Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755184AbaA1NGp (ORCPT ); Tue, 28 Jan 2014 08:06:45 -0500 Received: from mail-pb0-f44.google.com ([209.85.160.44]:54412 "EHLO mail-pb0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751569AbaA1NG2 (ORCPT ); Tue, 28 Jan 2014 08:06:28 -0500 From: Michel Lespinasse To: Mike Waychison , Andrew Morton , Greg Kroah-Hartman , LKML Cc: Matt Fleming , Tom Gundersen Subject: [PATCH 2/2] drivers-firmware: google memconsole driver fixes Date: Tue, 28 Jan 2014 05:06:22 -0800 Message-Id: <1390914382-3285-3-git-send-email-walken@google.com> X-Mailer: git-send-email 1.8.5.3 In-Reply-To: <1390914382-3285-1-git-send-email-walken@google.com> References: <1390914382-3285-1-git-send-email-walken@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The google memconsole driver is currently broken upstream, as it tries to read memory that is described as reserved in /proc/iomem, by dereferencing a pointer obtained through phys_to_virt(). This triggers a kernel fault as such regions are unmapped after early boot. The proper workaround is to use ioremap_cache() / iounmap() around such accesses. As some unrelated changes, I also converted some printks to use pr_info() and added some missing __init annotations. Tested: booted dbg build, verified I could read /sys/firmware/log Signed-off-by: Michel Lespinasse --- drivers/firmware/google/memconsole.c | 47 ++++++++++++++++++++---------------- 1 file changed, 26 insertions(+), 21 deletions(-) diff --git a/drivers/firmware/google/memconsole.c b/drivers/firmware/google/memconsole.c index 2a90ba613613..2f569aaed4c7 100644 --- a/drivers/firmware/google/memconsole.c +++ b/drivers/firmware/google/memconsole.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #define BIOS_MEMCONSOLE_V1_MAGIC 0xDEADBABE @@ -41,15 +42,25 @@ struct biosmemcon_ebda { }; } __packed; -static char *memconsole_baseaddr; +static u32 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); + char *memconsole; + ssize_t ret; + + memconsole = ioremap_cache(memconsole_baseaddr, memconsole_length); + if (!memconsole) { + pr_err("memconsole: ioremap_cache failed\n"); + return -ENOMEM; + } + ret = memory_read_from_buffer(buf, count, &pos, memconsole, + memconsole_length); + iounmap(memconsole); + return ret; } static struct bin_attribute memconsole_bin_attr = { @@ -58,43 +69,42 @@ static struct bin_attribute memconsole_bin_attr = { }; -static void found_v1_header(struct biosmemcon_ebda *hdr) +static void __init 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, " + pr_info("BIOS console v1 EBDA structure found at %p\n", hdr); + pr_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); + memconsole_baseaddr = hdr->v1.buffer_addr; } -static void found_v2_header(struct biosmemcon_ebda *hdr) +static void __init 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, " + pr_info("BIOS console v2 EBDA structure found at %p\n", hdr); + pr_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); + memconsole_baseaddr = 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) +static bool __init found_memconsole(void) { unsigned int address; size_t length, cur; address = get_bios_ebda(); if (!address) { - printk(KERN_INFO "BIOS EBDA non-existent.\n"); + pr_info("BIOS EBDA non-existent.\n"); return false; } @@ -122,7 +132,7 @@ static bool found_memconsole(void) } } - printk(KERN_INFO "BIOS console EBDA structure not found!\n"); + pr_info("BIOS console EBDA structure not found!\n"); return false; } @@ -139,8 +149,6 @@ MODULE_DEVICE_TABLE(dmi, memconsole_dmi_table); static int __init memconsole_init(void) { - int ret; - if (!dmi_check_system(memconsole_dmi_table)) return -ENODEV; @@ -148,10 +156,7 @@ static int __init memconsole_init(void) return -ENODEV; memconsole_bin_attr.size = memconsole_length; - - ret = sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr); - - return ret; + return sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr); } static void __exit memconsole_exit(void) -- 1.8.5.3 -- 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/