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From: Hans de Goede <hdegoede@redhat.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	"Luis R . Rodriguez" <mcgrof@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
	Peter Jones <pjones@redhat.com>, Dave Olsthoorn <dave@bewaar.me>,
	Will Deacon <will.deacon@arm.com>,
	Andy Lutomirski <luto@kernel.org>,
	Matt Fleming <matt@codeblueprint.co.uk>,
	David Howells <dhowells@redhat.com>,
	Mimi Zohar <zohar@linux.vnet.ibm.com>,
	Josh Triplett <josh@joshtriplett.org>,
	dmitry.torokhov@gmail.com, mfuzzey@parkeon.com,
	Kalle Valo <kvalo@codeaurora.org>,
	Arend Van Spriel <arend.vanspriel@broadcom.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	nbroeking@me.com, bjorn.andersson@linaro.org,
	Torsten Duwe <duwe@suse.de>, Kees Cook <keescook@chromium.org>,
	x86@kernel.org, linux-efi@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v4 1/5] efi: Export boot-services code and data as debugfs-blobs
Date: Thu, 26 Apr 2018 14:06:33 +0200	[thread overview]
Message-ID: <20180426120637.21258-2-hdegoede@redhat.com> (raw)
In-Reply-To: <20180426120637.21258-1-hdegoede@redhat.com>

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>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
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);
 
 	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;
+
 	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 232f4915223b..498a720a7684 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -18,6 +18,7 @@
 #include <linux/kobject.h>
 #include <linux/module.h>
 #include <linux/init.h>
+#include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/efi.h>
 #include <linux/of.h>
@@ -325,6 +326,55 @@ static __init int efivar_ssdt_load(void)
 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;
+		}
+
+		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++;
+		if (i == EFI_DEBUGFS_MAX_BLOBS)
+			break;
+	}
+}
+#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
@@ -369,6 +419,9 @@ static int __init efisubsys_init(void)
 		goto err_remove_group;
 	}
 
+	if (efi_enabled(EFI_DBG) && efi_enabled(EFI_BOOT_SERVICES))
+		efi_debugfs_init();
+
 	return 0;
 
 err_remove_group:
diff --git a/include/linux/efi.h b/include/linux/efi.h
index f1b7d68ac460..396bf18ace5c 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1144,6 +1144,7 @@ extern int __init efi_setup_pcdp_console(char *);
 #define EFI_DBG			8	/* Print additional debug info at runtime */
 #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_BOOT_SERVICES	11	/* Are EFI boot-services memory segments available? */
 
 #ifdef CONFIG_EFI
 /*
-- 
2.17.0

  reply	other threads:[~2018-04-26 12:06 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-26 12:06 [PATCH v4 0/5] efi/firmware/platform-x86: Add EFI embedded fw support Hans de Goede
2018-04-26 12:06 ` Hans de Goede [this message]
2018-04-26 16:51   ` [PATCH v4 1/5] efi: Export boot-services code and data as debugfs-blobs Ard Biesheuvel
2018-04-26 21:02     ` Hans de Goede
2018-04-26 21:35       ` Ard Biesheuvel
2018-04-27  8:13         ` Hans de Goede
2018-04-27  8:24           ` Ard Biesheuvel
2018-04-26 12:06 ` [PATCH v4 2/5] efi: Add embedded peripheral firmware support Hans de Goede
2018-04-26 12:06 ` [PATCH v4 3/5] platform/x86: Rename silead_dmi to touchscreen_dmi Hans de Goede
2018-04-26 12:06 ` [PATCH v4 4/5] platform/x86: touchscreen_dmi: Add EFI embedded firmware info support Hans de Goede
2018-04-26 12:06 ` [PATCH v4 5/5] platform/x86: touchscreen_dmi: Add info for the Chuwi Vi8 Plus tablet Hans de Goede
2018-04-26 16:53 ` [PATCH v4 0/5] efi/firmware/platform-x86: Add EFI embedded fw support Ard Biesheuvel

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