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 <gregkh@linuxfoundation.org> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20200115163554.101315-2-hdegoede@redhat.com Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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@ -243,6 +243,7 @@ int __init efi_memblock_x86_reserve_range(void)
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efi.memmap.desc_version);
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memblock_reserve(pmap, efi.memmap.nr_map * efi.memmap.desc_size);
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set_bit(EFI_PRESERVE_BS_REGIONS, &efi.flags);
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return 0;
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}
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@ -410,6 +410,10 @@ void __init efi_free_boot_services(void)
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int num_entries = 0;
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void *new, *new_md;
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/* Keep all regions for /sys/kernel/debug/efi */
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if (efi_enabled(EFI_DBG))
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return;
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for_each_efi_memory_desc(md) {
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unsigned long long start = md->phys_addr;
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unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
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@ -17,6 +17,7 @@
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/debugfs.h>
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#include <linux/device.h>
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#include <linux/efi.h>
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#include <linux/of.h>
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@ -325,6 +326,59 @@ free_entry:
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static inline int efivar_ssdt_load(void) { return 0; }
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#endif
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#ifdef CONFIG_DEBUG_FS
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#define EFI_DEBUGFS_MAX_BLOBS 32
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static struct debugfs_blob_wrapper debugfs_blob[EFI_DEBUGFS_MAX_BLOBS];
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static void __init efi_debugfs_init(void)
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{
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struct dentry *efi_debugfs;
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efi_memory_desc_t *md;
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char name[32];
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int type_count[EFI_BOOT_SERVICES_DATA + 1] = {};
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int i = 0;
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efi_debugfs = debugfs_create_dir("efi", NULL);
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if (IS_ERR_OR_NULL(efi_debugfs))
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return;
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for_each_efi_memory_desc(md) {
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switch (md->type) {
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case EFI_BOOT_SERVICES_CODE:
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snprintf(name, sizeof(name), "boot_services_code%d",
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type_count[md->type]++);
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break;
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case EFI_BOOT_SERVICES_DATA:
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snprintf(name, sizeof(name), "boot_services_data%d",
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type_count[md->type]++);
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break;
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default:
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continue;
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}
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if (i >= EFI_DEBUGFS_MAX_BLOBS) {
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pr_warn("More then %d EFI boot service segments, only showing first %d in debugfs\n",
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EFI_DEBUGFS_MAX_BLOBS, EFI_DEBUGFS_MAX_BLOBS);
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break;
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}
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debugfs_blob[i].size = md->num_pages << EFI_PAGE_SHIFT;
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debugfs_blob[i].data = memremap(md->phys_addr,
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debugfs_blob[i].size,
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MEMREMAP_WB);
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if (!debugfs_blob[i].data)
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continue;
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debugfs_create_blob(name, 0400, efi_debugfs, &debugfs_blob[i]);
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i++;
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}
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}
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#else
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static inline void efi_debugfs_init(void) {}
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#endif
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/*
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* We register the efi subsystem with the firmware subsystem and the
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* efivars subsystem with the efi subsystem, if the system was booted with
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@ -381,6 +435,9 @@ static int __init efisubsys_init(void)
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goto err_remove_group;
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}
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if (efi_enabled(EFI_DBG) && efi_enabled(EFI_PRESERVE_BS_REGIONS))
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efi_debugfs_init();
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return 0;
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err_remove_group:
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@ -1124,6 +1124,7 @@ extern int __init efi_setup_pcdp_console(char *);
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#define EFI_NX_PE_DATA 9 /* Can runtime data regions be mapped non-executable? */
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#define EFI_MEM_ATTR 10 /* Did firmware publish an EFI_MEMORY_ATTRIBUTES table? */
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#define EFI_MEM_NO_SOFT_RESERVE 11 /* Is the kernel configured to ignore soft reservations? */
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#define EFI_PRESERVE_BS_REGIONS 12 /* Are EFI boot-services memory segments available? */
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#ifdef CONFIG_EFI
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/*
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