Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755023Ab1COG72 (ORCPT ); Tue, 15 Mar 2011 02:59:28 -0400 Received: from smtp-out.google.com ([74.125.121.67]:21276 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754791Ab1COG7W (ORCPT ); Tue, 15 Mar 2011 02:59:22 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=subject:to:from:cc:date:message-id:in-reply-to:references: user-agent:mime-version:content-type: content-transfer-encoding:x-system-of-record; b=Sbgs2IB78gvYAd5rNkEMPEWwzm8UdAVV0mt+fa8MEv1bfW/T8If6KZbAwijxgiMut wRQNgaZbKaWerFG/a6SwA== Subject: [PATCH v3 5/5] driver: Google Memory Console To: Greg KH , Matt Domsch , Alan Cox From: Mike Waychison Cc: Duncan Laurie , Aaron Durbin , x86@kernel.org, linux-kernel@vger.kernel.org, Tim Hockin , San Mehat Date: Mon, 14 Mar 2011 23:59:06 -0700 Message-ID: <20110315065905.12047.71103.stgit@mike.mtv.corp.google.com> In-Reply-To: <20110315065839.12047.70666.stgit@mike.mtv.corp.google.com> References: <20110315065839.12047.70666.stgit@mike.mtv.corp.google.com> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7382 Lines: 252 This patch introduces the 'memconsole' driver. Our firmware gives us access to an in-memory log of the firmware's output. This gives us visibility in a data-center of headless machines as to what the firmware is doing. The memory console is found by the driver by finding a header block in the EBDA. The buffer is then copied out, and is exported to userland in the file /sys/firmware/log. Signed-off-by: San Mehat Signed-off-by: Mike Waychison --- Changelog: v3: - Use dmi_check_system to only load when on a Google board. - Use MODULE_DEVICE_TABLE to export matching DMI strings. - Default to 'n' in the Kconfig. - Fixed Kconfig description to reflect that this change no longer messes with the dmesg. v2: - Removed bits that had this driver muck with the kernel's ring dmesg buffer (log_buf). - Introduced the log as /sys/firmware/log, a binary file that isn't interpreted by the kernel. - Don't use C99 fixed width types; use kernel fixed width types. - Added file to Documentation/ABI for /sys/firmware/log --- Documentation/ABI/testing/sysfs-firmware-log | 7 + drivers/firmware/google/Kconfig | 8 + drivers/firmware/google/Makefile | 1 drivers/firmware/google/memconsole.c | 166 ++++++++++++++++++++++++++ 4 files changed, 182 insertions(+), 0 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-firmware-log create mode 100644 drivers/firmware/google/memconsole.c diff --git a/Documentation/ABI/testing/sysfs-firmware-log b/Documentation/ABI/testing/sysfs-firmware-log new file mode 100644 index 0000000..9b58e7c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-firmware-log @@ -0,0 +1,7 @@ +What: /sys/firmware/log +Date: February 2011 +Contact: Mike Waychison +Description: + The /sys/firmware/log is a binary file that represents a + read-only copy of the firmware's log if one is + available. diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig index 8190103..87096b6 100644 --- a/drivers/firmware/google/Kconfig +++ b/drivers/firmware/google/Kconfig @@ -20,4 +20,12 @@ config GOOGLE_SMI clearing the EFI event log and reading and writing NVRAM variables. +config GOOGLE_MEMCONSOLE + tristate "Firmware Memory Console" + depends on DMI + help + This option enables the kernel to search for a firmware log in + the EBDA on Google servers. If found, this log is exported to + userland in the file /sys/firmware/log. + endmenu diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile index fb127d7..54a294e 100644 --- a/drivers/firmware/google/Makefile +++ b/drivers/firmware/google/Makefile @@ -1,2 +1,3 @@ obj-$(CONFIG_GOOGLE_SMI) += gsmi.o +obj-$(CONFIG_GOOGLE_MEMCONSOLE) += memconsole.o diff --git a/drivers/firmware/google/memconsole.c b/drivers/firmware/google/memconsole.c new file mode 100644 index 0000000..2a90ba6 --- /dev/null +++ b/drivers/firmware/google/memconsole.c @@ -0,0 +1,166 @@ +/* + * memconsole.c + * + * Infrastructure for importing the BIOS memory based console + * into the kernel log ringbuffer. + * + * Copyright 2010 Google Inc. All rights reserved. