Hi, On 26-04-18 18:51, Ard Biesheuvel wrote:
On 26 April 2018 at 14:06, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:Sometimes it is useful to be able to dump the efi boot-services code and data. This commit adds these as debugfs-blobs to /sys/kernel/debug/efi, but only if efi=debug is passed on the kernel-commandline as this requires not freeing those memory-regions, which costs 20+ MB of RAM. Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- Changes in v4: -Add new EFI_BOOT_SERVICES flag and use it to determine if the boot-services memory segments are available (and thus if it makes sense to register the debugfs bits for them) Changes in v2: -Do not call pr_err on debugfs call failures --- arch/x86/platform/efi/efi.c | 1 + arch/x86/platform/efi/quirks.c | 4 +++ drivers/firmware/efi/efi.c | 53 ++++++++++++++++++++++++++++++++++ include/linux/efi.h | 1 + 4 files changed, 59 insertions(+) diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 9061babfbc83..568b7ee3d323 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -208,6 +208,7 @@ int __init efi_memblock_x86_reserve_range(void) efi.memmap.desc_version); memblock_reserve(pmap, efi.memmap.nr_map * efi.memmap.desc_size); + set_bit(EFI_BOOT_SERVICES, &efi.flags);I think it would be better if the flag conveys whether boot services regions are being preserved, because they will always exist when EFI_BOOT is set. The name should then reflect that as well, e.g., EFI_PRESERVE_BS_REGIONS.
Ok, I will rename the flag to EFI_PRESERVE_BS_REGIONS for v5 (I'm going to wait a bit with sending out v5 to give others a change to comment on v4).
return 0; } diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c index 36c1f8b9f7e0..16bdb9e3b343 100644 --- a/arch/x86/platform/efi/quirks.c +++ b/arch/x86/platform/efi/quirks.c @@ -376,6 +376,10 @@ void __init efi_free_boot_services(void) int num_entries = 0; void *new, *new_md; + /* Keep all regions for /sys/kernel/debug/efi */ + if (efi_enabled(EFI_DBG)) + return; +Why is this only necessary when EFI_DBG is enabled? How are you ensuring that the firmware is still in memory when the subsequent patches start relying on that?
The 2nd patch in this series makes init/main.c call efi_check_for_embedded_firmwares() before efi_free_boot_services(), efi_check_for_embedded_firmwares() then walks the dmi_system_id-s "registered" (its a static list) by drivers and if their is a dmi_match searches for the firmware described by the dmi_system_id.driver_data ptr. If a firmware gets found it gets memdup-ed, so that we do not have to keep all of the boot-services code around. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
