diff options
author | Michel Lespinasse <walken@google.com> | 2014-01-28 13:06:22 (GMT) |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-15 19:30:28 (GMT) |
commit | cb88759107292b4bf36d13c73129add580d4e26e (patch) | |
tree | 5dfc70e1d1692a705fc35acb48af63c06c6a9867 | |
parent | b12b73f1ca7763a94e0949a0d86eea40b5f69ea6 (diff) | |
download | linux-cb88759107292b4bf36d13c73129add580d4e26e.tar.xz |
firmware: google memconsole driver fixes
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 <walken@google.com>
Acked-by: Mike Waychison <mikew@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/firmware/google/memconsole.c | 47 |
1 files changed, 26 insertions, 21 deletions
diff --git a/drivers/firmware/google/memconsole.c b/drivers/firmware/google/memconsole.c index 2a90ba6..2f569aa 100644 --- a/drivers/firmware/google/memconsole.c +++ b/drivers/firmware/google/memconsole.c @@ -15,6 +15,7 @@ #include <linux/kobject.h> #include <linux/module.h> #include <linux/dmi.h> +#include <linux/io.h> #include <asm/bios_ebda.h> #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) |