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define BIOS_MEMCONSOLE_V1_MAGIC 0xDEADBABE +#define BIOS_MEMCONSOLE_V2_MAGIC (('M')|('C'<<8)|('O'<<16)|('N'<<24)) + +struct biosmemcon_ebda { + u32 signature; + union { + struct { + u8 enabled; + u32 buffer_addr; + u16 start; + u16 end; + u16 num_chars; + u8 wrapped; + } __packed v1; + struct { + u32 buffer_addr; + /* Misdocumented as number of pages! */ + u16 num_bytes; + u16 start; + u16 end; + } __packed v2; + }; +} __packed; + +static char *memconsole_baseaddr; +static size_t memconsole_length; + +static ssize_t memconsole_read(struct file *filp, struct kobject *kobp, + struct bin_attribute *bin_attr, char *buf, + loff_t pos, size_t count) +{ + return memory_read_from_buffer(buf, count, &pos, memconsole_baseaddr, + memconsole_length); +} + +static struct bin_attribute memconsole_bin_attr = { + .attr = {.name = "log", .mode = 0444}, + .read = memconsole_read, +}; + + +static void found_v1_header(struct biosmemcon_ebda *hdr) +{ + printk(KERN_INFO "BIOS console v1 EBDA structure found at %p\n", hdr); + printk(KERN_INFO "BIOS console buffer at 0x%.8x, " + "start = %d, end = %d, num = %d\n", + hdr->v1.buffer_addr, hdr->v1.start, + hdr->v1.end, hdr->v1.num_chars); + + memconsole_length = hdr->v1.num_chars; + memconsole_baseaddr = phys_to_virt(hdr->v1.buffer_addr); +} + +static void found_v2_header(struct biosmemcon_ebda *hdr) +{ + printk(KERN_INFO "BIOS console v2 EBDA structure found at %p\n", hdr); + printk(KERN_INFO "BIOS console buffer at 0x%.8x, " + "start = %d, end = %d, num_bytes = %d\n", + hdr->v2.buffer_addr, hdr->v2.start, + hdr->v2.end, hdr->v2.num_bytes); + + memconsole_length = hdr->v2.end - hdr->v2.start; + memconsole_baseaddr = phys_to_virt(hdr->v2.buffer_addr + + hdr->v2.start); +} + +/* + * Search through the EBDA for the BIOS Memory Console, and + * set the global variables to point to it. Return true if found. + */ +static bool found_memconsole(void) +{ + unsigned int address; + size_t length, cur; + + address = get_bios_ebda(); + if (!address) { + printk(KERN_INFO "BIOS EBDA non-existent.\n"); + return false; + } + + /* EBDA length is byte 0 of EBDA (in KB) */ + length = *(u8 *)phys_to_virt(address); + length <<= 10; /* convert to bytes */ + + /* + * Search through EBDA for BIOS memory console structure + * note: signature is not necessarily dword-aligned + */ + for (cur = 0; cur < length; cur++) { + struct biosmemcon_ebda *hdr = phys_to_virt(address + cur); + + /* memconsole v1 */ + if (hdr->signature == BIOS_MEMCONSOLE_V1_MAGIC) { + found_v1_header(hdr); + return true; + } + + /* memconsole v2 */ + if (hdr->signature == BIOS_MEMCONSOLE_V2_MAGIC) { + found_v2_header(hdr); + return true; + } + } + + printk(KERN_INFO "BIOS console EBDA structure not found!\n"); + return false; +} + +static struct dmi_system_id memconsole_dmi_table[] __initdata = { + { + .ident = "Google Board", + .matches = { + DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."), + }, + }, + {} +}; +MODULE_DEVICE_TABLE(dmi, memconsole_dmi_table); + +static int __init memconsole_init(void) +{ + int ret; + + if (!dmi_check_system(memconsole_dmi_table)) + return -ENODEV; + + if (!found_memconsole()) + return -ENODEV; + + memconsole_bin_attr.size = memconsole_length; + + ret = sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr); + + return ret; +} + +static void __exit memconsole_exit(void) +{ + sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr); +} + +module_init(memconsole_init); +module_exit(memconsole_exit); + +MODULE_AUTHOR("Google, Inc."); +MODULE_LICENSE("GPL"); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/