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Code Issues Releases Wiki Activity

virt_to_phys: fix %p vs %px

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Move doc to README
This commit is contained in:
Ciro Santilli
2018-07-05 03:42:26 +01:00
parent 65fc5b8527
commit 046bc25b6b
3 changed files with 71 additions and 35 deletions
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1
kernel_module/README.adoc
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@@ -10,7 +10,6 @@ Our kernel modules!
.. link:work_from_work.c[]
.. link:workqueue_cheat.c[]
. Misc
.. link:virt_to_phys.c[]
.. link:netlink.c[]
. Hardening
.. link:strlen_overflow.c[]

53
kernel_module/virt_to_phys.c
View File

@@ -1,16 +1,4 @@
/*
Also try on QEMU monitor:
xp 0x<vaddr>
Only works for kmalloc.
static inline phys_addr_t virt_to_phys(volatile void *address)
- https://stackoverflow.com/questions/5748492/is-there-any-api-for-determining-the-physical-address-from-virtual-address-in-li
- https://stackoverflow.com/questions/43325205/can-we-use-virt-to-phys-for-user-space-memory-in-kernel-module
- https://stackoverflow.com/questions/39134990/mmap-of-dev-mem-fails-with-invalid-argument-but-address-is-page-aligned
*/
/* https://github.com/cirosantilli/linux-kernel-module-cheat#virt_to_phys */
#include <asm/io.h> /* virt_to_phys */
#include <linux/debugfs.h>
@@ -21,26 +9,26 @@ static inline phys_addr_t virt_to_phys(volatile void *address)
#include <linux/seq_file.h> /* single_open, single_release */
#include <linux/slab.h> /* kmalloc, kfree */
static volatile u32 *k;
static volatile u32 i;
static volatile u32 *kmalloc_ptr;
static volatile u32 static_var;
static struct dentry *debugfs_file;
static int show(struct seq_file *m, void *v)
{
seq_printf(m,
"k 0x%llx\n"
"addr_k %p\n"
"virt_to_phys_k 0x%llx\n"
"i 0x%llx\n"
"addr_i %p\n"
"virt_to_phys_i 0x%llx\n",
(unsigned long long)*k,
k,
(unsigned long long)virt_to_phys((void *)k),
(unsigned long long)i,
&i,
(unsigned long long)virt_to_phys((void *)&i)
"*kmalloc_ptr = 0x%llx\n"
"kmalloc_ptr = %px\n"
"virt_to_phys(kmalloc_ptr) = 0x%llx\n"
"static_var = 0x%llx\n"
"&static_var = %px\n"
"virt_to_phys(&static_var) = 0x%llx\n",
(unsigned long long)*kmalloc_ptr,
kmalloc_ptr,
(unsigned long long)virt_to_phys((void *)kmalloc_ptr),
(unsigned long long)static_var,
&static_var,
(unsigned long long)virt_to_phys((void *)&static_var)
);
return 0;
}
@@ -60,18 +48,17 @@ static const struct file_operations fops = {
static int myinit(void)
{
k = kmalloc(sizeof(k), GFP_KERNEL);
*k = 0x12345678;
i = 0x12345678;
debugfs_file = debugfs_create_file(
"lkmc_virt_to_phys", S_IRUSR, NULL, NULL, &fops);
kmalloc_ptr = kmalloc(sizeof(kmalloc_ptr), GFP_KERNEL);
*kmalloc_ptr = 0x12345678;
static_var = 0x12345678;
debugfs_file = debugfs_create_file("lkmc_virt_to_phys", S_IRUSR, NULL, NULL, &fops);
return 0;
}
static void myexit(void)
{
debugfs_remove(debugfs_file);
kfree((void *)k);
kfree((void *)kmalloc_ptr);
}
module_init(myinit)