From 0e72a6a3cfc3a32273f5e99bfaa4407f4917d343 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Wed, 15 Jan 2020 17:35:45 +0100 Subject: [PATCH] efi: Export boot-services code and data as debugfs-blobs 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 Acked-by: Ard Biesheuvel Signed-off-by: Hans de Goede Link: https://lore.kernel.org/r/20200115163554.101315-2-hdegoede@redhat.com Signed-off-by: Ard Biesheuvel --- arch/x86/platform/efi/efi.c | 1 + arch/x86/platform/efi/quirks.c | 4 +++ drivers/firmware/efi/efi.c | 57 ++++++++++++++++++++++++++++++++++ include/linux/efi.h | 1 + 4 files changed, 63 insertions(+) diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index ae923ee8e2b4..8391d3c658b4 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -243,6 +243,7 @@ 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_PRESERVE_BS_REGIONS, &efi.flags); return 0; } diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c index 88d32c06cffa..bada1037b711 100644 --- a/arch/x86/platform/efi/quirks.c +++ b/arch/x86/platform/efi/quirks.c @@ -410,6 +410,10 @@ 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; + for_each_efi_memory_desc(md) { unsigned long long start = md->phys_addr; unsigned long long size = md->num_pages << EFI_PAGE_SHIFT; diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 621220ab3d0e..201a6799671d 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -325,6 +326,59 @@ free_entry: static inline int efivar_ssdt_load(void) { return 0; } #endif +#ifdef CONFIG_DEBUG_FS + +#define EFI_DEBUGFS_MAX_BLOBS 32 + +static struct debugfs_blob_wrapper debugfs_blob[EFI_DEBUGFS_MAX_BLOBS]; + +static void __init efi_debugfs_init(void) +{ + struct dentry *efi_debugfs; + efi_memory_desc_t *md; + char name[32]; + int type_count[EFI_BOOT_SERVICES_DATA + 1] = {}; + int i = 0; + + efi_debugfs = debugfs_create_dir("efi", NULL); + if (IS_ERR_OR_NULL(efi_debugfs)) + return; + + for_each_efi_memory_desc(md) { + switch (md->type) { + case EFI_BOOT_SERVICES_CODE: + snprintf(name, sizeof(name), "boot_services_code%d", + type_count[md->type]++); + break; + case EFI_BOOT_SERVICES_DATA: + snprintf(name, sizeof(name), "boot_services_data%d", + type_count[md->type]++); + break; + default: + continue; + } + + if (i >= EFI_DEBUGFS_MAX_BLOBS) { + pr_warn("More then %d EFI boot service segments, only showing first %d in debugfs\n", + EFI_DEBUGFS_MAX_BLOBS, EFI_DEBUGFS_MAX_BLOBS); + break; + } + + debugfs_blob[i].size = md->num_pages << EFI_PAGE_SHIFT; + debugfs_blob[i].data = memremap(md->phys_addr, + debugfs_blob[i].size, + MEMREMAP_WB); + if (!debugfs_blob[i].data) + continue; + + debugfs_create_blob(name, 0400, efi_debugfs, &debugfs_blob[i]); + i++; + } +} +#else +static inline void efi_debugfs_init(void) {} +#endif + /* * We register the efi subsystem with the firmware subsystem and the * efivars subsystem with the efi subsystem, if the system was booted with @@ -381,6 +435,9 @@ static int __init efisubsys_init(void) goto err_remove_group; } + if (efi_enabled(EFI_DBG) && efi_enabled(EFI_PRESERVE_BS_REGIONS)) + efi_debugfs_init(); + return 0; err_remove_group: diff --git a/include/linux/efi.h b/include/linux/efi.h index 7efd7072cca5..a6e1a2d8511e 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1124,6 +1124,7 @@ extern int __init efi_setup_pcdp_console(char *); #define EFI_NX_PE_DATA 9 /* Can runtime data regions be mapped non-executable? */ #define EFI_MEM_ATTR 10 /* Did firmware publish an EFI_MEMORY_ATTRIBUTES table? */ #define EFI_MEM_NO_SOFT_RESERVE 11 /* Is the kernel configured to ignore soft reservations? */ +#define EFI_PRESERVE_BS_REGIONS 12 /* Are EFI boot-services memory segments available? */ #ifdef CONFIG_EFI /*