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
>         struct efi_info *current_ei = &boot_params.efi_info;
>         struct efi_info *ei = &params->efi_info;
>
> +       if (!efi_enabled(EFI_RUNTIME_SERVICES))
> +               return 0;
> +
>         if (!current_ei->efi_memmap_size)
>                 return 0;
>
> --
> 2.20.1
>


-- 
Best Regards,
Kairui Song