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firmware: google memconsole driver fixes

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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>
This commit is contained in:
Michel Lespinasse 2014-01-28 05:06:22 -08:00 committed by Greg Kroah-Hartman
parent b12b73f1ca
commit cb88759107
1 changed files with 26 additions and 21 deletions
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47
drivers/firmware/google/memconsole.c
View file

@ -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)