Hi Andy,
On 31 January 2018 at 15:56, Andy Lutomirski <luto@xxxxxxxxxx> wrote:
> EFI is complicated enough that being able to view its pagetables is
> quite helpful. Rather than requiring users to fish it out of dmesg
> on an appropriately configured kernel, let users view it in debugfs
> as well.
>
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
This is more x86 code than EFI code, but from my side, this looks fine
(and even though we already have a similar facility on ARM/arm64,
there doesn't seem to be much point in attempting to reuse any of its
code for this)
Acked-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> ---
> arch/x86/mm/debug_pagetables.c | 32 ++++++++++++++++++++++++++++++++
> arch/x86/platform/efi/efi_64.c | 2 +-
> 2 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/mm/debug_pagetables.c b/arch/x86/mm/debug_pagetables.c
> index 421f2664ffa0..9861797b1fd5 100644
> --- a/arch/x86/mm/debug_pagetables.c
> +++ b/arch/x86/mm/debug_pagetables.c
> @@ -72,6 +72,31 @@ static const struct file_operations ptdump_curusr_fops = {
> };
> #endif
>
> +#if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
> +extern pgd_t *efi_pgd;
> +static struct dentry *pe_efi;
> +
> +static int ptdump_show_efi(struct seq_file *m, void *v)
> +{
> + if (efi_pgd)
> + ptdump_walk_pgd_level_debugfs(m, efi_pgd, false);
> + return 0;
> +}
> +
> +static int ptdump_open_efi(struct inode *inode, struct file *filp)
> +{
> + return single_open(filp, ptdump_show_efi, NULL);
> +}
> +
> +static const struct file_operations ptdump_efi_fops = {
> + .owner = THIS_MODULE,
> + .open = ptdump_open_efi,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> +};
> +#endif
> +
> static struct dentry *dir, *pe_knl, *pe_curknl;
>
> static int __init pt_dump_debug_init(void)
> @@ -94,8 +119,15 @@ static int __init pt_dump_debug_init(void)
> pe_curusr = debugfs_create_file("current_user", 0400,
> dir, NULL, &ptdump_curusr_fops);
> if (!pe_curusr)
> + goto err;
> +#endif
> +
> +#if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
> + pe_efi = debugfs_create_file("efi", 0400, dir, NULL, &ptdump_efi_fops);
> + if (!pe_efi)
> goto err;
> #endif
> +
> return 0;
> err:
> debugfs_remove_recursive(dir);
> diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
> index 2dd15e967c3f..a9734df2c1b7 100644
> --- a/arch/x86/platform/efi/efi_64.c
> +++ b/arch/x86/platform/efi/efi_64.c
> @@ -191,7 +191,7 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
> early_code_mapping_set_exec(0);
> }
>
> -static pgd_t *efi_pgd;
> +pgd_t *efi_pgd;
>
> /*
> * We need our own copy of the higher levels of the page tables
> --
> 2.14.3
>
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